Showing papers on "Biodiversity published in 2011"

Has the Earth’s sixth mass extinction already arrived?

Abstract: Palaeontologists characterize mass extinctions as times when the Earth loses more than three-quarters of its species in a geologically short interval, as has happened only five times in the past 540 million years or so. Biologists now suggest that a sixth mass extinction may be under way, given the known species losses over the past few centuries and millennia. Here we review how differences between fossil and modern data and the addition of recently available palaeontological information influence our understanding of the current extinction crisis. Our results confirm that current extinction rates are higher than would be expected from the fossil record, highlighting the need for effective conservation measures.

Ecological impacts of invasive alien plants: a meta-analysis of their effects on species, communities and ecosystems

Abstract: Biological invasions cause ecological and economic impacts across the globe. However, it is unclear whether there are strong patterns in terms of their major effects, how the vulnerability of different ecosystems varies and which ecosystem services are at greatest risk. We present a global meta-analysis of 199 articles reporting 1041 field studies that in total describe the impacts of 135 alien plant taxa on resident species, communities and ecosystems. Across studies, alien plants had a significant effect in 11 of 24 different types of impact assessed. The magnitude and direction of the impact varied both within and between different types of impact. On average, abundance and diversity of the resident species decreased in invaded sites, whereas primary production and several ecosystem processes were enhanced. While alien N-fixing species had greater impacts on N-cycling variables, they did not consistently affect other impact types. The magnitude of the impacts was not significantly different between island and mainland ecosystems. Overall, alien species impacts are heterogeneous and not unidirectional even within particular impact types. Our analysis also reveals that by the time changes in nutrient cycling are detected, major impacts on plant species and communities are likely to have already occurred.

How Many Species Are There on Earth and in the Ocean

Abstract: The diversity of life is one of the most striking aspects of our planet; hence knowing how many species inhabit Earth is among the most fundamental questions in science. Yet the answer to this question remains enigmatic, as efforts to sample the world's biodiversity to date have been limited and thus have precluded direct quantification of global species richness, and because indirect estimates rely on assumptions that have proven highly controversial. Here we show that the higher taxonomic classification of species (i.e., the assignment of species to phylum, class, order, family, and genus) follows a consistent and predictable pattern from which the total number of species in a taxonomic group can be estimated. This approach was validated against well-known taxa, and when applied to all domains of life, it predicts ∼8.7 million (±1.3 million SE) eukaryotic species globally, of which ∼2.2 million (±0.18 million SE) are marine. In spite of 250 years of taxonomic classification and over 1.2 million species already catalogued in a central database, our results suggest that some 86% of existing species on Earth and 91% of species in the ocean still await description. Renewed interest in further exploration and taxonomy is required if this significant gap in our knowledge of life on Earth is to be closed.

Transitions in bacterial communities along the 2000 km salinity gradient of the Baltic Sea

Abstract: Salinity is a major factor controlling the distribution of biota in aquatic systems, and most aquatic multicellular organisms are either adapted to life in saltwater or freshwater conditions. Consequently, the saltwater–freshwater mixing zones in coastal or estuarine areas are characterized by limited faunal and floral diversity. Although changes in diversity and decline in species richness in brackish waters is well documented in aquatic ecology, it is unknown to what extent this applies to bacterial communities. Here, we report a first detailed bacterial inventory from vertical profiles of 60 sampling stations distributed along the salinity gradient of the Baltic Sea, one of world's largest brackish water environments, generated using 454 pyrosequencing of partial (400 bp) 16S rRNA genes. Within the salinity gradient, bacterial community composition altered at broad and finer-scale phylogenetic levels. Analogous to faunal communities within brackish conditions, we identified a bacterial brackish water community comprising a diverse combination of freshwater and marine groups, along with populations unique to this environment. As water residence times in the Baltic Sea exceed 3 years, the observed bacterial community cannot be the result of mixing of fresh water and saltwater, but our study represents the first detailed description of an autochthonous brackish microbiome. In contrast to the decline in the diversity of multicellular organisms, reduced bacterial diversity at brackish conditions could not be established. It is possible that the rapid adaptation rate of bacteria has enabled a variety of lineages to fill what for higher organisms remains a challenging and relatively unoccupied ecological niche.

