No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Empirical Evidence that Declining Species Diversity May Alter the Performance of Terrestrial Ecosystems
Abstract
We examined experimentally the association between species diversity and
ecosystem processes in a series of terrestrial mesocosms. We developed
and maintained 14 mesocosms whose biota were assembled from a single
pool of plant and animal species and whose environmental conditions were
identically controlled. Each community contained four trophic levels:
primary producers (annual herbs), consumers (herbivorous molluscs and
phloem sucking insects), secondary consumers (parasitoids) and
decomposers (earthworms, Collembola and microbes). All mesocosms
received the same diurnal pattern of light, temperature, relative
humidity and water. The initial volume of soil, soil structure,
composition, nutrient content and inocula of both soil microbes and
nematodes were also identical among replicates. The only experimentally
manipulated factor was the number of plant and animal species within
each trophic level. High, medium and low diversity communities had nine,
15 or 31 plant and animal species, respectively. We measured five
ecosystem processes as response variables in these mesocosms over the
course of 206 days: (i) community respiration; (ii) productivity; (iii)
decomposition; (iv) nutrient retention; and (v) water retention. The
manipulation of diversity produced communities that differed
significantly in their ecosystem processes. Our results provide the
first evidence (obtained by a direct manipulation of diversity under
controlled environmental conditions) that ecosystem processes may be
affected by loss of diversity.
... In the case of autotrophs, Matzek and Vitousek (2009) find no clear link between N:P ratio in their tissues and the (pine) growth rate. However, in the case of many soil heterotrophs, such a link is according to Mulder and Elser (2009) not implausible and deserves further investigation under controlled environmental conditions, such as in the Ecotrons (Naeem et al., 1995;Stewart et al., 2013, and references therein). Being possibly the first test for a trait-mediated association of terrestrial webs with C:N:P stoichiometry (Peñuelas and Sardans, 2009), Mulder and Elser (2009) focused in fact on the potential size dependence of heterotrophs. ...
... Tiegs et al., 2008;Wallace et al., 1999). As such, Table 2.5 Major couplings between global warming, plant invasion, soil acidification and N eutrophication (change drivers), plant responses and soil biota (meta-analyses by Sardans and Peñuelas, 2012 (vascular plant-soil interactions), Sardans et al., 2012a,b (change drivers and responses), Bobbink and Hettelingh, 2011 (critical loads of N), and Naeem et al., 1995;Reich et al., 2005;Mulder and Elser, 2009;Griffiths et al., 2012;Vasseur et al., 2012;Cotrufo et al., 2013;Vonk and Mulder, 2013 (empirical " Plant production and growth (but the effects can be negative in short, extreme warming events) ...
... " Soil enzyme activity, counteracting the negative effect of litter production with higher C:N and C:P ratios " Bacterial population and microbial C, increased fungal sporulation, plant pests " Plant C:N and C:P ratios " Soil C:N and C:P ratios Table 2.5 Major couplings between global warming, plant invasion, soil acidification and N eutrophication (change drivers), plant responses and soil biota (meta-analyses by Sardans and Peñuelas, 2012 (vascular plant-soil interactions), Sardans et al., 2012a,b (change drivers and responses), Bobbink and Hettelingh, 2011 (critical loads of N), and Naeem et al., 1995;Reich et al., 2005;Mulder and Elser, 2009;Griffiths et al., 2012;Vasseur et al., 2012;Cotrufo et al., 2013;Vonk and Mulder, 2013 (empirical data and frameworks))-cont'd # Bacteria and plantparasitic nematodes (but higher relative contribution of nematodes to the total fauna), earthworms tend to disappear in acidic soils, and enchytraeids become rare " Plant competition intensity and mycorrhizal symbioses " C sequestration, less soil fertility " Total fungal biomass (incl. melanised hyphae) and total arthropods, with increased feeding preferences of grazing microarthropods N eutrophication " Above-ground growth and increase in shoot/root ratio " Soil respiration and accumulation of recalcitrant C # Extramatrical mycelium, reduced total microbial biomass " Plant investment in P uptake " P availability, increasing P-limiting role # Mesofaunal abundance (oribatids, gamasids, collembolans), but higher biodiversity " Plant N:P ratio (# C:N ratio) ...
We examine the potential of trait-based parameters of taxa for linking above- and below-ground ecological networks (hereafter 'green' and 'brown' worlds) to understand and predict community dynamics. This synthesis considers carbon, nitrogen and phosphorus-related traits, the abundance of component species and their size distribution across trophic levels under different forms of management. We have analysed existing and novel databases on plants, microbes and invertebrates that combine physico-chemical and biological information from (agro)ecosystems spanning the globe. We found (1) evidence that traits from above- and below-ground systems may be integrated in the same model and (2) a much greater than expected stoichiometric plasticity of plants and microbes which has implications for the entire food-web mass abundance scaling. Nitrogen and phosphorus are primary basal resources (hence, drivers) and more retranslocation of P than of N from leaves will lead to higher N:P in the litter and soil organic matter. Thus, under nutrient-rich conditions, higher foliar concentrations of N and P are reflected by lower N:P in the brown litter, suggesting less P retranslocated than N. This apparent stoichiometric dichotomy between green and brown could result in shifts in threshold elemental ratios critical for ecosystem functioning. It has important implications for a general food-web model, given that resource C:N:P ratios are generally assumed to reflect environmental C:N:P ratios. We also provide the first evidence for large-scale allometric changes according to the stoichiometry of agroecosystems. Finally, we discuss insights that can be gained from integrating carbon and nitrogen isotope data into trait-based approaches, and address the origin of changes in Delta C-13 and Delta N-15 fractionation values in relation to consumer-resource body-mass ratios.
... In the case of autotrophs, Matzek and Vitousek (2009) find no clear link between N:P ratio in their tissues and the (pine) growth rate. However, in the case of many soil heterotrophs, such a link is according to Mulder and Elser (2009) not implausible and deserves further investigation under controlled environmental conditions, such as in the Ecotrons (Naeem et al., 1995;Stewart et al., 2013, and references therein). Being possibly the first test for a trait-mediated association of terrestrial webs with C:N:P stoichiometry (Peñuelas and Sardans, 2009), Mulder and Elser (2009) focused in fact on the potential size dependence of heterotrophs. ...
... As such, 126 Christian Mulder et al. Table 2.5 Major couplings between global warming, plant invasion, soil acidification and N eutrophication (change drivers), plant responses and soil biota (meta-analyses by Sardans and Peñuelas, 2012 (vascular plant-soil interactions), Sardans et al., 2012a,b (change drivers and responses), Bobbink and Hettelingh, 2011 (critical loads of N), and Naeem et al., 1995;Reich et al., 2005;Mulder and Elser, 2009;Griffiths et al., 2012;Vasseur et al., 2012;Cotrufo et al., 2013;Vonk and Mulder, 2013 (empirical " Plant production and growth (but the effects can be negative in short, extreme warming events) ...
... Connecting the Green and Brown Worlds Table 2.5 Major couplings between global warming, plant invasion, soil acidification and N eutrophication (change drivers), plant responses and soil biota (meta-analyses by Sardans and Peñuelas, 2012 (vascular plant-soil interactions), Sardans et al., 2012a,b (change drivers and responses), Bobbink and Hettelingh, 2011 (critical loads of N), and Naeem et al., 1995;Reich et al., 2005;Mulder and Elser, 2009;Griffiths et al., 2012;Vasseur et al., 2012;Cotrufo et al., 2013;Vonk and Mulder, 2013 (empirical data and frameworks))-cont'd ...
... Ecosystem Services (ES) were classified according to the Common International Classification of Ecosystem Services (CICES; Haines-Young and Potschin, 2018): provisioning ES (e.g., food and water provision), regulating ES (e.g., water purification) and cultural ES (e.g., landscape aesthetics). Biodiversity was separately analyzed from ES because biodiversity is considered to be underlying structures that support ecosystem processes and functions to provide ES but not ES per se (Naeem et al., 1995;Cardinale et al., 2012). ...
... Ecosystem services (ES) provide food, water, pollination, water and air filtration, recreation, among other services (ibid.). Biodiversity plays an important role in the provision of ES by enabling structures that support ecosystem processes and functions (Naeem et al., 1995;Cardinale et al., 2012). Ecosystems can provide a better quality and more ES if the underlying ecological structures and functions are more diverse (Harrison et al., 2014). ...
Ecuador belongs to the megadiverse countries of the world. However, the high diversity in species, ecosystems and their services are under threat by land use changes, invasive species, overexploitation, pollution and climate change. There is a need to monitor, manage, protect and improve biodiversity and ecosystem services (BES) in Ecuador; however, Ecuador is marginally represented in the international policy-science interface for the protection of BES. We analyzed 266 international peer-reviewed papers that were published between 2000 and 2020 to assess the current impact of human disturbance and climate change on BES in continental Ecuador. We found that there were more studies available on the impact of human disturbance on BES than on climate change effects. Birds represented the most studied taxon in Ecuador (70 studies), whereas the total amount of available international scientific publications for other Ecuadorian plant and animal taxa were rather low (< 34 studies) and spatially and thematically scattered. Among ecosystem services, water provision was analyzed relatively often. Our literature review revealed that there is a need to conduct more studies on impacts of human disturbance and climate change on BES. Further research is needed; particularly in the coastal hinterland, in the central Andes and in the Amazon. We suggest that the investment of time, resources and effort into the documentation, standardization, sharing, and publishing of data are key towards supporting the monitoring and maintenance of BES.
... Reduction in summed variances of S with an increase in D also indicates that the D maintained the S by portfolio/statistical averaging (Tilman et al. 1998) and the covariance/competitive interaction effects (Lehman and Tilman 2000). Increase in averaged total biomass with an increase in D is an indication of overyielding (Naeem et al. 1995, Tilman et al. 1996, Hector et al. 2010, or selection effects (Loreau and Hector 2001). Further, the positive and quadratic relations of mean biomass, mean P and D with the N-input levels and quadratic but negative relation of standard deviation of mean biomass with the N-input levels, suggested that reduction in standard deviation and increment in the mean biomass due to increased D may have contributed to the portfolio/statistical averaging/overyielding effects (Naeem et al. 1995, Tilman et al. 1996, Hector et al. 2010. ...
... Increase in averaged total biomass with an increase in D is an indication of overyielding (Naeem et al. 1995, Tilman et al. 1996, Hector et al. 2010, or selection effects (Loreau and Hector 2001). Further, the positive and quadratic relations of mean biomass, mean P and D with the N-input levels and quadratic but negative relation of standard deviation of mean biomass with the N-input levels, suggested that reduction in standard deviation and increment in the mean biomass due to increased D may have contributed to the portfolio/statistical averaging/overyielding effects (Naeem et al. 1995, Tilman et al. 1996, Hector et al. 2010. ...
Atmospheric nitrogen (N) deposition is a matter of serious concern for the structure and functioning of global ecosystems, but the effect of N application of species diversity (D), primary productivity (P) and stability (S) of tropical grassland ecosystems is not known. The present study reports the effects of different levels of N application on species composition, and the D, P, S and their relationships in a tropical grassland. Within the experimental grassland, 72 1 × 1m plots with 6 N‐input levels and with 12 replicates, were established in 2013. For three years, different doses of urea as a source of N were applied to the plots. Data on individuals and biomass of each species were recorded and statistically analysed. The study revealed that the N applied caused variations in species composition, D, P and S. Below 90 kg N‐dose; D was positively related to P and S, while above this level, the relations were negative due to N induced responses of species and functional group composition as well as biomass distribution among them. The optimum applied N levels for maximum D (50‐60 Kg N), P (120 Kg N) and a positive relation of S with D up to 90‐Kg N‐treatment suggested that the 90 Kg N‐dose could be a maximum dose of N which the grassland can tolerate. Hence, N application should not exceed 90 Kg level for sustainability of the structure and functioning of tropical grassland ecosystem.
