No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Restoration of rain forest beneath pine plantations: A relay floristic model with special application to tropical South Asia
... However, this trajectory might differ for vegetation in plantations that are adjacent to other land-use types or primary forest (Gonzales & Nakashizuka 2010). For example, native forests beneath pine plantations in Sri Lanka reveal a dominance of pioneer and bird-dispersed species and conversely lower proportions of old-growth species (Ashton et al. 2014). Several old-growth species in Asia have poor dispersal abilities and also a larger seed size compared to the pioneer species (Gunatilleke & Ashton 1987, Osuri et al. 2017. ...
... Hence, succession guilds, dispersal guilds and seed size are interlinked (Russo et al. 2007). In this context, there are limited data from South Asia for an integrated structural and functional understanding of the facilitative roles of plantation forests (Ashton et al. 2014). ...
... The present work contributes towards bridging an important knowledge gap on the role of exotic tree plantations (other than pine) facilitating native forest regeneration in South Asia (Ashton et al. 2014). To our knowledge, this is the first study that evaluates both structural and functional aspects of regeneration in an Indian eucalyptus plantation landscape. ...
We monitored native forest regeneration over 11 y in a eucalyptus plantation and compared it with the neighbouring primary forest. For the plantation forest, we hypothesized that species richness, density, basal area and densities of old-growth species would increase over time, and compared to the primary forest, plantation forest would have higher species richness and density, but lower densities of old-growth species. In 2016, we repeated the protocol of a study that sampled the plantation forest in 2005, with thirty 10 × 10-m plots and enumerating trees (≥10 cm diameter), saplings (>1 to <10 cm diameter) and seedlings (<1 cm diameter). In the plantation forest, for trees, the species richness, density of gap, bird-dispersed and mammal-dispersed species increased by 67%, 156%, 116% and 238% respectively; whereas for saplings, density of gap, bird-dispersed and small-seeded species declined by 45.2%, 51% and 18.2% respectively over time; and seedling densities did not change across functional groups. Stand basal area increased by 80.1% in the plantation forest. The primary forest had 446% greater density of closed-canopy trees compared with plantation forest. Contrary to our prediction, the plantation forest did not accumulate significant densities of old-growth species over time, probably due to demographic filters that prevent them from attaining maturity.
... In addition, since forest fires have played an important role in driving the successional dynamics of the Himalayan forests (Brown et al. 2011;Joshi et al. 2013) they was specially assessed to evaluate the effect of fire on regeneration function of vegetation. According to Ashton et al. (2014) the most crucial component in promoting regeneration under pine canopy is protection from fire. Consequently a prolonged absence of fire, under a pine canopy, should lead to the regeneration of late-successional species in the presence of propagation units. ...
... High fire frequency in grasslands also inhibits the establishment of pine seedlings since they are vulnerable to fire when young. However, regular fires clearly hinder the establishment of late-successional tree species which are in general fire sensitive (see Ashton et al. 2014). If fires are absent for a longer time period, we find a relative increase in the density of late-successional oak species in pine and pine-oak forests (Fig. 6). ...
... The ability of pine to support the growth of native and late-successional species in the absence of disturbance has been established by past studies (e.g. see Onaindia and Mitxelena 2009;Ashton et al. 2014). Therefore, protection of pine stands from fire along with the assisted regeneration of oak under pine forest canopies can be utilized as a management tool to push the successional dynamic towards broadleaved oak forests in the study area. ...
We studied the influence of anthropogenic drivers on the distribution and regeneration of tree species in vegetation at different stages of succession from grasslands to oak forests in mid-montane Central Himalaya. We found fire, grazing, and lopping as the main factors hindering a progressive successional regime towards a late-successional oak community. Succession was studied in five vegetation formations (grasslands, pine, pine–oak, open oak, and dense oak), with similar site conditions, representing a theoretical successional sequence from early- to late-successional stages. A structured survey with uniform distribution of sampling plots in the five selected vegetation formations was conducted to gather information abut the vegetation communities. Early-successional grasslands and pine forests were found to harbour high densities of pine and oak seedling and sapling regeneration. However, recurring fires and chronic unsustainable levels of grazing in these vegetation formations obstructed progressive succession by eliminating regenerating seedling and saplings from the forest understorey. Similarly, in intermediate- and late-successional stages (including pine–oak, open oak, and dense oak), overexploitation of existing oaks trees via lopping and grazing of regenerating oak seedlings and saplings hampered oak regeneration and development. The possibility to convert pine forests into oak as well as the conservation of existing oak forests through controlled grazing and lopping are management options that can contribute to an enhanced functioning of forest ecosystems in the study area. We conclude that with strategic management that restricts the current anthropogenic disturbances, the extent of oak forest in the study area can be increased.
... Consequently, to continue providing the required protection services, they must be restored. This approach has been attempted in the tropics and its success in promoting secondary succession is highly site specific (Ashton et al., 2014). It is subjected to local climate and soils (Fimbel & Fimbel, 1996), plantation age (Lugo, 1992), proximity to seed sources and their dispersers (Keenan, Woldring, Irvine, & Jensen, 1997;Zanne & Chapman, 2001) and management systems (Wadsworth, 2008). ...
... Although vegetation traits responded to plot thinning, it was considerably less effective in promoting colonization. Low light availability is recognized as the primary barrier for restoration in pine plantations (Ashton, Gamage, Gunatilleke, & Gunatilleke, 1997;Gómez-Aparicio et al., 2009;De Abreu, de Assis, Aguirre, & Durigan, 2011;Ashton et al., 2014), but canopy removal also has secondary deterring effects as a probable cause of water stress due to higher air temperature and lower humidity, which lead to higher evaporative demands. Another negative effect of canopy removal is the increased vulnerability to opportunistic species, such as the locally important alien tree Syzigium jambos (rose-apple) (Baruch & Nozawa, 2014). ...
... Twenty (42.5 %) of the 47 species recorded thrive in the neighbouring montane forest (Baruch & Nozawa, 2014). Proximity to native vegetation is one of the major factors influencing restoration success (Zanne & Chapman, 2001;Chazdon, 2003;Ashton et al., 2014) and it was a main factor considered in the selection of the study site. Although Caribbean pine crowns are unattractive to bird and bat dispersers (Keenan et al., 1997;Goodale et al., 2014), plot clearings appeal to those feeding on the fruits of the early colonizers (e.g. the shrub Clidemia hirta in the study site; Navas, 2010), which may disperse other tree seeds into these cleared plots. ...
Pine plantations in the tropics are often employed to recondition eroded slopes from mudslides, as the
Pinus caribaea plantation that shields the Universidad Simón Bolívar campus in Caracas (Venezuela). However,
mismanagement of this plantation has led to its rapid degradation. The best option to maintain the protective
service is to restore the plantation and direct its successional trajectory towards the neighbouring montane forest.
Through experimental manipulation, we aimed to determine which factors block secondary succession and to
investigate their effects. Within the experimental constraints imposed by the plantation small area, we analysed
the effects of light and fertility limitation, litter accumulation and access to seed on plantation restoration. Light
availability was manipulated by clearing and thinning three 800 m2 main plots. Fertilization and litter removal
was applied to sub-plots within the light plots. Soils were analysed, microclimate was monitored and, for four
years, stem density, species richness and basal area were tallied. Our results showed that light accessibility was
the main factor deterring the successional trajectory of the plots, with varying grades of interaction with the
sub-treatments. By the end of the fourth year, the cleared plot showed the largest responses in all traits (triplicating
stem density and basal area and >20 times higher species richness). The main colonizers were Croton
megalodendron, Ocotea fendleri, and Clusia spp. all dominant trees in the nearby native forest. We concluded
that the results of this pioneer study, showed that small clearings, repeated in 3-4 year cycles are appropriate
for similar restoration schemes. This procedure would create a mosaic of vegetation patches at different successional
stages while protecting the slopes from erosion and increasing local biodiversity.
... Many of these lands outside of forest reserves and government lands are held privately by small-holders or commercial estates. Much of the private land as well as some government land has been abandoned and reverted to grass and fern (see Ashton et al., 2014). The most commercialized non-timber forest products (NTFP's) exploited from the remaining native forest in these two forest formations comprise medicinals (such as Coscinium fenstratum), cane (Calamus spp.) for artisanal work, resins for incense and fragrance (e.g. ...
... In circumstances like these, where little to no residual forest cover exists, establishing NTFP species within a new forest can be approached in two ways. The first approach is to establish a firetolerant, fast-growing, often exotic, pioneer tree plantation (pioneer trees of stem exclusion -Guild 3), that can shade out the invasive grass, fern or shrub, facilitating natural regeneration of NTFP's (Guilds 1-4) or allowing for NTFP species under plantings (Guilds 4-7) (see Ashton et al., 2014). ...
... This may be the only alternative if there is no nearby seed source from adjacent rain forest (Tomimura et al., 2012). NTFP vine's C. thwaitesii and C. fenestratum (Guild 4) establish well along the edges of canopy openings created within the pine (Ashton et al., 2014). Planted seedlings of C. urens (Guild 6) do best within the center of canopy openings of pine; and understorey trees and shrubs like E. cardamomum (Guild 5) do well beneath the pine canopy and along the edges of openings (see Ashton et al., 2014). ...
... Many of these lands outside of forest reserves and government lands are held privately by small-holders or commercial estates. Much of the private land as well as some government land has been abandoned and reverted to grass and fern (see Ashton et al., 2014). The most commercialized non-timber forest products (NTFP's) exploited from the remaining native forest in these two forest formations comprise medicinals (such as Coscinium fenstratum), cane (Calamus spp.) for artisanal work, resins for incense and fragrance (e.g. ...
... Former agricultural lands that have reverted to second growth are small-holder and commercial estates that originally cultivated plantation crops such as tea, rubber and coffee within the wet forest formations (mixed dipterocarp; evergreen dipterocarp; montane forests). In all these circumstances, when there is already some forest structure and composition present half the effort in NTFP species restoration has been avoided because of either the presence of a nearby seed source within the regrowth or because the regrowth structure provides the environmental protection needed for NTFP species establishment (see Ashton et al., 2014;Gunaratne et al., 2014). If appropriate the most economic Table 3 Guild categorization for some important native non-timber forest products in South Asia by evergreen and seasonal deciduous forest types. ...
... In circumstances like these, where little to no residual forest cover exists, establishing NTFP species within a new forest can be approached in two ways. The first approach is to establish a firetolerant, fast-growing, often exotic, pioneer tree plantation (pioneer trees of stem exclusion -Guild 3), that can shade out the invasive grass, fern or shrub, facilitating natural regeneration of NTFP's (Guilds 1-4) or allowing for NTFP species under plantings (Guilds 4-7) (see Ashton et al., 2014). ...
Rural communities have traditionally valued forests for a diversity of products and services, with timber serving a minor role. No-where has this diversity been greater than in tropical South Asia, and in particular south India and Sri Lanka. As economies advance towards full development and populations become increasingly urbanized, forests become increasingly valued for their services. National development generally occurs at differing rates in different regions, with rural forest dependent communities falling behind and pockets of poverty long remaining. The demand for ‘non-timber forest products’ (NTFPs) therefore changes from subsistence to monetary based values. Overall, though, forests have suffered an unprecedented decline with development in the tropics, especially in Asia. This necessitates restoration which takes account of the enrichment of economy, wellbeing and culture which forest products provide. Methods for such restoration, and the fundamental principles upon which these must rest, are presented for species yielding NTFP’s. In this paper we first review the history of NTFP species use within south India and Sri Lanka. Second we provide a description of the broad regional characterizations of the forest formations within this region in relation to their affiliated patterns of NTFP use and exploitation. We consider seven guilds as a way to categorize NTFP’s into autecological groups for application in restoration silviculture, and use it as a framework to suggest restoration protocols for South Asian forests. We use examples of scenarios based on experimental studies of NTFP’s in reforestation trials which take account of different social values and land tenures. We conclude with a call for further research.
... Many of these lands outside of forest reserves and government lands are held privately by small-holders or commercial estates. Much of the private land as well as some government land has been abandoned and reverted to grass and fern (see Ashton et al., 2014). The most commercialized non-timber forest products (NTFP's) exploited from the remaining native forest in these two forest formations comprise medicinals (such as Coscinium fenstratum), cane (Calamus spp.) for artisanal work, resins for incense and fragrance (e.g. ...