Primary forests are irreplaceable for sustaining tropical biodiversity

Abstract: Human-driven land-use changes increasingly threaten biodiversity, particularly in tropical forests where both species diversity and human pressures on natural environments are high. The rapid conversion of tropical forests for agriculture, timber production and other uses has generated vast, human-dominated landscapes with potentially dire consequences for tropical biodiversity. Today, few truly undisturbed tropical forests exist, whereas those degraded by repeated logging and fires, as well as secondary and plantation forests, are rapidly expanding. Here we provide a global assessment of the impact of disturbance and land conversion on biodiversity in tropical forests using a meta-analysis of 138 studies. We analysed 2,220 pairwise comparisons of biodiversity values in primary forests (with little or no human disturbance) and disturbed forests. We found that biodiversity values were substantially lower in degraded forests, but that this varied considerably by geographic region, taxonomic group, ecological metric and disturbance type. Even after partly accounting for confounding colonization and succession effects due to the composition of surrounding habitats, isolation and time since disturbance, we find that most forms of forest degradation have an overwhelmingly detrimental effect on tropical biodiversity. Our results clearly indicate that when it comes to maintaining tropical biodiversity, there is no substitute for primary forests.

Beyond species: functional diversity and the maintenance of ecological processes and services

Abstract: Summary 1. The goal of conservation and restoration activities is to maintain biological diversity and the ecosystem services that this diversity provides. These activities traditionally focus on the measures of species diversity that include only information on the presence and abundance of species. Yet how diversity influences ecosystem function depends on the traits and niches filled by species. 2. Biological diversity can be quantified in ways that account for functional and phenotypic differences. A number of such measures of functional diversity (FD) have been created, quantifying the distribution of traits in a community or the relative magnitude of species similarities and differences. We review FD measures and why they are intuitively useful for understanding ecological patterns and are important for management. 3. In order for FD to be meaningful and worth measuring, it must be correlated with ecosystem function, and it should provide information above and beyond what species richness or diversity can explain. We review these two propositions, examining whether the strength of the correlation between FD and species richness varies across differing environmental gradients and whether FD offers greater explanatory power of ecosystem function than species richness. 4. Previous research shows that the relationship between FD and richness is complex and context dependent. Different functional traits can show individual responses to different gradients, meaning that important changes in diversity can occur with minimal change in richness. Further, FD can explain variation in ecosystem function even when richness does not. 5. Synthesis and applications. FD measures those aspects of diversity that potentially affect community assembly and function. Given this explanatory power, FD should be incorporated into conservation and restoration decision-making, especially for those efforts attempting to reconstruct or preserve healthy, functioning ecosystems.

Beyond Predictions: Biodiversity Conservation in a Changing Climate

Abstract: Climate change is predicted to become a major threat to biodiversity in the 21st century, but accurate predictions and effective solutions have proved difficult to formulate. Alarming predictions have come from a rather narrow methodological base, but a new, integrated science of climate-change biodiversity assessment is emerging, based on multiple sources and approaches. Drawing on evidence from paleoecological observations, recent phenological and microevolutionary responses, experiments, and computational models, we review the insights that different approaches bring to anticipating and managing the biodiversity consequences of climate change, including the extent of species' natural resilience. We introduce a framework that uses information from different sources to identify vulnerability and to support the design of conservation responses. Although much of the information reviewed is on species, our framework and conclusions are also applicable to ecosystems, habitats, ecological communities, and genetic diversity, whether terrestrial, marine, or fresh water.

Reconciling Food Production and Biodiversity Conservation: Land Sharing and Land Sparing Compared

Abstract: The question of how to meet rising food demand at the least cost to biodiversity requires the evaluation of two contrasting alternatives: land sharing, which integrates both objectives on the same land; and land sparing, in which high-yield farming is combined with protecting natural habitats from conversion to agriculture. To test these alternatives, we compared crop yields and densities of bird and tree species across gradients of agricultural intensity in southwest Ghana and northern India. More species were negatively affected by agriculture than benefited from it, particularly among species with small global ranges. For both taxa in both countries, land sparing is a more promising strategy for minimizing negative impacts of food production, at both current and anticipated future levels of production.