... Since high-quality litter decomposes faster than lowquality litter, the relationship among litter quality, decomposition, and nutrient cycling is generally positive, and high-quality litter, in general, supports higher secondary production in detrital food webs (Swift et al. 1979;Wardle et al. 2004;García-Palacios et al. 2013). Additionally, accumulating evidence suggests that litter diversity has been shown to increase resource partitioning among detritivores and, consequently, the secondary production of microbial and invertebrate detritivores (Naeem et al. 1994(Naeem et al. , 1995Hansen and Coleman 1998;Jonsson and Malmqvist 2000). However, although less frequently, some evidence has pointed out the inhibitory effects of litter diversity on decomposition (Liu et al. 2020). ...
The quality and diversity of leaf litter are important variables in determining the availability of energy in detritus-based food webs. These factors can be represented by the stoichiometric proportion between carbon and multiple nutrients, and the mixture of litter from different taxonomic and/or functional origins. In aquatic ecosystems, factors that accelerate litter decomposition can influence the secondary productivity of planktonic microbiota, which act as a link between litter and higher trophic levels. This study aimed to analyze the influence of litter quality and diversity on the oviposition behavior of medically important mosquitoes. We hypothesized that both factors would have a positive effect on the attraction of female mosquitoes and would stimulate a greater amount of oviposition. To test this hypothesis, microcosms containing isolated leaf litter leachates from four plant species were used to manipulate gradients of litter quality, and microcosms with all leachates combined were used to test the effects of litter diversity. The results showed a positive effect of litter quality (p < 0.05) on mosquito oviposition rate, with lower C:P ratio litter species (high-quality litter) presenting higher oviposition rates than litter species with high C:P ratios (low-quality litter). However, contrary to our expectations, litter diversity had a negative effect (p = 0.002) on the magnitude of egg-laying by mosquitoes. Our results highlight the importance of litter quality and diversity for insect reproductive behavior. Our data shows that litter quality can serve as a crucial indicator of a suitable environment utilized by female mosquitoes for oviposition. This finding can enhance our ability to understand and develop effective methods for mitigating the reproduction of medically significant mosquitoes, whether by allowing us to predict, based on the composition of vegetation species, areas more prone to mosquito infestation, or by using high-quality litter in oviposition traps. Furthermore, maintaining vegetation diversity can help control mosquito reproduction.
... The role of species diversity in ecosystem functioning or services is a central topic in biodiversity and biological conservation (Cardinale et al., 2012;Giller et al., 2004;Hector & Hooper, 2002;Loreau et al., 2001;Naeem et al., 1995;Tilman et al., 2014). Most biological communities are characterised by a few dominant and many rare species (Hubbell, 2001;McNaughton & Wolf, 1970;Rabinowitz et al., 1986;Whittaker, 1960), which has led to rare biosphere concept, claiming that high richness of rare species in ecosystems is common (Jousset et al., 2017;Lynch & Neufeld, 2015;Pedrós-Alió, 2007). ...
There is increasing evidence that rare species play an important role in trophic interactions, but the function of rare species with low biomass in these processes remains unclear. Phytoplankton is placed at the base of lentic and marine food webs and is characterised by a few dominant species and many rare species. While the dominant species contribute most to the primary production, they are often low‐quality food for primary consumers. The rare species may instead provide the essential biochemical nutrients for consumers, especially in eutrophic waters.
We hypothesised that the biomass of rare eukaryotic phytoplankton species significantly determines the concentrations of sestonic long‐chain highly unsaturated fatty acids, directly linking them to the functioning of aquatic ecosystems. We applied redundancy analysis and Lasso regression models to identify the species whose population dynamics explain the variations of sestonic fatty acids concentrations in tropical reservoirs and lakes.
The lasso models predicted that the dominant phytoplankton species determined the concentration of saturated sestonic fatty acids and that rare phytoplankton species were the main determinant for polyunsaturated fatty acids, which are critical for the food quality of consumers such as zooplankton and promote the energy transfer from primary producers to higher trophic levels in natural waters. In particular, the biomass of the rare species Scenedesmus obliquus was a key variable explaining the variations of α‐linolenic acid, α‐linoleic acid, γ‐linolenic acid, and eicosapentaenoic acid concentrations.
We conclude that the population dynamics of rare phytoplankton species can define the food quality associated with eicosapentaenoic acid for consumers and thus play a critical role in the trophic transfer in the food webs of tropical waterbodies.
... Moreover, humanity has a limited understanding of the functions of most species. Biological diversity is valuable in many ways (Kellert 1986), including its contribution to ecosystem stability (Elton 1958;Naeem et al. 1995;Tilman and Downing 1994;Tilman et al. 1996). To best conserve and use species in managed ecosystems, they need to be collected and described. ...
Ectomycorrhizae are the mutually beneficial symbioses of fungi and fine roots, and are responsible for the uptake of nutrients that support tree growth. Many species of fungi form ectomycorrhizae with conifers; most are Basidiomycetes or Ascomycetes that form large mushrooms found in forests. It is, therefore, important to investigate how forest management practices affect the health, growth patterns, physiological function, and taxonomic diversity of ectomycorrhizae. Identification of ectomycorrhizae is fundamental to such research. To date, several hundred detailed descriptions of ectomycorrhizae have been published in books, journal articles, and on a compact disk database called DEEMY (DEtermination of EctoMYcorrhizae), but hundreds more are unavailable in researchers� private databases. The Database of Descriptions of Ectomycorrhizae (DDE) web site aims to be a comprehensive tool for the identification of ectomycorrhizae by bringing together as many published and unpublished descriptions as possible. A search function, available to all users, has been programmed to act as an electronic synoptic key. The DDE system also allows qualified researchers to add their unpublished descriptions to the database, and to update these descriptions as needed. The DDE database currently contains 338 descriptions; 318 from DEEMY and 20 from A Manual of Concise Descriptions of Ectomycorrhizae (CDE). Entry of descriptions and search profiles is done using a web form with all the characters in the CDE checklist and links to the CDE illustrated glossary.
... Biodiversity has recently emerged as an issue of both scientific and political concern primarily because of an increase in extinction rates caused by human activities (Ehrlich & Wilson, 1991). Several very large experiments (Tilman & Downing, 1994;Naeem et al., 1994;1995;Kareiva, 1994;1996;Tilman, 1996) have addressed the relationship between biodiversity, measured as species richness, and ecosystem function. However, they have failed to reveal a clear causal effect (Huston, 1994). ...
The investigation was carried out of wild vegetation along aridity gradient from Sakhi Sarwar to Ghazi Ghat in Dera Ghazi Khan Landscape. Presence/absence data were collected from 13 sampling sites. We used classification as well as ordination methods to analyze the data structure. The main emphasis was on classification, ordination being used in part to check whether the classification results reflect in an adequate way the main floristically gradients in the data set, and also to detect relations between some environmental factors and the compos ition and structure of natural vegetation. The major axes brought by the ordination were related to soil characteristics. The application of multivariate statistic {detrended correspondence analysis (DCA) and cluster analysis} allowed an interpretation of weed species spatial distribution and assemblage. From the results of classification (cluster analysis) samples from fields could be divided into distinct plant associations based on floristic composition. We have shown that there is a clear relation between physical and chemical features of the substrate and the association defined by numerical analysis. In this respect, soil texture and organic matter seems particularly important in shaping the natural communities .
... The role of species diversity in ecosystem functioning or services is a central topic in biodiversity and biological conservation (Naeem 1995 Hubbell 2001), which has led to concept 'rare biosphere', claiming that high richness of rare species in ecosystems is common (Pedrós-Alió 2007; Lynch and Neufeld 2015; Jousset et al. 2017). Due to their high abundance or biomass, dominant species have been widely considered to be responsible for key ecosystem processes, such as primary production, energy transfer and matter cycling, as predicted by the mass ratio hypothesis (Grime 1998). ...
There is increasing evidence that rare species play an important role in trophic interactions, but how rare species with low biomass disproportionately function in these processes remains unclear. Phytoplankton is placed at the base of lentic and marine food webs and is characterised by a few dominant species and many rare species. While the dominant species contribute most to the primary production, they are often low-quality food for primary consumers. The rare species may instead provide the essential biochemical nutrients for consumers, especially in eutrophic waters. We hypothesised that the biomasses of rare phytoplankton species significantly determine the concentrations of particulate PUFAs (polyunsaturated fatty acids), directly linking them to the functioning of aquatic ecosystems. We applied redundancy analysis and Lasso regression models to identify the species whose population dynamics explain the variations of particulate fatty acids concentrations in tropical reservoirs and lakes. The model predicted that the dominant phytoplankton species determined the concentration of saturated particulate fatty acids and that rare phytoplankton species were the main determinant for PUFAs. In particular, the biomass of the rare species Scenedesmus obliquus was a key variable explaining the variations of ALA (α-linolenic acid), LIN (α-linoleic acid), GLA (γ-linolenic acid) and EPA (eicosapentaenoic acid) concentrations in the studied waterbodies. We conclude that the population dynamics of rare phytoplankton species can define the food quality associated with PUFAs for consumers and thus play a critical role in the trophic transfer in the food webs of tropical waterbodies.
... Adicionalmente a este valor hay que destacar la fuerte dinámica temporal y espacial, la cual en ciertas localidades puede ser marcada causando un importante incremento en la riqueza local (Erwin y Scott 1981). El conocimiento de esta dinámica estacional en un determinado ecosistema puede ofrecer información importante para la generación de estrategias y planes de conservación enfocados a mantener la funcionalidad del mismo (Pimm 2002;Tilman y Downing 1994;Naeem et al. 1995;Johnson et al. 1996). ...
... A vast number of animals find their home and acquire all life necessities in forests. The existence of a variety of plant species in a healthy and connected forest enables the ecosystem to absorb environmental changes and thus ensuring the provision of ecosystem goods and services upon demands (Naeem et al., 1995;Naeem, 1998;Campbell et al., 2007). ...
The proposed study introduces a data driven approach where problems facing the forest
conservation initiatives, beekeepers, and beekeeping as an industry are identified and analyzed to understand problem roots using qualitative and quantitative methods. Feasible solutions are then proposed based on empirical evidence to accurately address existing beekeeping problems. The focus is made to assess the use of locally made bark and log beehives used in traditional beekeeping practices and their effects on forest degradation and honeybee post-harvest colony losses. The study then suggests feasible solutions to identified problems for improved beekeeping practices and biodiversity conservation.
... Paine, 1969;Flecker, 1996). Consequently, the existence of ecologically redundant species in ecosystems has been hypothesized to buffer ecosystems from disturbance or loss of component species (Naeem et al., 1995;Loreau, 2000). Evidence that redundancy in ecological function exists has been shown experimentally in studies that examined aquatic microbial decomposition (Naeem and Li, 1997;Scarff and Bradley, 2002) and plant productivity (Walker et al., 1999). ...
This book provides information on the historical and theoretical perspectives of biodiversity and ecology in tropical forests, plant and animal behaviour towards seed dispersal and plant-animal interactions within forest communities, consequences of seed dispersal, and conservation, biodiversity and management.
... Paine, 1969;Flecker, 1996). Consequently, the existence of ecologically redundant species in ecosystems has been hypothesized to buffer ecosystems from disturbance or loss of component species (Naeem et al., 1995;Loreau, 2000). Evidence that redundancy in ecological function exists has been shown experimentally in studies that examined aquatic microbial decomposition (Naeem and Li, 1997;Scarff and Bradley, 2002) and plant productivity (Walker et al., 1999). ...
The chapters of this book on seed dispersal are divided into four parts: (1) frugivores and frugivory (8 chapters); (2) seed and seedling shadows (7 chapters); (3) seed fate and establishment (eight chapters); and (4) management implications and conservation (six chapters). The book presents both recent advances and reviews of current knowledge.
... It is expected that increases in diversity will lead to an increase in productivity (reviewed in Tilman et al., 2014). This has been shown with experimental manipulations of primary producer diversity (e.g., Tilman et al., 1996Tilman et al., , 2001 and with increases in diversity at higher trophic levels (Naeem et al., 1994(Naeem et al., , 1995. Higher production across trophic levels suggests greater TTE because diverse communities are able to more efficiently use available resources (i.e., space, light, nutrients, prey resources, etc.;Lehman and Tilman, 2000;Naeem et al., 2000;Tilman, 2004;Tilman et al., 1996Tilman et al., , 2014Stachowicz et al., 1999). ...