... Former agricultural lands that have reverted to second growth are small-holder and commercial estates that originally cultivated plantation crops such as tea, rubber and coffee within the wet forest formations (mixed dipterocarp; evergreen dipterocarp; montane forests). In all these circumstances, when there is already some forest structure and composition present half the effort in NTFP species restoration has been avoided because of either the presence of a nearby seed source within the regrowth or because the regrowth structure provides the environmental protection needed for NTFP species establishment (see Ashton et al., 2014;Gunaratne et al., 2014). If appropriate the most economic Table 3 Guild categorization for some important native non-timber forest products in South Asia by evergreen and seasonal deciduous forest types. ...
... In circumstances like these, where little to no residual forest cover exists, establishing NTFP species within a new forest can be approached in two ways. The first approach is to establish a firetolerant, fast-growing, often exotic, pioneer tree plantation (pioneer trees of stem exclusion -Guild 3), that can shade out the invasive grass, fern or shrub, facilitating natural regeneration of NTFP's (Guilds 1-4) or allowing for NTFP species under plantings (Guilds 4-7) (see Ashton et al., 2014). ...
Rural communities have traditionally valued forests for a diversity of products and services, with timber serving a minor role. Nowhere has this diversity been greater than in tropical South Asia, and in particular south India and Sri Lanka. As economies advance towards full development and populations become increasingly urbanized, forests become increasingly valued for their services. National development generally occurs at differing rates in different regions, with rural forest dependent communities falling behind and pockets of poverty long remaining. The demand for 'non-timber forest products' (NTFPs) therefore changes from subsistence to monetary based values. Overall, though, forests have suffered an unprecedented decline with development in the tropics, especially in Asia. This necessitates restoration which takes account of the enrichment of economy, wellbeing and culture which forest products provide. Methods for such restoration, and the fundamental principles upon which these must rest, are presented for species yielding NTFP's. In this paper we first review the history of NTFP species use within south India and Sri Lanka. Second we provide a description of the broad regional characterizations of the forest formations within this region in relation to their affiliated patterns of NTFP use and exploitation. We consider seven guilds as a way to categorize NTFP's into autecological groups for application in restoration silviculture, and use it as a framework to suggest restoration protocols for South Asian forests. We use examples of scenarios based on experimental studies of NTFP's in reforestation trials which take account of different social values and land tenures. We conclude with a call for further research.
... Restoration might also adopt "active" strategies to assist recovery or reconstruct degraded ecosystems, using interventions such as invasive species management and tree planting (Chazdon & Guariguata 2016;Atkinson & Bonser 2020). Studies have shown that an overstory of planted trees can contribute to overcoming recovery barriers by shading out competitors, attracting seed dispersers, and creating favorable microhabitats for regeneration and survival of native species (Ashton et al. 2014). ...
... Our findings support the hypothesis that increasing canopy cover can facilitate rainforest recovery by creating favorable microhabitats for tree regeneration (Holl et al. 2000;Ashton et al. 2014). Canopy cover contributed to explaining patterns of seedling density, diversity, and composition across plots, and was positively associated with regeneration of late-successional species, but not early-successional species. ...
Restoration of canopy cover through tree planting can assist in overcoming barriers to natural regeneration and catalyze recovery of degraded tropical forests. India has made international pledges to restore millions of hectares of degraded forests by 2030, but lacks empirical research on regeneration under different types of planted and natural overstories to guide this mission. We conducted a field study (65 plots of 25 m²) to examine the influence of overstory type and canopy cover on naturally regenerating tree seedlings across degraded rainforests (DR), mixed-native species ecological restoration sites (ER), monoculture eucalypt plantations (MP), and mature “benchmark” rainforests (BR) in the Western Ghats mountains of peninsular India. ER had higher native tree seedling densities and recovered community composition towards BR levels compared to DR, while communities in MP shifted in the opposite direction. Densities of native late-successional species increased with canopy cover (particularly in ER), but greater canopy cover was also associated with increases in alien species, a few of which are shade-tolerant. Further, in a nursery experiment comprising four rainforest species, seed germination and early survival increased with shade, but did not vary across soils originating from DR, ER, and MP. Our findings show that while improving canopy cover is important, doing so by planting diverse native species, and controlling invasive alien species, can benefit rainforest recovery in degraded rainforest fragments. Conversely, planting non-native monocultures in degraded forests, which is a prevalent practice in India, could prove counterproductive for forest recovery in the long term.
This article is protected by copyright. All rights reserved.
... Under ERC regulations, concessionaires may develop native timber or NTFP plantations on a portion of their land. While this approach may seem counterintuitive to forest restoration, using agroforestry and multispecies silvicultural approaches to integrate NTFP production or fast-growing timber species with restoration can be an efficient means of generating short-term income and achieving restoration goals (Ashton et al. 2014;Brancalion et al. 2017;Maier Ferreira et al. 2018). Indeed, our economic analysis showed that combining commodity crops, such as rubber or bamboo, with native trees that have a commercial timber value was the best-performing business model for ERCs (Table 2). ...
... However, one potential disadvantage of the concession approach is that it may be perceived in association with a state's historical usurpation of forest assets from local people (Barr and Sayer 2012). Consequently, legitimizing restoration concessions in the eyes of local stakeholders would (Ashton et al. 2014). The pine trees act as nurse trees to the young native seedlings, thereby enhancing their survival and growth rates. ...
Logging has depleted timber resources across a considerable portion of the world's tropical forests, leaving them vulnerable to conversion to other land‐use types. This raises the question of whether management for restoration represents an economically viable alternative. We reviewed restoration concessions (areas of degraded state forest land leased to enterprises on long‐term [≥60‐year] licenses for restoration‐compatible business development) in Indonesia since their introduction in 2004 and found that, although many opportunities and actions are being explored, business models remain largely aspirational. Costs – including those associated with taxes and reporting, forest protection, community development, and restoration interventions – are high, while developing revenues at sufficient scale from carbon markets, non‐timber forest products, and ecosystem services is challenging. Potential solutions include the development of restoration‐compatible revenue streams and value‐added processing to generate income, investment in communities to bring them in as partners in restoration enterprises, and creation of a supportive regulatory environment by reducing statutory costs and eliminating perverse regulations. Restoration concessions are a scalable policy option for promoting private investment in restoration that could be replicated internationally to help meet ambitious global restoration targets.
... Several tropical forest studies have endorsed forest plantations as a viable option for reforesting or rehabilitating deforested landscapes, especially where invasive grasses or ferns pose a barrier to natural regeneration (Lugo, 1997;Campoe et al., 2010). This is primarily due to their generally rapid growth, high biomass accumulation (Omeja et al., 2011;Brancalion et al., 2019), and inherent ability, in many cases, to facilitate the regeneration of native tree species in their understories through modification of both physical and biological site conditions (Keenan et al., 1997;Parrotta et al., 1997;Butler et al., 2008;Baatuwie et al., 2011;Ashton et al., 2014;Pryde et al., 2015;Amazonas et al., 2018). These two forest types (plantations and secondary forests) are increasingly widespread and the dominant forms of tropical reforestation, thus stimulating comparison of their respective values Gilman et al., 2016), especially their relative climate change mitigation potential (Griscom et al., 2017). ...
... Furthermore, another factor may have been the active establishment in monocultures at relatively wide spacing (5 m × 5 m), which supported stem radial and apical growth, thus enabling the seedlings to circumvent initial biotic and abiotic hurdles to establishment, likely to be encountered by the naturally regenerating secondary forest stands. Additionally, the four selected tree species (Cedrela odorata, Aucoumea klaineana, Terminalia ivorensis, Tarrietia utilis) appeared to have facilitated the colonization of their stands by ameliorating and causing spatial and temporal variability in site conditions through early canopy formation and shading out of competing lightdemanding grasses and shrubs, thus serving as nurse crops for colonizing woody recruits (Parrotta, 1992;Ashton et al., 1997;Keenan et al., 1997;Lugo, 1997;Parrotta et al., 1997;Chapman & Chapman, 1999;Otsamo, 2000;Zanne & Chapman, 2001;Janzen, 2002;Butler et al., 2008;Farwig et al., 2009;Viani et al., 2010;Baatuwie et al., 2011;Omeja et al., 2011;Appiah, 2012;Ashton et al., 2014;Pryde et al., 2015;Viani et al., 2015a,b;Brancalion & van Melis, 2017;Brancalion et al., 2019), which contributed to overall stand AGC. Trees that provide medium shade or have dispersed crowns with rapidly decomposing leaf litter generally tend to create understorey micro-conditions suitable for germination and establishment of woody recruits, and thus serve as good nurse trees (Otsamo, 2000). ...
High deforestation rates, especially in the tropics, currently result in the annual emission of large amounts of carbon, contributing to global climate change. There is therefore an urgent need to take actions to mitigate climate change both by slowing down deforestation and by initiating new sinks. Tropical forest plantations are generally thought to sequester carbon rapidly during the initial years but there is limited knowledge on their long-term potential. In this study, we assessed the carbon sequestration in old (42–47 years) timber plantations of Aucoumea klaineana, Cedrela odorata, Tarrietia utilis, and Terminalia ivorensis, and secondary forests of similar ages, by comparing their basal areas and above-ground carbon stocks (AGC) to that of nearby primary forests. Additionally, we estimated and compared timber volume and stumpage value in the three forest types.
Systematic random sampling of ninety-three 20 m × 20 m plots in eleven forest sites (2 secondary forests, 2 primary forests, and 7 timber plantations) was undertaken to determine the effect of forest type on AGC, basal area, timber volume, and stumpage value.
After 42 years of growth, mean AGC of the timber plantations (159.7 ± 14.3 Mg ha⁻¹) was similar to that of primary forests (173.0 ± 25.1 Mg ha⁻¹) and both were significantly higher than the mean AGC of the secondary forests (103.6 ± 12.3 Mg ha⁻¹). Mean basal area and timber volume of the timber plantations and secondary forests were similar to that of the primary forests, though in each case the timber plantations had significantly higher values compared to the secondary forests. Mean timber value of the plantations ($8577 ha⁻¹) was significantly higher than both secondary ($1870 ha⁻¹) and primary forests ($3112 ha⁻¹). Contrary to our expectations, naturally regenerated trees (woody recruits) within the timber plantations had similar AGC levels, basal area, timber volume, and value compared to the secondary forests.
Long-rotation tropical forest plantations under low-intensity management could achieve higher AGC levels and thus have higher climate change mitigation potential and timber values compared to naturally regenerated secondary forests, and are able to reach values similar to primary forests. Monoculture timber plantations could facilitate the successful colonization of their understoreys by native woody recruits that contribute considerably to stand AGC and timber values. Long-rotation forest plantations in the tropics therefore have a critical role to play in forest rehabilitation and climate change mitigation while having the potential to provide modest financial returns to landowners through selective harvesting of timber and/or payments for carbon sequestration.
... This species is used for its timber, pulp, and resin, it is resilient to fire, and is effective at soil stabilization (Critchfield and Little, 1966). In addition, several studies on Caribbean pine plantations suggest it can improve soil water holding capacity and fertility of degraded soils formerly used for agriculture (Ashton et al., 2014b). ...
... This rhizomatous fern mostly reproduces via vegetative cloning through is roots. Kekilla fernlands are fire dependent and often burned by people repetitively (Ashton et al., 2014a(Ashton et al., , 2014b. Fire kills most of the fire sensitive rain forest regeneration that might establish; but post-fire, Kekilla fern re-sprouts and grows prolifically shading out any regeneration that might establish. ...
... Two restoration trials using different silvicultural prescriptions were conducted to determine the potential for converting Pinus caribaea plantations to mixed-species stands in the Sinharaja Man and the Biosphere Reserve and Hantana Environmental Protected Area in Sri Lanka (Ambagahaduwa et al. 2009, Ashton et al. 2014b. Pinus caribaea was planted in the Hantana Mountain range between 1980 and 1985 by the Forest Department under the upper Mahaweli water catchment reforestation project. ...
... In contrast, mixed-species plantations based on native trees have been found to be more productive and sustainable plantation systems over monocultures [18][19][20]. Thus, mixed-species plantations using indigenous species are increasingly being considered for sustainable reforestation and used worldwide to restore disturbed and degraded areas [18,[21][22][23][24]. Many native species have proven ability to grow well in deforested sites and have higher growth rates than introduced species [25]. ...