High plant diversity is needed to maintain ecosystem services

Abstract: Biodiversity is rapidly declining worldwide, and there is consensus that this can decrease ecosystem functioning and services. It remains unclear, though, whether few or many of the species in an ecosystem are needed to sustain the provisioning of ecosystem services. It has been hypothesized that most species would promote ecosystem services if many times, places, functions and environmental changes were considered; however, no previous study has considered all of these factors together. Here we show that 84% of the 147 grassland plant species studied in 17 biodiversity experiments promoted ecosystem functioning at least once. Different species promoted ecosystem functioning during different years, at different places, for different functions and under different environmental change scenarios. Furthermore, the species needed to provide one function during multiple years were not the same as those needed to provide multiple functions within one year. Our results indicate that even more species will be needed to maintain ecosystem functioning and services than previously suggested by studies that have either (1) considered only the number of species needed to promote one function under one set of environmental conditions, or (2) separately considered the importance of biodiversity for providing ecosystem functioning across multiple years, places, functions or environmental change scenarios. Therefore, although species may appear functionally redundant when one function is considered under one set of environmental conditions, many species are needed to maintain multiple functions at multiple times and places in a changing world.

Functional landscape heterogeneity and animal biodiversity in agricultural landscapes

Abstract: Biodiversity in agricultural landscapes can be increased with conversion of some production lands into 'more-natural'- unmanaged or extensively managed - lands. However, it remains unknown to what extent biodiversity can be enhanced by altering landscape pattern without reducing agricultural production. We propose a framework for this problem, considering separately compositional heterogeneity (the number and proportions of different cover types) and configurational heterogeneity (the spatial arrangement of cover types). Cover type classification and mapping is based on species requirements, such as feeding and nesting, resulting in measures of 'functional landscape heterogeneity'. We then identify three important questions: does biodiversity increase with (1) increasing heterogeneity of the more-natural areas, (2) increasing compositional heterogeneity of production cover types and (3) increasing configurational heterogeneity of production cover types? We discuss approaches for addressing these questions. Such studies should have high priority because biodiversity protection globally depends increasingly on maintaining biodiversity in human-dominated landscapes.

The functional role of producer diversity in ecosystems

Abstract: Over the past several decades, a rapidly expanding field of research known as biodiversity and ecosystem functioning has begun to quantify how the world's biological diversity can, as an independent variable, control ecological processes that are both essential for, and fundamental to, the functioning of ecosystems. Research in this area has often been justified on grounds that (1) loss of biological diversity ranks among the most pronounced changes to the global environment and that (2) reductions in diversity, and corresponding changes in species composition, could alter important services that ecosystems provide to humanity (e.g., food production, pest/disease control, water purification). Here we review over two decades of experiments that have examined how species richness of primary producers influences the suite of ecological processes that are controlled by plants and algae in terrestrial, marine, and freshwater ecosystems. Using formal meta-analyses, we assess the balance of evidence for eight fundamental questions and corresponding hypotheses about the functional role of producer diversity in ecosystems. These include questions about how primary producer diversity influences the efficiency of resource use and biomass production in ecosystems, how primary producer diversity influences the transfer and recycling of biomass to other trophic groups in a food web, and the number of species and spatial /temporal scales at which diversity effects are most apparent. After summarizing the balance of evidence and stating our own confidence in the conclusions, we outline several new questions that must now be addressed if this field is going to evolve into a predictive science that can help conserve and manage ecological processes in ecosystems.

Tracking apex marine predator movements in a dynamic ocean

Abstract: Pelagic marine predators face unprecedented challenges and uncertain futures. Overexploitation and climate variability impact the abundance and distribution of top predators in ocean ecosystems. Improved understanding of ecological patterns, evolutionary constraints and ecosystem function is critical for preventing extinctions, loss of biodiversity and disruption of ecosystem services. Recent advances in electronic tagging techniques have provided the capacity to observe the movements and long-distance migrations of animals in relation to ocean processes across a range of ecological scales. Tagging of Pacific Predators, a field programme of the Census of Marine Life, deployed 4,306 tags on 23 species in the North Pacific Ocean, resulting in a tracking data set of unprecedented scale and species diversity that covers 265,386 tracking days from 2000 to 2009. Here we report migration pathways, link ocean features to multispecies hotspots and illustrate niche partitioning within and among congener guilds. Our results indicate that the California Current large marine ecosystem and the North Pacific transition zone attract and retain a diverse assemblage of marine vertebrates. Within the California Current large marine ecosystem, several predator guilds seasonally undertake north-south migrations that may be driven by oceanic processes, species-specific thermal tolerances and shifts in prey distributions. We identify critical habitats across multinational boundaries and show that top predators exploit their environment in predictable ways, providing the foundation for spatial management of large marine ecosystems.

