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Adoption, use and perception of Australian acacias around the world
Diversity and Distributions
Abstract
Aim To examine the different uses and perceptions of introduced Australian acacias (wattles; Acacia subgenus Phyllodineae) by rural households and communities.
Location Eighteen landscape-scale case studies around the world, in Vietnam, India, Réunion, Madagascar, South Africa, Congo, Niger, Ethiopia, Israel, France, Portugal, Brazil, Chile, Dominican Republic and Hawai‘i.
Methods Qualitative comparison of case studies, based on questionnaire sent to network of acacia researchers. Information based on individual knowledge of local experts, published and unpublished sources.
Results We propose a conceptual model to explain current uses and perceptions of introduced acacias. It highlights historically and geographically contingent processes, including economic development, environmental discourses, political context, and local or regional needs. Four main groupings of case studies were united by similar patterns: (1) poor communities benefiting from targeted agroforestry projects; (2) places where residents, generally poor, take advantage of a valuable resource already present in their landscape via plantation and/or invasion; (3) regions of small and mid-scale tree farmers participating in the forestry industry; and (4) a number of high-income communities dealing with the legacies of former or niche use of introduced acacia in a context of increased concern over biodiversity and ecosystem services.
Main conclusions Economic conditions play a key role shaping acacia use. Poorer communities rely strongly on acacias (often in, or escaped from, formal plantations) for household needs and, sometimes, for income. Middle-income regions more typically host private farm investments in acacia woodlots for commercialization. Efforts at control of invasive acacias must take care to not adversely impact poor dependent communities.
... Here, we suggest the term cultural inception for the gradual process in which IAS become embedded in cultures and societies through collective memory, attention, knowledge, representations, uses, and cultural products. Cultural inception provides an umbrella term to include previously used notions, such as assimilation, incorporation, integration, adoption, and percolation of IAS (Pfeiffer & Voeks, 2008;Kull et al., 2011;Nuñez et al., 2018;Pissolito et al., 2020;Bortolus & Schwindt, 2022;Sax et al., 2022). The process of cultural inception can generate serious challenges in the sustainable management of IAS. ...
... The process of cultural inception can generate serious challenges in the sustainable management of IAS. It may affect peoples' interactions with nature, their values, identities, and sense of place, motivate instrumental and relational conflicts, and modify or displace the cultural presence and identity of native species (Nuñez & Simberloff, 2005;Weeks & Packard, 2009;Kull et al., 2011;Shackleton, Richardson et al., 2019). ...
... Research on social dimensions of inception lags behind the ecological work on biological invasions, partly because the sociocultural impacts of IAS are inherently complex, context-dependent at multiple levels, elusive and hardly quantifiable (Pfeiffer & Voeks, 2008;Pejchar & Mooney, 2009;Srithi et al., 2017;Souza et al., 2018). Sociological research on IAS has primarily focused on individual knowledge and perceptions of such species, their impacts on people's livelihoods, stakeholder engagement, and management dimensions (Kull et al., 2011;Nuñez et al., 2018;Shackleton, Richardson et al., 2019;. Better defining and unpacking the process of cultural inception can deliver a coherent and inclusive research framework for IAS, and help identify and address the culturally appropriate and relevant aspects of sustainable IAS management. ...
1. Many invasive alien species gradually become embedded within local cultures. Such species can increasingly be perceived by society as familiar and native elements of the social-ecological system and as integral parts of local cultures. 2. Here, we explore this phenomenon and define it as cultural inception. Cultural inception can greatly hinder our ability to successfully manage invasive alien species, by reducing public support to their management and contributing to secondary introductions. 3. Furthermore, cultural inception can affect societal values and cultural identities, and lead to erosion and homogenization of cultural diversity. Cultural inception can also modify or displace the cultural uses and values of native species, and even lead to their societal extinction. 4. We present the main mechanisms of cultural inception, its drivers and major implications, and provide key recommendations for the management and conservation of biological and cultural diversity.
... planting and uses of wattles in these regions, as well as naturalization and inva ion. Information on the introduction history of wattles in Africa in a global context is provided by Griffm et al. (Chapter 15,thjs volume), insights on changing perceptions of wattles globally are reviewed by Kull et al. (2011); see also Kull and Shackleton (Chapter 16,this volume), and details of management efforts in South Africa (the only country in the continent where extensive management of invasive wattles has been conducted) are provided by van Wilgen et al. (Chapter 26. this volume). Botella et al. (Chapter 9, this volume) discuss the changing trends in the global distribution of wattles, including insights on Africa. ...
... However, native forests cover only about 0.1 % of the country and there are very few native trees suitable for forestry (Cowling et al., 1997). Mainly, but not only, for this reason, South Africa has received a much greater number of alien tree species introductions than any other African country (Richardson et al., 2020) - Kull et al. (2011) write of South Africa as 'one of the earliest and most zealous recipients of AustraUan acacias·. ...
... Witt (2005) highlights the crucial role that A. meamsii plantations made in what is now the KwaZulu-atal province to the 'economic transformation or transition to capitalism' and to the 'restructuring of social relations in agriculture' in rural parts of that region. Although the area under formal A. ,nearnsii plantations has declined substantially in the ensuing decades (Kull et al., 2011). the area of 'wattle jungles' (abandoned plantations and invaded sites) has increased substantially (van Wilgen et al., 2011). ...
This chapter reviews the history of introductions, plantings, usage, naturalization and invasion of Australian Acacia species (‘wattles’) for African countries and several islands that are considered part of Africa in biogeographical or geological contexts. Although many more species have been introduced, our review focussed on 48 species that feature explicitly in discussions about wattles in 45 countries and islands/archipelagos. The history of introductions, plantings, naturalization and invasion is well documented for South Africa, where 40 Acacia species are known to be present, three species are commercially important, several species are important to rural and urban populations for fuelwood and other uses, and 16 species are currently regulated as invasive alien species in national legislation. Less detailed information is available for the rest of the continent. Introductions to South Africa were made mainly for dune stabilization, to create a forestry industry, and for ornamental horticulture, and were largely government-orchestrated. In most other parts of Africa, wattle introductions were mostly for other purposes - to address desertification and soil conservation, for reforestation of degraded ecosystems, for use in diverse forms of agroforestry, to supply fuelwood, for tannin production, and for human food. The interplay of drivers of wattle introductions has changed radically, and sometimes very quickly, over time across the continent. Whereas the implications of wattle introductions for native biodiversity and ecosystems received no attention a century ago, these concerns are now much more important in most areas. Trajectories for wattles in Africa will be affected by changing markets, global change, invasion debt, the effectiveness of management of invasive wattles, the emergence of problems with insect pests and diseases, and by changing requirements for timber, charcoal, fuelwood and food products.
... Industrial use of wattles has occurred in Europe, or is still occurring in some countries, namely in France, Italy and the UK. In these countries, several species are planted for non-forestry uses, such as the perfume, oil and cut-flower industries, and used in the ornamental plant trade (Griffin et al., 2011;Kull et al., 2011;Chapter 15, this volume), including as home-garden plants. European countries (especially France, but also Belgium, Germany, the Netherlands, Portugal and the UK) also import seeds of wattles from Australia and use wattle products sourced in other parts of the world, e.g. A. mearnsii wood pellets from Brazil and A. mangium furniture from South-East Asia (see Chapter 15, this volume and references therein). ...
... Between the late 1800s and mid-1900s, state foresters and private entrepreneurs propagated mainly A. dealbata, A. mearnsii, A. melanoxylon, A. pycnantha and A. saligna, to supply timber to the modernizing economy and for afforestation of communal lands. Along the central-north coast, from 1897 to the early 1940s, the forestry services introduced several Acacia species (mainly A. longifolia) during campaigns to stabilize sand dunes, prevent erosion, and provide wind protection for pine plantations (Kull et al., 2011). ...
... Acacia longifolia is the dominant species along the Atlantic coast, with A. saligna being dominant in southern coastal habitats. These species have been planted since the late 1800s and during the first few decades of the 1900s (Kull et al., 2011) and their expansion has been facilitated by frequent fires . In Spain, A. saligna invades mainly along the Mediterranean coast, whereas A. dealbata, A. longifolia and A. melanoxylon invade the coasts of Cantábria and Galicia in the north (Sanz-Elorza et al., 2004). ...
At least 316 Australian Acacia species (‘wattles’) are known to have been introduced into Europe since the late
1700s. Most of these species are found only occasionally in gardens, others may have not survived in the envir-
onment, some are used for gardening, perfume or the cut-fower industries, 13 species are considered naturalized
and ten are invasive. The uses and propensity for invasiveness of wattles are not uniform across Europe. In gen-
eral, in central and northern Europe some species are mostly used as ornamentals. For example, A. baileyana and
A. dealbata are frequently used in the UK and Switzerland but seldom persist in the wild. In south-western
and Mediterranean Europe, especially in France, Italy, Portugal and Spain, several wattle species have naturalized
and became invasive, notably A. dealbata, A. longifolia, A. mearnsii, A. melanoxylon and A. saligna. For the European
Union, only A. saligna is included in the List of Invasive Alien Species of Union concern under the European Union
Regulation No. 1143/2014. However, in Portugal all Acacia species are classifed as invasive, and in Spain a few
species are also listed as invasive in national legislation. In France and Italy, although several species are invasive,
wattles are cultivated for the cut-fower and perfume industries. This chapter summarizes the introduction
history, current status and the present or future uses of wattles in Europe.
... Over a decade ago a previous study investigated the diverse ways in which wattles are valued, used, adopted and perceived around the world (Kull et al., 2011). It showed that differences across countries and regions were explained by biology and environment (which wattle species, what environment they were growing in, how invasive they were), by the social and economic context (people's subsistence needs, the presence of markets, the structure of land ownership, prevalent ideas concerning the environment, economic development levels) and by people's familiarity with the trees (related to why and how the trees were introduced, knowledge and skills transfer, length of time that wattles have been present, and their proximity and abundance). ...
... Together, these coupled social and ecological factors shape contemporary uses and perceptions of the species (Shackleton et al., 2019a,b;Yapi et al., 2023) and their extent, role and influence in regional ecologies (Kueffer, 2017). Kull et al. (2011) proposed that the key differences in terms of use, relative levels of reliance and perceptions of wattles result from a combination of three categories of factors: ...
... We bring together and integrate the conceptual proposals of the two previous articles (Kull et al., 2011(Kull et al., , 2017 to illustrate the contextual factors shaping wattle extent, use, impacts, perceptions and management over time and across space, and altered by regime shifts (Fig. 16.1). One could imagine, for instance, this figure representing the story of a place like South Africa. ...
... Consequently, their ability to spread from sites of introduction to surrounding areas and further afield often causes unprecedented and diverse impacts on social-ecological systems Castro-Díez et al. 2019;Kapitza et al. 2019). Depending on the spatiotemporal context, some invasive alien plants (IAPs) negatively affect existing ES and create ecosystem disservices (EDS) (Kull et al. 2011;Potgieter et al. 2019;Shackleton et al. 2019d. Ecosystem disservices are defined as 'the ecosystem generated functions, processes and attributes that result in perceived or actual negative impacts on human well-being' (Shackleton et al. 2016). ...
... They have invaded large areas of grassland ecosystems in South Africa, with the potential to continue to spread into new areas (Gouws and Shackleton 2019b). Yet, although some of these species are desirable and provide a vital livelihood resource in local communities (Kull et al. 2011), negative perceptions surrounding wattles persist as they inevitably increase in abundance and extent of invasion (de Neergaard et al. 2005;Shackleton et al. 2007;van Wilgen et al. 2011;Witt et al. 2018;Ngorima and Shackleton 2019). In South Africa there is substantial evidence of the negative impacts of Australian wattles on biodiversity, ecosystem services, and livelihoods (Le Gwate et al. 2016Gwate et al. , 2021Oelofse et al. 2016;Yapi et al. 2018). ...
... These include reduced livestock grazing capacity, stream flows, biodiversity, and residents' sense of place and culture. From a social perspective, issues relating to the safety and security of vulnerable groups (mainly women and children) have led to negative perceptions surrounding wattle stands around villages (De Neergaard et al. 2005;Kull et al. 2011;Ngorima and Shackleton 2019). As with many other IAPs that provide benefits and EDS, conflicting perceptions underlying the management of these species hamper the effectiveness of control actions. ...
Many alien tree species were introduced into grassland ecosystems in South Africa by the commercial forestry industry for paper and timber for furniture. Over decades some of these introduced species escaped into neighbouring farms and community land. Adult trees from these alien species now provide other ecosystem services, notably fuelwood. Depending on the spatio-temporal context, many of these species can also negatively affect ecosystem services. We collected interview data from commercial and communal farmers in the upper Umzimvubu catchment in South Africa to compare farmers’ knowledge and perceptions of invasive wattle species invasion and their associated ecosystem services and disservices. Fuelwood and fencing poles were the most common uses of wattle by commercial (83%; 67%) and communal (99%; 49%) farmers. On the other hand, the reduction of grass cover and loss of grazing land were the most commonly mentioned negative impacts of wattles by commercial (83%; 75%) and communal (92%; 80%) farmers. Although both groups recognise the importance of wattles in providing ecosystem services, most communal farmers perceived wattles to have more negative effects than benefits. The findings demonstrate that both farmer groups highly depend on ecosystem services and are affected by disservices of wattles. However, while large-scale commercial households favour the presence of wattles in the landscape, communal households prefer complete removal of the wattles from the landscape. This may be due to lack of locally available alternative options or inability to replace or purchase ecosystem services affected by wattles from other sources or markets like commercial farmers.
... Moreover, some Acacia trees exacerbate respiratory diseases in humans due to their allergenic pollens (Criollo et al 2016). Kull et al. (2011) conducted a comprehensive study on the utilization and perceptions of invasive Acacia species, interviewing one or two local scientists per country in 18 locations over five continents, including central Chile. The authors concluded that the importance and value of Acacia for local communities have yet to be adequately assessed in almost all countries. ...
... In a review, Kapitza et al. (2019) suggest that perception studies of invasive species in general are still in their early stages. Following Kull et al. (2011), only two studies globally have addressed the perceptions of Acacia species (Oliveira Souza et al. 2018;Vaz et al. 2020). Vaz et al. (2020) focused on the recognition and perceptions of invasive Acacia in northern Portugal, where the genus is extensively spread. ...
Invasive species pose a significant threat to biodiversity, particularly when local communities view them positively, presenting a key challenge for effective control. Acacia trees, native to Australia, have been introduced in various regions worldwide, including Chile. Our study focuses on the geographical distribution, perceptions, memories, and willingness to control Acacia species, especially dealbata and A. melanoxylon, in a basin in Central Chile. Landsat 8 OLI/TIRS images captured during the tree’s flowering season were employed to analyse the species’ distribution. We conducted an open survey with 81 participants to gauge the community’s perceptions and memories of these tree species. A binomial model was constructed, incorporating social and geographic variables, and analyses were conducted to assess the significance of memories. We found in the basin 613.200 hectares of Acacia, constituting 1.7% of the analysed basin. 59 sentences of expressing memories were analyzed; most of them were positive towards Acacia. 45.68% of interviewed believed that Acacia is a native tree, and 35.8% recognized it as a harmful species. Despite 72.84% considering Acacia a useful tree, 60.49% expressed a willingness to limit its expansion. Counterintuitively, the willingness to control the species was positively correlated with its use. The use of Acacia also proved positive interaction with the perception that it is expanding and is harmful. Younger and moderately educated participants exhibited more interest in controlling Acacia trees, and older participants when these variables interacted with their use. We interpret these results as an indication that individuals with greater knowledge of Acacia possess increased awareness of the importance of limiting its expansion. Furthermore, perceptions appear to transition from positive in childhood and youth to negative in adult life. We conclude that the current juncture is opportune for initiating Acacia control measures.