Plant species confirmation is a crucial step in using native plant species for forest restoration. To enhance this, a hybrid method of DNA barcoding and high-resolution melting analysis (Bar-HRM) was investigated in this study. In total, 12 native plant species samples were collected from forest restoration sites in Nan, a province in Northern Thailand. Simulation HRM analysis was performed to find the most appropriate region for in vitro Bar-HRM analysis. After that, in vitro Bar-HRM was carried out to validate the performance of native plant species. Results from both simulation and in vitro analyses revealed that the nuclear ribosomal internal transcribed spacer (ITS) region can be used as a primer set that can clearly discriminate native plant species in this study. With our study, Bar-HRM was proved of use in native plant species confirmation, even if that species had no molecular data available. In this context, Bar-HRM would be useful for the identification of native plant species used in tropical forest restoration not only in Thailand but also in any areas with similar plant groups.
... Forest plantations in the tropics reportedly catalyze secondary successional processes and facilitate the recolonization of native flora in their understories (Lugo, 1992;Parrotta, 1992;Ashton et al., 1997;Keenan et al., 1997;Lugo, 1997;Ashton et al., 2014;Pryde et al., 2015;Brancalion et al., 2019;Brown et al., 2020). However, not much is known regarding the composition, structure, diversity, successional status, and conservation value of such recruits. ...
Considering the high rate of primary forest degradation and loss in the tropics, the ability to conserve plant diversity within alternative forest landscape components is critical to biodiversity conservation. This study compares the restoration potential of old forest plantations and secondary forests. We assessed and compared the floristics, plant species diversity, conservation value, and structure of old (42–47 years) timber plantations of Aucoumea klaineana Pierre, Cedrela odorata L., Tarrietia utilis Sprague, and Terminalia ivorensis A. Chev. and similar-aged secondary forests with nearby primary (old-growth) forests in the moist and wet forest zones of Ghana.
We established a systematic sampling set-up of ninety-three 20 m × 20 m plots in total on 11 sites, with smaller nested subplots for saplings and ground vegetation.
The floristic composition of the plantation and secondary forest stands were similar to that of the primary forests, with many rare and restricted-range species shared by the three forest types. Approximately 77% and 60% of primary forest plant species also occurred in plantation and secondary forests, respectively. Species diversity, measured by the Shannon-Wiener Diversity Index (H’) and Simpson Index (S), for the primary forest (H’=3.07, S = 0.91) was not statistically different from the plantation (H’=2.85, S = 0.87) or secondary (H’=2.95, S = 0.88) forests. Overall, species richness was higher in the primary and secondary forests compared to the plantations. At the tree stratum (≥10 cm DBH), the assessed diversity indices were significantly different between the primary forest and the plantations. However, such differences did not exist among the saplings (10 cm > DBH ≥ 2 cm) and ground vegetation (<2cm DBH). The plantations and secondary forests were similar to the primary forests for all the structural characteristics assessed. However, basal area and bole volume were significantly higher in the plantations compared with secondary forests. Conservation value (using Genetic Heat Index as an indicator) was highest in one of the C. odorata plantations (W-CO).
Our study demonstrates that plantation and secondary forests can develop into structurally complex and floristically diverse self-organized stands similar to primary forests. Passive conversion of plantations to more natural ecosystems is an effective and low-cost forest restoration strategy leading to diverse ecosystems with high conservation value.
... Forest plantations in the tropics reportedly catalyze secondary successional processes and facilitate the recolonization of native flora in their understories (Lugo, 1992;Parrotta, 1992;Ashton et al., 1997;Keenan et al., 1997;Lugo, 1997;Ashton et al., 2014;Pryde et al., 2015;Brancalion et al., 2019;Brown et al., 2020). However, not much is known regarding the composition, structure, diversity, successional status, and conservation value of such recruits. ...
... Distance from seed source is among the most important factors that affect colonization of plantations by native tree species (Nagaike et al., 2012). Numerous studies have reported a positive correlation between forest vicinity and regeneration of native species (Bremer and Farley, 2010;Miren et al., 2013;Ashton et al., 2014;Chambers et al., 2016;Korb et al., 2019;Randriambanona et al., 2019). These studies have focused on the regeneration of natural tree species in the understory of plantations. ...
Forests have been planted over large areas during forest restoration programs in Northeast China. An important challenge is transforming forest species structure by allowing colonization of native species in plantations, especially under the present policy of limited logging intensity and near-natural management practices. However, research on the entire process of native tree species restoration and conversion of tree species structure over time remains limited. Therefore, a multi-year field study was conducted to document native tree species restoration in plantations and different open land-cover types in Chinese temperate forests. We evaluated native tree species restoration in plantations (n = 30) and different types of natural recovery in open areas (n = 50) as controls. The first survey was conducted in 1990, with plots sampled in plantations of age 4–30 years, and repeat surveys were conducted in 1993, 2004, and 2016. We compared the importance of abiotic and biotic factors in the different survey periods using the Random Forest algorithm for restoration outcome (i.e., presence of ‘large trees’ (DBH ≥ 5 cm) of natural tree species in plantations) and the changes in plantation tree species composition during the survey periods. The aim was to test our hypothesis that abiotic and biotic factors, such as topography, habitat, and distance from nearest forest (i.e., seed source), differ in importance under different restoration periods. The results revealed that the basal area of large trees was the most important variable for native tree species restoration in plantations over the entire survey period. Abiotic factors, such as elevation and slope, differed in importance and relevance in the different recovery periods to the restoration outcomes in plantations and open areas. Increase in distance from seed source had a negative effect on natural tree species restoration in plantations and different types of open areas. Although the correlation of distance from seed source to restoration outcomes is consistent during the entire survey period, the importance of distance from seed source varied along a chronosequence. Different forest management measures require implementation. As succession progressed, the dominance of planted tree species in plantations gradually decreased. Compared with passive natural recovery, active planting of seedlings in open land not only promotes the restoration of coniferous species that no longer exist in an area owing to excessive logging, but also promotes the restoration of other native tree species.
... Mallotus tetracoccus, M. peltata, Croton malabaricus, and Leea indica have been identified as light demanding tree species compared to shade tolerant species [39]. Light demanding trees include M. peltata, Alstonia macrophylla, Mangifera indica, S. cohinchinensis, and Leea indica facilitate regeneration of other tree species beneath their canopy [40]. In tea plantations, fast growing G. sapium (Jacq.) ...
Fragmented and degraded ecosystems should be restored to ensure the biological connectivity among fragmented forest landscapes. The tropical rainforests of Southwestern Sri Lanka are highly degraded and fragmented due to plantation agriculture and human settlements. However, the high spatial variation in environmental factors and ecosystem functions challenge the success rate of restoration interventions. The aim of this study was to assess the vegetation composition and stand structure in relation to the spatial variation in key soil physicochemical parameters in the Endane Biodiversity Corridor that links peripheral forest reserve to the Sinharaja Rainforest Complex (SRC). The site that extends over 24 ha was classified into five land-use categories (productive tea lands, marginal tea lands, scrub—abandoned three years ago, and two woodlands—abandoned 15 years ago) in which the vegetation composition, stand structure, and physicochemical parameters of soil were assessed and mapped. Results revealed that the Shannon diversity index in the scrub and the woodlands were higher than in the tea lands. The diversity among the secondary forest patches was similar. However, with a mean record of 14 species, the species richness was high in sites close to the SRC. In comparison to the SRC (358 Mg ha−1), there was a substantial potential to sequester more carbon in the restoration sites (12–108 Mg ha−1). While explaining 31% of abundance and species distribution, the ordination results revealed a close relationship of the soil parameters to vegetation composition and species abundance. The calculated coefficient variation values for soil parameters (TN, EC, Av.P, Ex.K, OC, and BD) were beyond 12%, indicating high or moderate soil spatial variability among the land use categories. Coefficient of variation for soil pH was estimated to be 9%, revealing low soil spatial variability among the land use categories. The maps of these soil parameters corresponded with the type of land use and fertilizer application to tea fields. The highest and the lowest total N contents were observed in the scrub and woodlands, respectively, which appears to be mediated by the relative composition of N-fixing trees between the two groups. Our results facilitate effective matching of sites to species for restoration of the Endane Biodiversity Corridor that may be replicated in similar restoration contexts in tropical Asia.
... East Asia, Australia and South Asia including India, Nepal and Sri Lanka [3,4,5]. This species is exotic to Nepal but the importance of this species has been increasing because of high price. ...
The Santalum album is becoming a popular income generating tree species in Nepal but its growth performance has not been assessed so far yet. Thus, this study was objectively conducted to assess mean annual increment, income from Santalum album and value chain analysis. The Private plantation of Pyuthan district was selected for the study site. The diameter and height of 450 plants were measured and their age was recorded. Total fifteen key informant interviews, forty five farmers’ interviews and one focused group discussion were conducted to collect primary data. The collected data were analyzed using descriptive and inferential statistics .Mean annual increment, price of Santalum album and contribution of Santalum album in total income were analyzed. The result showed that the highest mean annual diameter increment was 51.94 cm and lowest mean annual increment was 28.25cm, the highest mean height increment was 6.39 m and the lowest mean annual height increment was4.47m and the highest mean volume increment was 0.678 m3but the lowest mean annual volume increment was 0.134 m3. The estimated maximum range of annual income from Santalum album was US$ 221-530 which was 10-15% contribution in farmers annual income while minimum range of this was US$ 194-265 and it contributes<10%.The difference of the price of Santalum album between the farmers and users in Kathmandu was2200 times more.
... For example, studying successional dynamics in central Amazonian, Norden et al. (2011) found that differences in recruitment (caused by the species that first colonized) were the major drivers of alternative states. Other examples of studies have found that tropical forest restoration can use exotic trees as nurse plants to establish late successional tree species and speed up the recovery of forest functions (Ashton et al. 2014;Brancalion et al. 2020). In Costa Rica, planting tree seedlings in small patches has been proposed as a good alternative restoration method that facilitates forest recovery (Holl et al. 2011;Zahawi et al. 2013). ...
Priority effects refer to the order or timing of species arrival, including how species that arrive early at a site either positively or negatively affect establishment, growth, or reproduction of species that arrive later. Despite the clear implications of priority effects for ecological restoration, there have been no reviews of how and where priority effects have been studied and the extent to which findings can be applied to restoration. Here, we systematically review the literature on priority effects by (1) synthesizing information from papers that compared simultaneous and nonsimultaneous planting or sowing; (2) discussing the mechanisms through which priority effects operate, (3) considering how these mechanisms might be manipulated to achieve restoration goals; and (4) highlighting future research needed to improve the use of priority effects in restoration. In a term‐targeted search, we found 43 studies that experimentally manipulated the order of arrival of different species. Overall, these concluded that even small delays in arrival time, as opposed to simultaneous arrival of species, can promote differences in subsequent community composition as well as ecosystem functions. There were very few studies on the long‐term stability of these priority effects, and the majority were conducted in temperate grasslands. Our findings suggest that creating alternative vegetation states via priority treatments is a promising avenue for restoration. However, for the concept to be best operationalized for restoration, we need research in more ecosystems that are priorities for restoration, and treatments that are followed over extended time periods.
... there are other known factors that influence natural forest regrowth that we did not capture in our analysis. For example, residual vegetation can accelerate forest regrowth by providing roosting sites for seed-dispersers 38 or shade for late-successional species 39 . Others have observed an increased likelihood of regrowth near rivers or existing forest fragments, far from roads or on steep (less-accessible) slopes, and in areas protected from browsing [40][41][42][43] . ...
To constrain global warming, we must strongly curtail greenhouse gas emissions and capture excess atmospheric carbon dioxide1,2. Regrowing natural forests is a prominent strategy for capturing additional carbon³, but accurate assessments of its potential are limited by uncertainty and variability in carbon accumulation rates2,3. To assess why and where rates differ, here we compile 13,112 georeferenced measurements of carbon accumulation. Climatic factors explain variation in rates better than land-use history, so we combine the field measurements with 66 environmental covariate layers to create a global, one-kilometre-resolution map of potential aboveground carbon accumulation rates for the first 30 years of natural forest regrowth. This map shows over 100-fold variation in rates across the globe, and indicates that default rates from the Intergovernmental Panel on Climate Change (IPCC)4,5 may underestimate aboveground carbon accumulation rates by 32 per cent on average and do not capture eight-fold variation within ecozones. Conversely, we conclude that maximum climate mitigation potential from natural forest regrowth is 11 per cent lower than previously reported³ owing to the use of overly high rates for the location of potential new forest. Although our data compilation includes more studies and sites than previous efforts, our results depend on data availability, which is concentrated in ten countries, and data quality, which varies across studies. However, the plots cover most of the environmental conditions across the areas for which we predicted carbon accumulation rates (except for northern Africa and northeast Asia). We therefore provide a robust and globally consistent tool for assessing natural forest regrowth as a climate mitigation strategy.