Ecosystem-based management relies on understanding how perturbations influence ecosystem structure and function (e.g., invasive species, exploitation, abiotic changes). However, data on unimpacted systems are scarce; therefore, we often rely on impacted systems to make inferences about ‘natural states.’ Among the Laurentian Great Lakes, Lake Superior provides a unique case study to address non-native species impacts because the food web is dominated by native species. Additionally, Lake Superior is both vertically (benthic versus pelagic) and horizontally (nearshore versus offshore) structured by depth, providing an opportunity to compare the function of these sub-food webs. We developed an updated Lake Superior EcoPath model using data from the 2005/2006 lake-wide multi-agency surveys covering multiple trophic levels. We then compared trophic transfer efficiency (TTE) to previously published EcoPath models. Finally, we compared ecosystem function of the 2005/2006 ecosystem to that with non-native linkages removed and compared native versus non-native species-specific approximations of TTE and trophic flow. Lake Superior was relatively efficient (TTE = 0.14) compared to systems reported in a global review (average TTE = 0.09), and the microbial loop was highly efficient (TTE > 0.20). Non-native species represented a very small proportion (<0.01%) of total biomass and were generally more efficient and had higher trophic flow compared to native species. Our results provide valuable insight into the importance of the microbial loop and represent a baseline estimate of non-native species impacts on Lake Superior. Finally, this work is a starting point for further model development to predict future changes in the Lake Superior ecosystem.
... O encontro resultou em um livro (Schulze & Mooney, 1993) e diversas outras publicações durante os anos 90 (e.g., , Tilman & Downing, 1994Naeem et al., 1995;Tilman et al., 1996;Chapin et al., 1997;Naeem & Li, 1997). Esses estudos, juntamente com as críticas em relação a validade das abordagens experimentais e interpretação dos resultados Huston, 1997;Wardle, 1998;, serviram de base para o refinamento não apenas do desenho experimental e dos métodos de análise empregados nos estudos B-EF, como também dos modelos propostos para explicar os mecanismos ecológicos subjacentes a relação entre a biodiversidade e os processos ecossistêmicos (Hooper & Vitousek 1997;Tilman et al., 1997;Loreau, 1998a;1998b;Hector, 1998;. ...
Given the unprecedented and growing threats to inland waters — eutrophication, cyanobacterial blooms, over-exploitation, and climate change — from multiple human activities, biodiversity is decreasing at faster rates in freshwater ecosystems than in marine or terrestrial. Since the early 1990s, hundreds of studies attempted to explain how ecosystems respond to biodiversity loss and how changes in biodiversity scale up to affect ecosystem functioning, as well as the provision of goods and services to humans. Recent studies have demonstrated that such biodiversity responses are commonly trait-mediated and the effects of communities on ecosystem functioning also depend on species traits. However, it remains unclear to what extent such biodiversity responses translate into changes in the rates of many ecosystem processes in naturally assembled communities. In this doctoral dissertation, I aimed at evaluating the effects of nutrient availability and cyanobacteria dominance on structure and composition of plankton communities (phytoplankton and zooplankton), and on two important ecosystem functions in aquatic systems: phytoplankton resource use efficiency (RUE) of limiting nutrients — phosphorus and nitrogen — and zooplankton top-down control of algae. For this, I structured this doctoral dissertation in three chapters to explore the mechanisms that underlie biodiversity-ecosystem functioning (B-EF) relationships, using a combination of experimental and fieldwork approaches, together with multiple aspects of biodiversity (i.e., taxonomic and functional diversity). In the first chapter, I and my coauthors analyzed the relationship between different measures of phytoplankton diversity, temporal turnover and RUE using 8-years monitoring data set from a cyanobacteria-dominated subtropical lake, which is now experiencing a shift in the trophic state from oligo-mesotrophic to eutrophic. Additionally, we aimed at evaluating the effect of resource availability on phytoplankton community structure and RUE. In the second chapter, using 1-year monitoring data set from the same lake, we evaluated the relative importance of size-based and taxon-based approaches in explaining the strength of zooplankton top-down control on algae, and also aimed at disentangling the mechanism by which zooplankton body size drives such ecosystem function. Finally, in the third chapter, we used an experimental metacommunity approach that simulated typical gradients of productivity and plant structural complexity to test how zooplankton body size diversity and composition responded to such gradients and whether and how such trait responses impacted top-down control of algae. Through these three chapters, we demonstrated that under environmental changes (i.e., nutrient increase and prolonged cyanobacteria dominance) approaches based on body size and taxonomic richness complement each other in explaining variation in zooplankton top-down control. Our results clearly indicate that zooplankton body size explains a substantial and independent part of the variance in top-down control, which corroborates several studies demonstrating the role of zooplankton body size to control phytoplankton biomass. But contrary to our expectations, species richness also plays a role, indicating that species richness may adequately represent some unmeasured traits that also influence ecosystem functioning. Moreover, we demonstrated that different aspect of biodiversity might have divergent responses and divergent effects on ecosystem functioning depending on environmental perturbation, which highlight the importance of considering multiple aspects of biodiversity — taxonomic and functional approaches — in B-EF research. Overall, our results illustrated the potential for trait-based approaches to reveal biodiversity responses to environmental change and their generalizable effects on ecosystems. Furthermore, given the lack of large grazers in tropical and subtropical regions, and the evidence that Cyanobacteria dominance will increase in freshwater ecosystems under the predicted future climate, the results herein highlight the concern about the energy flow in aquatic systems dominated by Cyanobacteria.
... These studies developed in line with ecological research on biodiversity and the consequences of its decline (Ehrlich, Ehrlich, 1982;Wilson, 1992). Mainly investigating the effects of species diversity on biomass production, these works employed theoretical approaches, models (Tilman et al., 1997), plot-scale experiments (Tilman, Downing, 1994), controlled ecosystem reconstructions (Naeem et al., 1995) or, more rarely, monitoring in the field (Wardle et al., 1997). ...
Beginning with an examination of the origins of the emergence of the ES concept in ecology, this chapter explores the different interpretations and uses of this concept, as well as the debates it has generated within the discipline. Indeed, for many specialists, ‘ecosystem services’ are not self-evident in ecology. As long as the concept served chiefly as a message of alert, its metaphorical nature was enough. But today, in the momentum created by the Millennium Ecosystem Assessment, and more particularly the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), the question of assessing ecosystem services has become central. Inevitably this then circles back to the problems that arise from the grey areas of this concept in relation to the more general issue of biodiversity conservation. This is very apparent when analysing the ES assessment frameworks proposed by different institutes or researchers. We will start by looking at the ecological roots of the ES concept and will then highlight its grey areas, illustrating the key issues through a study of the analytical frameworks most discussed in scientific literature and environmental institutes.
... Recognition that loss of species may affect the functioning of ecosystems has led to an impressive accumulation of literature on the effects of diversity loss over the last 10 yr. This work has revealed much about biotic controls on ecosystem functioning, especially on productivity (Naeem et al. 1995, Symstad et al. 1998, Hector et al. 1999, Engelhardt and Ritchie 2001 and nutrient retention (Tilman et 1997a, b, Symstad et al. 1998, Tilman 1999, Engelhardt and Ritchie 2001, on invasibility of a community (Knops et al. 1999, Levine 2000, Naeem et al. 2000, Prieur-Richard et al. 2000, and on stability of ecosystem processes (Naeem and Li 1997, Hughes and Roughgarden 1998, Yachi and Loreau 1999, Borrvall et al. 2000, Ives et al. 2000. However, results are sometimes equivocal across ecosystems and among spatial or temporal scales, which has lead to sometimes-heated discussion over the relative importance of biodiversity in affecting ecosystem functioning (Hughes and Petchey 2001). ...
... Functional redundancy is related to the stability of ecological communities (Naeem et al., 2002), since high levels could either allow for ecosystem recovery or for random extinctions or disturbances when species loss does not translate to a loss in ecosystem functioning (Naeem et al., 1995;Fonseca & Ganade, 2001;Pillar et al., 2013;Arnan et al., 2019). Differences in the relationship between species richness and functional diversity by habitat type shows that functional redundancy is potentially higher in forest habitat. ...
In this study, we investigated the mechanisms behind species coexistence and the relationships between functional diversity and species richness in ant assemblages in both forest and pasture habitats in the southwestern Brazilian Amazon. We addressed the specific question: What is the primary mechanism for species coexistence in forest and pasture habitats? According to the identified mechanism in each habitat, we had the following alternative expectations: (i) niche partitioning – we expected to observe a linear positive relationship between functional diversity and species richness, indicating a complementary relationship; or (ii) niche filtering – a positive constant asymptotic relation between functional diversity and species richness, indicating a functional redundancy relationship. In total, we sampled 91 ant species, 82 species in a forest habitat and 16, in a pasture habitat. In the forest habitat we identified niche filtering as the structuring mechanism of the ant assemblage, but we were unable to identify a clear mechanism in the pasture habitat. Although the relationship between functional diversity and species richness was positive in both habitats, the relationship was weaker in the forest habitat, indicating a greater functional redundancy among the ant species in this habitat. Our results reinforce the divergence of species coexistence mechanisms and ant assemblage structures in both natural and human-modified habitats in the Southwestern Brazilian Amazon.
... The idea that diverse communities would increase production was re-evaluated much later in the mid to late 1990s with early food web experiments testing how the loss of biodiversity may influence the performance of terrestrial ecosystems (Naeem et al., 1994(Naeem et al., , 1995. Grassland experiments showed that increasing the number of species increases productivity (e.g. percentage of plant cover) (Tilman et al., 1996). ...
Ecosystems worldwide are subject to an unprecedented loss of biodiversity, largely resulting from a range of human impacts such as over-exploitation, habitat loss and climate change. To understand the consequences of this biodiversity crisis on both land and oceans, scientists tried quantifying the relationship between biodiversity and ecosystem functioning (ability of an ecosystem to perform and maintain a suite of key properties such as biomass and flux of energy), ultimately trying to answer: what is the importance of biodiversity for ecosystems? A positive influence of biodiversity on ecosystem functioning has been shown in many experimental studies, demonstrating enhanced biomass production under higher number of species. However, the extent to which such findings hold in natural systems is unknown, especially in large and complex marine ecosystems. To address this knowledge gap, we use high-resolution
monitoring data on fish community composition and abundance in continental shelf seas across the North Atlantic and statistical modeling to test the existence of links between biodiversity and ecosystem functions at both regional and continental scales. This empirical approach is complemented with a mathematical food web model to establish theoretical hypotheses about the contribution of biodiversity and food web structure on several ecosystem functions. We demonstrate that while a positive relationship between the number of species and several ecosystem functions is expected in theory, that link is not necessarily emergent from observations of real fish communities. We highlight that the metric of biodiversity and ecosystem function evaluated matters to determine the overall ecosystem performance. This thesis is an attempt to understand the role of fish biodiversity for marine ecosystem functioning across several ecosystems and to develop hypotheses on the role of biodiversity in complex food webs. Quantifying the importance of biodiversity for ecosystem functioning is necessary for our understanding of ecosystem complexity in ecology, enhance biodiversity and ecosystem conservation and has the potential to trigger policy towards conservation of ecosystems.
... These effects were observed with small changes in species numbers, from one up to eight species per patch, highlighting the importance of every species in the ecosystem. Our findings support theoretical (Loreau, 1998;Naeem et al., 2002) and empirical studies (Naeem et al., 1995;Schmid et al., 2002) that relate diversity with a variety of ecosystem processes, such as respiration, productivity, mineralization, decomposition, and accumulation of phosphorus and potassium. ...
Questions
Niche complementarity has been proposed as the underlying mechanism for optimizing resource use of plants in diverse ecosystems, usually associated with their functional traits and not with the species number per se. Our main questions were: (a) does species diversity optimize the use of resources in arid ecosystems; (b) is there redundancy of species in the use of water and nutrients; and (c) what diversity components most affect ecosystem functions of water regulation and material cycling?
Location
Central Monte desert, Argentina.
Methods
We selected vegetation patches with different species (SD) and functional diversities (FD), where we measured indicators of water regulation and material cycling. At two soil depths, we measured soil nitrate, phosphate, organic matter, chloride, electrical conductivity, and pH. We also determined decomposition, plant water use efficiency (foliar δ¹³C of C3 plants), and nitrogen use (δ¹⁵N). These variables were used as response variables, while total plant cover, species richness, Shannon, Simpson, evenness, and Rao's functional diversity indexes were used as predictors.