Worldwide decline of specialist species: toward a global functional homogenization?

Abstract: Specialization is a concept based on a broad theoretical framework developed by evolutionary biologists and ecologists. In the past 10 years, numerous studies have reported that – in many contexts – generalist species are “replacing” specialist species. We review recent research on the concept of the ecological niche and species specialization, and conclude that (1) the observed worldwide decline in specialist species is predicted by niche theory, (2) specialist declines cause “functional homogenization” of biodiversity, and (3) such homogenization may be used to measure the impact of disturbance on communities. Homogenization at the community level could alter ecosystem functioning and productivity, as well as result in the deterioration of ecosystem goods and services. We propose community‐level specialization as an indicator of the impact of global changes (habitat and climate disturbances) on biodiversity.

Global Biodiversity Conservation: The Critical Role of Hotspots

Abstract: Global changes, from habitat loss and invasive species to anthropogenic climate change, have initiated the sixth great mass extinction event in Earth’s history. As species become threatened and vanish, so too do the broader ecosystems and myriad benefits to human well-being that depend upon biodiversity. Bringing an end to global biodiversity loss requires that limited available resources be guided to those regions that need it most. The biodiversity hotspots do this based on the conservation planning principles of irreplaceability and vulnerability. Here, we review the development of the hotspots over the past two decades and present an analysis of their biodiversity, updated to the current set of 35 regions. We then discuss past and future efforts needed to conserve them, sustaining their fundamental role both as the home of a substantial fraction of global biodiversity and as the ultimate source of many ecosystem services upon which humanity depends.

The forgotten stage of forest succession: early-successional ecosystems on forest sites

Abstract: Early-successional forest ecosystems that develop after stand-replacing or partial disturbances are diverse in species, processes, and structure. Post-disturbance ecosystems are also often rich in biological legacies, including surviving organisms and organically derived structures, such as woody debris. These legacies and post-disturbance plant communities provide resources that attract and sustain high species diversity, including numerous early-successional obligates, such as certain woodpeckers and arthropods. Early succession is the only period when tree canopies do not dominate the forest site, and so this stage can be characterized by high productivity of plant species (including herbs and shrubs), complex food webs, large nutrient fluxes, and high structural and spatial complexity. Different disturbances contrast markedly in terms of biological legacies, and this will influence the resultant physical and biological conditions, thus affecting successional pathways. Management activities, such as post-disturbance logging and dense tree planting, can reduce the richness within and the duration of early-successional ecosystems. Where maintenance of biodiversity is an objective, the importance and value of these natural early-successional ecosystems are underappreciated.

Climate change threatens European conservation areas

Abstract: Ecology Letters (2011) 14: 484–492 Abstract Europe has the world’s most extensive network of conservation areas. Conservation areas are selected without taking into account the effects of climate change. How effectively would such areas conserve biodiversity under climate change? We assess the effectiveness of protected areas and the Natura 2000 network in conserving a large proportion of European plant and terrestrial vertebrate species under climate change. We found that by 2080, 58 ± 2.6% of the species would lose suitable climate in protected areas, whereas losses affected 63 ± 2.1% of the species of European concern occurring in Natura 2000 areas. Protected areas are expected to retain climatic suitability for species better than unprotected areas (P < 0.001), but Natura 2000 areas retain climate suitability for species no better and sometimes less effectively than unprotected areas. The risk is high that ongoing efforts to conserve Europe’s biodiversity are jeopardized by climate change. New policies are required to avert this risk.

The bacterial biogeography of British soils.