... For example, studying successional dynamics in central Amazonian, Norden et al. (2011) found that differences in recruitment (caused by the species that first colonized) were the major drivers of alternative states. Other examples of studies have found that tropical forest restoration can use exotic trees as nurse plants to establish late successional tree species and speed up the recovery of forest functions (Ashton et al. 2014;Brancalion et al. 2020). In Costa Rica, planting tree seedlings in small patches has been proposed as a good alternative restoration method that facilitates forest recovery (Holl et al. 2011;Zahawi et al. 2013). ...
Priority effects refer to the order or timing of species arrival, including how species that arrive early to a site either positively or negatively affect establishment, growth, or reproduction of species that arrive later. Despite clear implications of priority effects on ecological restoration, to date there are no reviews of how and where priority effects have been studied and the extent to findings can be applied to restoration practice. Here, we survey the literature on priority effects and a) summarize patterns that are relevant to restoration; b) synthesize information on the mechanisms through which priority effects operate, and on how these mechanisms can be manipulated to achieve particular restoration goals; and c) highlight potential future research needed to improve use of priority effects in restoration. We found that even small delays in arrival time, as opposed to simultaneous arrival of species, can promote differences in subsequent community composition. Even so, there have been very few studies on the long-term stability of these priority effects, and the majority were conducted in temperate grasslands. Given the lack of information for other biomes, the general importance of priority effects, as well as its application to restoration, is unknown. Our findings suggest that creating alternative vegetation states via priority treatments might be a promising avenue to further explore, but that for the concept to be operationalized for restoration practice there is a need for research in the diverse types of ecosystems that are priorities for restoration and that occurs over longer time periods.
... The D. dyeri seedlings growing in the forest understory tended to have a lateral branching trait (S2C Fig), which allows maximum light capture in shade [88]. Our finding that D. dyeri seedlings occurred in sites with low light is consistent with previous research that concluded that the late-successional tropical seedlings in the Dipterocarpus genus are the most shade-tolerant genus in the Dipterocarpaceae family [42,[89][90][91]. ...
Understanding the requirements and tolerances of the seedlings of climax species is fundamental for tropical forest restoration. This study investigates how the presence and abundance of seedlings of a previously dominant, now threatened species (Dipterocapus dyeri Pierre), varies across a range of environmental conditions. Dipterocapus dyeri seedling abundance and site characteristics were recorded at 122 observation points (4 m²) at nine clusters from two sites. Seedling presence (p = 0.065) and abundance varied significantly (p = 0.001) between the two sites, and was strongly correlated with adult D. dyeri dominance and lower soil pH, and weakly correlated with canopy openness and total stand basal area. Dipterocarpus dyeri seedlings were also grown in shade houses with three light levels on two soils. Seedling survival was significantly lower at the lowest light level (<10% full irradiance) at 13% for the forest soil and 25% for degraded soil. At higher irradiance the seedling survival rates were greater than 99%. Moisture levels remained high at the lowest light level and many seedlings died from fungal infection. We concluded that secondary forests which contain adequate numbers of adult D. dyeri as seed sources, light availability, soil pH of < 5.0, and good drainage strongly favour survival and growth of D. dyeri seedlings. Historically, D. dyeri was dominant in moist deciduous tropical forest across south-eastern Vietnam, but today it is rare. Active management of these recovering forests is essential in order to recover this high-value, climax forest species.
... In East Kalimantan, plantation forests are used to facilitate the restoration of native forest on post-coal mine lands (Adman et al., 2012;Rinaldi & Yassir, 2017). Many studies have demonstrated that tree plantations can establish, ameliorate harsh environmental conditions, and facilitate succession of native secondary forest on degraded tropical landscapes (Kuusipalo et al., 1995;Lamb et al., 2005;Otsamo, 2000;Parrotta, 1995;Parrotta et al., 1997;Ashton et al., 2014). On Borneo, most of these lands were originally native mixed dipterocarp rain forests (Curran, 1999;Curran et al., 2004;Gaveau et al., 2014) that were repeatedly logged, then burned and cleared for plantation agriculture, and after This article is protected by copyright. ...
Land degradation in Borneo, one of the world's richest biodiversity hotspots, is extensive. In East Kalimantan, five million hectares of land are zoned for surface‐mined coal. Deforestation from this mining threatens biodiversity and results in soil degradation, erosion, and polluted runoff, all directly impacting human populations. Revegetation methods developed for temperate forests are commonly used globally for mine rehabilitation. However, few empirical studies of native forest restoration as part of mine rehabilitation exist from wet tropical regions. Here, a chronosequence was established to observe forest succession under leguminous plantations at the PT Singlurus Pratama coal mine in East Kalimantan, Indonesia. Soil and natural regeneration data were recorded from samples of ten 20 x 60 m plots randomly located in plantings aged 2, 7, and 9 years post‐mining. Linear models did not reveal greater soil pH, woody plant diversity, or soil phosphorus and nitrogen in older plantings. Rather, they showed higher soil carbon in older plantings, while nitrogen and pH were positively correlated with woody species diversity and abundance. Graminoids were less abundant but ferns were more abundant in older sites in an ordination analysis. The implications are exotic tree plantations shade‐out competitive understory herbaceous species (such as graminoids), opening growing space for other vegetation. However, the establishment of woody species is spatially limited possibly by differences in soil degradation among sites. Our results suggest that planting leguminous trees alone may not be sufficient to restore native forests and future management should conserve and facilitate the establishment of tropical forest topsoil.
... GLMM slopes were statistically different between AR and NR for all five responses. regrowth , increasing overstorey shade (Ashton et al. 2014), and the recovery of biotic processes such as pollination and seed dispersal (Kormann et al. 2016, de la Peña-Domene et al. 2016), but the impacts of these processes remain poorly understood. Forest recovery would also depend on the extent to which human disturbances such as pole cutting and fuelwood removal, which were recorded in a few of our restored sites (active and naturally regenerating) and are a common feature of tropical forests in human-dominated landscapes, can be effectively mitigated in the restored forest fragments. ...
Ecological restoration is a leading strategy for reversing biodiversity losses and enhancing terrestrial carbon sequestration in degraded tropical forests. There have been few comprehensive assessments of recovery following restoration in fragmented forest landscapes, and the efficacy of active versus passive (i.e., natural regeneration) restoration remains unclear. We examined 11 indicators of forest structure, tree diversity and composition (adult and sapling), and aboveground carbon storage in 25 pairs of actively restored (AR; 7–15 yr after weed removal and mixed‐native tree species planting) and naturally regenerating (NR) plots within degraded rainforest fragments, and in 17 less‐disturbed benchmark (BM) rainforest plots in the Western Ghats, India. We assessed the effects of active restoration on the 11 indicators and tested the hypothesis that the effects of active restoration increase with isolation from contiguous and relatively intact rainforests. Active restoration significantly increased canopy cover, adult tree and sapling density, adult and sapling species density (overall and late‐successional), compositional similarity to benchmarks, and aboveground carbon storage, which recovered 14–82% toward BM targets relative to NR baselines. By contrast, tree height–diameter ratios and the proportion of native saplings did not recover consistently in actively restored forests. The effects of active restoration on canopy cover, species density (adult), late‐successional species density (adult and sapling), and species composition, but not carbon storage, increased with isolation across the fragmented landscape. Our findings show that active restoration can promote recovery of forest structure, composition, and carbon storage within 7–15 yr of restoration in degraded tropical rainforest fragments, although the benefits of active over passive restoration across fragmented landscapes would depend on indicator type and may increase with site isolation. These findings on early stages of recovery suggest that active restoration in ubiquitous fragmented landscapes of the tropics could complement passive restoration of degraded forests in less fragmented landscapes, and protection of intact forests, as a key strategy for conserving biodiversity and mitigating climate change.
... Reports of restoration programs in the academic literature often do not provide adequate detail to critically analyse the seed distribution method or mechanism used. Many simply state the type of seed distribution technique with no further detail on the equipment or methods of direct seeding used (Mulligan 1996;King & Keeland 1999;Windsor et al. 2000;Bell 2001;Windsor & Clements 2001;Kiehl et al. 2010;Cole et al. 2011;Ashton et al. 2014). Others provide little to no specific detail as to how seeds were distributed (Allen et al. 2002;Mitsch et al. 2012). ...
The methods used to distribute seeds influence the success of a restoration project. We surveyed 183 restoration practitioners from across the globe with the aim of identifying common limitations to the effective use of mechanical direct seeding in large scale restoration practice to highlight avenues for design improvement to mechanised seeding equipment. Results from this survey show that direct seeding methods are commonly used for ecological restoration and agree with other studies that suggest the method can achieve results much quicker and cheaper than the alternative of distributing nursery grown tube stock. However, this study indicates that current mechanical direct seeding methods lack adequate control of seed sowing depth and spatial distribution and highlight that the inability to sow seeds of complex morphology over complex topography are common limitations to direct seeding. To improve restoration success engineering improvements to mechanical direct seeders used in large‐scale restoration should focus in particular on addressing issues of precision of delivery for diverse seed types and landscapes. This article is protected by copyright. All rights reserved.
... Forests are generally cleared in terms of shifting cultivation, leaving degraded areas of secondary vegetation (Styger et al., 2007). These habitats are of low ecological and productive value and are therefore not under further use (Styger et al., 2007;Ashton et al., 2014) but offer an excellent opportunity for reforestation approaches. ...
A majority of Madagascar's iconic lemurs (Primates, Strepsirrhini) is threatened with extinction due to anthro-pogenic activities like land use change (deforestation) and bushmeat hunting.
We used a multivariate approach combining land cover mapping, vegetation/degradation monitoring, the degree of anthropogenic disturbance and the status of forest protection by the local community to model their impact on lemur diversity, population densities and encounter rates within a rural area of lowland rain forest in northeastern Madagascar.
High mean annual deforestation rates (2.4%) were calculated since 1990, resulting in a landscape of small and isolated forest fragments. A limited number of eight lemur species belonging to five lemur families were encountered. Diurnal species were absent, while cathemeral lemurs avoided human disturbance. Small and nocturnal species were relatively abundant. Overall lemur diversity was best explained by forest size and a combination of disturbance and hunting. Encounter rates of three nocturnal taxa were influenced by forest size and habitat degradation. Community-level forest protection had no effect on lemur diversity, but coincided with lower levels of habitat degradation. Lemur population sizes were relatively small and only few forests remain that offer suitable habitats for viable populations.
We highly recommend external conservation NGOs to support local forest management by improving the existing community-based approach. Actions should include expansion of protected habitats to increase population connectivity (reforestation) and to decrease lemur disturbance by villagers. Without external support, the last remaining forest habitats will be devastated within a few years resulting in the local extinction of most lemur populations.
... Reforestation may involve trade-offs with alternative land uses, can incur high costs of establishment, and is more expensive than Avoided Forest Conversion (38). However, this conclusion from available marginal abatement cost curves ignores opportunities to reduce costs, such as involving the private sector in reforestation activities by establishing plantations for an initial commercial harvest to facilitate natural and assisted forest regeneration (39). The high uncertainty of maximum reforestation mitigation potential with safeguards (95% CI 2.7-17.9 ...
Significance
Most nations recently agreed to hold global average temperature rise to well below 2 °C. We examine how much climate mitigation nature can contribute to this goal with a comprehensive analysis of “natural climate solutions” (NCS): 20 conservation, restoration, and/or improved land management actions that increase carbon storage and/or avoid greenhouse gas emissions across global forests, wetlands, grasslands, and agricultural lands. We show that NCS can provide over one-third of the cost-effective climate mitigation needed between now and 2030 to stabilize warming to below 2 °C. Alongside aggressive fossil fuel emissions reductions, NCS offer a powerful set of options for nations to deliver on the Paris Climate Agreement while improving soil productivity, cleaning our air and water, and maintaining biodiversity.
... Native recolonization of non-forest land or natural regeneration in degraded forests are lower-cost alternatives to more intensive planting methods but require adequate seed sources, advance regeneration, or sprouts on-site or within effective dispersal distance (Ashton et al. 2014;Chazdon 2008;Vieira and Scariot 2006). Low-intensity methods are unreliable, however, if threatened by ungulate herbivory or competing vegetation. ...