... * Cristina Máguas cmhanson@ciencias.ulisboa.pt regions of the world for coastal dune stabilisation and as an ornamental plant, subsequently becoming invasive, especially in Mediterranean climate regions (Kull et al. 2011;Richardson et al. 2011;Souza-Alonso et al. 2017). This species has also been introduced to parts of Australia outside of its native range, such as the state of Western Australia, where it has also become invasive Harris et al. 2012). ...
... In this study, we assessed seedling growth responses and survival to water and nutrient availability of one of the most problematic plant invaders in Mediterranean areas of the world, Acacia longifolia (Kull et al. 2011;Richardson et al. 2011), by comparing the performance of seedlings from native and invasive ranges. The inclusion of seedlings from the two described A. longifolia subspecies also enabled us to determine whether stress responses differ between them. ...
Acacia longifolia (Andrews) Willd. is a legume native to southeast mainland Australia and Tasmania and has two described subspecies: A. l. subsp. longifolia and A. l. subsp. sophorae. The species has been introduced around the world and is considered invasive in several Mediterranean-type climate regions, including in South America, South Africa, and southern Europe. Previous studies comparing native and invasive populations of A. longifolia have focused on its reproductive ecology and population genetics, and little information exists on the species’ early life development and how abiotic factors influence it. Here, we performed a glasshouse experiment to compare the phenotypic responses of native and invasive (in Portugal) A. longifolia seedlings to different levels of water and nutrient availability. We found that seedlings of both subspecies responded similarly to different water and nutrient availability conditions in terms of biomass accumulation, root length, the number of phyllodes produced, phyllode water content, and root-to-shoot ratio. However, compared to native seedlings, invasive seedlings had limited capacity for stress responses. We found that invasive seedlings had lower drought tolerance than native seedlings, and thus the speed of invasion by A. longifolia into drier parts of Portugal may be hindered. Our results also hint of a possible role of seed “imprinting” in this species’ early growth responses, resulting in different resource allocation strategies such as favouring early growth and development over drought resistance in the invaded range. Further studies are required to better understand the species’ abiotic stress responses at the intraspecific level and their relation to its invasiveness.
... The benefits from A. dealbata reported by most respondents include firewood, construction materials and shade. Several studies have reported that some IAPs provide important services to rural communities (Kull et al. 2011;Ngorima and Shackleton 2019;Ruwanza and Thondhlana 2022). Ngorima and Shackleton (2019) also found that A. dealbata is also used for livestock forage and traditional medicine, although these benefits were reported by a few villagers. ...
... Ngorima and Shackleton (2019) also found that A. dealbata is also used for livestock forage and traditional medicine, although these benefits were reported by a few villagers. Kull et al. (2011) reported that Australian Acacias are used for various purposes around the globe, such as construction in South Africa, fuel for distillery in France, fuelwood in India, agroforestry in Niger, and furniture making in Vietnam. Estimates in South Africa suggest that the monetary value associated with A. dealbata is approximately US $224 per household per year in the form of rural household savings (Ngorima and Shackleton 2019). ...
... Australian Acacia species (wattles) have been introduced to many countries around the world over the past 250 years for many reasons, primarily for commercial production of wood, fibre and tannins, for land restoration or as ornamentals (Ratnayake and Joyce, 2010;Carruthers et al., 2011;Griffin et al., 2011;Kull et al., 2011;Richardson and Rejmánek, 2011;Chapters 9-15, this volume). Based on these diverse uses, several wattle introductions have proven to be beneficial, but there are also examples from many countries where these benefits are now being increasingly offset, or outweighed, by the negative ecological and ecosystem service impacts of invasions by these species into natural ecosystems (Le Maitre et al., 2011a;Richardson and Rejmánek, 2011;van Wilgen et al., 2011;Vaz et al., 2017;Wilson et al., 2017;Chapters 1 and 23, this volume). ...
... wildfires, as disservices because they adversely affect human welfare or well-being. We also touch on perceived impacts on ecosystem services and ecosystem disservices, which are covered in greater detail elsewhere Kull et al., 2011;Chapter 16, this volume). Actual impacts are easy to distinguish from perceptions when they alter production or material services, such as when they cause reductions in livestock-carrying capacity or water availability, or when they affect regulatory services, such as water purification, which affect human welfare. ...
... During recent decades exotic-species-based plantation forestry has seen increasingly widespread adoption around the world, with significant socioeconomic impacts (positive and/or negative) on rural people's livelihoods and environmental qualities. Such impacts were often particularly profound in fast developing tropical countries where tree plantations may have replaced highly biodiverse types of vegetation, and associated traditional land use systems (Malkamäki et al., 2018;D'Amato et al., 2017;Pirard et al., 2017;Kull et al., 2011;Nigussie et al., 2021; cf. Cochard 2017, Nguyen andKull 2022). ...
... In some cases exotic tree plantations have been reported to actually increase drought conditions (especially eucalypts: D' Amato et al., 2017, Vilhervaara et al. 2012, van Dijk and Keenan 2007, Albaugh et al., 2013; for acacias cf. Kull et al., 2011, Cochard et al., 2014, yet in the wet tropics transpiration measurements in Acacia mangium plantations have been shown to be similar to surrounding rainforest vegetation (Cienciala et al., 2000). Accordingly, the observed slight increase in ratings along the upland-lowland gradient may partly mirror the generally more or less densely forested surrounding landscape which serves as a perceptual background reference for effects of differently-stocked acacia plantations (cf. ...
The rise of exotic-species-based plantation forestry in biodiverse tropical countries transforms livelihoods and environmental qualities in various ways. Through 180 structured interviews of different types of acacia plantation owners (producers of woodchips/sawlogs, with/without membership in a recent Forest Stewardship Council [FSC] program) we investigated such transformations in three districts along a lowland-upland gradient in Thừa Thiˆen Huế Province, Central Vietnam. We focused on how trajectories of livelihood and income changes related to the farmers’ perceptions on environmental changes, and how this, in turn, was linked to the farmers’ assessments of opportunities, risks, and concrete plans in tree cultivations. Sawlog producers (especially with FSC-certification) in the lowlands had been among the first to plant acacias in the 1990s, and in 2018 usually owned large plantations. In contrast, most farmers producing just woodchips were smallholders. Before acacias the farmers’ livelihoods were often more diversified in terms of agricultural products. Since then, many farmers (especially in the lowlands) abandoned rice/cassava production and/or livestock keeping to concentrate on wood production, willingly and/or as an outcome of land conversion (enclosure) to privatised plantations. Farmers’ incomes and material assets usually increased (especially FSC farmers), but most smallholders still depended on incomes from subsidiary wage labor. Within a context of ‘development’ improvements were also seen in infrastructure (buildings, roads, water provisioning) and public services (education, health). Considering acacia planting most farmers (especially FSC-farmers in the lowlands) saw environmental improvements in terms of soil
fertility and landscape amenity, but not wildlife habitat. Most farmers also saw plantation value (especially on longer rotations) in terms of natural hazards mitigation (i.e. floods, droughts, soil erosion), but storms were also noted as the main risk to plantations (especially in the uplands). Another emerging risk was posed by plant diseases affecting acacias in the mid-/lowlands. Projective future plans to change plantation areas and/or crop rotations depended on the farmers’ economic strengths in terms of plantation land or other capital. Regarding future risks most farmers noted environmental impacts (storms, plant diseases) rather than economic factors (with wood market prices considered stable). Overall, the results suggest an appreciable value of acacia plantations to farmers, however with some marked distinctions between richer (FSC-certified) and poorer (smallholder) farmers as well as farmers in different regions with distinct terrain and land use management histories. We discuss such distinctions whilst also noting relevant study limitations connected to the complex socio-politics of land titling and uses, especially in the uplands.
... Acacia longifolia (Andrews) Willd., also known as the Sydney Golden Wattle, is one of the most widespread invasive acacias. This species is native to southeast mainland Australia and Tasmania and has been introduced to many regions of the world for coastal dune stabilisation and as an ornamental plant, subsequently becoming invasive, especially in Mediterranean climate regions (Kull et al. 2011; Richardson et al. 2011; Souza-Alonso et al. 2017). Two subspecies have been described for A. longifolia based on morphological characters such as phyllode shape, seed pod size and shape, as well as their slightly different, but overlapping, distributions: ssp. ...
... In this study, we assessed seedling survival and early development and growth to water and nutrient availability of one of the most problematic plant invaders in Mediterranean areas of the world, Acacia longifolia (Kull et al. 2011;Richardson et al. 2011), by comparing the performance of seedlings from native and invasive ranges. The inclusion of seedlings from the two described A. longifolia subspecies also enabled us to determine whether stress responses differ between them. ...
The legume Acacia longifolia (Andrews) Willd. is native to southeast mainland Australia and Tasmania and has two described subspecies: A. l. ssp. longifolia and A. l. ssp. sophorae . The species has been introduced around the world and is considered invasive in several Mediterranean-type climate regions, including in South America, South Africa, and southern Europe. Previous studies comparing native and invasive populations of A. longifolia have focused on its reproductive ecology and population genetics, and little information exists on the species’ early life development and how abiotic factors influence it. Here, we performed a glasshouse experiment to compare the phenotypic responses of native and invasive (in Portugal) A. longifolia seedlings to different levels of water and nutrient availability. We found that seedlings of both subspecies responded similarly to different water and nutrient availability conditions in terms of biomass accumulation, root length, number of phyllodes, phyllode water content, and root:shoot ratio. However, compared to native seedlings, invasive seedlings had limited capacities for stress responses. We found that invasive seedlings had lower drought tolerance than native seedlings, and thus the speed of invasion by A. longifolia into drier parts of Portugal may be hindered. Our results also hint of a possible role of seed “imprinting” in this species’ early growth responses, resulting in different resource allocation strategies such as favouring early growth and development over drought resistance in the invaded range. Further studies are required to better understand the species’ abiotic stress responses at the intraspecific level and their relation to its invasiveness.
... In some cases, alternative ecosystem services promoted by continued woody invasion may become the dominant option unless there is a large investment in habitat restoration (Kull et al., 2011). For example, if climate change accelerates woody encroachment to the point where it favors white-tailed deer (Odocoileus virginianus) over bobwhite habitat, deer hunters will have more opportunities while bobwhite hunters may need to travel to other regions. ...
... Many citizens either do not realize that grasslands are threatened, or they depend on ecosystem services that invasive woody plants might provide. For example, Kull et al. (2011) noted that economic conditions often dictate perceptions about the value of Acacia shrubs globally as poorer communities rely more strongly on these shrubs. However, many government programs, likely driven by economically richer sections of society, are designed to reduce Acacia species that are viewed as harmfully invasive (van Wilgen et al., 2011). ...
Climate change, interacting with and exacerbating anthropogenic modifications to the landscape, is altering ecosystem structure and function, biodiversity, and species distributions. Among the most visible short-term impacts are the altered ecological roles of foundation species—those species, native or non-native—that create locally stable environmental conditions and strongly influence ecosystem services. Understanding the future of these species is crucial for projecting impacts on ecosystem services at both local and regional scales. Here we present foundation species by ecoregion study cases across the US South-Central Region (Louisiana, New Mexico, Oklahoma, and Texas), including C4 grasses, mesquite, and northern bobwhite in the Southern Great Plains, mangroves and nutria in coastal Louisiana wetlands, tiger salamanders and sandhill cranes in wetlands of the Southern Great Plains, and post and blackjack oaks and eastern redcedar in the Cross Timbers ecoregion. These case studies explore the impacts of climate change on foundation species and the consequences for ecosystem services, the outlook for climate adaptation efforts, and the sustainability of restoration in these systems. We underscore risks and vulnerabilities that stakeholders should consider when managing or restoring natural resources and conserving ecosystem services in an increasingly extreme and variable climate. We show that past management, through a lack of understanding or implementation of actions, has exacerbated shifts in invasive species, resulting in significant changes in ecosystem structure and function. These changes, interacting with landscape fragmentation and shifting land use and exacerbated by climate change, can result in critical losses of biodiversity. Unfortunately, lack of public understanding may hinder political support for restoration efforts and climate adaptation strategies crucial for the continued supply of traditional ecosystem services. Furthermore, the resulting invaded systems may provide opportunities for income via new ecosystem services valued by society that may reduce support for restoration to historical baselines, thus further shifting management priorities. These priorities should be informed by an understanding of past and ongoing ecological trends in region-specific situations, such as those we present, to highlight the immediacy of climate change impacts on the environment and society and provide evidence for the critical nature of informed management decisions.
... Depending on people's preferences and the spatiotemporal context, plant invaders can be both beneficial and a nuisance for human well-being (Tassin and Kull, 2015;Simberloff et al., 2013;Kueffer and Kull, 2017). In certain situations, invasive plants improve regulating functions like soil protection and coastal sediment dynamics, or they support people's daily necessities and economic incomes (Kull et al., 2011). However, in other situations, plant invasions may have negative effects on human health. ...
... Acacia melanoxylon, belonging to the Leguminosae family and Acacia genus, is an evergreen tree species native to southeastern Australia [1]. It is regarded as an ideal tree species that combines economic, ecological, and greening benefits, leading to its widespread introduction and cultivation across the globe [2][3][4]. A. melanoxylon possesses high-quality timber with reddish brown-colored heartwood, which produces high-end furniture, musical instruments, joinery, flooring, and crafts [2,5]. It belongs to the short and medium management cycle tree species with a primary cutting cycle of 13 to 16 years in South China. ...
The research of functional genes in Acacia melanoxylon, a precious and fast-growing timber species with wide adaptability, has been greatly limited due to the absence of reliable and suitable reference genes. To fill this gap, five different algorithms (comparative ΔCt, NormFinder, geNorm, BestKeeper, and RankAggreg) were employed to assess the expression stability of ten candidate genes under nine different experimental sets and their three combined groups. The results showed that PP2a and RPL4 maintained stable expression in all 144 samples and a group of different tissues or organs. PAT10 and TIP41 were the best-performing genes in different clonal varieties, pinnate compound leaves at different growth states, salt, and indole acetic acid sets. PP2a and PAT10 were the top two choices for gibberellin and abiotic stress groups. PP2a and UBI11 exhibited stable expression in drought treatment. UBI3 combined with OTUD6B, RPL4, or PP2a were identified as the optimal reference genes in the heat, ethephon, or exogenous hormone groups, respectively. The reliability of the selected reference genes was further confirmed by evaluating the expression patterns of AmWRKY6 and AmWRKY33 genes. This study provides the first comprehensive evaluation of reference gene stability in A. melanoxylon and promotes future research on the gene expression analysis of the species.