Abstract: Despite recognition of the importance of soil bacteria to terrestrial ecosystem functioning there is little consensus on the factors regulating belowground biodiversity. Here we present a multi-scale spatial assessment of soil bacterial community profiles across Great Britain (> 1000 soil cores), and show the first landscape scale map of bacterial distributions across a nation. Bacterial diversity and community dissimilarities, assessed using terminal restriction fragment length polymorphism, were most strongly related to soil pH providing a large-scale confirmation of the role of pH in structuring bacterial taxa. However, while α diversity was positively related to pH, the converse was true for β diversity (between sample variance in α diversity). β diversity was found to be greatest in acidic soils, corresponding with greater environmental heterogeneity. Analyses of clone libraries revealed the pH effects were predominantly manifest at the level of broad bacterial taxonomic groups, with acidic soils being dominated by few taxa (notably the group 1 Acidobacteria and Alphaproteobacteria). We also noted significant correlations between bacterial communities and most other measured environmental variables (soil chemistry, aboveground features and climatic variables), together with significant spatial correlations at close distances. In particular, bacterial and plant communities were closely related signifying no strong evidence that soil bacteria are driven by different ecological processes to those governing higher organisms. We conclude that broad scale surveys are useful in identifying distinct soil biomes comprising reproducible communities of dominant taxa. Together these results provide a baseline ecological framework with which to pursue future research on both soil microbial function, and more explicit biome based assessments of the local ecological drivers of bacterial biodiversity.

The effect of biodiversity on tree productivity: from temperate to boreal forests

Abstract: Aim An important issue regarding biodiversity concerns its influence on ecosystem functioning.Experimental work has led to the proposal of mechanisms such as niche complementarity.However,few attempts have been made to confirm these in natural systems, especially in forests. Furthermore, one of the most interesting unresolved questions is whether the effects of complementarity on ecosystem functioning (EF) decrease in favour of competitive exclusions over an increasing productivity gradient. Using records from permanent forest plots, we asked the following questions.(1) Is tree productivity positively related to diversity? (2) Does the effect of diversity increase in less productive forests? (3) What metric of diversity (e.g. functional or phylogenetic diversity) better relates to tree productivity? Location Temperate, mixed and boreal forests of eastern Canada. Methods Over 12,000 permanent forest plots, from temperate to boreal forests, were used to test our hypotheses in two steps.(1) Stepwise regressions were used to identify the best explanatory variables for tree productivity. (2) The selected climatic and environmental variables,as well as density and biodiversity indices,were included in a structural equation model where links (paths) between covarying variables are made explicit, making structural equation modelling the best tool to explore such complicated causal networks. Results This is the first large-scale demonstration of a strong, positive and significant effect of biodiversity on tree productivity with control for climatic and environmental conditions. Important differences were noted between the two forest biomes investigated. Main conclusions We show for the first time that complementarity may be less important in temperate forests growing in a more stable and productive environment where competitive exclusion is the most probable outcome of species interactions, whereas in the more stressful environment of boreal forests, beneficial interactions between species may be more important. The present work is also a framework for the analysis of large datasets in biodiversity‐ecosystem functioning (B-EF) research.

The Influence of Late Quaternary Climate-Change Velocity on Species Endemism

Abstract: The effects of climate change on biodiversity should depend in part on climate displacement rate (climate-change velocity) and its interaction with species’ capacity to migrate We estimated Late Quaternary glacial-interglacial climate-change velocity by integrating macroclimatic shifts since the Last Glacial Maximum with topoclimatic gradients Globally, areas with high velocities were associated with marked absences of small-ranged amphibians, mammals, and birds The association between endemism and velocity was weakest in the highly vagile birds and strongest in the weakly dispersing amphibians, linking dispersal ability to extinction risk due to climate change High velocity was also associated with low endemism at regional scales, especially in wet and aseasonal regions Overall, we show that low-velocity areas are essential refuges for Earth’s many small-ranged species