The global magnitude of degraded and deforested areas is best approached by restoring landscapes. Heightened international perception of the importance of forests and trees outside forests (e.g., woodlands, on farms) demands new approaches to future landscapes. The current need for forest restoration is two billion ha; most opportunities are mosaic restoration in the Tropical and Temperate Zones where human pressure is moderate. A rapidly changing global environment introduces uncertainty, however, that questions the usefulness of success criteria based on present or past ecosystems conditions. Considerable uncertainty arises from future climate and the timing of significant departures from current conditions, social system responses to drivers of global change, and ecosystem responses to changes in coupled socio-ecological systems. Three active approaches to reducing vulnerability and increasing adaptive capacity (incremental, anticipatory, transformational adaptation) differ in their future orientation but share similar objectives of favoring genotypes adapted to future conditions; resisting pathogens; managing herbivory to ensure adequate regeneration; encouraging species and structural diversity at the stand-level, landscape-level, or both; and providing connectivity and reducing fragmentation. Integrating attempts to restore landscapes and mitigate and adapt to climate change may synergistically increase adaptive capacity. Behavioral, institutional, and/or social barriers to implementing change can stop or delay adaptation. Stratagems for overcoming these barriers include conducting “risky” research that pushes the bounds of knowledge and practice and developing plant materials adapted to future conditions. © 2015, Springer Science+Business Media Dordrecht(outside the USA).
... The increased survival of J. pyriformis and O. mexicana under the P. patula canopy suggests the presence a process of facilitation and provides valuable practical information with which to assist programs of reintroduction of intermediate and late-successional state species that are threatened, endangered or of commercial interest. This recalls the findings of Moles and Drake (1999), Pausas et al. (2004), Urbieta et al. (2011) and Ashton et al. (2014) who indicate that pine plantations may be a suitable habitat for the incorporation of native species, by mitigating the adverse effect of physical disturbances and factors of environmental stress. In short, the viability of pine plantations as a substitute or alternative habitat for the native species may be determined (Carnus et al. 2006; Brockerhoff et al. 2008). ...
Coniferous plantations have been widely used by reforestation programs seeking to mitigate the effects of deforestation in mountainous areas in different parts of the world. However, some studies show that pine plantations can simulate natural mechanisms of succession, thereby facilitating the incorporation of other native species of mid- and late-successional stages. Existing pine plantations could function as a substitute habitat and facilitate the establishment of native and endangered cloud forest species. To test this hypothesis, we planted two endangered species from the family Juglandaceae (Juglans pyriformis and Oreomunnea mexicana) under twelve-year-old canopy plantations of Pinus patula and compared them to individuals planted in open (control) sites and recorded their survival and growth. The results show that the survival of J. pyriformis and O. mexicana was significantly higher below the canopy of P. patula plantations than in the open site. However, growth rates varied significantly among species and sites. Although pine plantations may favor the survival of seedlings, they cannot ensure the growth of plants without additional forest management.
... Other potential techniques that they suggest include the creation of fire breaks, and scarification and exposure of mineral soil of grassland adjacent to forest patches. In the second paper, Mark Ashton and colleagues describe the use of pine plantations as a technique, both to secure the natural recruitment of native tree regeneration beneath the pine canopy and to facilitate the plantings of native trees (Ashton et al., 2014a). They provide a case for restoration for both conservation and utilitarian values, and make a strong economic case for the economic restoration of native species in the everwet regions of South Asia in comparison to the intensive cultivation of tea. ...
... Other potential techniques that they suggest include the creation of fire breaks, and scarification and exposure of mineral soil of grassland adjacent to forest patches. In the second paper, Mark Ashton and colleagues describe the use of pine plantations as a technique, both to secure the natural recruitment of native tree regeneration beneath the pine canopy and to facilitate the plantings of native trees (Ashton et al., 2014a). They provide a case for restoration for both conservation and utilitarian values, and make a strong economic case for the economic restoration of native species in the everwet regions of South Asia in comparison to the intensive cultivation of tea. ...
During the past 30 years, the global forest area has been subject to a continuous increase in planted forests and a decline in natural forests, raising significant concerns about biodiversity protection. Once these plantations are abandoned due to changes in conservation or forest management policies, can they recover to the same state as natural forests during secondary succession? The key ecological processes supporting the stable coexistence or competitive elimination mechanisms between post-abandonment plantations and natural secondary forest tree species are still poorly understood and may be the decisive ecological processes driving secondary forest restoration. A 12-ha long-term forest plot was established in an abandoned Chinese fir plantation that has been protected under an in situ protection policy for 40 years. In total, 66,317 individual trees were stem mapped and identified at the species level, and the spatial survival strategies and species coexistence mechanisms between Chinese fir and natural secondary forest tree species were investigated. The results showed that the spatial survival strategy of Chinese fir could effectively trade off a high conspecific density-dependent mortality rate of individuals during the early stage of secondary succession for the long-term survival of the whole population, which promoted its dominance during later stages of succession. By contrast, although the higher survival rate and larger intraspecific aggregation scale of natural secondary forest individuals favored their survival during initial colonization, this spatial survival strategy might occur at the cost of neglecting suitable habitats and the loss of competitive advantages at the later stage of succession. Regarding interspecific competition, the asymmetric competition process further ensured the advantages of Chinese fir in individual size growth and increased the competitive advantage of Chinese fir over natural secondary forest tree species by exclusion through interspecific competition during the later secondary succession stage. Our results suggest that implementing a forest recovery program or an in situ protection policy based on post-abandonment monoculture plantations may involve great uncertainty about whether the goal can be achieved. Specifically, although this strategy could quickly increase forest coverage and restore the forest landscape, it may also create difficulties in restoring the forest to its original state.
This article evaluates the capacity of Brazilian savannas’ landscapes in providing climate regulation and regulation of ecosystem services from natural forests and generating financial in-comes from silvicultural activity, in territories with different proportions of natural and commercial forest cover. This research defines thresholds and tradeoffs between the supply of ecosystem services and cellulose markets. We identified the role of compositional and structural attributes of the native forests on carbon stock results.
Seedling planting is the most common strategy used to reintroduce tropical native tree species; however, direct sowing has simplicity and operational ease advantages. Functional traits such as seed size and growth rates have been shown to be relevant for better plant performance. We evaluated the effects of intraspecific variation in seed size and the reintroduction strategy simultaneously on the development of Hymenaea courbaril (L.) and Enterolobium timbouva (Mart.) introduced in an abandoned eucalyptus plantation over 462 days. Plants from small, medium and large seeds were reintroduced by planting seedlings and direct seeding. Both species achieved high rates of emergence and survival was high in the two reintroduction strategies. Seed size was not related to emergence and mean time to emergence for either species. The survival of both species was higher than 74% in the field, and seed size had little effect on survival rates. In general, H. courbaril plants introduced by direct sowing had higher growth, and seed size correlated positively with stem size. In contrast, the growth of E. timbouva plants introduced by seedling planting was higher than in plants introduced by direct sowing regardless of seed size. The light requirements of this species seem higher than for H. courbaril. Our results suggest the feasibility of reintroducing species by direct sowing in eucalyptus understory, but since plant growth varies between species, there may be a balance between the advantage of the initial plant size provided by planting seedlings and the advantage of a better root development provided by direct sowing.
The rate of species and natural habitat loss across our planet is steadily accelerating. This book argues that existing practises of plant conservation are inadequate and firmly supports the placement of ecological restoration at the cornerstone of biodiversity conservation. The author unifies different aspects of conservation into one coherent concept, including natural area protection, ex situ conservation and in situ interventions through either population management or ecological restoration. Assisted colonization, experimentation, and utilization of threatened plant species are raised as crucial elements in restoration, with partly novel ecosystems being among its major target areas. Covering a wide spectrum of plant conservation examples, and offering practical methodologies alongside the theoretical context, this is a vital resource for students, research scientists and practitioners in conservation biology and restoration ecology.
Forest plantations occupy 2% of Earth's land surface and are increasingly important in biological conservation both through their establishment and removal. To restore conservation-priority oak savannas and prairies in the Midwestern United States, we began a conifer plantation removal experiment in northwestern Ohio in 2002 and measured plant community response, including nectar plants for conservation-priority invertebrates, during a 14-year period. Oak (Quercus) trees, crucial to restoring savanna structure, only became established on plots where conifers were cut. In the understory, native species richness/0.05 ha was 34–50% higher on plots where conifers were cut than on control plots in uncut plantations. By year 14, cut plots accrued 13 species with high coefficients of conservatism (specialist species typifying high-quality natural habitats) and 10 state-listed rare species; uncut plantations did not contain any such species. With 71 wetland species detected during the experiment (out of 370 total plant species), only cut plots developed a wetland-upland biophysical gradient diagnostic of diverse Midwestern savanna-prairie landscapes. Between year 1 and 14 after plantation cutting, cover of nectar plants utilized by federally endangered Karner blue butterflies (Lycaeides melissa samuelis) doubled, while cover of these plants remained negligible in uncut plantations. Similarly, cover of plants utilized by bees increased by 24 × after plantation cutting. Cutting plantations rapidly and persistently benefited native species for at least 14 years, with minimal increase in non-native plants.
Demand for restoration of resilient, self-sustaining, and biodiverse natural ecosystems as a conservation measure is increasing globally; however, restoration efforts frequently fail to meet standards appropriate for this objective. Achieving these standards requires management underpinned by input from diverse scientific disciplines including ecology, biotechnology, engineering, soil science, ecophysiology, and genetics. Despite increasing restoration research activity, a gap between the immediate needs of restoration practitioners and the outputs of restoration science often limits the effectiveness of restoration programs. Regrettably, studies often fail to identify the practical issues most critical for restoration success. We propose that part of this oversight may result from the absence of a considered statement of the necessary practical restoration science questions. Here we develop a comprehensive framework of the research required to bridge this gap and guide effective restoration. We structure questions in five themes: (1) setting targets and planning for success, (2) sourcing biological material, (3) optimizing establishment, (4) facilitating growth and survival, and (5) restoring resilience, sustainability, and landscape integration. This framework will assist restoration practitioners and scientists to identify knowledge gaps and develop strategic research focused on applied outcomes. The breadth of questions highlights the importance of cross-discipline collaboration among restoration scientists, and while the program is broad, successful restoration projects have typically invested in many or most of these themes. Achieving restoration ecology's goal of averting biodiversity losses is a vast challenge: investment in appropriate science is urgently needed for ecological restoration to fulfill its potential and meet demand as a conservation tool.
Pine plantations in the tropics are often employed to recondition eroded slopes from mudslides, as the Pinus caribaea plantation that shields the Universidad Simón Bolívar campus in Caracas (Venezuela). However, mismanagement of this plantation has led to its rapid degradation. The best option to maintain the protective service is to restore the plantation and direct its successional trajectory towards the neighbouring montane forest. Through experimental manipulation, we aimed to determine which factors block secondary succession and to investigate their effects. Within the experimental constraints imposed by the plantation small area, we analysed the effects of light and fertility limitation, litter accumulation and access to seed on plantation restoration. Light availability was manipulated by clearing and thinning three 800 m2 main plots. Fertilization and litter removal was applied to sub-plots within the light plots. Soils were analysed, microclimate was monitored and, for four years, stem density, species richness and basal area were tallied. Our results showed that light accessibility was the main factor deterring the successional trajectory of the plots, with varying grades of interaction with the sub-treatments. By the end of the fourth year, the cleared plot showed the largest responses in all traits (triplicating stem density and basal area and >20 times higher species richness). The main colonizers were Croton megalodendron, Ocoteafendleri, and Clusia spp. all dominant trees in the nearby native forest. We concluded that the results of this pioneer study, showed that small clearings, repeated in 3-4 year cycles are appropriate for similar restoration schemes. This procedure would create a mosaic of vegetation patches at different successional stages while protecting the slopes from erosion and increasing local biodiversity. Rev. Biol. Trop. 64 (2): 461-471. Epub 2016 June 01.
Pinus contorta is a widespread and ecologically damaging invasive tree in the southern hemisphere. Land managers want control methods that limit reinvasion by P. contorta and promote the recovery of native plant communities and ecosystem functions. Recovery of native vegetation may be slow if native seed supply is limited and/or introduced mammals destroy seeds and seedlings. We investigated how tree control method (felling or poisoning), seed addition, and exclusion of introduced mammals affected subsequent seedling establishment in montane stands of invasive P. contorta. Tree control method had a significant effect on seedling establishment: felling trees promoted establishment of P. contorta seedlings, whereas poisoning trees favoured establishment of native seedlings (provided seeds were available). Native seedling establishment was higher where seeds were sown, indicating native seed limitation at these sites. Excluding introduced mammals increased P. contorta seedling establishment, but did not have a significant effect on native seedling establishment. Our results indicate that poisoning P. contorta is a better management approach than felling where native seedling establishment is the desired outcome, and that this outcome can be enhanced by sowing native seed.
