Biodiversity and Ecosystem Functioning Tilman, David; Isbell, Forest; Cowles, Jane M
Annual review of ecology, evolution, and systematics,
11/2014, Letnik:
45, Številka:
1
Journal Article
Recenzirano
Species diversity is a major determinant of ecosystem productivity, stability, invasibility, and nutrient dynamics. Hundreds of studies spanning terrestrial, aquatic, and marine ecosystems show that ...high-diversity mixtures are approximately twice as productive as monocultures of the same species and that this difference increases through time. These impacts of higher diversity have multiple causes, including interspecific complementarity, greater use of limiting resources, decreased herbivory and disease, and nutrient-cycling feedbacks that increase nutrient stores and supply rates over the long term. These experimentally observed effects of diversity are consistent with predictions based on a variety of theories that share a common feature: All have trade-off-based mechanisms that allow long-term coexistence of many different competing species. Diversity loss has an effect as great as, or greater than, the effects of herbivory, fire, drought, nitrogen addition, elevated CO
2
, and other drivers of environmental change. The preservation, conservation, and restoration of biodiversity should be a high global priority.
Anthropogenic changes in biodiversity and atmospheric temperature significantly influence ecosystem processes. However, little is known about potential interactive effects of plant diversity and ...warming on essential ecosystem properties, such as soil microbial functions and element cycling. We studied the effects of orthogonal manipulations of plant diversity (one, four, and 16 species) and warming (ambient, +1.5°C, and +3°C) on soil microbial biomass, respiration, growth after nutrient additions, and activities of extracellular enzymes in 2011 and 2012 in the BAC (biodiversity and climate) perennial grassland experiment site at Cedar Creek, Minnesota, USA. Focal enzymes are involved in essential biogeochemical processes of the carbon, nitrogen, and phosphorus cycles. Soil microbial biomass and some enzyme activities involved in the C and N cycle increased significantly with increasing plant diversity in both years. In addition, 16-species mixtures buffered warming induced reductions in topsoil water content. We found no interactive effects of plant diversity and warming on soil microbial biomass and growth rates. However, the activity of several enzymes (1,4-β-glucosidase, 1,4-β-N-acetylglucosaminidase, phosphatase, peroxidase) depended on interactions between plant diversity and warming with elevated activities of enzymes involved in the C, N, and P cycles at both high plant diversity and high warming levels. Increasing plant diversity consistently decreased microbial biomass-specific enzyme activities and altered soil microbial growth responses to nutrient additions, indicating that plant diversity changed nutrient limitations and/or microbial community composition. In contrast to our expectations, higher plant diversity only buffered temperature effects on soil water content, but not on microbial functions. Temperature effects on some soil enzymes were greatest at high plant diversity. In total, our results suggest that the fundamental temperature ranges of soil microbial communities may be sufficiently broad to buffer their functioning against changes in temperature and that plant diversity may be a dominant control of soil microbial processes in a changing world.
Ecosystems worldwide are increasingly impacted by multiple drivers of environmental change, including climate warming and loss of biodiversity. We show, using a long‐term factorial experiment, that ...plant diversity loss alters the effects of warming on productivity. Aboveground primary productivity was increased by both high plant diversity and warming, and, in concert, warming (≈1.5 °C average above and belowground warming over the growing season) and diversity caused a greater than additive increase in aboveground productivity. The aboveground warming effects increased over time, particularly at higher levels of diversity, perhaps because of warming‐induced increases in legume and C4 bunch grass abundances, and facilitative feedbacks of these species on productivity. Moreover, higher plant diversity was associated with the amelioration of warming‐induced environmental conditions. This led to cooler temperatures, decreased vapor pressure deficit, and increased surface soil moisture in higher diversity communities. Root biomass (0–30 cm) was likewise consistently greater at higher plant diversity and was greater with warming in monocultures and at intermediate diversity, but at high diversity warming had no detectable effect. This may be because warming increased the abundance of legumes, which have lower root : shoot ratios than the other types of plants. In addition, legumes increase soil nitrogen (N) supply, which could make N less limiting to other species and potentially decrease their investment in roots. The negative warming × diversity interaction on root mass led to an overall negative interactive effect of these two global change factors on the sum of above and belowground biomass, and thus likely on total plant carbon stores. In total, plant diversity increased the effect of warming on aboveground net productivity and moderated the effect on root mass. These divergent effects suggest that warming and changes in plant diversity are likely to have both interactive and divergent impacts on various aspects of ecosystem functioning.