Ecology of Marine Bivalves: An Ecosystem Approach, Second Edition

Abstract: Introduction Historical/Geological Setting Ecosystems Historical Ecology of Bivalves Physical Environmental Interactions Temperature Salinity Temperature-Salinity and Other Factor Combinations Acidification Water Flow Tides Sediments Organismic Scale Processes Feeding Suspension-Feeding Larviphagy Deposit Feeding Shipworms Symbiotic Nutrition Chemoautotrophic Symbioses Population Processes Life Cycle Statistical Measures of Populations Density Reproduction Population Growth Bivalves As Open Or Metapopulations Life and Fecundity Tables Mortality Abiotic Mortality Predation Competition-Induced Mortality Aggregated Distributions Zonation Diseases and Parasites Population Energy Budgets Ecosystem Grazing Introduction Grazing Theory as Applied to Bivalves Conceptualizing Grazing Methods Used to Estimate System Grazing Upstream-Downstream Observations Laboratory Flumes Ecosystem Comparisons Ecosystem Metabolism and Nutrient Cycling Nutrient Cycling Theoretical Background Conclusions The Case of the Missing Nitrogen Ecosystem Experiments Models Model Formulation Model Analysis Ecosystem Field Experiments Case Study Ecosystem Health, Restoration, and Services Bivalve Responses Systems Measures Ecosystem Services Biodiversity A Case Study: The Wadden Sea and the Invasion of Crassostrea gigas Index

The Potential Conservation Value of Non‐Native Species

Abstract: Non-native species can cause the loss of biological diversity (i.e., genetic, species, and ecosystem diversity) and threaten the well-being of humans when they become invasive. In some cases, however, they can also provide conservation benefits. We examined the ways in which non-native species currently contribute to conservation objectives. These include, for example, providing habitat or food resources to rare species, serving as functional substitutes for extinct taxa, and providing desirable ecosystem functions. We speculate that non-native species might contribute to achieving conservation goals in the future because they may be more likely than native species to persist and provide ecosystem services in areas where climate and land use are changing rapidly and because they may evolve into new and endemic taxa. The management of non-native species and their potential integration into conservation plans depends on how conservation goals are set in the future. A fraction of non-native species will continue to cause biological and economic damage, and substantial uncertainty surrounds the potential future effects of all non-native species. Nevertheless, we predict the proportion of non-native species that are viewed as benign or even desirable will slowly increase over time as their potential contributions to society and to achieving conservation objectives become well recognized and realized.

Calibrating the End-Permian Mass Extinction

Abstract: The end-Permian mass extinction was the most severe biodiversity crisis in Earth history. To better constrain the timing, and ultimately the causes of this event, we collected a suite of geochronologic, isotopic, and biostratigraphic data on several well-preserved sedimentary sections in South China. High-precision U-Pb dating reveals that the extinction peak occurred just before 252.28 ± 0.08 million years ago, after a decline of 2 per mil (‰) in δ13C over 90,000 years, and coincided with a δ13C excursion of −5‰ that is estimated to have lasted ≤20,000 years. The extinction interval was less than 200,000 years and synchronous in marine and terrestrial realms; associated charcoal-rich and soot-bearing layers indicate widespread wildfires on land. A massive release of thermogenic carbon dioxide and/or methane may have caused the catastrophic extinction.

Disentangling the Drivers of β Diversity Along Latitudinal and Elevational Gradients

Abstract: Understanding spatial variation in biodiversity along environmental gradients is a central theme in ecology. Differences in species compositional turnover among sites (β diversity) occurring along gradients are often used to infer variation in the processes structuring communities. Here, we show that sampling alone predicts changes in β diversity caused simply by changes in the sizes of species pools. For example, forest inventories sampled along latitudinal and elevational gradients show the well-documented pattern that β diversity is higher in the tropics and at low elevations. However, after correcting for variation in pooled species richness (γ diversity), these differences in β diversity disappear. Therefore, there is no need to invoke differences in the mechanisms of community assembly in temperate versus tropical systems to explain these global-scale patterns of β diversity.

Functional and phylogenetic diversity as predictors of biodiversity–ecosystem‐function relationships

Abstract: How closely does variability in ecologically important traits reflect evolutionary divergence? The use of phylogenetic diversity (PD) to predict biodiversity effects on ecosystem functioning, and more generally the use of phylogenetic information in community ecology, depends in part on the answer to this question. However, comparisons of the predictive power of phylogenetic diversity and functional diversity (FD) have not been conducted across a range of experiments. To address how phylogenetic diversity and functional trait variation control biodiversity effects on biomass production, we summarized the results of 29 grassland plant experiments where both the phylogeny of plant species used in the experiments is well described and where extensive trait data are available. Functional trait variation was only partially related to phylogenetic distances between species, and the resulting FD values therefore correlate only partially with PD. Despite these differences, FD and PD predicted biodiversity effects across all experiments with similar strength, including in subsets that excluded plots with legumes and that focused on fertilization experiments. Two- and three- trait combinations of the five traits used here (leaf nitrogen percentage, height, specific root length, leaf mass per unit area, and nitrogen fixation) resulted in the FD values with the greatest predictive power. Both PD and FD can be valuable predictors of the effect of biodiversity on ecosystem functioning, which suggests that a focus on both community trait diversity and evolutionary history can improve understanding of the consequences of biodiversity loss.