Results
At the soil surface, response variables were better explained by models that included diversity (SD, FD or both) instead of evenness, total plant cover or null model. A diversity effect was not detected in deeper soil layers for most variables, except for electric conductivity, which had a positive effect on FD. Richness explained plant δ¹³C but had no influence on plant δ¹⁵N.
Conclusions
Diversity of plant community influences ecosystem processes, as it increases decomposition, soil organic matter, and nutrient availability at the surface, and decreases water losses to the subsoil and plant water use efficiency. Both SD and FD explained one or more ecosystem processes of water regulation and material cycling, suggesting that individual species contribute to ecosystem functioning, with a low redundancy for arid areas.
... Among different levels of Biological Organizations, soil microbial community have a genetic variability, richness and evenness in communities. The interest is growing in finding out the relationships among ecosystem diversity, structure, function and a number of theories have been formulated regarding that how microbial composition and diversity are related to the functional capability of terrestrial ecosystem (Müller, Westergaard et al. 2002).it is a research that the more microbial species diversity is beneficial for the ecosystem (Naeem, Naeem et al. 1995) and while others suggest that the properties of ecosystem depend more on functional capabilities of particular microbial species than on the total no of species. (Islam and Wright) Soil contain billions of microorganism ranging in size from 0.5 to 5 μm which consist primarily of Bacteria, fungus, actinomycetes and lichens. ...
... Among different levels of Biological Organizations, soil microbial community have a genetic variability, richness and evenness in communities. The interest is growing in finding out the relationships among ecosystem diversity, structure, function and a number of theories have been formulated regarding that how microbial composition and diversity are related to the functional capability of terrestrial ecosystem (Müller, Westergaard et al. 2002).it is a research that the more microbial species diversity is beneficial for the ecosystem (Naeem, Naeem et al. 1995) and while others suggest that the properties of ecosystem depend more on functional capabilities of particular microbial species than on the total no of species. (Islam and Wright) Soil contain billions of microorganism ranging in size from 0.5 to 5 μm which consist primarily of Bacteria, fungus, actinomycetes and lichens. ...
... Elles portent majoritairement sur les effets de la diversité spécifique sur la production de biomasse. Elles s'appuient sur des approches théoriques, sur des modèles (Tilman, Lehman et Thomson, 1997), sur des expérimentations à l'échelle de la parcelle (Tilman et Downing, 1994) ou sur des reconstitutions d'écosystèmes en milieu contrôlé (Naeem et al., 1995) et, plus rarement, sur des suivis en milieu réel (Wardle et al., 1997)� L'émergence des travaux sur les relations entre biodiversité et fonctionnement des écosystèmes est attribuée aux inquiétudes de leurs auteurs sur les conséquences des pertes de biodiversité liées aux activités humaines (Hooper et al., 2005) au sein d'une mouvance post-Rio 1992 (Cardinale et al., 2012)� Cet intérêt de la part des écologues a été renforcé par l'émergence des problématiques associées aux changements globaux (Symstad et al., 2003)� Toutefois, selon les auteurs et les périodes, les finalités de ces travaux sont variables� Certains auteurs semblent être motivés par la volonté de démontrer le rôle de la biodiversité sur le fonctionnement des écosystèmes (Tilman, Lehman et Thomson, 1997)� Si les questions sont étroitement liées, les méthodes pour y répondre sont différentes. Au regard des méthodes utilisées, les premières études sur les relations entre biodiversité et fonctionnement des écosystèmes étudiaient plutôt les effets dus à un changement du nombre d'espèces ou de groupes fonctionnels, et non les conséquences des pertes d'espèces liées aux activités humaines� Entre 1990 et 2012, ces études étaient justifiées par leur capacité à répondre aux questions relatives à la fourniture de services écosystémiques et pour leur utilité dans le domaine de la conservation de la biodiversité� L'utilisation des résultats sur les relations entre biodiversité et fonctionnement des écosystèmes, obtenus à partir d'études expérimentales, pour tenter de répondre à des questions plus pragmatiques relatives aux conséquences des pertes de biodiversité sur la fourniture de services écosystémiques en milieu réel, soulève un certain nombre de questions méthodologiques (Cardinale et al., 2012 ;Kremen, 2005). ...
... Une attention particulière a été portée sur les communautés de plantes, faciles à manipuler, pour établir un lien entre le nombre d'espèces mises en co-occurrence et la productivité primaire. Plusieurs auteurs ont ainsi mis en évidence l'effet positif de l'augmentation de la diversité taxonomique des plantes sur la productivité primaire (Naeem et al., 1995;Hector et al., 1999;Hooper et al., 2012;Tilman et al., 2012). La présence d'espèces et de groupes fonctionnels particuliers, ainsi que la richesse en groupes fonctionnels au sein des assemblages de plantes sont aussi des facteurs explicatifs d'une productivité élevée (Hooper & Vitousek, 1997;Hooper, 1998;Hector et al., 1999). ...
Ce projet de thèse vise à mieux comprendre l’effet des activités pastorales sur les communautés d'insectes coprophages et, en conséquence, sur le fonctionnement des écosystèmes. L'objectif est premièrement d'analyser les réponses fonctionnelles de ces insectes face à une diversité de pratiques pastorales, et en particulier le long de gradients de pression de pâturage. L'intensité du pâturage conditionne plusieurs facteurs (perturbation du sol, disponibilité de la ressource) susceptibles de contraindre la présence locale des espèces via des effets sur des traits biologiques et écologiques particuliers. Deuxièmement, nous souhaitons comprendre les effets du pâturage sur les rôles écologiques fournis par les communautés de coprophages, et en particulier sur la dégradation des excréments et l'enrichissement des sols en nutriments. Les réponses à ces questions mettront en lumière les processus écologiques, et notamment le rôle des coléoptères coprophages dans le fonctionnement des écosystèmes pâturés. Nous privilégierons la compréhension des mécanismes à la description des patrons, et nous placerons notre réflexion dans le cadre conceptuel de l’écologie des communautés avant d’envisager la valorisation des résultats pour le pastoralisme. Cette valorisation passera entre autres par la prise en compte des bousiers dans les enjeux de préservation de la biodiversité liés à la gestion actuelle des parcours. Enfin, nous travaillerons dans des contextes bioclimatiques différents et en collaboration avec trois aires protégées (la Réserve Naturelle Nationale des Coussouls de Crau, et les Parcs Nationaux des Cévennes et de la Vanoise) pour mettre en évidence les déterminismes généraux caractéristiques de l’entomofaune coprophage ouest-européenne.
... The aims of the present study were to (1) compare patterns of taxonomic and functional diversity of macrofaunal species along a depth gradient (19-2639 m), (2) identify the factors governing functional diversity patterns, and (3) find out if the functional diversity responds in the same way as species richness to environmental variation. The functional diversity of organisms can be expressed in several ways (Naeem et al., 1995;Hiddink et al., 2009). The present study uses the Biological Trait Analysis (BTA) and multivariate diversity indices to understand the role of macrofauna functional diversity pattern from the shallow (19 m) to deep sea (2639 m) system of the southern Indian continental region. ...
Identifying the drivers that shape the biodiversity of a region is important to predict the response of ecosystems to environmental changes. Macrofaunal distribution pattern in the North Indian Ocean has so far been mainly studied considering small geographical areas, and using taxonomic diversity. The present study is a functional trait based approach aimed to identify the environmental drivers of macrofaunal distribution and diversity pattern from the relatively unexplored southern Indian continental margin. A total of 53 stations were sampled along six transects from a depth range of 19–2639 m. Along with taxonomic diversity (α and β), functional structure was assessed by using Biological Trait Analysis (BTA) and multivariate functional indices (richness, evenness, dispersal, divergence and Rao's Entropy). Principal Component Analysis identified a clear depth-related variability in the measured environmental parameters. Alpha diversity of the macrofaunal community decreased with increasing depth, a trend driven by depth related changes in the environmental factors (dissolved oxygen, sediment organic carbon and texture). However, functional diversity was only partially explained by the studied environmental variables which may be due to different factors governing the taxonomic and functional diversity pattern of macrofauna. Among the functional indices, only functional richness and evenness showed a clear trend of increase from shallow to deeper depths indicating that biodiversity-environment relations are complex. Therefore, investigating the response of macrofaunal community using multiple measure of diversity (α, β- and, functional diversity) was useful for providing an understanding of macrofaunal diversity pattern. The results of our study contribute to the growing knowledge on large-scale diversity gradients for marine macroinvertebrates, which may be critical for understanding ecological patterns and its response to both habitat and climatic change.
... In man made landscapes, agricultural activities are the most frequent causes of species loss and, in addition to these deterministic causes of extinction, reductions in area and increases in isolation of semi natural habitats lead to further stochastic species losses (Saunders et al., 1991;Rosenzweig, 1995). Loss of biodiversity may result in loss of stability and functioning of ecosystems (Lawton, 1994;Naeem et al., 1995). ...
A comparative study was carried out in two different valleys of Ganga river system viz; Alaknanda and Bhagirathi. In both of valleys total 134 species with 118 genera and 56 families were recorded. Poaceae was the dominant family representing maximum (11) number of species followed by Asteraceae (10) Fabaceae (9) and Lamiaceae (9). In different vegetation strata a total of 39 species were encountered under tree layer, 36 species were under shrub layer and 59 species were under herb layer in both of the valleys. Out of them 31 tree species were recorded in Alaknanda valley and 27 were in Bhagirathi valley. In shrub layer 32 and 30 species were recorded in Alaknanda and Bhagirathi valley respectively. In the herb layer Bhagirathi valley showed highest (51) species richness in its influence zone and submergence zone (45). The proportion of family to species was recorded greater in both of valleys compare to the proportion of family to genus and genus to species. Abstract-A comparative study was carried out in two different valleys of Ganga river system viz; Alaknanda and Bhagirathi. In both of valleys total 134 species with 118 genera and 56 families were recorded. Poaceae was the dominant family representing maximum (11) number of species followed by Asteraceae (10) Fabaceae (9) and Lamiaceae (9). In different vegetation strata a total of 39 species were encountered under tree layer, 36 species were under shrub layer and 59 species were under herb layer in both of the valleys. Out of them 31 tree species were recorded in Alaknanda valley and 27 were in Bhagirathi valley. In shrub layer 32 and 30 species were recorded in Alaknanda and Bhagirathi valley respectively. In the herb layer Bhagirathi valley showed highest (51) species richness in its influence zone and submergence zone (45). The proportion of family to species was recorded greater in both of valleys compare to the proportion of family to genus and genus to species.
... Elles portent majoritairement sur les effets de la diversité spécifique sur la production de biomasse. Elles s'appuient sur des approches théoriques, sur des modèles (Tilman et al., 1997), sur des expérimentations à l'échelle de la parcelle (Tilman, Downing, 1994) ou sur des reconstitutions d'écosystèmes en milieu contrôlé (Naeem et al., 1995) et plus rarement, sur des suivis en milieu réel (Wardle et al., 1997). ...
D’abord imaginé par des écologues, le concept de service écosystémique (SE) a été produit dans le but de souligner l’importance du rôle du fonctionnement des écosystèmes pour les sociétés humaines (Daily, 1997; De Groot, 1992; Ehrlich, Ehrlich, 1982). Dans un contexte prégnant de dégradation des écosystèmes et de disparition des espèces, le concept visait à sensibiliser sur la nécessité de maintenir ce fonctionnement, au-delà de la conservation de la biodiversité au sens strict. A partir de l’analyse des origines de l’émergence du concept de SE au sein de l’écologie, ce chapitre explore les différents usages et sens pris par la notion, ainsi que les débats qu’elle a suscités au sein de la discipline. En effet, pour de nombreux spécialistes, l’appellation SE ne va pas de soi en écologie. Tant que le concept visait un message d’alerte, le caractère métaphorique pouvait suffire. Mais aujourd’hui, dans la dynamique Post-MEA telle qu’elle émerge avec l’IPBES notamment, la question de l’évaluation de ces services devient centrale. Elle renvoie donc inévitablement aux problèmes posés par les zones d’ombre de ce concept par rapport à l’enjeu plus général de conservation de la biodiversité. Ceci est largement perceptible lorsque l’on observe les cadres d’évaluation proposés par différentes institutions ou chercheurs. Dans une première section, nous revenons sur les racines écologiques de la notion de SE. Dans une deuxième section, nous identifions ces zones d’ombre à travers l’exposé de quelques questions clés. Dans une troisième section, nous illustrons ces problèmes à travers l’étude des cadres d’analyse les plus discutés dans la littérature et dans les institutions environnementales.