Choosing species for reforestation programs or community forestry in species-rich tropical rainforest ecosystems is a complex task. Reforestation objectives, social preferences, and ecologicalattributes must be balanced to achieve landscape restoration, timber production, or community forestry objectives. Here we develop a method to make better species choices for reforestation programs with nativespecies when limited silvicultural information is available. We conducted community surveys to determine social preference of tree species and inferred their ecological suitability for open-field plantations fromgrowth rates and frequency in forest plots at different successional stages. Several species, for which silvicultural data was available, were correctly classified as promising or unsuitable for open-fieldreforestation. Notably, we found a strong negative correlation between ecological suitability indicators and socioeconomic preference ranks. Only a single outlier species ranked very high in both categories. Thisresult highlights the difficulty of finding suitable native species for community forestry and offers an explanation why reforestation efforts with native species often fail.We concluded that the approach shouldbe a useful first screening of species-rich forest communities for potential reforestation species. Our results also support the view that species-rich tropical rainforests are not an easily renewable natural resource in asense that secondary forests will not provide an equivalent resource value to local communities.
Rates and patterns of colonization of the predominantly avian dispersed eastern red cedar were investigated in 3 abandoned pastures in SW Virginia. The populations, with median ages of 2, 5 and 14 yr, showed sigmoid cumulative net increases in numbers of individuals over time. Exponential increase occurred during the first 6-9 yr after initial establishment. Densities peaked at 8-10 yr. Only the youngest population showed a significant spatial gradient in the distribution of red cedar individuals, decreasing exponentially with distance from the nearest cone-bearing trees along the edge of the pasture. A decreasing activity gradient of avian dispersers with distance from the seed source may have influenced a differential seed input in the pasture. No relationship existed between age and location of individuals within stands. The apparent spatial uniformity of overall density of individuals with increasing age is probably due to several factors, including the increasing availability of avian perching sites and the addition of seed sources with increasing age of invading red cedar populations.-from Authors
Rates and patterns of colonization of the predominantly avian dispersed eastern red cedar were investigated in 3 abandoned pastures in SW Virginia. The populations, with median ages of 2, 5 and 14 yr, showed sigmoid cumulative net increases in numbers of individuals over time. Exponential increase occurred during the first 6-9 yr after initial establishment. Densities peaked at 8-10 yr. Only the youngest population showed a significant spatial gradient in the distribution of red cedar individuals, decreasing exponentially with distance from the nearest cone-bearing trees along the edge of the pasture. A decreasing activity gradient of avian dispersers with distance from the seed source may have influenced a differential seed input in the pasture. No relationship existed between age and location of individuals within stands. The apparent spatial uniformity of overall density of individuals with increasing age is probably due to several factors, including the increasing availability of avian perching sites and the addition of seed sources with increasing age of invading red cedar populations.-from Authors
Distribution of the W Himalayan forest types dominated by Pinus roxburghii, P. wallichiana and Quercus semecarpifolia is discussed. All of the principal zonal forests of the W Himalaya are found in the wet E Himalaya, where they occur as relict patches on local dry habitats, such as S-facing convex slopes. The successional status of these W Himalayan species changes along the W-E gradient of the Himalaya: in the W Himalaya they persist as climax species; from the central to the E Himalaya they are pioneer trees in disturbed sites; and in the wet E Himalaya they comprise relict patches. The pioneer trees found in the E Himalaya are classified into 4 ecological types according to their nature: habit pioneer, the undifferentiated canopy component, and the understory component. The 3 W Himalayan elements discussed here are included in the habitat pioneer type.-from Authors
This study examined the vegetation growing beneath Caribbean pine (Pinus caribaea) plantations established within previously abandoned tea lands adjacent to intact rain forest in southwest Sri Lanka. To examine the pattern and composition of secondary succession and factors affecting it, vegetation was sampled in different relative locations (interior and edge conditions) within plantations. Results demonstrated that more vegetation was found near the plantation edges than in the interior, and this pattern was prominent for both wind- and bird- dispersed species. The vegetation represented a mixture of species belonging to a range of successional guilds representing early (17 species, 42.4% in stem count) and late-successional species (52 species, 40.6%), although native long-lived canopy tree species were mostly absent. Bird-dispersed species dominated the flora (80 species, 86.7% in stem count). Abundance of an exotic shrub Clidemia hirta (Melastomataceae) showed a negative correlation with that of other species, indicating its impact on native flora. Underplanting of native canopy species may be effective in assisting secondary succession and control C. hirta in the plantations.
Woody vegetation was surveyed in 58 forest stands in northern Virginia to examine the effects of previous land-use history on past and present-day forest composition and dynamics. Stands were separated using detrended correspondence analysis (DCA) and overstory importance values into three forest, groups: (i) white oak (Quercus alba L.) - tulip-poplar (Liriodendron tulipifera L.) (ii) white oak - scarlet oak (Quercus coccinea Muenchh.) and (iii) Virginia pine (Pinus virginiana Mill.) The first DCA axis represents a successional continuum from more recently disturbed areas containing young pine forests to less disturbed mature oak stands, and is negatively correlated with stand age and species diversity. White oak and red oak (Quercus rubra L.) dominated presettlement forests in the area. Following European settlement, forests experienced intense logging associated with the charcoal iron industry, large-scale clearing for agriculture, and subsequent land abandonment. By coupling radial growth analysis with age-diameter figures, we evaluated the responses of stands to disturbances associated with various land-use practices. This analysis indicated that many Virginia pine stands resulted from agricultural abandonment during the early 1900s, while a majority of oak stands experienced peak recruitment and radial growth following periodic logging disturbances in the 1800s. Canopy closure, forest protection, and reduced fire and logging disturbance this century led to increases in dogwood (Cornus florida L.) and blackgum (Nyssa sylvatica Marsh.) in area forests. The oldest stands exhibited a lack of tall oak regeneration; however, they also contained a scarcity of potential oak replacement species. Therefore, oak will seemingly share future dominance with several mixed-mesophytic species, although the exact successional status of these stands is unresolved.
Indigenous peoples with a historical continuity of resource-use practices often possess a broad knowledge base of the behaviour of complex ecological systems in their own localities. They are aware that biological diversity is a crucial factor in generating the ecological services and natural resources on which they depend. Some indigenous groups manipulate the local landscape to augment its heterogeneity, and some have been found to be motivated to restore biodiversity in degraded landscapes. Their practices for the conservation of biodiversity were grounded in a series of rules of thumb which are apparently arrived at through a trial and error process over a long historical time period. It is vital that the value of the knowledge-practice-belief complex of indigenous peoples relating to conservation of biodiversity is fully recognized if ecosystems and biodiversity are to be managed sustainably. Conserving this knowledge would be most appropriately accomplished thorugh promoting the community-based resource-management systems of indigenous peoples. -from Authors
Rates and patterns of colonization of the predominantly avian dispersed eastern red cedar (Juniperusvirginiana L.) were investigated in three abandoned pastures in southwest Virginia. The three populations, with median ages of 2, 5, and 14 years, showed sigmoid cumulative net increases in numbers of individuals over time. Exponential increase occurred during the first 6–9 years after initial establishment. Densities peaked in about 8–10 years. Only the youngest population showed a significant spatial gradient in the distribution of red cedar individuals, decreasing exponentially with distance from the nearest cone-bearing trees along the edge of the pasture. A decreasing activity gradient of avian dispersers with distance from the seed source may have influenced a differential seed input in the pasture, resulting in the observed spatial trend in tree density. No relationship existed between age and location of individuals within stands. The apparent spatial uniformity of overall density of individuals with increasing age (as noted in the 5- and 14- year-old populations) is probably due to several factors, including the increasing availability of avian perching sites and the addition of seed sources with increasing age of invading red cedar populations.
Forest structure and species distribution patterns were examined among eight topographically defined habitats for the 205 species with stems [greater-than-or-equal] 1 cm dbh inhabiting a 25-ha plot in the Sinharaja rain forest, Sri Lanka. The habitats were steep spurs, less-steep spurs, steep gullies and less-steep gullies, all at either lower or upper elevations. Mean stem density was significantly greater on the upper spurs than in the lower, less-steep gullies. Stem density was also higher on spurs than in gullies within each elevation category and in each upper-elevation habitat than in its corresponding lower-elevation habitat. Basal area varied less among habitats, but followed similar trends to stem density. Species richness and Fisher's alpha were lower in the upper-elevation habitats than in the lower-elevation habitats. These differences appeared to be related to the abundances of the dominant species. Of the 125 species subjected to torus-translation tests, 99 species (abundant and less abundant and those in different strata) showed at least one positive or negative association to one or more of the habitats. Species associations were relatively more frequent with the lower-elevation gullies. These and the previous findings on seedling ecophysiology, morphology and anatomy of some of the habitat specialists suggest that edaphic and hydrological variation related to topography, accompanied by canopy disturbances of varying intensity, type and extent along the catenal landscape, plays a major role in habitat partitioning in this forest.
We examined the effects of species, habitat type (open pasture, forest, and beneath isolated pasture trees), and distance from the forest/pasture edge (25 m and 250 m) on post-dispersal seed predation of ten animal-dispersed species near the Las Alturas Biological Station in southern Costa Rica. We also compared the amount of seed predation due to vertebrate and insect predators. Levels of seed predation were extremely species-specific, ranging from 20–100 percent of seeds consumed during the 30 day study period. However, the proportion of seeds remaining was not correlated with seed size. Overall, seed mortality did not differ between the forest and open pasture habitats, but was significantly lower under isolated pasture trees. Individual species differed in which habitat they suffered the highest levels of predation. For eight of ten species studied, levels of seed predation did not vary significantly with distance from the foredpasture edge in any habitat. The majority of the post-dispersal seed predation was due to mammalian predators. The results of this and other studies suggest that post-dispersal seed predation may influence patterns of forest regeneration in disturbed areas.
Lack of seed dispersal has been shown to be a major factor limiting tropical forest recovery in abandoned pasture land. The goal of this work was to determine whether bird perching structures serve to enhance seed dispersal and seedling establishment in an abandoned pasture in Costa Rica. Two types of perching structures (crossbar and branch) were tested. Bird visitation rates were significantly higher on branch than on crossbar perches. The number of animal-dispersed seeds was significantly higher below branch perches than below crossbar perches or in open pasture. Despite differences in seed rain, percent cover of animal-dispersed plants and the number of seedlings of animal-dispersed plant species were similar below both perch types and in open pasture. Baiting perches with bananas did not increase either bird visitation rates or seed rain. These results suggest that, although bird perching structures increase seed dispersal, they do not overcome other barriers to tropical forest recovery such as seed predation and low seed germination.
Policies to reduce emissions from deforestation would benefit from clearly derived, spatially explicit, statistically bounded
estimates of carbon emissions. Existing efforts derive carbon impacts of land-use change using broad assumptions, unreliable
data, or both. We improve on this approach using satellite observations of gross forest cover loss and a map of forest carbon
stocks to estimate gross carbon emissions across tropical regions between 2000 and 2005 as 0.81 petagram of carbon per year,
with a 90% prediction interval of 0.57 to 1.22 petagrams of carbon per year. This estimate is 25 to 50% of recently published
estimates. By systematically matching areas of forest loss with their carbon stocks before clearing, these results serve as
a more accurate benchmark for monitoring global progress on reducing emissions from deforestation.
Conservation increasingly seeks to limit human activities in biodiversity-rich areas, especially in the South. Forced relocation, impoverishment, cultural destruction and the undermining of traditional systems of natural resource management have been common. Conflicts between indigenous peoples and conservation agencies have resulted, sometimes making protected areas unmanageable and inoperative. Conservationists have experimented by creating buffer zones, implementing profit sharing and joint management schemes, and recognizing indigenous territorial rights. The author argues that conservation agencies need to be made much more accountable to indigenous peoples. This is most likely to be achieved by effective indigenous mobilization. -from Author
Tropical forest land is increasingly influenced by man-caused wildfires. The vast majority of the forested area burnt and cleared annually is in the tropics. The use of fire in rural land-use systems is the major cause of the wildfires. Five broad causative agencies of wildfires are presented, shifting cultivation, grazing, non-wood forest products, migration programs and the wildland/residential interface. Integrated concepts of prescribed burning and prescribed grazing may offer solutions to the tropical wildland fire problems.