Biodiversity enhances many of nature's benefits to people, including the regulation of climate and the production of wood in forests, livestock forage in grasslands and fish in aquatic ecosystems. ...Yet people are now driving the sixth mass extinction event in Earth's history. Human dependence and influence on biodiversity have mainly been studied separately and at contrasting scales of space and time, but new multiscale knowledge is beginning to link these relationships. Biodiversity loss substantially diminishes several ecosystem services by altering ecosystem functioning and stability, especially at the large temporal and spatial scales that are most relevant for policy and conservation.
Biodiversity loss decreases ecosystem functioning at the local scales at which species interact, but it remains unclear how biodiversity loss affects ecosystem functioning at the larger scales of ...space and time that are most relevant to biodiversity conservation and policy. Theory predicts that additional insurance effects of biodiversity on ecosystem functioning could emerge across time and space if species respond asynchronously to environmental variation and if species become increasingly dominant when and where they are most productive. Even if only a few dominant species maintain ecosystem functioning within a particular time and place, ecosystem functioning may be enhanced by many different species across many times and places (β‐diversity). Here, we develop and apply a new approach to estimate these previously unquantified insurance effects of biodiversity on ecosystem functioning that arise due to species turnover across times and places. In a long‐term (18‐year) grassland plant diversity experiment, we find that total insurance effects are positive in sign and substantial in magnitude, amounting to 19% of the net biodiversity effect, mostly due to temporal insurance effects. Species loss can therefore reduce ecosystem functioning both locally and by eliminating species that would otherwise enhance ecosystem functioning across temporally fluctuating and spatially heterogeneous environments.
Recent developments in complex systems analysis have led to new techniques for detecting causal relationships using relatively short time series, on the order of 30 sequential observations. Although ...many ecological observation series are even shorter, perhaps fewer than ten sequential observations, these shorter time series are often highly replicated in space (i.e., plot replication). Here, we combine the existing techniques of convergent cross mapping (CCM) and dewdrop regression to build a novel test of causal relations that leverages spatial replication, which we call multispatial CCM. Using examples from simulated and real-world ecological data, we test the ability of multispatial CCM to detect causal relationships between processes. We find that multispatial CCM successfully detects causal relationships with as few as five sequential observations, even in the presence of process noise and observation error. Our results suggest that this technique may constitute a useful test for causality in systems where experiments are difficult to perform and long time series are not available. This new technique is available in the multispatialCCM package for the R programming language.
Abiotic environmental change, local species extinctions and colonization of new species often co‐occur. Whether species colonization is driven by changes in abiotic conditions or reduced biotic ...resistance will affect community functional composition and ecosystem management. We use a grassland experiment to disentangle effects of climate warming and community diversity on plant species colonization. Community diversity had dramatic impacts on the biomass, richness and traits of plant colonists. Three times as many species colonized the monocultures than the high diversity 17 species communities (~30 vs. 10 species), and colonists collectively produced 10 times as much biomass in the monocultures than the high diversity communities (~30 vs. 3 g/m2). Colonists with resource‐acquisitive strategies (high specific leaf area, light seeds, short heights) accrued more biomass in low diversity communities, whereas species with conservative strategies accrued most biomass in high diversity communities. Communities with higher biomass of resident C4 grasses were more resistant to colonization by legume, nonlegume forb and C3 grass colonists, but not by C4 grass colonists. Compared with effects of diversity, 6 years of 3°C‐above‐ambient temperatures had little impact on plant colonization. Warmed subplots had ~3 fewer colonist species than ambient subplots and selected for heavier seeded colonists. They also showed diversity‐dependent changes in biomass of C3 grass colonists, which decreased under low diversity and increased under high diversity. Our findings suggest that species colonization is more strongly affected by biotic resistance from residents than 3°C of climate warming. If these results were extended to invasive species management, preserving community diversity should help limit plant invasion, even under climate warming.