... Earleaf acacia (Acacia auriculiformis) is a significant fast-growing tree in the Fabaceae family when planted according to its provenance (Harwood et al., 2015). It is an evergreen perennial plant that can be grown to create cover in degraded forest areas as part of forest management and is utilized to address global warming and energy issues (Kull et al., 2011). Acacia plants are globally important resources in the wood business, particularly in Southeast Asian countries, where they are utilized as a significant resource in global furniture production and in the pulping industries, and are essential to the wood industry (Huong et al., 2020;Viet et al., 2021;Haque et al., 2021). ...
The global expansion of freight transport across business types has impacted supply chain logistics in terms of coordinating the storage and delivery of goods and services across the supply chain. Wooden pallets are in high demand due to their price and environmental impact; however, the wood raw materials needed for making pallets are in short supply. This research was aimed at analyzing the possibility of using local wood instead of imported wood in the production of standard industrial pallets. Industrial pallets were designed using local acacia wood to replace some or all of the imported Radiata pine. This local acacia wood was utilized to prepare and construct pallets of the standard dimensions that were in accordance with the designs. Pallets made from the same type of wood and mixed woods were heat treated to meet the criteria of the ISPM 15 protocol for export. Flat pallet testing was conducted in accordance with industrial standards for the evaluation of the finished products. All types of pallets, including pallets containing local wood components, showed no visible damage during drop tests and compression strength assessments. However, the variability in diagonal span rates was influenced by the wood used in the fabrication process. Pallets frabricated from both partial and full acacia wood exhibited increased bending rates of 2081 and 2650 MPa, respectively, due to the higher levels of cellulose and lignin found in acacia wood. Our research suggests that there is an opportunity to manufacture standard pallets using locally sustainable wood resources, with some modifications to current industrial processes required.
... In ecosystems, the IAPS helps in erosion control and enhanced dune stabilization [8]. For human well-being, it serves as a source of generating income [9,10], food, and medicine [11,12] to IAPS users. For instance, IAPS such as Acacia dealbata Link, Acacia mearnsii De Wild., and Opuntia ficus-indica (L.) Mill. ...
This systematic review focused on the benefits of invasive alien plant species (IAPS) for human well-being. It examines the intellectual structure of knowledge of these benefits to identify knowledge gaps for future research and explore sustainable management practices to manage IAPS. The screening of bibliometric data from 1601 publications in Scopus based on the PRISMA protocol resulted in the identification of 69 publications for detailed review. The findings show an increasing trend in studies on IAPS benefits for human well-being since 2009. These benefits include provisioning services (food, medicines, fodder, bioenergy, and construction materials), regulating services (bioagents and shades), cultural services (aesthetics and ornamentals) and supporting services (soil and land reclamation). Additionally, the findings reveal geographical disparity in the distribution of research produced by researchers from different regions, with most research produced in Europe and limited to Africa, the Americas, and Oceania. The findings also show skewness in the management practices of IAPS, though some of them enhance IAPS benefits. Furthermore, there are limited applications of interdisciplinary approaches to investigate the benefits of IAPS for human well-being. Employing interdisciplinary mixed methodologies may help to generate new knowledge with a better understanding of complex interactions between IAPS and human well-being. Given the unique sociocultural, economic, and ecological settings of the IAPS, future research is expected to include comparative perspectives on how different countries and regions use the IAPS for their benefit while considering both the positive and negative impacts of the IAPS on human well-being to develop sustainable management practices.
... Once established in a new habitat, invasive species can cause harm to the environment, economy, or human health (US DOI 2021). Although not all invasive plants can cause harm (Kull et al. 2011), previous studies have reported that invasive plants can contribute to the decline of native species (Young et al. 2007) and modify abiotic and biotic ecosystem characteristics (Ehrenfeld 2010;Vermeij 2005). Although previous work has discussed the potential impacts of biological invasions on ecosystems (Barney et al. 2013;D'Antonio and Vitousek 1992;Hulme et al. 2013;Pyšek et al. 2012;Vila et al. 2011), quantifying such impacts is rather challenging, primarily due to inconsistencies in sampling methods and the context-dependency of the impacts of biological invasions on various ecosystems (González-Moreno et al. 2014;O'Loughlin, Panetta, and Gooden 2021;Pyšek et al. 2012). ...
Invasive plants are threats to biodiversity, ecosystem functioning, and services. Previous studies have reported that the impacts of biological invasions on ecosystem characteristics can be scale- and ecosystem-dependent. Current methods to assess the impacts of biological invasions have mainly focused on traditional field observations, limiting the scale at which biological invasions can be studied. With its synoptic view, remote sensing can contribute to improving our understanding of the impacts of biological invasions across large spatial scales. However, the application of remote sensing to determine the impacts of invasive plants on ecosystem characteristics, including aboveground and belowground, has not yet been explored. Therefore, our goals were to (1) determine the impacts of invasive plants on aboveground functional traits and productivity, (2) assess the underlying mechanisms through which species invasion impacts belowground characteristics, and (3) determine the capability of remotely-sensed data to capture the impacts of species invasion on aboveground and belowground characteristics. To address our goals, we focused on Lespedeza cuneata (L. cuneata), an invasive legume at the Joseph H. Williams Tallgrass Prairie Preserve in Oklahoma, U.S. We measured percent cover of L. cuneata, quantified aboveground biomass, collected top-of-canopy foliage samples and soil samples in the field, and collected airborne imaging spectroscopy. We used remotely-sensed spectral data and in situ-measured traits to estimate plant functional traits and aboveground biomass. We then assessed the impacts of L. cuneata invasion on aboveground functional traits and biomass using generalized additive models. We also identified the mechanisms through which L. cuneata impacted belowground characteristics using structural equation models. We developed generalized joint attribute models using in situ aboveground and belowground characteristics and predicted belowground characteristics throughout our study site by applying the developed model to remotely-sensed aboveground characteristics. Our findings showed that L. cuneata invasion shifted aboveground functional traits toward those of L. cuneata by significantly increasing community-weighted mean (CWM) foliar nitrogen and phosphorus concentrations. Moreover, L. cuneata significantly increased aboveground biomass, a proxy for aboveground productivity. We also showed that imaging spectroscopy captured the impacts of species invasion on aboveground functional traits and productivity. More importantly, we provided substantial evidence suggesting that imaging spectroscopy can be used to predict belowground characteristics through the aboveground-belowground linkages. These findings can significantly advance our understanding of the impacts of biological invasions on belowground characteristics across large scales which is often challenging to quantify using field methods.
... (Fabaceae: Mimosoideae), is an invasive plant species native to south-eastern Australia. This species was introduced to many Mediterranean regions around the globe, from South Africa to South America and the Iberian Peninsula (Vélez-Gavilán, 2022;Richardson et al., 2023) to curb sand erosion and/or for ornamental purposes (Kull et al., 2011). In Portugal, this is one of the most widespread and impactful invasive plants along the coast Marchante et al., 2008;Marchante et al., 2011;Marchante et al., 2015;Marchante et al., 2023;Richardson et al., 2023). ...
... This lower density might be due to selective exploitation for construction, firewood, charcoal and other domestic uses by local peoples. Tree cutting was mainly associated with expansion of settlements and agriculture, fuel wood for home consumption and sale, raw materials for house and households' utilities construction (Gebreegziabher, 2007;Kull et al., 2011). Similarly, the highest densities of some species like L. camara could be due to their unpalatable nature for both wild and domestic animals and wide range of dispersal mechanisms and rapider reproductions strategies (Belayneh and Demissew 2011; Senbeta and Teketay 2003). ...
The study was conducted at Dengago Mountain in Eastern Ethiopia to identify and analyze species' diversity, population structure, and regeneration status along altitudinal gradients. A systematic sampling procedure was employed with 6 transect lines and 45 quadrats established along the transect lines. Data were collected on the tree, shrubs, climbers, and herbaceous plants along altitudinal gradients. The vegetation data were statistically analyzed in one-way ANOVA using R software (version 4.0.5). A total of 49 species within 23 families and 34 genera were identified of which 42.8% were shrubs, 40.8% trees, 10.2% climbers, and 6.1% tree/shrubs. Tiliaceae was the dominant and Lower Altitude had significantly higher plant density than MA and UA. On the other hand, Middle altitude had a significantly higher Shannon's diversity index value and the Jaccard's similarities index showed the highest species similarity between MA and UA. The diameter and height class distribution of the population exhibited an inverted J-shape and the regeneration status of the forest was in fair condition. The study identified the presence of anthropologic disturbances and suggest the conservation the of Dengego mountain.
... Generally, Acacia species are considered an important source of income for families in rural areas in various tropical regions. They are a source of production of construction wood, gum, tannin, firewood and fodder for livestock [63]. ...
Background
The traditional knowledge in southern Yemen is rich in wild medicinal and food plants, which has been documented in our previous studies. In addition, other significant and general traditional usage for the daily livelihood requirements of local people (beyond medicinal and food plant uses) has not been studied before and needs urgent documentation.
Methods
Ethnobotanical data on of wild plants used by local people in southern Yemen were collected by oral questionnaire interviews. Most informants (n = 1020) were local elderly from 15 different localities in southern Yemen. The local names and non-medicinal and non-food uses of plants were identified and analyzed.
Results
The ethnobotanical data resulted various traditional uses of 73 plant species distributed in 28 families. The most represented families were Fabaceae, Asteraceae and Malvaceae. The most growth forms were trees and shrubs. Seven main and common categories of traditional uses were determined and classified as handicraft, health aids, livestock husbandry and beekeeping, economic and commercial plant products, agriculture tools, construction timber and fuel. The most cited species were identified for Ziziphus spina-christi, Vachellia tortilis, Vachellia nilotica, Anisotes trisulcus, Dracaena hanningtonii (Sansevieria ehrenbergii) and Aerva javanica, which have multi-purpose values of traditional usage. Nine major traditional uses of local wild plants were recorded: handicraft, agriculture tools, products aid general health, economic products, construction timber, livestock husbandry, bee keeping, fuel and ornamental.
Conclusions
Despite the challenges on local traditional knowledge of wild plants, it still requested vital to many usages of traditional life and still have an economic value and heritage required of develop the daily livelihood level of the local people especially in rural areas. This includes the traditional uses of wild plants in handicraft skills, tools of agriculture, constructions. The importance of the continuity of traditional industries and their transmission to generations lies in the local population’s reliance on local natural resources without relying on external resources in situations such as wars. This is the first study that contributes to documenting and analyzing the indigenous knowledge on traditional general usage of wild plants in southern Yemen.
... For example, several wattle (Acacia Mill. spp.), gum (Eucalyptus L'Hér spp.), pine (Pinus L. spp.), mesquite (Prosopis L. spp.) and locust (Robinia L. spp.) species, which are extensively used for timber production, agroforestry or silviculture in many areas of the world, are also highly invasive, causing negative social-ecological impacts (Kull et al., 2011;Moran et al., 2000;Shackleton et al., 2014). The Tasmanian blue gum (Eucalyptus globulus Labill.) for instance, which is widely used in forest plantations along the Atlantic coast of the via GG-NNTs), and a deeper understanding of the barriers and reluctance of stakeholders to manage NNT invasions. ...
A large number of non‐native trees (NNTs) have been introduced globally and widely planted, contributing significantly to the world's economy. Although some of these species present a limited risk of spreading beyond their planting sites, a growing number of NNTs are spreading and becoming invasive leading to diverse negative impacts on biodiversity, ecosystem functions and human well‐being. To help minimize the negative impacts and maximize the economic benefits of NNTs, Brundu et al. developed eight guidelines for the sustainable use of NNTs globally—the Global Guidelines for the Use of NNTs (GG‐NNTs).
Here, we used an online survey to assess perceptions of key stakeholders towards NNTs, and explore their knowledge of and compliance with the GG‐NNTs.
Our results show that stakeholders are generally aware that NNTs can provide benefits and cause negative impacts, often simultaneously and they consider that their organization complies with existing regulations and voluntary agreements concerning NNTs. However, they are not aware of or do not apply most of the eight recommendations included in the GG‐NNTs.
We conclude that effectively managing invasions linked to NNTs requires both more communication efforts using an array of channels for improving stakeholder awareness and implementation of simple measures to reduce NNT impacts (e.g. via GG‐NNTs), and a deeper understanding of the barriers and reluctance of stakeholders to manage NNT invasions.
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... Research is progressively revealing the adverse effects of invasive alien plants on ecosystem stability and human well-being (livelihoods, health and social relations) Pratt et al. 2017;Shackleton et al. 2017b;Mazza and Tricarico 2018;Witt et al. 2018;Bajwa et al. 2019;Shackleton et al. 2019;Linders et al. 2019;Rai and Singh 2020;Reynolds et al. 2020). Despite the impacts of invasive alien plants and them being labelled as "dangerous aid" (Low 2012), there are some that provide benefits to local communities (Kull et al. 2011;Kull and Tassin 2012;Hirsch et al. 2020) and, on the bases that they are utilized by people, and can be considered as 'multiple purpose species' (Rejmánek and Richardson 2013;Shackleton et al. 2015). Further, some invasive alien plant species can provide services and have functions that are not readily available from local species (Shackleton et al. 2017a). ...
Biological invasions can have major social-ecological consequences for rural communities across the world. However, the dimensions (characteristics, infestation and socio-ecological impacts) of emerging invasive alien plants are often less known and urgent information is needed to guide policy and management. In light of this, this paper assesses the social-ecological impacts of Vernonanthura polyanthes, an emerging invasive alien plant found in a Zimbabwean upland landscape which supports conservation and livelihoods. The paper employs qualitative methods—community mapping, time series analysis, and key informant interviews—involving individuals from diverse socio-economic backgrounds, to examine the socio-ecological and economic implications of V. polyanthes and its management in Chimanimani, Zimbabwe. We found that there are nuanced perspectives regarding this invasive alien plant among different socio-economic groups in the region who have different experiences of living with V. polyanthes. Some are embracing it for apiculture, firewood, and ethnomedicine while, on the other hand, some see the tree as negatively affecting key livelihoods (crop farming, pastoralism, and tourism) that are common in the region. Local people also identified that V. polyanthes is associated with ecological impacts that include loss of biodiversity, promoting pests, and negatively affecting watersheds and associated water sources. These mixed experiences concerning the plant are leading to different management practices, in turn inducing some conflicts among various actors. Based on our findings, we suggest more should be done to better manage this invasive alien plant in the region before negative impacts become too great, particularly in protected areas.
... The commercialisation of Acacia mearnsii is another example that resulted in the establishment of companies that harvested tannin barks from Indian forests to reduce reliance on the import of tannin barks from South Africa because of trade suspension. But once the trade suspension was revoked, the demand for the Indian tannin barks dwindled, and as a result, the invasion of A. mearnsii aggravated in Nilgiri Hills and Palni Hills of India (Kull et al., 2011;Tassin et al., 2012). The apprehension of the respondents concerning the commercialisation of Lantana is, therefore, not unfounded. ...