One of the most striking ecological features of the mountains of the eastern United States and adjacent Canada is the high elevation forest dominated by the needle-leaved, evergreen genera Picea (spruce) and Abies (fir). Spruce-fir forests are found on the upper slopes of the Adirondack and Appalachian Mountains, over an area that extends from western North Carolina, USA (ca. 35°N), to central Quebec and New Brunswick, Canada (ca. 49°N). In addition to these montane (Cogbill and White 1991, Siccama 1974, Harries 1966) or subalpine (MacMahon and Andersen 1982) forests, similar spruce-fir forests dominate some low elevation sites, particularly in the northern United States and adjacent Canada. Although eastern spruce-fir forests vary considerably across elevations, latitudes, and sites, red spruce (Picea rubens) is a dominant tree throughout. In fact, red spruce is restricted to the Appalachians, Adirondacks, and adjacent areas and, thus, serves as a unifying element of these varying forests.
Native forest species exhibit a well-known range of ecological roles with respect to natural disturbance regimes, from pioneer phase to mature phase, and they regenerate from a range of sources, including dormant seeds, seed rain, pre-established juveniles, and resprouts from damaged adults. In contrast, the ecological roles of invasive, non-indigenous species in forest communities after natural disturbances are not well understood. Some previous studies of invasive species have emphasized their weedy nature and their ability to colonize anthropogenic disturbances. Tropical hardwood hammock forests in southern Florida experience frequent disturbance by hurricanes. Our studies of forest regeneration during two years following a recent severe hurricane suggest that invasive non-indigenous forest species exhibit the same range of ecological roles as native forest species and compete with native species for particular kinds of regeneration opportunities. To study ecological roles of non-indigenous species in regenerating forests after Hurricane Andrew, we set up four large study areas at each of three study sites that had differing amounts of hurricane-caused canopy disturbance. There were two pairs of 30 x 60 m research plots per site, and in each pair there was one control plot and one restoration plot; restoration areas were subject to an aggressive management program, focused on reducing non-indigenous vine cover. Within these study areas we subsampled vegetation in small study plots that were regularly spaced, and conducted vegetation censuses in April (the end of the dry season) and October (the end of the rainy season) for 2 yr, beginning in April 1993. We found that the source of regeneration for forest species was dependent upon the amount of canopy disturbance, the time since disturbance, and the autecology of the constituent species. Overall, 28% of the 90 species were non-indigenous: 34% of the vines (N = 32) and 24% of other life-forms (N = 58). Non-indigenous vines seemed to have a special role; not only could they compete with native vines, but they could also negatively affect the regeneration of other natives from a diverse array of sources including pre-established juveniles and resprouts from damaged adults. Both native and non-indigenous vine cover in unmanipulated study areas increased following the hurricane. Non-indigenous vine species had higher cover than native vine species, and many species formed dense "blankets." Non-indigenous species in general (not just vines) did not differ significantly from native species in seed mass, nor were they restricted to the pioneer type of life history. Many non-indigenous species had invaded forests prior to hurricane disturbance and had their own banks of pre-established juveniles; others recruited from dormant seeds, seed rain, and/or resprouts from pre-established adults. Based on information on source of regeneration and impact on native species, we propose a classification scheme for functional roles of non-indigenous invasive species in forests. To investigate whether non-indigenous taxa had roles in other geographic regions similar to those they had in Florida, we reviewed literature for 50 taxa belonging to genera that have species known to be invasive in southern Florida. We found that these taxa were invasive or had congeners that were invasive in other geographic regions (Western Australia, the Mariana Islands, Hawaii, the Mascarene Islands, and South Africa). We propose that taxa predominantly retain their invasive, functional-role type across regions. Thus, studies of ecological roles of invasive species with respect to natural disturbance regimes in one region may help us predict invasive roles in other regions.
Density, height, diameter, and age structure of Pinus taeda L. were examined in a 21-year-old abandoned field. A density estimate of 924 trees ha-1 was obtained, a factor of 17 over that found for the area 14 years earlier. Age frequencies resembled an inverse J-shaped depletion model, with 4.3% of all trees examined being in the 1-year age class. Median ecological longevity was estimated to be 3.2 years. Linear correlations between age, height, and dbh data were also determined. /// Исследовали густоту, высоту, диаметр и возраст Pinus taeda L. в запущенном насаждении 21-летнего возраста. Густота составляет 924 дерева/га-1, фактор 17-кратности, который был установлен для этой посадки 14 лет назад. Распределение возрастов соходно с обратной J-образной моделью, при этом 4,3% из всех исследованных деревьев относились к 1-летнему возрастному классу. Средняя экологическая продолжительность составляет 3,2 года. Определены линейные корреляции между возрастом, высотой и данными dbh.
In North Carolian Piedmont old fields, Acer rubrum, Fraxinus americana, Liquidambar styraciflua, Liriodendron tulipifera, Pinus taeda and Ulmus alata relative seedling performance (survival and growth) was examined with respect to 1) competition from old-field vegetation (weeded vs. vegetated plots) and 2) browsing by vertebrate herbivores (exclosures vs. open plots). Most seedling mortality occurred in the 1st growing season. In 1984, old-field vegetation reduced survival of all species, but competitive reductions were not large except in Liriodendron, which appeared unable to survive in herbaceous cover, and in Acer, which survived poorly in the absence of competition as well. In the other 4 species, survival in old-field vegetation was similar; after high mortality in the 1st year, seedlings exhibited continued slow mortality with time. The dry spring of 1985 resulted in greater overall mortality in all species and greater variation in species responses to vegetation cover. Height growth was strongly reduced by herbaceous vegetation in all hardwood species, but Pinus grew fairly well in competition with the herbaceous community. Characterization of these responses as tolerance vs. inhibition requires consideration or long-term demographic behavior. Fraxinus, Liquidambar and Ulmus were damaged by browsers, but browsing intensity varied according to site and was most severe in Ulmus. A factor that may account for discrepancies is differential seed rain, which can numerically offset low rates of seedling survival. -from Author
Endemism is concentrated in the lowland Mixed Dipterocarp forests. Within the wet zone, soils and historical geography play a more important role, and altitude a less important role in floristic differentiation than formerly thought. The endemic flora is found to dominate the mature phase, and comprises a greater proportion of stand density and basal area than its floristic representation would suggest. The capacity of the endemic component to re-invade cleared land is poor, however. Gap phase species, many of which are also endemic, play a more important role in wet zone forests than is the rule in the Far East. Contour mapping of floristic variation within this plot using a nearest neighbour technique revealed an unexpected pattern of past disturbance. -from Authors
Much of the world’s biodiversity has been in the hands of traditional peoples, societies of hunters and gatherers, herders, fishers, agriculturists, for a great many generations. Most living resources of the earth have been utilised for a historically long time; exceptions are few (e.g., open-ocean and deep-sea species). As Gomez-Pompa and Kaus [1990] observed, even tropical forests of the Amazon were not untouched environments but the result of the last ‘cycle of abandonment’ by traditional users. The fact is that pre-scientific, traditional systems of management have been the main means by which societies have managed natural resources for millennia [Berkes and Farvar, 1989; Gadgil et al., 1993]. In many cases, the main reason we have any biological diversity to speak about is because of these systems of management.
In Australia, as in many countries, there has been a shift in timber production from native forests to plantations. While plantations are primarily considered an efficient means of producing timber, there is increasing interest in their potential contribution to biodiversity conservation. Plantations may have both positive and negative consequences for biodiversity, at a range of scales. We compiled a list of these consequences from the literature, and used them to assess plantation scenarios proposed for cleared rainforest landscapes in tropical and subtropical Australia. The scenarios were monocultures of: (i) hoop pine, (ii) exotic pine and (iii) eucalypts; (iv) mixed species plantations; (v) a mosaic of monoculture plantations; and (vi) a mosaic of plantations and ecological restoration plantings. Of these scenarios, plantations of eucalypts and exotic pines have the least positive consequences for biodiversity: they have little or no intrinsic value in rainforest landscapes, provide poor quality habitat for rainforest biota, and (particularly eucalypts) are characterised by a relatively open canopy which in cleared landscapes favours the recruitment of grasses and other weeds. The three scenarios based on plantations of rainforest trees have similar, moderately positive consequences for biodiversity, while a mosaic of plantations and restoration plantings has the most positive consequences for biodiversity in cleared rainforest landscapes. All scenarios may have negative impacts on biodiversity conservation if plantations replace remnant forest, provide habitat for weeds, or the tree species used in plantations or their genes escape into native forests. In practice, the relative importance of positive and negative impacts, and hence the ranking of scenarios may vary with landscape forest cover. Scenarios with strongly positive consequences for biodiversity would be favoured for the reforestation of heavily cleared landscapes, whereas scenarios with few negative consequences for biodiversity would be favoured in well-forested landscapes. Consequently, any plantation of rainforest trees may have acceptable consequences for biodiversity in well-forested landscapes, provided the trees are not invasive or carrying exotic genotypes, and plantations are managed to control weeds and feral animals. With the same caveats, plantations of exotic pines may also be acceptable from a biodiversity conservation perspective in well-forested landscapes. At present, our capacity to design and manage rainforest plantations for both timber and biodiversity objectives is limited by a lack of information on factors affecting timber production, biodiversity values and trade-offs or synergies between these objectives. Obtaining this information will require the integration of large-scale, long-term biodiversity research in broadscale plantation projects.
We examine the financial aspects of three silvicultural systems to encourage the sustainability of valuable hardwood species in mixed-dipterocarp forests of southwest Sri Lanka. We compare the net present value (NPV) of the current forest management approach (diameter limit harvests) with shelterwood harvests that promote light hardwood timber species. In this analysis, we also consider the potential of enrichment planting various precious timber (Diospyros quaesita — calamander), and non-timber forest product (NTFP) species (Caryota urens — fishtail palm; Elettaria cardamomum var. major — cardamom; Calamus zeylanicus — rattan) in conjunction with timber harvests. Two real (inflation adjusted) discount rates were used, 4 and 6%, respectively. Results show that when real discount rates are low (4%), and advance regeneration is present, NPV is highest for the one-cut shelterwood (US $9983 ha−1). At a high discount rate (6%), reflecting the current short-term concession system and unstable rights to harvest, and where no advance regeneration was present, the diameter limit system (US $7173 ha−1) was the optimum. On sites with advanced regeneration, the one-cut shelterwood system is clearly preferable. For all but rattan, shelterwood treatments provide higher NPVs for NTFPs than diameter limit cuttings primarily because of the higher light regimes and more growing space made available early in the rotation. The value for tea cultivation (US $26,000 ha−1) far exceeds the value of managing these lands for timber alone, explaining the dramatic expansion in tea plantations on private lands. However, our results suggest that managing these lands for a combination of timber and enrichment plantings of NTFPs (US $23,000 ha−1) can be comparable to tea plantations. By managing for NTFPs and timber, forest managers have new opportunities to solve the old problems of high-grading and land-use conversion.
There are an estimated 2,077 million ha of degraded lands in the tropics, of which 758 million ha have a theoretical potential for forest replenishment if the substantial area of low productivity rangelands is disregarded. The total includes 418 million ha in dry or montane areas requiring afforestation or reforestation; 137 million ha of tropical rain forests in need of protected regeneration or silvicultural manipulation; and 203 million ha of forest fallows in the humid tropics which could be reforested. Based upon previous forecasts of future demand for fuelwood and industrial wood it is estimated that reforestation of a third of all degraded lands in montane regions (26.8 million ha) and afforestation of about a fifth of the degraded area of croplands in dry regions (61.5 million ha) would prevent projected fuelwood deficits in those regions by the year 2000. In the humid tropics, an additional 26.6 million ha of medium- rotation high-grade hardwood plantations could, with the current plantation area, produce enough wood to supply the level of world demand for tropical hardwoods forecast for the year 2000. These plantations would require the conversion of two thirds of the estimated area of alang-alang infested grasslands in South East Asia, or 13% of all forest fallow in the humid tropics but would not start to mature until the second quarter of the next century. The total area afforested and reforested would be 114.9 million ha or 15% of all degraded areas.