... Intact shrub-steppe with sagebrush is needed as habitat for a number of birds [10], such as the sage grouse [1], which is now rare. Highly diverse communities dominated by native plant species are likely to be more productive [7] and thus support more diverse wildlife. ...
... It could be subsequently expected that the high variety of organics delivered by a diverse plant community could trigger microbial productivity through the more efficient resource use by a large array of soil microbial decomposers with complementary niches (Steinauer et al., 2016). Such a complementarity effect has been supported by manipulative inter-trophic experiments (Naeem, Thompson, Lawler, Lawton, & Woodfin, 1995;Zak et al., 2003). We detected, however, no diversity effect on the variation in soil microbial productivity within NF, but a negative below-ground mass effect. ...
Nurse plants drive the assembly of facilitated communities and commonly promote plant–soil feedbacks, and are thus recognized as key engineers in abiotically stressful ecosystems. The literature neglects; however, the role of the communities which benefit from the presence of the nurse as contributors to soil ecosystem functions. We hypothesized that the nurse and its beneficiaries synergistically enhance essential ecosystem functions mediated by soil microbiota.
To track how plant–plant facilitation impacts plant–soil feedbacks, we selected three nurse species in semi‐arid mine tailings and defined three microsites (open space, nurse canopy and nurse + facilitated canopy). In each microsite, we quantified 18 abiotic and biotic variables associated with four functions: reduction in climatic stress, reduction in edaphic stress, soil fertility and soil microbial productivity (decomposition and nutrient cycling).
Litter biomass increased from open spaces to the microsite beneath the nurses, and further beneath the nurses and their beneficiaries. Litter biomass was a good predictor of both the reduction in climatic stress and increase in edaphic stress (likely owing to metal bioaccumulation). We attributed increments in soil organics and heterotrophic respiration beneath the nurses and their beneficiaries, compared to nurses alone, to biomass effects through increased litter deposition. Variation in fertility and microbial productivity among microsites shaped by the nurses and their facilitated communities was attributed to both diversity and biomass effects. In particular, fertility was promoted beneath phenotypically diverse facilitated communities, as inferred from ten above‐ and below‐ground traits. However, microbial productivity increased at low levels of root biomass likely due to reduced plant–microbe competition for nutrients.
Synthesis . Our results show that facilitated plant communities sheltered by nurse species relieve local abiotic stress and promote plant–microbe interactions, both through biomass and biodiversity effects. These observations shift the conception of facilitated species from simple beneficiaries of the nurse's effects to co‐drivers of essential ecosystem functions.
... Bird et al. 2012). Several studies have found little support for a relationship between herbivore diversity and plant damage (Agrawal et al. 2005;Maron and Vilà 2001;Naeem et al. 1995;Pennings and Silliman 2005). Second, it is not clear that plants on islands experience less herbivory than do plants on mainlands. ...
Aims
Organisms on islands are thought to escape biotic pressure and lose defensive capabilities. However, broadscale, evidence-based tests of this idea are rare. In this study, we asked: 1) whether the proportion of spinescent plant species differed between islands and mainlands; and 2) whether the proportion of spinescent species increased with increasing island area and with decreasing island distance to mainland.
Methods
We compiled species lists for 18 island-mainland pairs around Australia. We classified 1129 plant species as spinescent or non-spinescent using published species descriptions.
Important Findings
There was no significant difference between the proportion of spinescent species found on islands and on mainlands. Proportions of spinescent species were not significantly related to island area or distance to mainland. Our results suggest that spinescence is just as important to islands plants as it is to mainland plants, even for plants inhabiting small or distal islands. This is unexpected, given prevailing thought and previous work on island-mainland comparisons. Our study demonstrates the importance of testing well-accepted, yet untested ideas.
... Biodiversity confers protection against ecosystem instability and loss of functioning (Naeem et al. 1995;Worm et al., 2006;Cardinale et al., 2012) by providing services such as soil formation, erosion control, nutrient and hydrological cycling, and carbon storage (Daily,1997;Rands et al., 2010;Ten Brink et al., 2016;Hungate et al., 2017). Moreover, research has shown that economic value can be derived from retaining landscape features that promote biological diversity (Costanza et al., 1997;Balmford et al., 2002;Dee et al., 2017). ...
Despite building a clear and compelling message about the importance of conserving biodiversity and what we risk in depleting it, meaningful engagement from implicated stakeholders remains limited. Past studies have examined the gap between the possession of environmental knowledge and displaying behavior that would help to conserve it. Essentially, increasing awareness and interest in environmental issues does not ensure that individuals will make the necessary changes in behaviours detrimental to biological conservation. This is a concern as failure to meaningfully engage the public into acting on conservation strategies will hamper efforts to curb biodiversity loss. Herein the authors investigate why action to address biodiversity loss has been slow or deficient in many jurisdictions. The authors draw from models and theories developed in health and social sciences to provide context to the key factors that prevent action and propose steps that could be taken to stimulate it.
... There is a heated debate about the relationship between biodiversity and ecosystem stability (Srivastava and Vellend, 2005;Balvanera et al., 2006;Cardinale et al., 2012;Loreau and de Mazancourt, 2013;Brose and Hillebrand, 2016). Generally speaking, species richness has a positive effect on ecosystem stability (Naeem et al., 1995). Within our theoretical framework, ecosystem stability is associated with functional resilience, which depends on both functional redundancy and response diversity. ...
... Intact shrub-steppe with sagebrush is needed as habitat for a number of birds [8], such as the sage grouse [1], which is now rare. Highly diverse communities dominated by native plant species are likely to be more productive [5] and thus support more diverse wildlife. ...
This paper involves restoration principles of pastures in degraded territories of Kashkadarya basinand received data are based on the floristic and cenotic principles in pastures, besides restoration process includesof the principle of ecological-cenotic depency of pasture ecosystems, adaptive strategy of plants and differentiationprinciples of ecological nicha based on various species of complementary, ecotypes and plant species on the basis ofpasture phytocenosis formation
(15) (PDF) ECOLOGICAL PRINCIPLES OF RESTORATION OF DEGRADED PASTURES IN KASHKADARYA BASIN. Available from: https://www.researchgate.net/publication/332880630_ECOLOGICAL_PRINCIPLES_OF_RESTORATION_OF_DEGRADED_PASTURES_IN_KASHKADARYA_BASIN#fullTextFileContent [accessed Oct 05 2023].
... Earlier studies were conducted to find out if there is a relationship between biodiversity effects on ecosystem properties (Naeem et al. 1995, Tilman et al. 1996, Jonsson and Malqvist 2000, Engelhardt and Ritchie 2001. Species diversity as taxonomic concept would not necessarily link to such relationship. ...
Der Begriff nachhaltige landwirtschaftliche Produktion zielt auf zukunftsfähige ressourcenschonende Wirtschaftsweise ab, die in der Gesellschaft zunehmend Akzeptanz findet. Wie sich Nachhaltigkeit gestaltet ist regional und zeitlich variabel und wird von politischen, sozialen und ökonomischen Themen beeinflusst. Die Landwirtschaft ist unter anderem durch die Nutzung von Pflanzenschutz und chemischen Pflanzenschutzmitteln in der Lage, dauerhaft stabile Erträge zu sichern. Der intensive Einsatz von nicht-nachhaltigen Praktiken kann jedoch zu verheerenden Auswirkungen auf die Vielfalt und die Fülle von nützlichen Arthropoden führen. Eine nachhaltige Bewirtschaftung kann dagegen natürliche Gegenspieler von Schaderregern fördern, aber die vom Gesetzgeber verursachten Interventionen, wie das breit angelegte Spektrum von Pestiziden, können die Selbstkontrolle von natürlichen Gegenspielern als Regulatoren verzerren bzw. negativ beeinträchtigen. Die konventionelle Landwirtschaft kann Lebensräume, ökologische Strukturen, Nahrungsnetze und funktionelle Biodiversität zerstören. Die Folgen sind Emigration, der Verlust von Arten und vereinfachte interspezifische Wechselwirkungen. Die Umsetzung von Maßnahmen zur nachhaltigen landwirtschaftlichen Produktion bedürfen geeigneter Parameter zur Abschätzung des Status quo und des Erfolgs der durchgeführten Maßnahmen. Diese Parameter sind nicht immer vorhanden und müssen erarbeitet werden. Diese Arbeit hatte das Ziel, anhand von Erhebungen des Artenaufkommens der Wickler (Tortricidae) und ihrer Larvalparasitoide in Apfelanlagen mit unterschiedlicher Bewirtschaftungsintensität und der davon abgeleiteten ökologischen Indices geeignete Parameter zu erarbeiten. Diese sollten die Auswirkung der Benutzungsintensität auf die funktionelle Biodiversität wiederspiegeln und geeignet sein, die Umsetzung von Nachhaltigkeitsmaßnahmen zu bewerten. Um den Einfluss konventioneller bzw. ökologischer Bewirtschaftung auf Wirbellosengesellschaften zu untersuchen, wurde eine Vergleichsstudie durchgeführt, die Nahrungsnetze der Larval-parasitoide, Biodiversitäts Indizes und Parasitierungsraten in Apfelanlagen mit vier verschiede-nen Bewirtschaftungsweisen erfasst. Die Probenahmen erfolgten 2011-2015 in Baden-Württemberg. Nach Intensität der Pflanzenschutzmittelanwendung wurden die Anlagen in die Kategorien Bewirtschaftet (ökologische und integrierte Bewirtschaftung) und Streuobst eingeteilt. Sie lagen in Denzlingen, Emmendingen, Goldener Grund, Versuchsstation Hohenheim, Ilsfeld, Neuhausen, Plieningen, Rommelshausen, Scharnhausen und am Bodensee. Die Probenahmen bestanden im Sammeln der Raupen (Tortricidae und Gelechiidae) mit Fallen aus Wellpappe und durch Zufallsfunde. Im Labor wurden die daraus schlüpfenden adulten Parasitoide taxonomisch bestimmt. In 7923 Larven fanden sich 324 Individuen von Parasitoiden aus drei Unterfamilien der Braconidae, Ichneumonidae und Perilampidae. Die größte Vielfalt, Häufigkeit und gleichmäßige Verteilung an Larvalparasitoiden fand sich auf Streuobstwiesen (z.B. in Plieningen), die keine oder nur minimale Pestizid Anwendungen erhielten. Die Interaktionsmuster der Nahrungsnetze (Verknüpfungs-grad) im Streuobst wiesen die meisten trophischen Links auf, verglichen mit anders bewirtschafteten Anlagen unter denen die kommerziellen (konventionellen) die geringste Biodiversität an Nutzarthropoden beherbergten. Ihre prozentualen Anteile wurden ebenfalls erhoben, um die Ähnlichkeit der Larvalparasitoid-Gesellschaften unter verschiedenen Bewirtschaftungen darzustellen. Es stellte sich heraus, dass Anlagen mit gleicher Bewirtschaftung ähnliche Parasitoiden-Gesellschaften aufweisen. Vier Parasitoiden-Arten erwiesen sich als positiv dichteabhängig von ihren Wirtsarten, während die anderen Arten entweder nicht dichteabhängig reagierten oder in zu geringen Zahlen auftraten, um eine Korrelation zu berechnen. Um Informationen über Bewirtschaftung im Apfelanbau, Bedingungen für den Pflanzenschutz, Schädlingsbefall und Haupthindernisse für die Förderung nachhaltiger Anbaumethoden im Iran zu erhalten und zu analysieren wurden im Juli 2014 mittels Fragebogen 39 Apfelanbauer aus Ost-Aserbeidschan, Fars, Isfahan, Teheran und West-Aserbeidschan befragt. Die Bewirtschaftung der Anlagen stand meist unter Aufsicht der Apfelanbauer. Bauern aus Isfahan litten unter mangelhaftem Ausbau der Straßen was ihnen den Zugang zu Märkten für den Absatz ihrer Produkte erschwerte. Die räumliche Entfernung zu Fachleuten beeinflusste die Intensität des Pflanzenschutzmittel Einsatzes durch die Bauern. Konventioneller Anbau überwog in allen Provinzen; Zugang zu biologischen Pflanzenschutzmitteln war weitgehend auf Teheran beschränkt. Insgesamt 29 Pestizide wurden gegen Obstschädlinge im Iran eingesetzt. Im regionalen Maßstab wurden die höchsten Schäden durch Unkräuter verursacht, auf der Ebene der Provinzen durch Schädlinge. Ausbrüche des Sekundär Schädlings Tetranychus urticae waren ein Anzeichen für menschliche Störfaktoren in der Landwirtschaft des Iran. Die Provinz Teheran verfügte über mehrere Apfelsorten während andere Provinzen eine geringe Vielfalt aufwiesen. Unter den Apfelproduzenten erfolgte die Sortenauswahl vorrangig nach Kriterien der Vermarktbarkeit.