This multi-site case study on the invasive alien plant Lantana camara in protected areas of Nilgiri Biosphere Reserve, India, addresses the reasons for inadequate institutional responses from stakeholders in managing the species despite the seriousness. The study uses thematic analysis and qualitative systems approach. The themes are converted into a qualitative-system-dynamics model and are then abstracted into system archetypes. The study identified three major themes: the dilemma involving stakeholders, the dilemma of alternative and commercial use of lantana, and the lantana management conundrum. The study translated these dilemmas into four generalisable archetypes: "drifting goals", "modified-shifting-the-burden", "fixes-that-fail", and "substitution rebound". The latest is a novel contribution to the systems literature. Practically, the study helps understand the recurring undesired behavioural patterns in invasive species management and suggests policy and governance changes to tackle them. The study also points towards building stakeholder relationship protocols, focusing on fundamental solutions, and having clear lantana management targets. KEYWORDS: Lantana camara; causal loop diagrams; system archetypes; invasive species management; Nilgiri Biosphere Reserve
... at an increasing frequency and abundance (Shackleton et al. 2007;Kull et al. 2011;Castro-Díez et al. 2019). Well-known examples are those of common crop plants, such as wheat, rice, corn, or potato, which nowadays are grown worldwide. ...
Invasive plants affect the capacity of ecosystems to perform key functions, including primary production, nutrient and water cycling, decomposition, energy flow through food webs, or control of disturbance regimes, hydrology, and sedimentation. Invasive plants can also change the composition and structure of the resident community through different mechanisms, including direct competition, allelopathy, habitat alterations, and hybridization. Both changes in ecosystem functionality and community structure affect the capacity of ecosystems to deliver the three categories of services that contribute to human well-being: provisioning (e.g., food, water, wood, medicines, etc.), regulating and maintenance (e.g., climate regulation, erosion control, flood regulation, fire protection, regulation of soil fertility and water quality, etc.), and cultural (e.g., spiritual, intellectual, or symbolic assets). Invasive plants can also increase the negative effects of ecosystems on human well-being (i.e., ecosystem disservices, such as allergies and infrastructure damage). Impacts on ecosystem services may vary in magnitude and direction depending on the type of invader, the invasion scenario, and the spatio-temporal scale. Also, synergies and trade-offs between ecosystem services may arise when invasive species promote many services simultaneously or favor some services at the expense of impairing others. For example, some invasive plants can act as C sinks, increase timber provision, and contribute to the formation and protection of soil against erosion, while simultaneously increasing fire risk through increased fuel input, declining water provision through high water consumption, or reducing landscape aesthetics. Climate change may create opportunities for some invasive species and alter the severity of their impacts on ecosystem services, through alterations in species distributions, biological interactions, and ecosystem processes. Indeed, the synergistic effect of invasive species and climate change often cause the most detrimental outcomes for ecosystems.
In this chapter, we first compile information regarding the impacts of plant invasions on ecosystem functionality, focusing on key functions that regulate the fluxes of energy and cycles of matter. Then, we examine how those changes affect the delivery of provisioning, regulating, and cultural ecosystem services. Lastly, we analyze the role of climate change in altering the impacts of invasive plants on ecosystem functionality and ecosystem service delivery. We recommend that future studies investigate how climate change affects the impact of invasive plants on multiple ecosystem processes and services, rather than considering them in isolation. This would improve decision-making on invasive species management under climate change.
... Therefore, even though wattles have many uses (e.g. as ornamental plants and for wood and soil stabilization). and although in some regions the public appreciates their aesthetic value, in most cases people accept that invasive wattles have more negative than positive impacts (Kull et al., 2011;Chapter 16, this volume) and understand the need to manage them (Chapters 10, 26 and 2 7, this volume). ...
... Since the early 1800s, numerous Acacia species (sensu stricto) have been translocated from Australia around the world and they are known to occur in over 80 countries Richardson and Rejmánek, 2011;Chapter 9, this volume). While many are renowned for positive attributes such as provision of timber for furniture, tannin and pulp, as garden ornamentals and for production of oils for perfumes (Roland, 2006;Griffin et al., 2011;Kull et al., 2011;Chapter 15, this volume), many species are now recognized as invasive Richardson and Rejmánek, 2011). The introduction and spread of wattles across the globe are dealt with elsewhere in this book (Chapters 9-13, this volume). ...
... A contrasting example comes from South Africa. where people are more dependent on wattles (Kull et al .. 2011; also see Chapter 16, this volume). Ngorima and Shackleton (2019) analysed the benefits and costs of A. dealbata to rural communities in the Eastern Cape province and reported that all respondents recognize the species (although they were not aware that it was alien). ...
... This paper was designed to undertake an overview of Prosopis to act as a prerequisite for proposing holistic management strategies of the species in Ethiopia. This review could be useful for guiding and prioritizing management and improving knowledge in other groups of woody invasive plants (Kull et al., 2011;Wilson et al., 2011). Therefore, the objective of this review was to explore the occurrence, potential distribution, harmful and beneficial effects as well as the available controlling measures against Prosopis. ...
p> Prosopis juliflora, an evergreen shrub, is one of the most invasive alien species causing economic and environmental harm in arid and semi-arid areas. It is spreading rapidly in the rangelands, croplands and forests and in particular is threatening pastoral and agro-pastoral livelihoods. Prosopis has invaded parts of wildlife reserves and National Parks threatening biodiversity. There are several factors favoring its rapid distribution in the environment. Its ability to adapt wide range of climatic condition, effective dispersal mechanism, its allelopathic effect, prolific nature, having large seed bank in the soil environment, fast growing and vigorous coppicing ability are among the principal factors. Prosopis has the capacity to decrease the composition and diversity of plant species and it has adverse effects on crop yield, as well as animal and human health. Despite its negative effects, the tree has potential uses such as fuel, charcoal, fodder, food, bio-char, bio- control, windbreaks, shade, construction and furniture materials, and soil stabilization. It can be also be used against different disease and ameliorated environmental conditions through carbon sequestration. On the other hand, manual, mechanical, chemical and biological control methods as well as control by utilization have been pointed out as an effective control ways and management of this weed. There is urgent need to develop management strategies that are environmentally friendly and economically viable to bring them under control. Therefore, objective of this review was to explore the distribution, impacts, benefits and as well as the possible management approaches against Prosopis .</p
... During the 1990s, the concept developed into a subfield of biology and was gradually incorporated into environmental conventions as a key issue on which action is needed. Since then, invasive species management and control programs supported by public policies, scientists and environmentalists have emerged [19] in parallel with the increasing interest in biodiversity [20]. ...
Background
To understand how local ecological knowledge changes and adapts, here in the case of the recent introduction of plant species, we report the knowledge and perceptions of the Ndjuka (Maroon) of French Guiana concerning two tree species, Acacia mangium and niaouli (Melaleuca quinquenervia), which are categorized as “invasive alien plants” in the savannas of their territory.
Methods
To this end, semi-structured interviews were conducted between April and July 2022, using a pre-designed questionnaire, plant samples and photographs. The uses, local ecological knowledge, and representations of these species were surveyed among populations of Maroon origin in western French Guiana. All responses to closed questions collected during the field survey were compiled into an Excel spreadsheet in order to perform quantitative analyses, including the calculation of use reports (URs).
Results
It appears that the local populations have integrated these two plant species, which are named, used and even traded, into their knowledge systems. On the other hand, neither foreignness nor invasiveness seem to be relevant concepts in the perspective of the informants. The usefulness of these plants is the determining factor of their integration into the Ndjuka medicinal flora, thus resulting in the adaptation of their local ecological knowledge.
Conclusion
In addition to highlighting the need for the integration of the discourse of local stakeholders into the management of "invasive alien species,” this study also allows us to observe the forms of adaptation that are set in motion by the arrival of a new species, particularly within populations that are themselves the result of recent migrations. Our results furthermore indicate that such adaptations of local ecological knowledge can occur very quickly.
... Outras classificações conflitantes podem estar ligadas ao valor econômico e à capacidade de se naturalizar e espalhar em áreas perturbadas (Olckers, 2011). O conhecimento técnico também influencia as percepções e conclusões dos agentes que definem o conceito de espécie invasora (Goodland et al., 1998), cujos impactos podem ser positivos ou negativos, seja na economia, na ecologia ou na sociedade, além de serem dependentes do referencial adotado (Thiele et al., 2010;Kull et al., 2011;Dodet e Collet, 2012). ...
Dodonaea viscosa Jacq. (Sapindaceae), espécie exótica, de origem australiana, é uma árvore com potencial para a recuperação de áreas degradadas, pois cresce rápido, tolera a seca, forma bancos de sementes no solo e possui boas taxas de germinação. Estas características permitem considerá-la também como invasora potencial, ao se dispersar agressivamente no ambiente, quando comparada às espécies nativas do Brasil. A germinação das sementes foi avaliada em três experimentos, sendo submetidas às seguintes condições: (a) duas intensidades de luz, sobre dois substratos, em cinco regimes de temperatura; (b) cinco comprimentos de onda luminosa, sobre papel fltro, a 30 °C; (c) ausência e presença de dormência, sobre vermiculita, a 25 °C, divididos por matrizes. Os testes demonstraram que as sementes possuem dormência física, germinaram melhor no escuro (ou luz verde), no intervalo entre 20 e 25 °C, características também observadas em espécies pioneiras e invasoras, como Leucaena leucocephala e Pinus spp., caracterizando-a como tal. Ressalta-se que o conceito de espécie invasora é muito amplo e dependente do contexto, permitindo múltiplas interpretações por parte dos autores, por isso, estudos do impacto da espécie no entorno são necessários, a fm de aliar a fsiologia à paisagem.
... Complimenting the national scale mapping in Henderson (2020), based on quarter-degree squares (that includes the Wild Coast), are a few spatially localised studies that report on one or more IAPS at specific sites, such as the extensive invasion by Chromolaena odorata and Pereskia aculeata around Port St Johns (UNDP 2004;Berliner 2011), and Lantana camara at Mazeppa Bay (Jevon and Shackleton 2015), or the importance of Araujia sericifera as a medicinal plant near Nqabara (Kierungi and Fabricius 2005). The presence of woody IAPS can affect local livelihoods, either positively or negatively, depending on the how they are used to satisfy local needs (Kull et al. 2011;. For example, Lantana camara is used as a decorative hedge species, but escaped populations suppress recruitment of indigenous forest species (Jevon and Shackleton 2015). ...
Invasive alien plant species (IAPS) frequently offer both ecosystem services and disservices to rural communities with high livelihood dependency on local landscapes. However, biocultural relationships with IAPS may go deeper than just provisioning uses, as they may be assimilated into local belief systems manifest in them becoming embedded in cultural constructions such as naming, stories, songs and ceremonies. It is likely that IAPS that are culturally assimilated will represent a greater conflict of interest in the face of proposed controls of IAPS in biodiversity hotspots where conservation priorities are frequently deemed paramount by external agencies. Using a mixed-methods approach we undertook roadside surveys of 17 selected IAPS along the 250 km Wild Coast section of the Maputaland-Pondoland-Albany biodiversity hotspot, accompanied by questionnaire interviews with 48 local people. The mean number of IAPS per site was four, ranging from zero (only one site) to ten, and local inhabitants deemed the abundance of all but one of the species to be increasing. All species had been in the region for decades, had a vernacular name, and all but one had direct consumptive uses. Species with multiple uses were more widely recognised. However, there was only marginal incorporation of the IAPS into stories, songs and ceremonies, although medicinal uses of some IAPS were for cultural/spiritual needs rather than physical ailments per se. These results show that despite widespread use, there was as yet relatively limited cultural assimilation of the IAPS in the Wild Coast region.
... The most influential individual beliefs about carp, especially of people who had seen a change in the characteristics of the lake, appear to be views on carp's abundance, impact on water quality, and on other fish species. One of the key factors that influence human perceptions of invasive alien species generally relates to abundance of the invader (Kull et al., 2011;Shackleton et al., 2007). In Groenvlei 66% ...
Public view on invasive alien species (IAS) can burden or facilitate management. Understanding the factors driving perception and support of IAS, is critical to effectively tackle the problems associated with invasion. To identify these factors, we analyze the public perception, knowledge, and attitude of Cyprinus carpio invasion in Groenvlei, a lake situated in the Goukamma Natural Reserve, Western Cape of South Africa. A total of 88 interviews, with qualitative and quantitative questions, were conducted with seven groups of stakeholders. Respondents showed a general concern of the changes that have altered the lake ecosystem, and a high level of engagement to control carp population. Quantitative and qualitative analysis was used to identify factors affecting perception and willingness to pay. Results showed that sociodemographic variables did not influence people’s opinion and support to control carp. Within this framework, four variables were identified as drivers for perception and attitude: knowledge of the meaning of IAS, awareness of native species in Groenvlei, use of the lake’s resources, and the change seen on the character of the lake. Perception was the strongest variable which influenced willingness to pay. Hierarchical cluster and principal component analyses identified three categories of respondents with different levels of concern. Stakeholders from the highest concerned group had a direct experience of carp impact in Groenvlei. Respondents within the medium and least concern group were generally tourist, hoteliers, fishers, and residents with a low level of knowledge. This result highlights the need for improved awareness around the impact of carp invasion as this is a primary factor driving support for management. Synthesizing and understanding the main factors that influence people’s perception of carp invasion can help circumvent and mitigate conflicts, support prioritization plans, improve stakeholder’s engagement and implement control measurements
... During the 1990s, the concept developed into a sub eld of biology and was gradually incorporated into environmental conventions as a key issue on which action is needed. Since then, invasive species management and control programs supported by public policies, scientists and environmentalists have emerged (19) in parallel with the increasing interest in biodiversity (20). ...
Background: To understand how local ecological knowledge changes and adapts, here in the case of the recent introduction of plant species, we report the knowledge and perceptions of the Ndjuka (Maroon) of French Guiana concerning two tree species, Acacia mangium and niaouli(Melaleuca quinquenervia), which are categorized as “invasive alien plants” in the savannas of their territory.
Methods: To this end, semi-structured interviews were conducted between April and July 2022, using a pre-designed questionnaire, plant samples and photographs. The uses, local ecological knowledge, and representations of these species were surveyed among populations of Maroon origin in western French Guiana. All responses to closed questions collected during the field survey were compiled into an Excel spreadsheet in order to perform quantitative analyses, including the calculation of use reports (URs).
Results: It appears that the local populations have integrated these two plant species, which are named, used and even traded, into their knowledge systems. On the other hand, neither foreignness nor invasiveness seem to be relevant concepts in the perspective of the informants. The usefulness of these plants is the determining factor of their integration into the Ndjuka medicinal flora, thus resulting in the adaptation of their local ecological knowledge.
Conclusion: In addition to highlighting the need for the integration of the discourse of local stakeholders into the management of "invasive alien species”, this study also allows us to observe the forms of adaptation that are set in motion by the arrival of a new species, particularly within populations that are themselves the result of recent migrations. Our results furthermore indicate that such adaptations of local ecological knowledge can occur very quickly.
... Currently, most Acacia spp. are subjected to legislation aimed at controlling invasive species and prohibiting their further use and planting [3,4]. As other invasive species, Acacia dealbata can present itself in areas with difficult ground access, due both to topography and remote accessibility. ...
... In Portugal, specimens of A. longifolia were recorded in the catalogue of the University of Coimbra's Botanical Gardens in 1878 (Henriques 1879). However, the first official introduction record of the species into Portugal likely dates to 1897 (Fernandes 2008;Carruthers et al. 2011;Kull et al. 2011). Irrespective of when the species was introduced, the origins of these introduction(s) remain unknown. ...