Empirical evidence from temperate Europe and North America indicates that old-field succession, resulting in reforestation and a protracted period of forest fallow, can improve soil condition on lands once badly degraded. However, the ability of trees to ameliorate degraded sites in the tropics is widely debated. In 1988 eight native tree species: Hyeronima alchorneoides Allemao, Inga edulis Mart., Pentaclethra macroloba (Willd.) Ktze, Pithecellobium macradenium Pittier, Stryphnodendron microstachyum Poepp. et Endl., Virola koschnyi Warb., Vochysia guatemalensis J.D. Smith, and Vochysia ferruginea Mart. and three exotic tree species: Acacia mangium Willd., Gmelina arborea L., and Pinus tecunumanii (Schw.) Equiluz et Perry were planted on abandoned pasture land in northeastern Costa Rica cleared of rain forest 25 yr earlier. Four replicates of 0.25-ha plots of the 11 species and a control were established in a randomized in a randomized complete block design. All species survived fairly well, but some grew much better than others. The soil was thoroughly sampled before trees were planted and again 4 yr after trees were established. Although bulk density decreased significantly beneath eight of the 11 species, organic C increased significantly under only three species. Significant increases in base cations also occurred beneath the majority of species. Nitrogen did not increase as much as expected beneath the N 2 -fixing legumes; however, the availability of P was significantly enhanced beneath both species of Vochysia. The changes in soil properties were dramatic, and significant amelioration of these degraded soils occurred in a short time beneath the majority of species
. Reclamation of former, degraded forest lands occupied by Imperata cylindrica is one of the crucial environmental and forestry issues in the humid tropics, notably Southeast Asia. We suggest that it is possible to gradually restore the original natural forest cover with the help of a sacrifice fallow crop of fast-growing exotic tree species. Recently, a set of suitable fast-growing plantation tree species has been identified and stand establishment methods developed for this purpose. We assessed the regeneration of natural vegetation in stands of different plantation tree species and evaluated the ecological impact of species composition in the plantation understorey. PCA ordination, regression analysis and analysis of covariance were applied at different stages of the study. We found a marked vegetational resemblance between stands dominated by Acacia mangium: they had the highest number of indigenous trees in their understorey, whereas stands of other plantation trees supported more diverse grass and herb vegetation. A high proportion of evergreen woody vegetation reduces the risk of fire and grass competition and enhances secondary succession towards natural forest.
Understorey colonization by native species was assessed in timber plantations on the Atherton Tablelands in North Queensland, Australia (latitude 17°S). We surveyed 151 plots (each 78.5 m2 in area) in plantation monocultures of the exotic Pinus caribaea and the natives Araucaria cunninghamii, Flindersia brayleyana and Toona ciliata ranging in age from 5 to 63 years. A total of 350 species, including 176 tree species, were found beneath the plantations. On similar sites, F. brayleyana had a significantly greater number of colonizing species than A. cunninghamii which, in turn, had significantly greater numbers than P. caribaea. Tree species richness and the number of species regarded as `late successional' increased significantly with age for the two species where a range of ages were measured. Age explained a considerably greater proportion of the variation in richness in P. caribaea plantations (r2=0.79) than in A. cunninghamii plantations (r2=0.22), and there tended to be more late successional species in younger A. cunninghamii plantations. The distance from the rainforest to the plantation edge generally had little effect on the number of tree species, although there was a slight trend of richness decreasing away from the plantation boundary for younger plantations and in F. brayleyana plantations at one site. Between 80 and 90% of the tree species found in the plantations were primarily bird-dispersed, with similar proportions of primarily bird- and wind-dispersed species among the plantations of different tree species. The implications of these results for conservation of biodiversity and ways of managing plantations to conserve this diversity are discussed.
The purpose of our study was to determine the effect of groundstory fire on natural regeneration within 18–20-year-old Pinus caribaea plantations. Plots were established within three treatment types: unburned, once burned (within the last 5 years), and multiple burned (within the last 5 years). Three plantations within each treatment type were selected. The diversity, stem density, and basal area of vegetation greater than 1.5m in height were quantified within 10m×10m plots which were replicated four times within each plantation. Vegetation less than 1.5m was quantified in 1m×1m subplots. Results showed that tree stem density and diversity were greater in unburned treatments than within the two burned treatments. Once-burned plantations were distinguished by lower diversity and density of recruitment yet higher soil fertility as compared with multiple-burned plantations. We attribute this difference to greater fire intensity associated with once-burned plantations. We suggest that plantations that have been established for restoration purposes should be protected from groundstory fire.
Performance of seedlings of seven rain forest, canopy dominant Shorea species was studied in a transplant experiment in forest sites at three different elevations (low, mid and high) within the humid zone of southwest Sri Lanka. Five species generally inhabit low- to mid-elevations, one at mid- and lower montane elevations, and one exclusively at lower montane elevations. Temperature, rainfall and cloudiness varied with elevation. For each site seedlings were grown in pots under partial shade conditions using similar soils and evermoist conditions. All growth measures showed differences among elevation sites, among species and in the interaction between species and elevation sites. Performances of species collectively showed (i) decline in height and leaf number with increase in elevation, (ii) higher dry mass at low- and mid-elevation sites compared to that at high-elevation and (iii) a higher mass of single leaves at the mid-elevation site than at the high-elevation site. Rank order of species changed across elevations for both height and dry mass. Dry mass declined with elevation in four of the seven species studied. S. gardneri, the only exclusively lower montane species, increased dry mass with elevation. Height declined with elevation for six of the species with only S. gardneri showing no change. Changes with elevation in the rank order of species for total leaf number and mass of single leaves were small. However, total leaf number and masses of single leaves differed among species and among elevations. S. megistophylla and S. disticha had a few leaves with high individual masses, while S. gardneri, S. affinis and S. trapezifolia had many leaves with less mass per individual leaf. One group of species showed relatively little change in leaf number per seedling and large changes in mass of single leaves. The other group varied more in leaf number but mass of individual leaves remained constant. Growth allocation to leaf production versus individual leaf size appears related to the successional division of Shorea section Doona. Also all species grew better at the low-elevation site irrespective of their natural ranges except S. gardneri, whose natural range is restricted to high elevations, and exhibits markedly lower growth responsiveness than the other wide ranging species.
1. In the moist tropics, studies have demonstrated poor seedling establishment of late-successional trees on lands cleared of forest. Our study examined the potential for establishing late-successional tree species that dominate the canopy of rainforest by planting within and adjacent to experimental openings that were created within a Pinus caribaea plantation. 2. We tested five canopy tree species (Dipterocarpus zeylanicus, Mesua ferrea, Shorea disticha, S. megistophylla and S. trapezifolia) of tropical forest in south-western Sri Lanka. Seedlings were monitored for 2 years within treatments that removed either three rows or one row of Pinus canopy, a canopy edge treatment and a control that left the canopy intact. 3. The greatest growth and dry mass for all species were in the canopy removal treatments. In particular, S. trapezifolia and S. disticha exhibited the greatest height growth in these treatments. In the three-row canopy removal treatment, M. ferrea had a significantly lower dry mass than the other species. 4. Differences were shown in the number and area of leaves among species. Shorea trapezifolia and, to a lesser degree, S. disticha increased area by increasing leaf production. Dipterocarpus zeylanicus and, to a lesser degree, M. ferrea increased area by increasing the size of individual leaves. 5. Guidelines based on results from this study recommend that species grow best when seedlings are planted within opening created by the removal of three rows of Pinus canopy. Where planting without canopy removal is required, S. disticha or S. megistophylla should be selected because of greater shade and drought tolerance. 6. This experiment demonstrated that Pinus can be used as a nurse for facilitating the establishment of site-sensitive tropical forest tree species that are late-successional. In particular, results have application for similar mixed dipterocarp forest types in south-east Asia.
Trees slowly colonize old fields on sandy outwash in the prairie-forest eco- tone of the north-central United States, and in the absence of fire, succession is expected to proceed toward oak woodland. We analyzed whether a case of unusually rapid and spatially extensive invasion by white pine (Pinus strobus) could be explained by the pres- ence of specific temporal or spatial opportunity windows suitable for such invasion. We tested whether the invasion was temporally restricted to the period immediately after aban- donment or to periods of favorable climate, and whether it was spatially restricted to areas of high seed rain or high forest-edge shade. White pine invasion into the field occurred in two waves separated from each other by a 1987-1989 drought period. The first wave (1980- 1985) occurred during a period of average climate and led to the establishment of dense sapling patches in shade near forest edges. The second wave (1991-1994) occurred during a period of high precipitation and cooler than normal temperature, and resulted in colo- nization of the unshaded field center. In addition to the two temporal windows, white pine invasion occurred within two spatial windows: in areas highly sheltered by forest edge and in areas receiving high white pine seed rain. Overall these windows produced three different successional pathways: (1) a slow, creeping white pine invasion into highly shaded areas with low seed rain near forest edges; (2) a rapid, discrete-step invasion in areas where seed rain was abundant enough to overcome mortality in lower shade and where early arrivals facilitate filling in by later arrivals; and (3) a deferred invasion in the field center where low seed rain and lack of shade allowed the persistence of a grassland stage until favorable climate resulted in a white pine recruitment pulse. Temporal variation in climate can ac- celerate or decelerate any of the three successional pathways.
We investigated the suitability of Acacia mangiumWilld., a fast-growing tropical leguminous tree, as a nurse tree for reforestation with indigenous species on severely degraded sandy soils in southern Thailand. Planting A. mangium yielded a survival rate of 91% and satisfactory growth (7.7 m height, 56 mm dbh, 59 Mg dry weight ha-1 aboveground biomass) 45 months after planting, indicating the species' suitability for reforestation. Three dipterocarp species (Dipterocarpus alatus Roxb. ex G. Don, Hopea odorata Roxb., and Shorea roxburghii G. Don.) planted simultaneously with A. mangium showed better growth than when planted alone. Seedlings of all three dipterocarp species that survived transplanting showed better survival when planted with A. mangium. The findings suggest A. mangium is an effective nurse tree for dipterocarp seedlings. The carbon and nitrogen contents of surface soil did not increase in the A. mangium stands. Microclimate measurements showed moderated air temperature, relative humidity, and soil temperature in the mixed planting. The moderated microclimate under the A. mangium canopy is thought to be responsible for the improved growth of the dipterocarp seedlings. If dipterocarp seedlings are planted after A. mangium grows enough to provide shade, initial survival rates should improve. FOR. SCI. 51(5):498510.
This study characterizes the microclimate and soilwater conditions of three gaps within mixed-dipterocarp rainforest of southwest Sri Lanka. The gaps were each of a different size and within a particular part of the forest topography. The largest gap was in a valley and the smallest on a ridge. Soil water, light quantity, and temperature were recorded within demarcated zones across each gap.Although trends between gaps and within gaps are relatively easily explained, the numerical values reported give a good impression of differences and amplitudes concerned as well as of the actual values in the rainforest understory.Surface soilwater measurements revealed that the ridge gap was more prone to water stress than the valley and midslope gaps. Gap centers of all three disturbances appeared to have lower amounts of surface soil water than adjacent forest understories.Light quantities on a sunny day in the forest understory were between 0.26 and 0.92 mols, of which sunflecks contributed between 24 and 62%. These understory light levels are approximately 1% of full sun exposure. The central zone of the valley gap had the longest duration of full sun (17–54% of the daily photosynthetic photon flux density (PPFD) of full sun). The center of the midslope gap had between 12 and 22% and the ridge had between 7 and 16% of daily PPFD of full sun.Diurnal temperature ranges in gap centers are wider than in adjacent forest understories. Sunny days had the greatest ranges of difference with a maximum of 34°C on the soil surface of the valley gap center, while surface temperatures in the understory did not exceed 25°C.
In this study four species of the genus Shorea section Doom were investigated. All occur together as canopy trees in the Sinaraja rainforest of south-west Sri Lanka. Partitioning of the regeneration niche can be one explanation for the co-existence of ecologically similar canopy tree species within a forest. Seedlings were planted in plots located in five zones that represent a range of forest groundstorey microenvironments found adjacent to and across canopy openings of three sites – valley, midslope, ridgetop. Experiments were designed to monitor survíval and growth of planted seedlings for two years. At the end of two years percentage survival was calculated, height increment recorded and destructive samples taken to measure dry mass gain of root, stem and leaves. Comparisons were made of establishment and growth performance of seedlings planted in the different plots and sites. Results demonstrated clear differences in survival and growth among species. These differences appeared related to availability of soil moisture and groundstorey radiation regimes. Disturbance patterns that determine species co-existence are suggested.
Large areas of the world's tropical forests are being degraded, with a consequent loss of species diversity. Only some of these are able to recover unaided. Where attempts are being made to restore such forests, the scale of the attempts is usually small. Timber plantations are one of the few means by which large areas of cleared or degraded landscape can be reforested. These usually restore the productive capacity of the landscape but do little to recover biological diversity. But a number of approaches might be used to redesign such plantations so that they would both yield the timber needed to justify the investment and also contain some proportion of their former biodiversity. These