Biodiversity improves water quality through niche partitioning

Abstract: Studies in recent years have suggested that the conservation of biodiversity improves the ability of an ecosystem to retain nutrients and remain productive. These papers have proved controversial, in part because of a lack of direct evidence for a mechanism to explain the phenomenon. Now, in experiments involving manipulation of the number of algal species in model stream systems, Bradley Cardinale provides one such mechanism. Uptake of nitrogen nutrients increased linearly with species richness in response to changes in flow habitats and disturbance regimes. But when niche structure was experimentally removed, the relationship disappeared. This suggests that habitats with more species take greater advantage of the niche opportunities in an environment than do less-species-rich habitats, allowing the more diverse systems to capture a greater fraction of biologically active resources such as nitrogen. More diverse stream communities have increased uptake of nutrients, including nitrate, a major pollutant, but the mechanism is little understood. This study manipulated algal species diversity in stream mesocosms with different flow habitats and disturbance regimes. Nitrogen uptake increased linearly with species richness, but when niche structure was experimentally removed the relationship disappeared. Excessive nutrient loading of water bodies is a leading cause of water pollution worldwide1,2, and controlling nutrient levels in watersheds is a primary objective of most environmental policy3. Over the past two decades, much research has shown that ecosystems with more species are more efficient at removing nutrients from soil and water than are ecosystems with fewer species4,5,6,7. This has led some to suggest that conservation of biodiversity might be a useful tool for managing nutrient uptake and storage7,8,9,10, but this suggestion has been controversial, in part because the specific biological mechanisms by which species diversity influences nutrient uptake have not been identified10,11,12. Here I use a model system of stream biofilms to show that niche partitioning among species of algae can increase the uptake and storage of nitrate, a nutrient pollutant of global concern. I manipulated the number of species of algae growing in the biofilms of 150 stream mesocosms that had been set up to mimic the variety of flow habitats and disturbance regimes that are typical of natural streams. Nitrogen uptake rates, as measured by using 15N-labelled nitrate, increased linearly with species richness and were driven by niche differences among species. As different forms of algae came to dominate each unique habitat in a stream, the more diverse communities achieved a higher biomass and greater 15N uptake. When these niche opportunities were experimentally removed by making all of the habitats in a stream uniform, diversity did not influence nitrogen uptake, and biofilms collapsed to a single dominant species. These results provide direct evidence that communities with more species take greater advantage of the niche opportunities in an environment, and this allows diverse systems to capture a greater proportion of biologically available resources such as nitrogen. One implication is that biodiversity may help to buffer natural ecosystems against the ecological impacts of nutrient pollution.

The Impact of Land-Use Change on Ecosystem Services, Biodiversity and Returns to Landowners: A Case Study in the State of Minnesota

Abstract: Land-use change has a significant impact on the world's ecosystems. Changes in the extent and composition of forests, grasslands, wetlands and other ecosystems have large impacts on the provision of ecosystem services, biodiversity conservation and returns to landowners. While the change in private returns to landowners due to land-use change can often be measured, changes in the supply and value of ecosystem services and the provision of biodiversity conservation have been harder to quantify. In this paper we use a spatially explicit integrated modeling tool (InVEST) to quantify the changes in ecosystem services, habitat for biodiversity, and returns to landowners from land-use change in Minnesota from 1992 to 2001. We evaluate the impact of actual land-use change and a suite of alternative land-use change scenarios. We find a lack of concordance in the ranking of baseline and alternative land-use scenarios in terms of generation of private returns to landowners and net social benefits (private returns plus ecosystem service value). Returns to landowners are highest in a scenario with large-scale agricultural expansion. This scenario, however, gen- erated the lowest net social benefits across all scenarios considered because of large losses in stored carbon and negative impacts on water quality. Further, this scenario resulted in the largest decline in habitat quality for general terrestrial biodiversity and forest songbirds. Our results illustrate the importance of taking ecosystem services into account in land-use and