Abiotic environmental change, local species extinctions and colonization of new species often co‐occur. Using a unique grassland experiment that isolates abiotic effects of warming from indirect biotic effects, we find that the biomass, richness and traits of plant colonists is more strongly affected by biotic resistance from residents than 6 years of 3°C‐above‐ambient temperatures. If these results were extended to invasive species management, preserving community diversity should help limit plant invasion, even under climate warming.
Ecological stoichiometry (ES) has become one of the most pervasive theoretical frameworks in environmental sciences and biology in the last two decades. ES allows predicting processes on all ...organizational levels from subcellular structures to ecosystems by relating the elemental composition and demand of organisms to the relative availability of resources. However, ES has been rarely used to understand and predict the relationship between biodiversity and ecosystem functioning (BEF), although ES would be ideally suited as it makes predictions on both population processes underlying biodiversity as well as on matter transformations underlying ecosystem processes. Here, we propose to link the two fields of research on ES and BEF relationships and highlight a number of potential avenues for further research. First, we cast a stoichiometric view on drivers of biodiversity change. Second, we address the stoichiometric underpinning of biodiversity–productivity relationships. Third, we discuss potential interactions between stoichiometry and diversity in a food web context.
Ökologische Stöchiometrie (ecological stoichiometry, ES) hat sich in den letzten beiden Jahrzehnten zu einer der grundlegenden Theorien der Umweltwissenschaften und der Biologie entwickelt. Durch den Vergleich von elementarer Zusammensetzung von Organismen und ihren Ressourcenansprüchen mit der relativen Verfügbarkeit der Ressourcen sagt ES Prozesse auf allen Organisationsebenen von subzellulären Strukturen bis hin zu Ökosystemen voraus. Allerdings wurde ES bisher selten angewandt um den Zusammenhang zwischen Biodiversität und Ökosystemfunktion zu verstehen, obwohl ES ideal dazu geeignet wäre, da es sowohl Vorhersagen zu Prozessen macht, die Biodiversität beeinflussen, als auch zu Materieflüssen und –transformationen, auf denen wichtige Ökosystemfunktionen basieren. In diesem Artikel untersuchen wir den Zusammenhang dieser beiden Forschungsfelder und zeigen zukünftige Forschungsfelder anhand von drei Themen auf: i) stöchiometrische Aspekte der Treiber des Biodiversitätswandels, ii) stöchiometrische Grundlagen des Zusammenhangs zwischen Biodiversität und Produktivität, iii) potentielle Interaktionen zwischen Biodiversität und Stöchiometrie im Nahrungsnetzkontext.
Global climate change is affecting and will continue to affect ecosystems worldwide. Specifically, temperature and precipitation are both expected to shift globally, and their separate and ...interactive effects will likely affect ecosystems differentially depending on current temperature, precipitation regimes, and other biotic and environmental factors. It is not currently understood how the effects of increasing temperature on plant communities may depend on either precipitation or where communities lie on soil moisture gradients. Such knowledge would play a crucial role in increasing our predictive ability for future effects of climate change in different systems. To this end, we conducted a multi‐factor global change experiment at two locations, differing in temperature, moisture, aspect, and plant community composition, on the same slope in the northern Mongolian steppe. The natural differences in temperature and moisture between locations served as a point of comparison for the experimental manipulations of temperature and precipitation. We conducted two separate experiments, one examining the effect of climate manipulation via open‐top chambers (OTCs) across the two different slope locations, the other a factorial OTC by watering experiment at one of the two locations. By combining these experiments, we were able to assess how OTCs impact plant productivity and diversity across a natural and manipulated range of soil moisture. We found that warming effects were context dependent, with the greatest negative impacts of warming on diversity in the warmer, drier upper slope location and in the unwatered plots. Our study is an important step in understanding how global change will affect ecosystems across multiple scales and locations.
Our multi‐factor global change in the Mongolian Steppe experiment assessed how increased temperatures impact plant productivity and diversity across a natural and manipulated range of soil moisture. We found the response to experimental warming via open‐top chambers to be dependent on location within a landscape and the addition of supplemental precipitation, thus highlighting the context dependency of global change impacts on ecosystems. Our study is therefore an important step in understanding how global change will affect ecosystems across multiple scales and locations.
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