Several key international policy frameworks involve forests, including the Paris Agreement on Climate Change and the Convention on Biological Diversity (CBD). However, rules and guidelines that treat forest types equally regardless of their ecosystem integrity and risk profiles in terms of forest and carbon loss limit policy effectiveness and can facilitate forest degradation. Here we assess the potential for using a framework of ecosystem integrity to guide policy goals. We review the theory and present a conceptual framework, compare elements of integrity between primary and human-modified forests, and discuss the policy and management implications. We find that primary forests consistently have higher levels of ecosystem integrity and lower risk profiles than human-modified forests. This underscores the need to protect primary forests, develop consistent large-scale data products to identify high-integrity forests, and operationalize a framework of ecosystem integrity. Doing so will optimize long-term carbon storage and the provision of other ecosystem services, and can help guide evolving forest policy at the nexus of the biodiversity and climate crises.
Despite building a clear and compelling message about the importance of conserving biodiversity and what we risk in depleting it, meaningful engagement from implicated stakeholders remains limited. Past studies have examined the gap between the possession of environmental knowledge and displaying behavior that would help to conserve it. Essentially, increasing awareness and interest in environmental issues does not ensure that individuals will make the necessary changes in behaviours detrimental to biological conservation. This is a concern as failure to meaningfully engage the public into acting on conservation strategies will hamper efforts to curb biodiversity loss. Herein the authors investigate why action to address biodiversity loss has been slow or deficient in many jurisdictions. The authors draw from models and theories developed in health and social sciences to provide context to the key factors that prevent action and propose steps that could be taken to stimulate it.
This chapter reviews the role experiments have played in advancing biodiversity and ecosystem functioning (BEF) knowledge. In BEF experiments, the defining feature is that some measure of diversity – species richness, functional diversity – is manipulated as the independent fixed variable and response variables related to ecosystem functioning are measured as dependent random variables. Randomization of species composition among replicated diversity levels has since become an important feature of BEF experiments (e.g. BIODEPTH). BIODEPTH was the first study to report an explicit test of selection and complementarity effects. Some experiments manipulate environmental variables in addition to diversity in order to determine the effect of the abiotic environment on the BEF relationship. Experiments can introduce some complexity by testing for diversity effects under a range of contexts – with and without consumers or with resource limitation, for example. Modern coexistence theory is perhaps the most utilized theoretical framework for formal tests of coexistence in diverse communities of competing species.
An analysis of the literature review available in the open access has determined the relevance of studying the resistance of animals in natural habitats and zooculture as marker of ecosystem stability. This article provides a variety of methods for determining and the versatility of assessing animal resistance, which requires the development of ap-proaches that can help to solve this problem comprehensively. It is shown that it is necessary to study the processes of formation of animal resistance and to establish the relationship between resistance, sustainability and tolerance and the reasons (conditions, abiotic and biotic factors) that change their characteristics.
The loss of aboveground plant diversity alters belowground ecosystem function; yet, the mechanisms underpinning this relationship and the degree to which plant community structure and climate mediate the effects of plant species loss remain unclear. Here, we explored how plant species loss through experimental removal shaped belowground function in ecosystems characterized by different climatic regimes and edaphic properties. We measured plant community composition as well as potential carbon (C) and nitrogen (N) mineralization and microbial extracellular enzyme activity in soils collected from four unique plant removal experiments located along an elevational gradient in Colorado, USA. We found that regardless of the identity of the removed species or the climate at each site plant removal decreased the absolute variation in potential N-mineralization rates and marginally reduced the magnitude of N-mineralization rates. While plant species removal also marginally reduced C-mineralization rates, C-mineralization, unlike N-mineralization, displayed sensitivity to the climatic and edaphic differences among sites, where C-mineralization was greatest at the high elevation site that receives the most precipitation annually and contains the largest soil total C pools. Plant removal had little impact on soil enzyme activity. Removal effects were not contingent on the amount of biomass removed annually, and shifts in mineralization rates occurred despite only marginal shifts in plant community structure following plant species removal. Our results present a surprisingly simple and consistent pattern of belowground response to the loss of dominant plant species across an elevational gradient with different climatic and edaphic properties, suggesting a common response of belowground ecosystem function to plant species loss regardless of which plant species are lost or the broader climatic context.
The process of agricultural colonization occurred from the 1970s in Rondônia significantly reduced the original forest cover in areas of agricultural use in the state. In Castanheiras, Novo Horizonte D'Oeste, and Rolim de Moura, where this study was conducted, 81% of municipal territories have been deforested until 2020. The fragmentation of natural vegetation has reduced the ecological stability of agroecosystems and nature's ability to provide ecosystem services. In attempt to minimize these effects, six ecological restoration initiatives supported, between 2008 and 2020, 585 rural establishments to recompose more than one thousand hectares of forests (0.3% of the total area of these municipalities). This thesis results from transdisciplinary research in the field of ethnosciences, in order to categorize the ideologies presented in the discourses of family farmers (AF) from two groups, engaged and not engaged in forest recomposition. We sought to identify AF's socioeconomic challenges to ecological restoration; the ideologies present in the discourses of AF regarding ecosystem services; to characterize extrinsic and intrinsic discursive formations related to the AF's decision-making process; to investigate the positions and influences of sociocommunity relations and their interference in conservation and/or recomposition of vegetation. Data collection was carried out with 40 AF, randomly drawn from a reference population composed of 235 rural establishments, engaged in forest recomposition initiatives between the years 2013 to 2015 and 2017 to 2019. From the consent of the interviewed subjects, socioeconomic information was recorded and their responses to open-ended questions were recorded. As a method to identify ideologies, characterize discursive formations, and investigate positioning and influences, the transcription of the answers was carried out for the evaluation of ethno-knowledge by the French Discourse Analysis (fDA). The coding of this analytical process was supported by the use of MAXQDA Analytics Pro 2020 Software-Release 20.0.4. From the tabulation of socioeconomic information and fDA coding, descriptive and inferential analysis were used to present and discuss the results. Two socioeconomic challenges of family farming for ecosystem restoration were defined. Seven ideologies identified, obtained by coding 32 discourse formations, grouped under four perspectives of ethno-knowledge. Ecosystem services was the most representative perspective, present in 60% of the 625 coded discourse segments. It is subdivided into four ideologies, characterized by 17 discourse formations. Provisioning services is the only ideology present in 100% of the interviews, regulation is in 70%, cultural 58% and habitat 35%. Intrinsic decision factors represent 25% of the segments, consisting of one ideology and five discourse formations. Extrinsic decision factors account for 8% of the segments, consists of one ideology and six discourse formations. Socio-community relations occurs in 7% of the segments, it is made up of two ideologies, underpinned by four discursive formations. The theoretical framework established offers paths for the development of strategies of rural communication for ecosystem restoration programs in the Amazon, as well as in the planning of processes of land use and occupation, which mainly consider the formation of people to understand the functioning of the forest and its importance for rural socioeconomy
Plant diversity has a positive influence on the number of ecosystem functions maintained simultaneously by a community, or multifunctionality. While the presence of multiple trophic levels beyond plants, or trophic complexity, affects individual functions, the effect of trophic complexity on the diversity–multifunctionality relationship is less well known. To address this issue, we tested whether the independent or simultaneous manipulation of both plant diversity and trophic complexity impacted multifunctionality using a mesocosm experiment from Cedar Creek, Minnesota, USA. Our analyses revealed that neither plant diversity nor trophic complexity had significant effects on single functions, but trophic complexity altered the diversity–multifunctionality relationship in two key ways: It lowered the maximum strength of the diversity–multifunctionality effect, and it shifted the relationship between increasing diversity and multifunctionality from positive to negative at lower function thresholds. Our findings highlight the importance to account for interactions with higher trophic levels, as they can alter the biodiversity effect on multifunctionality. We used a manipulated grassland mesocosm experiment to test the effects of higher trophic levels on ecosystem multifunctionality. We find that the number and identity of trophic levels affect the jack‐of‐all‐trades relationship between biodiversity and ecosystem multifunctionality. Our findings have implications in refining predictions for ecosystem multifunctionality in the face of ongoing biodiversity loss.
While greater biodiversity is often assumed to predict greater ecological function, a number of recent meta-analyses have challenged this notion, arguing instead that a few dominant species can contribute the majority of ecological function provided in a given ecosystem. In the case of mobile ecosystem service providers, such as pollinating insects, the abundance and diversity of the most common taxa (e.g. bees) is often assumed to be the primary driver of service provision across ecosystems. This assumption persists despite the presence and possible contribution of less-dominant service-providing taxa. In this study, we investigate the taxonomic contribution of different pollinator orders to multiple axes of functional complementarity in US Gulf Coast cotton agroecosystems. We find that, contrary to conventional wisdom, non-bee pollinators, including butterflies and flies, contribute significantly to pollination function and expand the multidimensional functional space of visitation by more than 50%. Specifically, butterflies and flies provide critical functional complementarity by visiting spatially and temporally unique flowers that otherwise may have gone without pollination service. We estimate that butterflies and flies together may contribute as much as 120 million USD (of the 1.8 billion USD) per annum of cotton production in the state of Texas. We conclude that conservation efforts should target not only dominant service providers, but also those that complement their service, such as butterflies and flies, to maintain functional breadth and resulting crop profitability in the face of dynamic future agricultural scenarios.
Larger easily visible animals and plants are negatively affected by agrochemicals used for intensive food production, but we do not understand the general spatial and temporal effects of agrochemicals on the multitudes of bacteria, fungi and small invertebrate animals that underpin ecosystem productivity. We sequenced the 16S, ITS2 and COI DNA barcode regions from 648 New Zealand vineyard soil samples managed under either conventional or low-agrochemical-input conservation approaches across two regions and three seasons in one year and discovered at least 170,000 phylotypes (taxa) with >97% genetic identity. Management approach correlated with a significant 2-10% difference in the abundances of phylotypes that differed over regions and seasons. While the data show agrochemicals do not have a large effect on soil biodiversity on average, the important finding is that the magnitude of impact differs between taxa types and locations, and some taxa most affected also influence the quality of agricultural produce.
Plant diversity and plant-consumer/pathogen interactions likely interact to influence ecosystem carbon fluxes but experimental evidence is scarce. We examined how experimental removal of foliar fungi, soil fungi and arthropods from experimental prairies planted with 1, 4 or 16 plant species affected instantaneous rates of carbon uptake (GPP), ecosystem respiration (R e) and net ecosystem exchange (NEE). Increasing plant diversity increased plant biomass, GPP and R e , but NEE remained unchanged. Removing foliar fungi increased GPP and NEE, with the greatest effects at low plant diversity. After accounting for plant biomass, we found that removing foliar fungi increased mass-specific flux rates in the low-diversity plant communities by altering plant species composition and community-wide foliar nitrogen content. However, this effect disappeared when soil fungi and arthropods were also removed, demonstrating that both plant diversity and interactions among consumer groups determine the ecosystem-scale effects of plant-fungal interactions .