Acacia longifolia (Sydney golden wattle) is considered one of the most problematic plant invaders in Mediterranean-type ecosystems. In this study, we investigate the species’ invasion history by comparing the genetic diversity and structure of native (Australia) and several invasive range (Brazil, Portugal, South Africa, Spain, and Uruguay) populations and by modelling different introduction scenarios using these data. We sampled 272 A. longifolia individuals – 126 from different invasive ranges and 146 from the native range – from 41 populations. We genotyped all individuals at four chloroplast and 12 nuclear microsatellite markers. From these data we calculated diversity metrics, identified chloroplast haplotypes, and estimated population genetic structure based on Bayesian assignment tests. We used Approximate Bayesian Computation (ABC) models to infer the likely introduction history into each invaded country. In Australia, population genetic structure of A. longifolia appears to be strongly shaped by the Bass Strait and we identified two genetic clusters largely corresponding to mainland Australian and Tasmanian populations. We found invasive populations to represent a mixture of these clusters. Similar levels of genetic diversity were present in native and invasive ranges, indicating that invasive populations did not go through a genetic bottleneck. Bayesian assignment tests and chloroplast haplotype frequencies further suggested a secondary introduction event between South Africa and Portugal. However, ABC analyses could not confidently identify the native source(s) of invasive populations in these two countries, probably due to the known high propagule pressure that accompanied these introductions. ABC analyses identified Tasmania as the likely source of invasive populations in Brazil and Uruguay. A definitive native source for Spanish populations could also not be identified. This study shows that tracing the introduction history of A. longifolia is difficult, most likely because of the complexity associated with the extensive movement of the species around the world. Our findings should be considered when planning management and control efforts, such as biological control, in some invaded regions.
... In Portugal, A. longifolia, also known as Sydney Golden Wattle, is an important plant invader (Vicente et al. 2018). This species originates from south-east mainland Australia and Tasmania, and the first official record of introduction in the coastal areas of Portugal is in 1897 (Fernandes 2008;Carruthers et al. 2011;Kull et al. 2011) with the aim of stabilising the dunes and controlling their erosion (Marchante et al. 2008;Vicente et al. 2018). Following its introduction, A. longifolia has spread to adjacent environments and it is currently present in most of the Portuguese territory, including forest and agricultural areas. ...
Context
Acacia longifolia is an aggressive invader, disrupting habitats and communities worldwide. Understanding what drives its expansion is of paramount importance. Key functional traits include fast growth and the presence of bacterial symbionts performing nitrogen fixation.
Aims
To address early plant development of A. longifolia under different soils and growth conditions (water and nutrition availability), establishing the key factors that influence above and belowground responses.
Methods
Plants were grown in pots with soils collected from forest, agricultural and dune areas in relative proximity, in a controlled experiment designed to study water effect and nutrient availability on early growth. Growth parameters included shoot and root length, nodule number and weight. Bacteria were isolated from nodules for genetic diversity evaluation. Photosynthetic pigments and isotopic nitrogen and carbon analyses were performed to address nitrogen fixation and photosynthesis.
Key results
Soil origin influenced plant growth and bacterial diversity. Largest plant development was achieved in forest soils with added nutrition and water. Plants from agricultural soil displayed higher aboveground development; however, belowground nodule number and bacterial biodiversity decreased, possibly due to anthropogenic activities. Forest soil promoted belowground development and bacterial diversity. In dune soils overall growth was lower and nitrogen fixation was higher.
Conclusion
Abiotic factors influenced juvenile acacia development; nutrition acts as a growth enhancer, and soil origin, including its microbial communities, can be considered a development modulator. Bacterial diversity varied according to soil type.
Implications
Several above and belowground interactions showed the need for an integrative perspective to understand acacias invasive potential.
Plant resources are vital components of urban and peri-urban ecosystems, yet research on their sustainable utilization remains limited. These resources provide a wide array of benefits to local communities, particularly those are located in the peripheries of urban areas, where they serve as critical sources of firewood, construction materials, and livelihood support. However, the growing demand for these resources, coupled with the pressure of urbanization, threatens their availability and the ecological stability of the regions they inhabit. This study, therefore, aimed to conduct a comprehensive ecological assessment of plant resources, examining plant stem harvesting, the sustainability of their utilization and the observed changes in plant density and diversity in the peri-urban areas of George, South Africa. The study focused on three selected sites: Saasveld Rd, Thembalethu, and Saiuwerfountain are chosen based on their proximity to woody patches and the visual evidence of resource use for firewood, fencing, and construction in low-income suburbs. Key ecological parameters such as species density, basal area, and importance value indices (IVIs) were analyzed to understand species composition and utilization patterns. The golden ratio (Φ) and Fibonacci sequencing were employed to detect self-organizing trends and optimality within the plant communities, revealing insights into ecosystem dynamics, resilience and resource management. Results indicated a higher tree density at Saasveld Rd (78.53%) and Thembalethu (58.33%), while shrubs and trees were nearly equally distributed at Saiuwerfountain (50.83% shrubs vs. 49.17% trees). The high demand for plant resources, particularly in the low-income areas of Thembalethu and Saiuwerfountain, had significantly reduced plant density. Acacia mearnsii was identified as the most harvested species across all sites due to its abundance, rapid regeneration, and suitability for firewood and construction purposes. The maximum number of harvested stems (51.15%) was recorded at Saiuwerfountain, reflecting the heavy dependence of local communities on these resources for their daily needs. The current study demonstrated the importance of managing both native and invasive species for sustainable utilization and biodiversity conservation. While invasive species like Acacia mearnsii offer immediate benefits to local communities, their unchecked proliferation poses significant risks to native biodiversity and ecosystem health. The findings call for the establishment of sustainable energy plantations and woodlots to address the escalating wood-based needs of low-income communities, alongside policies promoting sustainable harvesting practices and biodiversity conservation thereby contributing to a region specific conservation and energy strategies for a long-term sustainability. Additionally, the identification of self-organizing trends, an indicative of ecological optimization through signatures of the golden ratio, highlights the inherent resilience and adaptive capacity of these ecosystems, reinforcing the need for adaptation oriented restorative management approaches. Results of this study generally supported the relevance of conservation by utilization strategy of invasive alien plant species control and management in similar global cases for environmental sustainability.
Accelerating anthropogenic pressures threaten over two in five plant species globally with extinction, with an estimated 21% of threatened species on the IUCN Red List holding socio-economic value, imperiling species vital for global health. Important Plant Areas (IPAs) is an area-based conservation tool that recognizes the importance of useful species for human well-being and livelihoods. This study aims to identify hotspots of useful plants in Uganda using criterion B(iii) of the IPA framework. A comprehensive checklist of useful plants is presented, identifying 1,037 species with known human uses, equating to over one-fifth of vascular plant diversity in Uganda. A species richness analysis reveals a potential IPA network with 54 cells triggered using criterion B(iii). While Uganda’s current protected area network contains a significant percentage (55%) of species on the useful plant checklist, the top 15 cells capture a higher number of species (59%) in a quarter of the total land area of the protected area network. Concerningly, 56% of Uganda’s crop wild relatives are not recorded from the existing protected areas. Threatened and endemic species distribution correlates significantly with useful plant distribution, suggesting that countries with IPAs based upon threatened and endemic species could also capture useful plants.
The characterization of secondary metabolites extracted from acacia gums (AGs) is crucial for understanding their chemical composition and potential benefits. Various analytical techniques, such as chromatography and spectroscopy, have been used to determine the structures and properties of these compounds. Identifying and characterizing secondary metabolites from AGs can shed light on their chemical composition and biological activities, thereby providing valuable insights into their potential applications in medicine, agriculture, and industry. This chapter provides a comprehensive overview of the characterization of secondary metabolites extracted from AGs and sheds light on their chemical composition.
The ecological impacts of invasive alien species are well known, as are the large-scale economic losses caused by these species. Less well known are the impacts of these species on human
wellbeing. In developing countries, like India, where a large proportion of the population is rural and intricately dependent on natural resources for its sustenance, the impacts of invasive species
on people’s wellbeing are likely to be as important as their ecological impacts. In this paper, we undertake a qualitative review of the literature on impacts of invasive alien species, specifically
plants, on human wellbeing in India. Our results show that impacts are diverse across various aspects of wellbeing and are both positive or negative based on local contexts. This plurality is
indicative of the need for a more nuanced approach to impact analysis and stakeholder mapping. We use constituents of human wellbeing as outlined in the Socioeconomic Impact Classification
for Alien Taxa (SEICAT) and the Sustainable Livelihoods Framework (SLF) to analyze invasive plant impacts, identify knowledge gaps, and discuss recommendations for future research on
impacts of invasive species. Although the widespread natural resource dependency among rural, tribal, and other marginalized communities of India gives biological invasions a socioeconomic
dimension (due to impacts of invasion on these resources), the human and social dimensions of species invasions have been neglected compared to their ecological dimension. We suggest that
understanding the pluralities of wellbeing circumstances with invasive species could help improve policies for management of invasive species in India.
Biological invasions can have major social-ecological consequences for local communities across the world. However, the dimensions (characteristics, infestation and socio-ecological impacts) of emerging invasive alien plants are often less well known but urgent information is needed to guide policy and management. In light of this, this paper assesses the social-ecological impacts of Vernonathura Polyanthes an emerging invasive alien plant, in a Zimbabwean upland landscape which supports conservation and livelihoods. Informed by exploratory participatory qualitative methodologies we discussed the socio-ecological and economic implications (benefits and impacts) of Vernonathura Polyanthes and how it is managed in the eastern parts of Chimanimani, Zimbabwe. We found that there are nuanced perspectives of this invasive tree among different socio-economic groups in the region who have different experiences of living with Vernonathura polyanthes . Some are embracing it for apiculture, firewood, and ethnomedicine, on the other hand for others the tree is negatively affecting key livelihoods (crop farming, pastoralism and tourism) that are common in the region. Local people also identified that Vernonathura Polyanthes is associated with ecological impacts that include loss of biodiversity, promoting pests and negatively affecting watersheds and associated water security. Mixed experiences on the plant are leading to different management practices, in turn inducing some conflicts among various actors. Based on our findings we suggest more should be done to better manage this invasive plant in the region before negative impacts become too great, particularly in the protected areas in the region.
The global rise in issues related to the invasion of alien tree species is becoming increasingly prominent. Genus Acacia is one of the most pervasive invaders among the non-native flora introduced to Portugal over the centuries. This research aimed to pinpoint the key players engaged in its management, their expertise, and the methodologies applied to control acacias or decrease affected regions. Data were gathered via an online survey and subjected to diverse statistical analyses. Numerous stakeholders have emerged in recent decades, employing various methods to fight acacia invasion. Mechanical, chemical, and combined methods are the most frequently applied. The findings highlight the need for continued funding for long-term acacia control in the same invaded areas, increased training actions and best practices demonstration in the field and increased public awareness and engagement in local communities and the general public.
Reconstructing the history (spatio-temporal patterns) of biological invasions at a small spatial scale is challenging, notably because the required data are often not available in sufficient quantity and quality. In this study, we present a mixed approach using six different data sources to explore the spreading history of four non-native invasive tree species, Ailanthus altissima , Celtis occidentalis , Prunus serotina and Acer negundo in a high conservation value foreststeppe habitat with an area of 1000 ha (Peszér Forest, Central Hungary). We carried out a literature search, compiled all the archived and currently valid data of the National Forestry Database (NFD) in a GIS database, conducted a full-coverage field survey, mapped all the large/old tree specimens and carried out annual ring counts, performed a hotspot analysis on the abundance data provided by the field survey and gathered local knowledge. Each of these approaches proved indispensable and their complementary use made it possible to reconstruct the invasion history of all four tree species. According to the available source literature, P. serotina was first planted in the area in 1937 and the first known occurrence of A. altissima could also be traced back to the 1930s. The examination of large specimens of C. occidentalis and querying the NFD for data related to A. negundo provided evidence that these species have been present in the area since at least the 1940s. However, based on the NFD and local knowledge, it is certain that the rapid expansion of the four tree species occurred simultaneously and only around the turn of the millennium, with a lag of at least 60-70 years. The exploration of local knowledge revealed three possible explanations, which interestingly also coincided in time. With the change in the political regime, the intensity of forest use started to decrease in the 1990s, the population of game was drastically reduced at the end of the decade and droughts became more frequent from 2000 onwards. The field survey clearly showed that these tree species were 2-3 times more prevalent and abundant than the relevant NFD data indicated. Finally, the primary hotspots of A. altissima and A. negundo overlapped with the locations of their first known occurrences, while in the case of C. occidentalis and P. serotina , they did not. However, local knowledge revealed that the former two had been ignored since at least the 1950s, while the latter two were occasionally planted until the 1990s. It is likely that the primary hotspots of C. occidentalis and P. serotina indicate the locations of these undocumented plantations.
Dans certaines situations rurales où se conjuguent pauvreté des populations et rareté des ressources, l'analyse des conséquences de l'invasion d'une espèce ligneuse nécessite l'emploi d'un cadre d'approche large et objectif, qui inclue les interactions entre les paysans et les espaces envahis. L'article tire parti d'une courte étude conduite dans la commune d'Ambatofitorahana, au sud d'Ambositra, dans la région des Hautes Terres. Introduit d'Australie à Madagascar, où il est devenu invasif, le mimosa (Acacia dealbata) y constitue aujourd'hui une ressource renouvelable pour le paysannat. Les types d'usages relatifs à cet arbuste ont été préalablement sommairement caractérisés. La discussion des résultats, qui représente l'essentiel du corps de cet article, donne lieu à la proposition d'un cadre de représentation à différentes échelles pour appréhender correctement une bioinvasion en milieu rural. L'investigation de l'ensemble de l'impact socio-économique et écologique de ce processus nécessite de recourir à une gamme de niveaux d'organisation etd'échelle allantde la parcelle à l'ensemble du pays. Les avantages et inconvénients que recouvre l'invasion du mimosa à Madagascar se révèlent en effet spécifiques de chacun de ces niveaux d'analyse. À l'échelle des espaces ruraux, la valorisation apparaît essentiellement centrée sur la réalisation de jachères ligneuses et la production de combustibles (bois de feu et charbon de bois). L'analyse montre qu'au niveau des territoires ruraux, l'invasion de A. dealbata obéit à des phases de stabilisation suivies d'extensions, en lien étroit avec des périodes de valorisation suivies d'un relâchement dans l'utilisation de cette ressource. Les incidences socio-économiques de cette bioinvasion varient dès lors avec la période historique considérée. De manière permanente, la valorisation paysanne et l'occupation agricole des espaces ruraux demeurent le meilleur rempart à l'extension des surfaces envahies par le mimo sa dans les Hautes Terres malgaches. (Résumé d'auteur)
In French overseas territories, woody invasions can occur in rural areas. A good example is provided by Acacia mearnsii invasion, which covers over 5 000 ha in Reunion Island. Diagnosis of such an invasion needs an appropriate framework to analyse rural landscapes at several organisational levels and must consider the dynamic processes induced by farming activities. It is furthermore important to clarify predisposing, aggravating and triggering factors for invasion. Several bio-indicators (e.g. birds at the landscape level, flora at the invasion patch level) need to be measured to assess the invasion's environmental impact. All these results must be reviewed in the light of social factors and stakeholder expectations before reaching conclusions as to recommended means of control.