Does conservation on farmland contribute to halting the biodiversity decline

Abstract: Biodiversity continues to decline, despite the implementation of international conservation conventions and measures. To counteract biodiversity loss, it is pivotal to know how conservation actions affect biodiversity trends. Focussing on European farmland species, we review what is known about the impact of conservation initiatives on biodiversity. We argue that the effects of conservation are a function of conservation-induced ecological contrast, agricultural land-use intensity and landscape context. We find that, to date, only a few studies have linked local conservation effects to national biodiversity trends. It is therefore unknown how the extensive European agri-environmental budget for conservation on farmland contributes to the policy objectives to halt biodiversity decline. Based on this review, we identify new research directions addressing this important knowledge gap.

Ecosystems and Human Well-Being

Abstract: Over the past 50 years, humans have altered their environment to a significant extent, although human well-being is dependent on ecosystem functioning. Ecosystems are particularly affected by unsustainable use of resources, such as, food, water, and timber. Ecosystem functions depend on water, carbon, and other nutrients cycles. Human activities have modified these cycles in a number of way. Use of ecosystems for recreation, spiritual enrichment, cultural purposes, and for other short term benefits is growing continuously, although ecosystem capacity to provide such services has reported to be declined significantly. Human well-being depends on material welfare, health, good social relations, security and freedom, which are affected by changes in ecosystem services. Intensive ecosystem use often produces short-term advantage. Poverty level remains high in more than one billion people, who are dependent on ecosystems with an income of less than $1 per day as reported elsewhere. Regions including some parts of Africa, Asia and Latin America have the greatest ecosystemrelated problems and are facing developmental challenges. Habitat change occurs, for instance, when the area of land used for agriculture or cities is expanded. Instability and unproductivity including desertification, water logging, mineralization and many other unwanted outcomes throughout the world are continuing. Habitat fragmentation by roads, canals, power lines limits the species potential for dispersal and colonization. Indirect drivers, like changes in human population, economic activity and technology as well as socio-political and cultural factors affect ecosystems by influencing direct drivers. World climate has changed and continues to change, affecting temperature, rainfall and sea levels. Intensive fertilizer use has polluted ecosystems. Climate change and high nutrient levels in water are becoming increasing problems. Ecosystem management for shortterm benefits is increasing. Loss of biodiversity makes it difficult for ecosystems to recover from damage. Once an ecosystem has undergone an abrupt change, recovery to the original state is slow, costly, and sometimes impossible. Changes in ecosystems complexity- functioning relationships could diminish the stability, resistance and resilience of managed terrestrial ecosystems, and may jeopardize important food and fibre sources, and ability of natural ecosystems both to provide natural resources, and to remove pollutants from atmosphere. Ecological complexity and ecosystem functioning depend on factors that govern species coexistence. Complexity of landscapes is determined by number of ecosystem types, their characteristics, their sizes and shapes, and associated connectivity. Complexity at this scale would have large consequences on regional to global scale processes. Presence and arrangement of keystone ecosystem types, such as, wetlands often determine total carbon and nitrogen balance of a region. Changes in average or extreme environmental events and intense land use management are believed to increase species extinction rate in isolated habitat fragments. Loss of key species, such as, top predators, fruit dispersers and pollinators from habitat may severely disrupt ecosystems functioning. Land use changes due to expanding urbanization, concomitant landscape fragmentation and intensification of production systems. Such change results in transformation of an ecosystem, form one state to another state, via a transition phase. The combined value of 17 ecosystem services has been reported in the estimated range of US$16-54 trillion per year by Costanza and others. About 30% of modern medicines are developed from plants and animals, and 10 of the world's 25 topselling drugs in 1997 were reported to be derived from natural sources. Global market value of pharmaceuticals derived from genetic resources is estimated at US $ 75 000-150 000 million annually. Some 75% of the world's populations rely for health care on traditional medicines, which are derived directly from natural sources as recorded elsewhere. Socio-economic development of human civilization and human well-being depends on long-term health of environment including ecosystems. Environmental problems are generally addressed in isolation, but practically such problems are interrelated, and originate from the root cause of unsustainable development. Damage to natural ecosystems and release of environmental pollutants must be minimized for protecting natural ecosystem, and human well-being.