The idea that biodiversity is necessary in order for ecosystems to function properly has long been used as a basic argument for the conservation of species, and has led to an abundance of research exploring the relationships between species richness and ecosystem function. Here we present a meta-analysis of global ecosystems using the Bray-Curtis index to explore more complex changes in the species composition of natural ecosystems, and their relationship with ecosystem functions. By using data recorded, firstly in reference sites and secondly in recovering sites, captured in restoration ecology studies, we pose the following questions: Firstly, how much variation is there in species composition and in ecosystem function in an intact ecosystem? Secondly, once an ecosystem has become degraded, is there a general relationship between its recovery in species composition and its recovery in ecosystem function? Thirdly, is this relationship the same for all types of ecosystem func-tions? Data from 21 studies yielded 478 comparisons of mean values for ecosystems. On Average, sites within the same intact natural ecosystems shared only a 48% similarity in species composition but were 69% similar in ecosystem functioning. In recovering ecosystems the relationship between species composition and ecosystem function was weak and saturating (directly accounting for only 2% of the variation). Only two of the six types of ecosystem function examined, biomass and biotic structure, showed a significant relationship with species composition, and the three types that measured soil functions showed no significant relationship. To date, most biodiversity-ecosystem function (BEF) research has been conducted in simplified ecosystems using the simple species richness metric. This study encourages a broader examination of the drivers of ecosystem functions under realistic scenarios of biodiversity change, and highlights the need to properly account for the extensive natural variation.
Soil biodiversity is fundamental for ecosystems, ensuring many ecosystem functions, such as nutrient cycling, organic matter decomposition, soil formation, and organic carbon pool increase. Due to these roles, there is a need to study and completely understand how soil biodiversity is composed through different habitats. The aim of this study was to describe the edaphic soil community of the alpine environments belonging to the Gran Paradiso National Park, thus detecting if there are any correlation with environmental features. We studied soil fauna through environmental DNA metabarcoding. From eDNA metabarcoding, 18 families of arthropods were successfully detected, and their abundance expressed in terms of the relative frequency of sequences. Soil faunal communities of mixed coniferous forests were characterized by Isotomidae, Entomobriydae, Hypogastruridae, and Onychiuridae; while mixed deciduous forests were composed mostly by Isotomidae, Cicadidae, Culicidae, and Neelidae. Calcicolous and acidic grasslands also presented families that were not detected in forest habitats, in particular Scarabaeidae, Curculionidae, Brachyceridae, and had in general a more differentiated soil community. Results of the Canonical Component Analysis revealed that the main environmental features affecting soil community for forests were related to vegetation (mixed deciduous forests, tree basal area, tree biomass, Shannon index), soil (organic layers and organic carbon stock), and site (altitude); while for prairies, soil pH and slope were also significant in explaining soil community composition. This study provided a description of the soil fauna of alpine habitats and resulted in a description of community composition per habitat and the relation with the characteristic of vegetation, soil, and topographic features of the study area. Further studies are needed to clarify ecological roles and needs of these families and their role in ecosystem functioning.
In this chapter, the concept of biological diversity, or biodiversity, is illustrated using different definitions of the term and by describing the different facets of plant diversity, including compositional, structural and functional diversity. In the second section, the causes that determine plant diversity at different spatial scales are presented. Here, we discuss the underlying factors of latitudinal gradients of diversity, the role of environmental heterogeneity for plant diversity at the scale of single ecosystems or communities, and the relationship between productivity and plant species richness. The section ends with an introduction to assembly rules and environmental filters that determine species coexistence and, hence, the number of species present. The third section elaborates the recently burgeoning field of functional biodiversity research, which studies the role of biodiversity for ecosystem functioning. It begins with a description of species identity and dominance effects, followed by examples of how plant diversity affects biomass production, other ecosystem processes such as biogeochemical cycling, multitrophic interactions and the simultaneous provision of a multitude of ecosystem functions and services, that is, multifunctionality. We then explore the role of diversity for ecosystem stability and ask the question whether biodiversity–ecosystem functioning relationships differ with context. The underlying mechanisms of these relationships are discussed, followed by a critical discourse about the value and relevance of this field of research.
Intensive agriculture is dominated by monocultures of high‐yielding plants that receive large applications of nitrogen (N) fertilizers to boost plant productivity. However, these systems have low N use efficiency (NUE) as fertilized plants generally take up less than half of the N applied. A large fraction of the remainder N is susceptible to be lost from the agroecosystem generating a cascade of environmental and socio‐economic problems. Climate change and projected global increases in fertilizer use pose further risks to N losses and yield stability.
We review and translate concepts from ecology in natural systems to demonstrate that NUE in intensive agroecosystems can be strongly increased by fine‐tuning the traits of the plant communities to the levels of N fertilization intensity.
We present key plant traits of importance for N‐cycling (architectural, morphological and physiological traits, as well as symbiotic associations and exudation patterns); discuss ecological (with soil fauna and N‐cycling microbial communities) and agronomic interactions of this approach; propose interdisciplinary methodologies for future research ranging from pot to global scales; and highlight possible solutions leading to an optimal balance between N fertilizer use and productivity.
Synthesis and applications . By showing the strong links between plant traits and nitrogen (N) cycling, our work opens possibilities to test ecologically informed hypotheses across gradients of soil fertility and N fertilizer management intensity, setting a research agenda for the coming years. Accordingly, the choice of plant species based on their functional traits will play a central role for the development of modern and productive agroecosystems that retain and use N more efficiently.
ONE of the ecological tenets justifying conservation of biodiversity is that diversity begets stability. Impacts of biodiversity on population dynamics and ecosystem functioning have long been debated1-7, however, with many theoretical explorations2-6,8-11 but few field studies12-15. Here we describe a long-term study of grasslands16,17 which shows that primary productivity in more diverse plant communities is more resistant to, and recovers more fully from, a major drought. The curvilinear relationship we observe suggests that each additional species lost from our grasslands had a progressively greater impact on drought resistance. Our results support the diversity-stability hypothesis5,6,18,19, but not the alternative hypothesis that most species are functionally redundant19-21. This study implies that the preservation of biodiversity is essential for the maintenance of stable productivity in ecosystems.
Carbon, nutrient, and water balance as well as key plant and soil processes were simultaneously monitored for humid tropical plant communities treated with CO(2)-enriched atmospheres. Despite vigorous growth, no significant differences in stand biomass (of both the understory and overstory), leaf area index, nitrogen or water consumption, or leaf stomatal behavior were detected between ambient and elevated CO(2) treatments. Major responses under elevated CO(2) included massive starch accumulation in the tops of canopies, increased fine-root production, and a doubling of CO(2) evolution from the soil. Stimulated rhizosphere activity was accompanied by increased loss of soil carbon and increased mineral nutrient leaching. This study points at the inadequacy of scaling-up from physiological baselines to ecosystems without accounting for interactions among components, and it emphasizes the urgent need for whole-system experimental approaches in global-change research.
One argument for the conservation of biodiversity is that we cannot tell which species will have commodity value in the future. The uncertainty is so great that the term "serendipity value' is applied to non-resource species to indicate that new biological resources will continue to be discovered primarily by chance. Examples are used to show how the biological sciences, especially natural history, ecology, systematics and evolutionary biology, can be developed by a rational approach to the identification of new resources. An unanticipated variety of species, species interactions, behaviours, tissues and natural products emerge with either proven or potential application. -from Author
Biodiversity should be valued for four general reasons. 1) As the dominant species on Earth, Homo sapiens has an ethical, stewardship responsibility towards humanity's only known living companions in the universe. 2) Biodiversity has aesthetic values. 3) Humanity has derived many direct economic values from biodiversity, including all of its food and many of its medicines and industrial products. The potential of nature's genetic library for providing more of these benefits is enormous. 4) Plants, animals and microorganisms help to supply human beings with an array of free ecosystem services, without which civilization could not persist. These include such things as controlling the gaseous mix of the atmosphere, generating and maintaining soils, controlling pests, and running biogeochemical cycles. The present extinction episode caused by human activity seriously jeopardizes the ethical, aesthetic, direct economic and life-support values of biodiversity; it may be the single most important externality associated with human economic activity. -from Authors
In this chapter we are concerned with the significance of biodiversity in the functioning of a particular type of ecosystem. In the broadest sense all the concepts and principles covered in the other chapters of this book are relevant to this discussion. Our main purpose is thus to establish a context for considering the role and significance of biodiversity in the functioning of agricultural systems.
The number of species within a region usually varies unimodally with the rate of ecosystem energy flow. This hump-shaped pattern shows up in many biogeographical provinces. Plant and animal taxa, including vertebrates and invertebrates, follow it. We find it in marine and in terrestrial biomes. Most ecologists agree that the increase in diversity that occurs over low productivities comes about because the total abundance of all species together increases over that range of productivities. The authors describe and evaluate nine hypotheses to explain the decrease phase of the pattern, ie why diversity declines as productivity grows past a certain point. They discuss the relationship of the regional pattern to global patterns such as the latitudinal gradient. The effect of productivity on diversity is best studied at the regional level. -from Authors
Small open top chambers (0.8 m x 1.0 m) were developed to maintain elevated CO2 concentrations in three plant communities in a brackish marsh ecosystem. Mean annual CO2 concentrations were 350 ± 22 μl l-1 in chambers which received no added CO2 and 686 ± 30 μl l-1 in chambers with elevated CO2 concentrations. Light quality was not affected in the photosynthetically active wavelengths but the chamber reduced light quantity by 10%. Night-time air temperatures inside the chamber (T(i)) averaged 2°C above air temperature outside the chamber (T(o)) due to heating from the air blowers. Air temperature profiles through the plant canopy and boundary layer showed that daytime temperature differences (T(i) - T(o)) were greater than night-time differences and this day/night difference also depended on the plant community. Effects of the chamber on the micro-environment of the plant communities resulted in a significant growth enhancement in the plant community dominated by the C3 sedge Scirpus olneyi Grey but not in the other two communities.
An automated, COz-controlled, long-term greenhouse system ('C02LT') has been developed to provide replicated in situ ecosystem-level manipulation of atmospheric C02 concentration and temperature for intact plots of tussock tundra, and to measure the instantaneous ecosystem-level C02 exchange rates within each of the plots under the treatments imposed . This is a computer-controlled, closed , null-balance greenhouse system consisting of 12 chambers with individual control of C02 concentration and temperature. Carbon dioxide can be maintained in each chamber at concentrations from well below ambient (150-200µ1 l-1) to more than 900µ1 1-1. Air temperature can be fixed, set to track ambient, or can track ambient temperature with a specified offset allowing studies of the interaction of C02 and temperature . Despite the complications involved in tracking a naturally fluctuating environment, the C02LT system performs very well . Temperatures in individual chambers average within 1°C of ambient or target temperatures over a 24-h period and carbon dioxide concentration control rivals that of laboratory-based, control environment systems. Photon flux density within the chambers is within 93% of ambient values. Comparison to unenclosed tundra indicates minimal chamber effects on depth of thaw, air, leaf, or soil temperatures, or net ecosystem C02 flux. Chamber effects are generally small, and the experimental design allows separation and interpretation of treatment effects despite any unavoidable chamber effects. Both diurnal and seasonal patterns of net ecosystem C02 flux can be accurately tracked with this system. Field measurements indicate net ecosystem C02 loss under current environmental conditions, a possible response to recent climate change. Field measurements also indicate initial enhancement of net ecosystem C02 uptake with elevated atmospheric C02. Photosynthetic adjustment to elevated C02 lowers ecosystem response to that of ambient chambers by mid-season. Also indicated is the possibility of delayed senescence of photosynthetic capacity at elevated C02.
An improved estimate of the mean cover repetition in the centres of
tussocks may be obtained by fitting a negative binomial distribution by successive
approximation.