Dans les DOM-TOM notamment, des invasions d'essences forestieres exotiques peuvent se manifester en milieu rural. Un exemple majeur est fourni par Acacia mearnsii qui couvre plus de 5 000 ha dans l'ile de la Reunion. Le diagnostic de ce type d'invasion impose de definir un cadre d'analyse approprie aux paysages agricoles qui integre les differents niveaux d'organisation de l'invasion et place celle-ci dans la perspective de la dynamique des activites agricoles. Il est ensuite important de preciser les facteurs predisposants, aggravants et eventuellement declenchants de cette invasion. L'evaluation de son impact sur l'environnement necessite ensuite de recourir a differents jeux de bio-indicateurs (par exemple l'avifaune au niveau des paysages, et la flore a celui des taches d'invasion). Enfin, il convient de confronter l'ensemble de ces resultats d'etude aux determinants sociaux et aux attentes des acteurs, avant de degager des preconisations de lutte.
In French overseas territories, woody invasions can occur in rural areas. A good example is provided by
Acacia mearnsii invasion, which covers over 5 000 ha in Reunion Island. Diagnosis of such an invasion needs
an appropriate framework to analyse rural landscapes at several organisational levels and must consider the
dynamic processes induced by farming activities. It is furthermore important to clarify predisposing, aggravating
and triggering factors for invasion. Several bio-indicators (e.g. birds at the landscape level, flora at the
invasion patch level) need to be measured to assess the invasion’s environmental impact. All these results
must be reviewed in the light of social factors and stakeholder expectations before reaching conclusions as
to recommended means of control.
The book Alien Invasive Plants in Israel by Dr. Jean-Marc Dufour-Dror, is now available in a new 2012 English-language edition, which has been updated since the publication of the 2010 edition in Hebrew. This full color, soft-cover book is divided into three chapters: The first chapter is dedicated to the definitions of several basic concepts required for understanding the topic of invasive plant ecology. An overview of the main ecological and biological characteristics typical of invasive plants is presented in this chapter, with all examples taken from invading taxa in Israel. The second chapter presents a brief analysis of the major characteristics of the phenomenon of invasive plants in natural areas in Israel. The first section of this chapter discusses the factors underlying the spread of invasive plants in Israel. The second section reviews their main effects on local ecosystems, focusing on habitats that are particularly susceptible to invasion. In the third section we present a summary of the control techniques and methods currently implemented in Israel to cope with the proliferation of invasive plants in natural areas. The third chapter that makes up the bulk of this book provides detailed and up to date information on the 50 most significant species of alien plants that invade natural and semi-natural habitats in Israel. The information includes a short description of the plant, information on its natural range (origin), background related to its introduction to Israel, information on its known biological and ecological traits, a description of its invasive status in Israel and an explanation of how it affects local ecosystems. Existing and relevant control methods are described for each species. The main regions in the world invaded by the species are mentioned, and a list of references is presented for each species. Finally there is an appendix with a current list of all the alien plant species recorded in natural and disturbed areas in Israel up to early 2010.
Tree invasions can lead to changes in the plant community composition and reductions in the number of native species. Acacia dealbata Link (silver wattle) was introduced to Chile as an ornamental. This species originated in Australia and Tasmania has been documented as invader in several ecosystems in the world. In Chile, this species is strongly associated to roads, rivers and human disturbances, performing as an invader in natural and semi-natural ecosystems. However, A. dealbata impacts at community levéis have been scarcely studied. In order to determínate the relationship between A. dealbata invasión and the species richness and composition of plants in natural communities of south-central of Chile, we recorded the plant composition in three study conditions: wader Acacia canopy, inside an adjacent native forest and in the edges between both conditions. We selected five study sites near to Concepción, Chile (37° S) and in each condition we surveyed three transects of 20x2 m2 with a total of 15 transects at the three conditions. Results showed that the total species richness is significantly lower under Acacia canopy compared with the stand edge and native forest. Native species richness is higher within native forest and alien species richness is significantly higher in the stand edge. Plant composition also changes in the presence of A dealbata. This study demonstrates the positive relationship between the presence of A dealbata stands and the reduction of plant diversity in the south-central área of Chile.
The forest reserves of Hawai‘i were established in the early 1900s in response to concerns about supplies of freshwater in the islands and the degraded condition of the native forests protecting the watersheds. Tree-planting was a coordinated effort involving both Harold Lyon and the Hawaiian Sugar Planters' Association and Territorial Forestry under the direction of R. S. Hosmer. The early foresters planted many types of trees on an experimental basis, but concluded that native species were of limited utility and turned largely to introduced species for large-scale reforestation efforts. The number of trees planted rose to many millions by the 1930s, when Depression-era labor was available for planting. Lyon envisioned the plantations as a buffer zone that would be established between the remaining native forests and the lower-elevation agricultural lands to protect the native forests and perform the functions (maintaining input of water to aquifers) that native forest no longer could. This large-scale attempt to engineer nature was probably the largest environmental project ever carried out in the islands. Forestry introductions have been a significant contributor to Hawaii's alien-species crisis, with many of these tree species now problem invasives.
Aim The genetic makeup and evolutionary potential of alien species can be profoundly influenced by their introduction history, but without detailed historical records, it can be difficult to ascertain the strength of this historical contingency. We explore how the known introduction histories combined with phylogeographic patterns in the native range have affected the genetic diversity in the invasive range for five Australian trees introduced to South Africa (Acacia cyclops, Acacia mearnsii, Acacia pycnantha, Acacia saligna and Paraserianthes lophantha).
Location Western Australia, South Australia, Victoria and New South Wales (native and invasive ranges), and South Africa and the Hawaiian Islands (invasive range).
Methods DNA sequence data were generated for all study species for either the external transcribed spacer (ETS) or plastid rpl32-trnL(UAG) gene regions (combined total of 180 DNA sequences). Using statistical parsimony networks and genetic diversity indices, we compared genetic structure and variation in native and invasive ranges.
Results Australian acacia species tend to have high genetic diversity at the population level in their native ranges, often showing high intra-specific divergence. In most instances, these species have similar levels of population genetic diversity in their adventive ranges in South Africa, but lack structure. For A. cyclops, A. saligna and P. lophantha, we found evidence for intra-specific hybridization between mixed genetic entities in the invasive range, arguably as a result of the structured native range being broadly sampled prior to introduction.
Main conclusions Invasive species that have been extensively used in forestry often have complex introduction histories resulting in equally complex genetic signatures in the invasive range. Our results show that extreme caution should be taken when using indirect inferences (molecular genetic data) of introduction histories in the absence of detailed introduction records.
Abstract La Réunion Island has the largest area of intact vegetation of the islands in the Mascarene archipelago. Biological invasions are the primary threat to biodiversity in the intact habitats of the island (those not already transformed by agriculture and urbanization). Our study aimed to identify areas to prioritize in managing invasive alien plants for biodiversity conservation. We used extensive surveys of 238 distinct untransformed areas on La Réunion to define the current distribution patterns of all invasive species. Using expert knowledge, we compiled maps of the current distribution of the 46 most widespread/important invasive plants at the habitat scale (identified according to vegetation structure). Data from 440 botanical relevés for the 20 most threatening invasive alien plant species across the island and climatic envelope models were used to derive climatic suitability surfaces; these were used to map potential distributions for these species. More than 10 species invade 16.7% of the remaining habitat. Five habitat types are invaded by 25 or more species, and eight have fewer than 10 invasive alien plant species. Cluster analysis based on presence/absence of species in the 18 habitat types produced eight groups of species that invade particular habitats. Potential distribution models show that some species have invaded large parts of their potential range (e.g. Fuchsia magellanica, Furcraea foetida, Hiptage benghalensis), whereas others have the potential to increase their range substantially (e.g. Clidemia hirta, Strobilanthes hamiltonianus, Ulex europaeus). Management implications are identified for both groups. Three broad groups of habitats were identified: (i) intact habitats with a low level of invasion (e.g. subalpine shrubland); (ii) moderately invaded habitats with varying levels of intactness (ranging from windward submountain rainforest to the Acacia heterophylla forest); and (iii) habitats with little remaining intact area and high levels of invasion (e.g. lowland rainforest). Different management interventions are appropriate for these three groups.
Aim The biophysical impacts of invasive Australian acacias and their effects on ecosystem services are explored and used to develop a framework for improved restoration practices.
Location South Africa, Portugal and Chile.
Methods A conceptual model of ecosystem responses to the increasing severity (density and duration) of invasions was developed from the literature and our knowledge of how these impacts affect options for restoration. Case studies are used to identify similarities and differences between three regions severely affected by invasions of Australian acacias: Acacia dealbata in Chile, Acacia longifolia in Portugal and Acacia saligna in South Africa.
Results Australian acacias have a wide range of impacts on ecosystems that increase with time and disturbance, transform ecosystems and alter and reduce ecosystem service delivery. A shared trait is the accumulation of massive seed banks, which enables them to become dominant after disturbances. Ecosystem trajectories and recovery potential suggest that there are important thresholds in ecosystem state and resilience. When these are crossed, options for restoration are radically altered; in many cases, autogenic (self-driven and self-sustaining) recovery to a pre-invasion condition is inhibited, necessitating active intervention to restore composition and function.
Main conclusions The conceptual model demonstrates the degree, nature and reversibility of ecosystem degradation and identifies key actions needed to restore ecosystems to desired states. Control and restoration operations, particularly active restoration, require substantial short- to medium-term investments, which can reduce losses of biodiversity and ecosystem services, and the costs to society in the long term. Increasing restoration effectiveness will require further research into linkages between impacts and restoration. This research should involve scientists, practitioners and managers engaged in invasive plant control and restoration programmes, together with society as both the investors in, and beneficiaries of, more effective restoration.
There is a strong bias concerning the regions of the globe where research on biological invasions is conducted, with notably
lower representation of developing countries. However, in developing countries, effective management strategies to control
invasions could be more beneficial in conserving global biodiversity since these countries tend to have larger, highly diverse
natural habitats. Lower levels of development are seen as an obstacle to tackling biological invasions, but little thought
is given to the advantages of developing countries in dealing with invasive species. We analyzed differences between developed
and developing countries regarding the problem of invasive species and their historical and current patterns of international
trade, disturbance levels and land use, research and monitoring, control and mitigation, and social awareness. Developed nations
have some advantages, especially in levels of social awareness and means for controlling and studying exotics, but developing
nations also enjoy important advantages given their lower levels of international trade and the availability of low-cost labor.
Also, there is evidence that the process of economic development, which results in more efficient ways to transform landscapes
and increases international trade, is strongly associated with increasing rates of biological invasion. Differences in data
quality and availability between developed and developing countries make comparative analyses of biological invasions a difficult
task. Thus, these differences creates a challenge in forming global strategies to deal with invasions. There have been calls
for creating international plans to deal with invasive species, but we believe that it is important first to acknowledge the
challenges and understand both the advantages and disadvantages of developing countries.
KeywordsAnthropogenic disturbance-Control of invasions-Development-International trade-Management
The Lowland Mayan culture has been one of the most successful in Mesoamerica. Being an agricultural society, part of their success was based on plant genetic resources which satisfied their needs of social reproduction. This article reviews recent evidence on early agriculture in the geographic area where Lowland Maya culture originated, and discusses its implications for the study of plant domestication and evolution under human selection within this cultural sub-area. Questions of interest for future research are posed. As working hypotheses, we list two categories of species possibly implicated in the origin of this civilization: (1) native species that could have been the subject of local human selection or to some degree of agricultural manipulation by 3400 B.C., and (2) species that could have been introduced from other cultural areas of America by 3400 B.C. and subsequently subjected to local human selection. © 2004 by The New York Botanical Garden Press, Bronx, NY 10458-5126 U.S.A.
The detrimental impacts of invasive alien species (IAS) on ecosystem goods and services and local and regional economies are
well documented. However, the use of IAS by rural communities is little understood, and rarely factored into IAS control programmes.
Understanding the use of IAS by rural communities and factoring these into cost-benefit models is complex, depending upon
a range of local-level attributes such as the time since invasion, abundance, and local-level costs and benefits. This paper
reports on two case studies examining the role of IAS in rural livelihoods in the Eastern Cape, South Africa. In both cases,
rural communities made widespread consumptive use of the IAS and generally would prefer higher densities, except in certain
key localities. Several households traded in IAS products to generate supplementary income. We present a conceptual framework
to guide interpretation of these and future case studies, considering attributes such as time since invasion, the competitiveness
of the species, and the relative costs and benefits.
Reforestation efforts in Bangladesh need information on the biophysical performance and social suitability of potential species. We investigated the biophysical and social suitability of three species, Acacia auriculiformis Benth (Leguminosae, Mimosaceae), Acacia mangium Willd., and Eucalyptus camaldulensis Dehnh. (Myrtaceae) in 8-year-old monoculture plantations for reforestation of woodlots in Dhaka Forest Division, Bangladesh. The prevailing site conditions of the study area were suitable for all three species. Seven regression models were tested to find the best-fit model for volume and productivity calculation of each species. A simple linear regression model as a function of height (h) and diameter at breast height (dbh), i.e. V = b0 + b1 (dbh + dbh2 + dbh2 × h) was selected to compute volume and productivity for all three species. Survival, average height, productivity, and gross revenue earned from A. mangium were greatest, followed by A. auriculiformis; both were substantially higher than E. camaldulensis. Local people preferred A. auriculiformis most, followed by A. mangium and finally E. camaldulensis. However, the discrepancy between the productivity/revenue projections and local perception index suggests that there should be sufficient attention paid to both the interests and objectives of implementing agencies, as well as the needs and preferences of rural communities in selecting suitable species for future woodlot establishment in the same site. Therefore, the findings of this study serve as a benchmark for more in-depth investigation regarding preferences, and gaining an historical perspective on how a more secure market might affect local people's choice of species.
A payments for ecosystem services (PES) system came about in South Africa with the establishment of the government-funded Working for Water (WfW) programme that clears mountain catchments and riparian zones of invasive alien plants to restore natural fire regimes, the productive potential of land, biodiversity, and hydrological functioning. The success of the programme is largely attributed to it being mainly funded as a poverty-relief initiative, although water users also contribute through their water fees. Nevertheless, as the hydrological benefits have become apparent, water utilities and municipalities have begun to contract WfW to restore catchments that affect their water supplies. This emerging PES system differs from others in that the service providers are previously unemployed individuals that tender for contracts to restore public or private lands, rather than the landowners themselves. The model has since expanded into other types of ecosystem restoration and these have the potential to merge into a general programme of ecosystem service provision within a broader public works programme. There is a strong case for concentrating on the most valuable services provided by ecosystems, such as water supply, carbon sequestration, and fire protection, and using these as ‘umbrella services’ to achieve a range of conservation goals. The future prospects for expansion of PES for hydrological services are further strengthened by the legal requirement that Catchment Management Agencies be established. These authorities will have an incentive to purchase hydrological services through organisations such as WfW so as to be able to supply more water to their users.