Fertility of a volcanic-ash derived Inceptisol was monitored at a site in the humid tropics of Costa Rica. After forest felling and burning, the authors established four treatments in a randomized block design with six blocks: a sequence of monocultures (two crops of maize Zea mays followed by cassava Manihot esculenta, then the tree Cordia alliodora), successional vegetation, a mimic of successional vegetation, and a species-enriched version of successional vegetation. Species-rich successional vegetation was effective at maintaining soil fertility, although there were general trends of soil-nutrient decline beneath all treatments, presumably because of plant uptake. Successive peaks of nitrate-N in soil solution, extractable P and extractable K occurred during the 1st yr, perhaps driven by an early increment of organic matter from postburn debris and roots. Organic matter, total N and extractable S were remarkably stable during the 5-yr period. Depletions of cations, decreases in effective cation exchange capacity, and increases in acid saturation were related to treatment in the following order: bare soil > monocultures > the three diverse, successional communities. In the bare-soil plot, fertility decreased dramatically: there was a net loss of exchangeable cations and inorganic N, the P-fixation capacity increased, and acid saturation reached a potentially toxic 86%. The less fertile soil under monocultures proved exceptionally vulnerable to loss of fertility; after 5 yr under monocultures, for example, acid saturation reached 38% in the more fertile soil and 75% in the less fertile soil. In the species-rich communities, however, changes in soil fertility were far less marked. -from Authors
This paper reports on aspects of the design and philosophy of the Ecotron, an integrated series of 16 controlled environmental chambers at the NERC Centre for Population Biology. The Ecotron serves as an experimental means for analysing population and community dynamics and ecosystem processes under controlled physical conditions. Within the chambers, terrestrial experimental communities are assembled into foodwebs of desired complexity from a pool of species selected for their preadaptations to the physical conditions of the Ecotron. These species include decomposers (earthworms, snails, microarthropods and microbes), primary producers (16 species of plants), primary consumers (four species of herbivorous arthropods), and secondary consumers (four species of parasitoids). The design of the Ecotron is unique in several aspects with respect to its blend of biology and technology. It supports small, dynamic communities of up to 30 plant and metazoan species, thereby making it among the more biologically complex controlled environmental systems currently in use. Its architecture permits replication and variation of spatial scale in experimental design. Its artificial climate simulates natural environmental conditions within chambers allowing experimental control over light, water, temperature, humidity, and in the near future CO2 and UV-B radiation. Sensors monitor both macro- and micro-environmental conditions of a number of physical factors within the chambers. Preliminary experiments show the Ecotron to be an excellent facility for long-term population and community-level experiments. We discuss the results of one of these early experiments and briefly consider ongoing and future experiments.
The effect of biological diversity on ecosystem biogeochemistry has not been widely studied in recent years, due in part to widespread recognition that our understanding of population/ecosystem interactions was insufficient to sustain the pioneering discussions of the late 1960s (cf. Woodwell and Smith 1969). Indeed, the fields of population biology and ecosystem studies largely pursued different approaches throughout much of the 1970s and 1980s. The gap between population and ecosystem ecology is now narrowing substantially, and the linked nature of human alterations to both biological diversity and ecosystem functioning is increasingly appreciated. These developments have led to renewed interest in the connections between diversity and many aspects of ecosystem function.
In a commentary entitled “Science literacy” (Pool 1991), there is a table of “Science’s top 20 greatest hits” as chosen by biologist Robert Hazen and physicist James Trefil. They suggested that these “great ideas” might be the basis for a course in general science, and comments from readers were invited.
IN short-term experiments under productive laboratory conditions, native herbaceous plants differ widely in their potential to achieve higher yields at elevated concentrations of atmospheric carbon dioxide1–8. The most responsive species appear to be large fast-growing perennials of recently disturbed fertile soils7,8. These types of plants are currently increasing in abundance9 but it is not known whether this is an effect of rising carbon dioxide or is due to other factors. Doubts concerning the potential of natural vegetation for sustained response to rising carbon dioxide have arisen from experiments on infertile soils, where the stimulus to growth was curtailed by mineral nutrient limitations2,3,10. Here we present evidence that mineral nutrient constraints on the fertilizer effect of elevated carbon dioxide can also occur on fertile soil and in the earliest stages of secondary succession. Our data indicate that there may be a feedback mechanism in which elevated carbon dioxide causes an increase in substrate release into the rhizosphere by non-mycorrhizal plants, leading to mineral nutrient sequestration by the expanded microflora and a consequent nutritional limitation on plant growth.
Four coexisting annual plant species were grown in competition at three levels of CO2 (300, 600, and 1,200 ppm) and two levels of soil moisture (moist and dry). Plant height was higher at high CO2 concentrations for the three C3 species but not for the C4 species (Amaranthus retroflexus). Total community biomass increased with increasing CO2 at both soil moisture levels. The contribution of each species to total community biomass was influenced by CO2 concentration. The effects were especially pronounced for Polygonum pensylvanicum which contributed more to community production as CO2 and soil moisture increased. Amaranthus behaved in exactly the reverse way; it did best under ambient CO2 and dry soil moisture conditions. The results suggest that changes in competitive interactions and community structure will occur with the anticipated rise in global CO2 concentration.
Snails and earthworms affected the dynamics of a simple, three-species plant community, in the Ecotron controlled environment facility. Earthworms enhanced the establishment, growth and cover of the legume Trifolium dubium, both via the soil and interactions with other plant species. Worms increased soil phosphates, increased root nodulation in T. dubium, and enabled T. dubium seedlings to establish in the presence of grass (Poa annua) litter, by increasing soil heterogeneity. Worms also buried the seeds of Poa annua and Senecio vulgaris, reducing the germination of new seedlings. Snails reduced nitrogen-fixing Trifolium dubium and increased cover of plant litter, thereby reducing ammonia-nitrogen concentrations in the soil. These effects and their interactions demonstrate that the detritivore food chain, and earthworms in particular, cannot be ignored if we are to understand the spatial and temporal dynamics of plant communities.
Redundant means surplus to requirements. Redundant words in a sentence can be deleted with no loss of clarity of meaning; factories make workers redundant but continue to produce cars, and so on. How much species redundancy is built into ecological processes? To what extent are patterns of biological diversity important in determining the behaviour of ecological systems (Lubchenco et al. 1991; Solbrig 1991; Walker 1991)?
COMMUNITIES of species and their associated biological, chemical and
physical processes, collectively known as ecosystems, drive the Earth's
biogeochemical processes1,2. Currently most ecosystems are
experiencing loss of biodiversity associated with the activities of
human expansion3-5, raising the issue of whether the
biogeochemical functioning of ecosystems will be impaired by this loss
of species6-8. Current ecological knowledge supports a wide
range of views on the subject9-13, but empirical tests are
few9,14-16. Here we provide evidence from direct experimental
manipulation of diversity by over an order of magnitude, using
multi-trophic level communities and simultaneous measures of several
ecosystem processes, that reduced biodiversity may indeed alter the
performance of ecosystems.
Does biodiversity influence ecosystem function? Darwin believed it did. In Chap. IV of On the Origin of Species by Means of Natural Selection, he wrote (p. 97), “The more diversified in habits and structures the descendants … become, the more places they will be enabled to occupy. … It has been experimentally proved, if a plot of ground be sown with one species of grass, and a similar plot be sown with several distinct genera of grasses, a greater number of plants and a greater weight of dry herbage can be raised in the latter than the former case.” This is a clear statement of the ideas that (a) the biodiversity of communities is due to niche diversification of the co-occurring species and (b) such diversification will lead to greater community productivity due to more effective resource exploitation.
Issues: Why link species and ecosystems?: a perspective from ecosystem ecology-- Nancy B. Grimm Organisms and species as complex adaptive systems: linking the biology of populations with the physics of ecosystems-- James H. Brown Scope: Bioturbators as ecosystem engineers: control of the sediment fabric, inter-individual interactions, and material fluxes-- Jeffrey Levinton Biogeochemical processes and marine benthic community structure: which follows which?-- Anne E. Giblin, Kenneth H. Foreman and Gary T. Banta Marine snow: what it is and how it affects ecosystem functioning-- M. W. Silver, S. L. Coale, D. K. Steinberg and C. H. Pilskahn Floods, food chains, and ecosystem processes in rivers-- Mary E. Power Population variability in experimental ecosystems-- Michael L. Pace Stephen R. Carpenter, and Patricia A. Soranno How important are consumer species to ecosystem functioning?-- Nancy Huntly Linking tree population dynamics and forest ecosystem processes-- Charles D. Canham and Stephen W. Pacala Soil organisms as engineers: microsite modulation of macroscale processes-- J. M. Anderson Soil fauna: linking different levels of the ecological hierarchy-- Robert W. Parmelee Beaver as engineers: influences on biotic and abiotic characteristics of drainage basins-- Michael M. Pollock, Robert J. Naiman, Heather E. Erickson, Carol A. Johnston, John Pastor and Gilles Pinay Atmospheric oxygen and the biosphere-- Heinrich D. Holland Approaches: Linking species and ecosystems: organisms as ecosystem engineers-- John H. Lawton and Clive G. Jones Top-level carnivores and ecosystem effects: questions and approaches-- James A. Estes Food webs in soil: an interface between population and ecosystem ecology-- Jan Bengtsson, David Wei Zheng, Goran I. Agren and Tryggve Persson Unifying ecological subdisciplines with ecosystem food webs-- Neo D. Martinez Coupling the dynamics of species and materials-- William S. C.Gurney, Alex H. Ross and Niall Broekhuizen Exploring aggregation in space and time-- Monica G. Turner and Robert V. O'Neill Aggregation of species properties for biogeochemical modeling: empirical results-- David S. Schimel, V. B. Brown, K. A. Hibbard, C. P. Lund and S. Archer Functional redundancy and process aggregation: linking ecosystems to species-- Edward B. Rastetter and Gaius R. Shaver Species compensation and complementarity in ecosystem function-- Thomas M. Frost, Stephen R. Carpenter, Anthony R. Ives and Timothy K. Kratz Elemental stoichiometry of species in ecosystems-- Robert W. Sterner Species, nitrogen and grassland dynamics: the constraints of stuff-- David A. Wedin Relationships between the energetics of species and large scale species richness-- Donald L. DeAngelis Linking species and ecosystems: where's Darwin?-- Robert D. Holt Ecological flow chains and ecological systems: concepts for linking species and ecosystem perspectives-- Moshe Shachak and Clive G. Jones Context: The relevance of ecology: the societal context and disciplinary implications of linkages across levels of ecological organization-- Jane Lubchenco Linking species and ecosystems through training of students-- Lawrence B. Slobodkin Linking species and communities to ecosystem management: a perspective from the experimental lakes experience-- D. W. Schindler Why link species conservation, environmental protection, and resource management?-- Jerry F. Franklin References Index.
1 Introduction.- 2 General concepts of nutrient flux and stability.- 3 Nutrients and autotrophs.- 4 Nutrients and autotrophs: variable internal nutrient levels.- 5 Effects of nutrients on autotroph-herbivore interactions.- 6 Herbivores and nutrient recycling.- 7 Nutrient interactions of detritus and decomposers.- 8 Nutrient limitation and food webs.- 9 Competition and nutrients.- 10 Temporally varying driving forces and nutrient-limited food webs.- 11 Effects of spatial extent.- 12 Implications for global change.- Appendices.- References.
Biodiversity studies comprise the systematic examination of the full array of different kinds of organisms together with the
technology by which the diversity can be maintained and used for the benefit of humanity. Current basic research at the species
level focuses on the process of species formation, the standing levels of species numbers in various higher taxonomic categories,
and the phenomena of hyperdiversity and extinction proneness. The major practical concern is the massive extinction rate now
caused by human activity, which threatens losses in the esthetic quality of the world, in economic opportunity, and in vital
ecosystem services.
Global biodi living resources' a report compiled by the World Conservation Monitoring Centre
- B Groombridge
Performance and productivity of forage in the field
- J L Monteith
- J Elston
The effect of earthworms and
- S Lawton
The ecological consequences of
- F I Woodward
The McGill University Phytotron: a centre for research in plant ecology
- Lechowicz M.J.
Biodiversity and ecosystemfunction
- E D Schulze
- H A Mooney
Ecological com:conceptual issues and the evidence
- D R Strong
- D Simberloff
- L G Abele
The use and abuse of vegetational
- A G Tansley
Ecology: i n d i v i d u a l s populations and communities. Sunderland: Sinauer simple and complex laboratory systems
- M Begon
- J L Harper
- C R Townsend
Growth dynamics introduction to the problem
- M A Leonard
- J M Anderson
Available technologies for field experimentation with elevated C 0 2 in global change research
- B R Strain
Canopy structure and light interception
- P S Nobel
- S P Long
Biotic interactions and global change
- P M Karieva
- J G Kingsolver
- R B Huey