Some alien tree species used in commercial forestry cause major problems as invaders of natural ecosystems. One such case, the black wattle tree, was introduced into South Africa from Australia in the 19th century. It is an important commercial species, as well as an aggressive invader, giving rise to significant environmental impacts and conflicts of interest. This paper provides an analysis of costs and benefits associated with this species in South Africa at a national level. The results suggest that a ‘do nothing’ scenario (with no attempts being made to control the spread of the species beyond the limits of plantations) is not sustainable, as the benefit–cost ratio is around 0.4. The most attractive control option will be to combine physical clearing and plant-attacking biological control with the continuation of the commercial growing activities. In case this is not practically feasible the next best option is a combination of seed-attacking biological control, physical control and the development of secondary industries based on wood products from clearing programmes. There is, however, a 40% loss of benefits involved with this option when compared with the first best option. The techniques used in this study, and the findings relating to the scenarios that deliver the best returns on investment, should be of broad relevance to the problem of dealing with conflicts of interest relating to invasive alien plants that have commercial value.
The Lowland Mayan culture has been one of the most successful in Mesoamerica. Being an agricultural society, part of their success was based on plant genetic resources which satisfied their needs of social reproduction. This article reviews recent evidence on early agriculture in the geographic area where Lowland Maya culture originated, and discusses its implications for the study of plant domestication and evolution under human selection within this cultural sub-area. Questions of interest for future research are posed. As working hypotheses, we list two categories of species possibly implicated in the origin of this civilization: (1) native species that could have been the subject of local human selection or to some degree of agricultural manipulation by 3400 b.c., and (2) species that could have been introduced from other cultural areas of America by 3400 b.c. and subsequently subjected to local human selection.
This study analyzes the structure and floristic composition of the regeneration of native forest species under black-wattle plantation, established 16 years ago in a riparian area, and it verifies the possibility of the black-wattle be considered an invasive species of this environment. The tree stratum (circumference at breast height (CBH) ≥15 cm) was evaluated in 12 plots of 100 m2, established in four blocks. The natural regeneration stratum (0.3 m height to ≤15 cm CBH) was evaluated in two subplots of 9 m2, established in opposite vertexes of each plot. The tree stratum was composed by 26 species of 14 families and the natural regeneration stratum by 49 species of 23 families. The Shannon diversity index for species, considering all plots, was 2.60 and 3.06 to the tree and natural regeneration strata, respectively. The native species, Casearia sylvestris, Myrsine lorentziana and Zanthoxylum petiolare presented the larger importance value in the tree stratum and Faramea marginata, Myrsine lorentziana and Myrcia glabra the biggest density in the natural regeneration stratum. The ecological characteristics of the species found in several height strata indicated that the forest succession process is in evolution. The black-wattle did not regenerate in this area and the planted trees of this species are in the senescence phase. Only 100 tree/ha of black-wattle were found, which represents 4.5% of the original population. Thus, black-wattle is not an invasive species for this environment.
Manas Biosphere Reserve (MBR) spreads across Baksa and Chirang district in Assam is a part of Indo-Burma hotspot of biodiversity of the sphere having very rich vegetation. This province of the reserve abounds in natural wealth including enormous potential for medicinal plants. The present paper communicates a total of 14 angiospermic taxa used by Bodo tribe inhabited in the fringe of Manas Biosphere Reserve for curing various diseases. The moist subtropical climate supports the growth of a number of exotic as well as indigenous medicinal, aromatic and other value plants and about 14 medicinal plant species have acclimatized and have been identified and documented along with their healing properties for the treatment of many human diseases. The ethnopharmaceutical uses of these plants recorded in this paper are hitherto unknown or less known to the world.
Australian bipinnate acacias, known locally as mimosa, are widespread on the plateaus and mountains of Madagascar. Rarely, however, do these trees attain their full size, leading to a surprising landscape of 'scrubby' wattles. We review the introduction of the wattles, survey their multiple uses in rural livelihoods and environmental management, and analyze the forestry policies, tenure rules, and ecological factors that maintain the trees' scrubby state. This well-adapted plant is an important resource for farmers and serves to green treeless hills, but it may become a conundrum to conservation managers due to its non-native, invasive status.
The seeds of certain Australian Acacia species are tasty, safe to consume and nutritious. Being perennial, mature acacias can take advantage of rains that would be ineffective for annual crops, such as out of season or poorly distributed rains. Acacia seeds are easily harvested and processed into flour using simple technologies which already exist in typical African villages. The flour can be incorporated into local dishes and "non-traditional" foods such as spaghetti, bread and biscuits. The seed also has great potential as livestock feed. Alternatively, the hard-coated seeds can be easily stored for many years and act as a famine reserve food. Much effort has gone into safety testing and promoting edible seeded Australian acacias for direct human consumption, but the rate of adoption has been slow. However, other characteristics of these same species may have an even greater impact on food security than actual consumption of the seed. The Farmer Managed Agro-forestry Farming System (FMAFS) that incorporates a range of annual and perennial crops is being promoted as a sustainable rainfed farming alternative to traditional and destructive slash-and-burn monocultures.
Some alien tree species used in commercial forestry, and agroforestry cause major problems as invaders of natural and seminatural ecosystems. The magnitude of the problem has increased significantly over the past few, decades, with a rapid increase in afforestation and changes in land use. Trends can be explained by analyzing natural experiments created by the widespread planting of a small number of species in different parts of the world. The species that cause the greatest problems are general those that have been planted most widely and for the longest time. The most affected areas have the longest histories of intensive planting. Pinus spp. are especially problematic, and at least 19 species are invasive over large areas in the southern hemisphere, where some species cause major problems. The most invasive Pinus species have a predictable set of life-history, attributes, including low, seed mass, short juvenile period, and short interval between large seed crops. Pine invasions have severely, impacted large areas of grassland and scrub-brushland in the southern hemisphere by causing shifts in life-form dominance, reduced structural diversity, increased biomass, disruption of prevailing vegetation dynamics, and changing nutrient cycling patterns. The (unavoidable) negative impacts of forestry with alien species are thus spilling over into areas set aside for conservation or water production. There is an urgent need to integrate the various means available for reducing the negative impacts of current invaders and to implement protocols to regulate the translocation of species that are known to be invasive.
A number of Australian trees - particularly acacias (’wattles’ or ’mimosas’) and eucalypts - have been cultivated over large areas of South Africa for the forest industry. They have become quite controversial in recent years for their alleged impacts on water resources and native biodiversity. In post-Apartheid South Africa, government poverty alleviation policies paradoxically engage poor rural blacks to both rip out these water-hungry ‘alien invasive’ trees while also encouraging people to plant them in small-scale plantations as part of black economic empowerment. This paper investigates how such a paradoxical situation arises and its impacts on specific rural landscapes and livelihoods, using the case of the black wattle (Acacia mearnsii) in the eastern highveld of Mpumalanga province. It traces the development of competing policy discourses (environmental, forest industry, rural livelihoods) and presents a case study of their impacts on local landscapes and livelihoods.
O objetivo deste trabalho foi avaliar a freqüência, a intensidade e o padrão de invasão da acácia-negra em ambientes campestres e propor medidas de monitoramento e controle. Foram avaliados sete ambientes localizados em áreas a menos de 30 m de povoamentos jovens (1 ano) e adultos (5 anos). A invasão da acácia-negra esteve relacionada ao grau de perturbação do solo. A Área de Preservação Permanente (APP) em recuperação, o ambiente mais perturbado, apresentou também o maior número de invasoras, sendo encontradas 152 plantas/0,1 ha. Em ambientes pouco perturbados, como o banhado, campo nativo e APP sem uso recente, verificou-se menos de 11 plantas/0,1 ha. Foi verificado um maior número de invasoras nas áreas mais próximas de povoamentos jovens (50 plantas/0,1 ha) que de plantios adultos (10 plantas/0,1 ha), indicando que perturbações que resultaram em invasão foram as causadas principalmente por máquinas durante a colheita e estabelecimento da nova rotação. A ocorrência de novas invasões durante o ciclo de crescimento do cultivo foi insignificante (<1 plantas/0,1 ha). A mortalidade no período de um ano foi de 80,4, 14,0, 6,8 e 5,5 %, respectivamente, para plantas <0,5, 0,5 a 1,9, 2,0 a 4,0 e >4,0 m de altura, reduzindo significativamente a população de invasoras nos anos seguintes à invasão. A invasão da acácia-negra está condicionada a perturbações no solo, por isso deve ser considerada uma invasora causal de ambientes campestres.
Australian bipinnate acacias, known locally as mimosa, are widespread on the plateaus and mountains of Madagascar. Rarely, however, do these trees attain their full size, leading to a surprising landscape of 'scrubby' wattles. We review the introduction of the wattles, survey their multiple uses in rural livelihoods and environmental management, and analyze the forestry policies, tenure rules, and ecological factors that maintain the trees' scrubby state. This well-adapted plant is an important resource for farmers and serves to green treeless hills, but it may become a conundrum to conservation managers due to its non-native, invasive status.
Global economic change and the discourses, models and practice of international sustainable development are major forces of ecological construction and restructuring. The paper illustrates how the social and ecological co-construction of forests in the Zambrana-Chacuey region in the Dominican Republic has material consequences for distinct groups of people and for other species in rural landscapes. The introduction of the Acacia mangium - a fast growing tree - as a timber cash crop for smallholder farmers in the region between 1984 and 1994 had major social, economic and ecological consequences. A rural federation collaborated with ENDA-Caribe, an international non-government organization, in a ten-year social forestry experiment to develop and promote economically and environmentally viable timber cash cropping systems for smallholder farmers. The experience of the federation members provides a window on the workings of gender, class and popular organization in the making of forest ecologies, and demonstrates the influence of transnational sustainable development models and organizations in the social and biological transformation of rural life. The encounter between the complex social and ecological context with an apparently simple project yields insights into the social, political and material construction, destruction and transformation of biotic assemblages in forests, fields, pastures and gardens in this forest/farm matrix. The research findings also illuminate the distinct effects of the resulting restructured ecologies on the diverse interest groups and plant communities within the regional agroforest.
Aim Acacia is the largest genus of plants in Australia with over 1000 species. A subset of these species is invasive in many parts of the world including Africa, the Americas, Europe, the Middle East, Asia and the Pacific region. We investigate the phylogenetic relationships of the invasive species in relation to the genus as a whole. This will provide a framework for studying the evolution of traits that make Acacia species such successful invaders and could assist in screening other species for invasive potential.
Location Australia and global.
Methods We sequenced four plastid and two nuclear DNA regions for 110 Australian Acacia species, including 16 species that have large invasive ranges outside Australia. A Bayesian phylogenetic tree was generated to define the major lineages of Acacia and to determine the phylogenetic placement of the invasive species.
Results Invasive Acacia species do not form a monophyletic group but do form small clusters throughout the phylogeny. There are no taxonomic characters that uniquely describe the invasive Acacia species.
Main conclusions The legume subfamily Mimosoideae has a high percentage of invasive species and the Australian Acacia species have the highest rate of all the legumes. There is some evidence of phylogenetic clumping of invasive species of Acacia in the limited sampling presented here. This phylogeny provides a framework for further testing of the evolution of traits associated with invasiveness in Acacia .
Aim A range of approaches and philosophies underpin national-level strategies for managing invasive alien plants. This study presents a strategy for the management of taxa that both have value and do harm.
Location South Africa.
Methods Insights were derived from examining Australian Acacia species in South Africa (c. 70 species introduced, mostly > 150 years ago; some have commercial and other values; 14 species are invasive, causing substantial ecological and economic damage). We consider options for combining available tactics and management practices. We defined (1) categories of species based on invaded area (a surrogate for impact) and the value of benefits generated and (2) management regions based on habitat suitability and degree of invasion. For each category and region, we identified strategic goals and proposed the combinations of management practices to move the system in the desired direction.
Results We identified six strategic goals that in combination would apply to eight species categories. We further identified 14 management practices that could be strategically combined to achieve these goals for each category in five discrete regions. When used in appropriate combinations, the prospect of achieving the strategic goal will be maximized. As the outcomes of management cannot be accurately predicted, management must be adaptive, requiring continuous monitoring and assessment, and realignment of goals if necessary.
Main conclusions Invasive Australian Acacia species in South Africa continue to spread and cause undesirable impacts, despite a considerable investment into management. This is because the various practices have historically been uncoordinated in what can be best described as a strategy of hope. Our proposed strategy offers the best possible chance of achieving goals, and it is the first to address invasive alien species that have both positive value and negative impacts.
Aim Anthropogenic introductions of Australian Acacia spp. that become classed as alien invasive species have consequences besides the physical, spatial and ecological: there are also cultural, ethical and political considerations that demand attention from scholars in the humanities and social sciences. As practitioners in these disciplines, our aim is to reflect upon some of the social and conceptual ideas and attitudes relating to the spread of Australian Acacia spp. around the world. We therefore provide a longer‐term historical and philosophical perspective using South Africa as a key example. We explain some of the cultural aspects of Australian acacias, relating them to history, philosophy and societal ideas that were once, or indeed remain, important, either regarding their exportation from Australia or their importation into other countries. Focussing principally on South Africa and Australia but including brief references to other locations, we augment the literature by making connections between acacia introductions and environmental ethics and aesthetics, national and environmental history and symbolic and other discourses. We evaluate a number of the cultural and philosophical dimensions of invasion biology as a societal response and explicate the interesting contradiction of Australian acacia introductions as simultaneously economically valuable and environmentally transformative in South Africa.
Location South Africa, Australia, with references to other parts of the world.
Methods This paper has been written by an interdisciplinary team (two historians, two geographers, a philosopher and an ecologist) and is conceptual and historical, conforming in language and structure to the humanities style. It relies on published and unpublished literature from this disciplinary domain and the critical evaluation of these sources.
Results Many Acacia spp. from Australia have been introduced around the world, generally guided in different eras by a variety of overarching mindsets, including the colonial ethos of ‘improvement’ (1800s to mid 1900s), an economically driven mindset of ‘national development’ (1900s), by a people‐centred frame combining concerns of environment and livelihood in ‘sustainable development’ (1980s onwards), and an aesthetic ethos of ornamental planting that surfaces in all periods. The newest ethos of controlling or managing alien invasive species, a normative attitude deriving from the burgeoning of invasion biology, has more recently shaped the ideology of these plant exchanges and sharpened the focus on species that may be simultaneously both weeds and commercially valuable crops. Our perspective from the humanities and social sciences calls for a more transparent approach that clearly acknowledges such contradictions.
Main conclusions We conclude that the global experiment of human‐mediated Australian acacia introductions raises a number of issues that reflect changing societal concerns and demand attention from scholars in disciplines apart from the natural sciences. Here we highlight the impact of historical context in plant exchanges, the history and philosophy of science as it relates to invasion biology, and changing – sometimes divisive – societal priorities in terms of aesthetic, economic and conservation values. In particular, the case of Acacia spp. in South Africa highlights the contradictory aspects of introductions in that some species are both commercially important and environment‐altering invasive plants. We argue that the contribution of disciplines beyond ecology to the debates about the invasive status of acacias enlarges our understanding and provides useful insights for botanists, foresters, managers and policy makers.
Aim Many Australian Acacia species have been planted around the world, some are highly valued, some are invasive, and some are both highly valued and invasive. We review global efforts to minimize the risk and limit the impact of invasions in this widely used plant group.
Location Global.
Methods Using information from literature sources, knowledge and experience of the authors, and the responses from a questionnaire sent to experts around the world, we reviewed: (1) a generalized life cycle of Australian acacias and how to control each life stage, (2) different management approaches and (3) what is required to help limit or prevent invasions.
Results Relatively few Australian acacias have been introduced in large numbers, but all species with a long and extensive history of planting have become invasive somewhere. Australian acacias, as a group, have a high risk of becoming invasive and causing significant impacts as determined by existing assessment schemes. Moreover, in most situations, long‐lived seed banks mean it is very difficult to control established infestations. Control has focused almost exclusively on widespread invaders, and eradication has rarely been attempted. Classical biological control is being used in South Africa with increasing success.
Main conclusions A greater emphasis on pro‐active rather than reactive management is required given the difficulties managing established invasions of Australian acacias. Adverse effects of proposed new introductions can be minimized by conducting detailed risk assessments in advance, planning for on‐going monitoring and management, and ensuring resources are in place for long‐term mitigation. Benign alternatives (e.g. sterile hybrids) could be developed to replace existing utilized taxa. Eradication should be set as a management goal more often to reduce the invasion debt. Introducing classical biological control agents that have a successful track‐record in South Africa to other regions and identifying new agents (notably vegetative feeders) can help mitigate existing widespread invasions. Trans‐boundary sharing of information will assist efforts to limit future invasions, in particular, management strategies need to be better evaluated, monitored, published and publicised so that global best‐practice procedures can be developed.
Aim This study reports on the contribution of the Australian Tree Seed Centre (ATSC) to the international dissemination of Australian acacias. It also describes the current uses and the scale of economic benefits derived from planting Australian acacias, and speculates about possible future trends in usage. This information is crucial for the evaluation of overall human-mediated transfers of Australian acacias as a global experiment in biogeography.
Location Australia and Global.
Methods ATSC databases were used to determine which taxa were sent to which regions of the world and in what numbers. Location, scale and value of uses of the most important species were described from a review of published and grey literature, and we drew on our collective experience to speculate about future trends.
Results The ATSC despatched samples of 322 taxa (or roughly a third of Acacia species native to Australia) between 1980 and 2010 to 149 countries. Plantations in SE Asia and South Africa supplying the pulp and paper industry cover an area of over 2 M ha and produce pulp worth around $US4.3B p.a. In SE Asia, pulpwood species also provide logs for an expanding industry based on solid wood product. Tannin is produced from Acacia mearnsii in South Africa and Brazil. A suite of multi-purpose species helps meeting the demand for food, fodder, fuelwood, poles and site amelioration in dry zone regions of Africa and elsewhere and are widely incorporated into agro-forestry systems. Acacia saligna is the most widely planted non-timber species with around 600,000 ha established worldwide. Many acacia species also have horticultural uses particularly in Europe.
Main conclusions The ATSC has been the major agent for systematic exploration and worldwide dissemination of Australian acacias over the past 30 years, but seed from local and regional sources of exploited species will dominate future movements. The scale of production from currently planted species will expand to meet the demands of population growth, using improved varieties. Plantations for energy and carbon sequestration might become increasingly widespread.
Aim Australian acacias (1012 recognized species native to Australia, which were previously grouped in Acacia subgenus Phyllodineae ) have been moved extensively around the world by humans over the past 250 years. This has created the opportunity to explore how evolutionary, ecological, historical and sociological factors interact to affect the distribution, usage, invasiveness and perceptions of a globally important group of plants. This editorial provides the background for the 20 papers in this special issue of Diversity and Distributions that focusses on the global cross‐disciplinary experiment of introduced Australian acacias.
Location Australia and global.
Methods The papers of the special issue are discussed in the context of a unified framework for biological invasions. Distributions of species were mapped across Australia, their representation in bioclimatic zones examined and the potential global distribution of the group modelled. By collating a variety of different lists, we determined which Australian acacias have reached different stages in the introduction‐naturalization‐invasion continuum in different parts of the world. Paradigms and key research questions relating to barriers to invasion, stages of invasion and management perceptions are sketched.
Results According to our global database of Australian acacia records, 386 species have been moved outside Australia by human agency, 71 species are naturalized or weedy, and 23 are unequivocally invasive. Climatic models suggest that about a third of the world’s land surface is climatically suitable for Australian acacias. Many species are commercially important crops or are useful for other purposes and have been extensively planted, and many different human perceptions of Australian acacias exist in different parts of the world. The papers in the special issue cover all the barriers, stages and processes that define biological invasions and touch on many aspects: history and the human dimension; aspects of the species pool; species traits; biotic interactions; climate and niche; and management.
Main conclusions Australian acacias are an excellent model group for examining interactions between evolutionary, ecological and socio‐economic drivers of species introductions. New insights have emerged on the biological, ecological and evolutionary correlates of naturalization and invasion, but human usage factors permeate all explanatory models. Understanding and managing introduced Australian acacias requires a fundamental and integrative appreciation of both intrinsic (e.g. species traits) and extrinsic (e.g. human usage and perceptions) aspects.
To determine annual litter production of regenerating forest areas in the Tigray highlands of northern Ethiopia monthly litter production was monitored over a two-year period in areas with varying degree of vegetation cover restoration. Total annual litter production varied from 30 to 425 g m−2 and increased significantly where areas were closed for a longer time. Litter production was depending on vegetation cover through an exponential relation and was influenced also by soil fertility. Leaf litter typically constituted between 70 and 85% of total litter production, while contributions of woody and reproductive litter varied according to species composition. Strong seasonality in litterfall was explained by pronounced seasonal variation in rainfall. Standing crop of litter built up once an area was closed for grazing, increasing from around 20 g m−2 in degraded grazing lands to nearly 600 g m−2 in an old exclosure. Litter accumulation was mainly determined by litter input, but was also influenced by litter quality, species composition and microclimate development in the restoring forest areas. A detailed study of nine dominant shrub and tree species revealed three distinct litter production patterns, corresponding to drought-deciduous species, evergreen species and (semi-)evergreen Acacia species respectively.
In 1922, the colonial government introducedAcacia mearnsii in the tobacco-growing region of Wonosobo. Soon this species was accepted by the local people who developed an agroforestry
system based on a rotation ofA. mearnsii and agricultural crops.
Now, the growing of the black wattle is becoming less popular. To study the prospects for this agroforestry system 143 farmers
from 5 villages were interviewed. The functions of this agroforestry system are the production of fuelwood and bark (which
contains tannin for the leather industry), soil conservation and soil improvement. The following factors affectA. mearnsii growing: population density (which affects farm size and demand for domestic fuelwood), tobacco-processing (which requires
fuel), topography and commercialization. If current trends continue, the contribution of the functions of this agroforestry
system to welfare will not be sufficient to compete successfully with subsistence and cash crops like potatoes and tobacco.
Therefore,A. mearnsii cultivation is expected to decline further.
Alien species that are desirable and commercially important in parts of the landscape, but damaging invaders in other parts, present a special challenge for managers, planners, and policy-makers. Objective methods are needed for identifying areas where control measures should be focussed. We analysed the distribution of forestry plantations and invasive (self-sown) stands of Acacia mearnsii and Pinus spp. in South Africa; these two taxa account for 60% of the area under commercial plantations and 54% of the area invaded by alien trees and shrubs. The distribution of commercial forestry plantations and invasive stands of these taxa were mapped and the data was digitised and stored as Geographic Information System (GIS) (Arc/Info) layers. A series of environmental parameters were derived from GIS layers of climate, topography, geology, land use, and natural vegetation. The current distribution of the two taxa was subdivided into three groups according to the degree of invasion, planting history and the precision of the data collection. We used regression-tree analysis to relate, for each taxon, the distribution of invasive stands with environmental variables, and to derive habitat suitability maps for future invasion. The current distribution of invasive stands in South Africa was largely influenced by climatic factors. At a national scale, the distribution of large commercial plantations was a poor predictor of areas invaded by both taxa. Using environmental factors identified by the regression trees, we found that 6.6% and 9.8% of natural habitats currently not invaded and untransformed by urbanisation or agriculture are suitable for invasion by Pinus spp. and A. mearnsii, respectively. We then derived guidelines for policy on alien plant management based on vegetation type, degree of transformation, extent of invasion, and the risk of future alien spread. These factors were used to identify demarcated areas where these alien species can be grown with little risk of invasions, and areas where special measures are needed to manage spread from plantations.
Plantation forests not only impact carbon and water cycles, but also affect biodiversity, livelihoods, and shape regional
economies. Each of these impacts differs across varying scales of analysis. This paper illustrates how forest, climate change
and hydrology debates play out in the context of the forest plantations of Australian black wattle (Acacia mearnsii) in the upper Palni hills of southern India. We outline the contradictory perspectives of different local groups regarding
the impact of plantations on catchment hydrology and water availability, and examine these in relation to changes in the regional
economy and rainfall patterns. Our analysis indicates that changes in these two factors have played a more significant role
than existing wattle plantations in affecting local and regional water availability. We suggest that ongoing debates regarding
forest plantation–hydrology–climate change relationships need to broaden their scope to include changes in regional rainfall
patterns and shifts in regional economic activity. This approach is likely to provide a more realistic assessment of plantation
forests in a dynamic regional context, and offer more resilient strategies for regional landscape and catchment management
under conditions of high variability in rainfall patterns.
KeywordsPlantation forests-Social perspectives and debates-Kodaikanal (Tamil Nadu, India)-
Acacia mearnsii
-Catchment hydrology-Regional climate change
Very few Australian acacias were introduced into dry tropical Africa before 1970. Thanks in large measure to a seed collection made by the Centre Technique Forestier Tropical (CTFT) in North and West Australia, about 50 species are now undergoing trials in Burkina Faso, Cameroon, Niger, Senegal and to a lesser extent in Cape Verde, Mali, and Mauritania. The largest number of experiments in the last ten years have been in Senegal, where about 50 trials with more than 40 different species have been undertaken. Initial results show that on the whole these species are sensitive to drought conditions. This behavior is undoubtedly related to the essentially coastal origin of the plant material that has been introduced so far, and the most encouraging results have been obtained in coastal test sites in Senegal. The species distinguishing themselves by good performance in this zone are Acacia coriacea, A. schlerosperma and to a lesser extent itA. bivenosa for resistance to drought, and potential for prevention and control of erosion; and A. holosericea, A. trachycarpa, A. tumida for high productivity and fodder value. A. tumida is still only adapted to a restricted number of sites because of its particular sensitivity to drought.In September-October 1984 the CTFT, in collaboration with the Commonwealth Scientific and Industrial Research Organization (CSIRO), made a new seed collection in the interior semiarid and arid regions of Australia between 16° and 21° South latitude. Thirty-eight species totaling 78 provenances were collected and introduced into West Africa, combined with rhizobium inoculation trials. The first results of these tests are promising, and continued work in this area should allow the selection of genetic material capable of both good performance and better drought resistance.
Plants are frequently moved around the world, creating new regional landscapes and environmental imaginaries. Building on previous work in environmental history and geography, we develop a three-part approach to analyzing plant movements and apply it to trees from the Acacia genus (sens. lat.) exchanged between Australia and the rest of the world. First, we investigate the agents, circuits, and frequencies of acacia movements, including transoceanic transfers, regional diffusion, and ecological dispersal. Second, we trace bundles of knowledge or technology that accompany the acacias, highlighting how they help shape regional biogeographies. Finally, we analyze how different societies, with distinct economies, politics, and environmental sensibilities, receive introduced plants. This approach allows us to see transferred plants as active agents in region-forming processes, and to avoid normative tropes like ‘miracle plants’ or ‘alien invasives’. The highlighted species include Acacia colei, Acacia melanoxylon, Acacia mearnsii, Acacia farnesiana, Acacia nilotica, Acacia mangium, and their close relatives.
The release of biological control agents for the control of environmental weeds is often resisted by parties which utilize these plants. This conflict is difficult to resolve because of the social, economic and ecological complexities involved. We construct an ecological-economic model to simulate the complex dynamics of the release of a biological control agent with the aim of developing a tool which can be used to facilitate conflict resolution in such situations. The model is applied to an environmental weed which has invaded the lowland fynbos ecosystems of South Africa, Acacia saligna; its biological control agent, Uromycladium tepperianum; and a commercially desirable indigenous wildflower plant, Protea repens. The model is parameterized using data from field studies and a number of management scenarios are investigated. The analysis indicates that the benefits of biological control have the potential to outweigh the costs, if the opportunities provided by the biological control agent are exploited. It is concluded that ecological-economic models have much potential for facilitating conflict resolution.
An investigation into the spread of two alien wattle species (Acacia mearnsii and Acacia dealbata) in rural parts of the Drakensberg region of South Africa and the importance of the trees to the livelihoods of the local communities was carried out. With the aid of aerial photography two plots near the village were selected. Wattle aerial cover increased from 7% and 20% in the two plots, respectively, in 1953, over 21% and 33% in 1975, to 48% and 58% in 2000. In 1995, a government-sponsored national programme, “Working for Water” was established, with the expressed purpose of employing people described as being from the poorest and disadvantaged rural communities to clear areas of invasive alien species from river catchments and water courses. Whilst the programme provides an income to thousands of families in rural areas, it may also be jeopardising the livelihoods of the same communities.
The olive (Olea europaea) and the wattles (mimosas or Acacia spp.) are typical tree species of the Mediterranean and Australia, respectively. Both trees have been subject to trans-oceanic movements, including the introduction of Mediterranean olives to Australia, and the introduction of Australian wattles to the Mediterranean. In each case, the trees have naturalised and become problematic invasives. Based on case studies of such movements, we compare and contrast the processes of transfer, dispersal, and genetic changes of these trees, with particular attention to crop–feral–wild complexes in both their home ranges and in introduced areas. Contrasting ecological, social, and economic landscapes shape the possibilities for crop–feral–wild interactions and for invasiveness.
Since the early 1980s several new approaches towards forest management, which include active participation of local communities, have been tried out in many tropical regions. As a result of these efforts recognition has increased about the various ways in which many local communities are already actively managing their forest resources. The planning of development interventions to stimulate more efficient community involvement in forest management can often be based on such indigenous forest management systems. This paper aims to improve the understanding about the diversity and dynamics of indigenous forest management. The analysis consists of three parts. First an overview of the various types of indigenous forest management and their dynamics is presented. Subsequently, the basic principles of forest management are discussed. Forest management is characterized as involving a set of both technical activities and social arrangements for the protection and utilization of forest resources and the distribution of forest products. Three major categories of forest management practices are identified, e.g. controlled utilization of forest products, protection and maintenance of forest stands, and purposeful regeneration. The practices in the first category are both socially and biologically oriented, whereas the activities of the last two categories are biologically oriented. These principles are then used to develop a classification model of the various evolutionary phases in forest management. Along the lines of a similar model developed for exploitation of agricultural crops, various stages of forest management are distinguished along a gradient of increasing input of human energy per unit of exploited forest. This gradient represents a continuum of forest-people interactions; it illustrates how the various manifestations of indigenous forest management may be arranged along a nature-culture continuum.