Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter ecosystem properties and the goods and services they provide to humanity. Ecological experiments, observations, and theoretical developments show that ecosystem properties depend greatly on biodiversity in terms of the functional characteristics of organisms present in the ecosystem and the distribution and abundance of those organisms over space and time. Species effects act in concert with the effects of climate, resource availability, and disturbance regimes in influencing ecosystem properties. Human activities can modify all of the above factors; here we focus on modification of these biotic controls. The scientific community has come to a broad consensus on many aspects of the re- lationship between biodiversity and ecosystem functioning, including many points relevant to management of ecosystems. Further progress will require integration of knowledge about biotic and abiotic controls on ecosystem properties, how ecological communities are struc- tured, and the forces driving species extinctions and invasions. To strengthen links to policy and management, we also need to integrate our ecological knowledge with understanding of the social and economic constraints of potential management practices. Understanding this complexity, while taking strong steps to minimize current losses of species, is necessary for responsible management of Earth's ecosystems and the diverse biota they contain.

/pdf/effects-of-biodiversity-on-ecosystem-functioning-a-consensus-13j8vabcus.pdf

Effects of biodiversity on ecosystem functioning: a consensus of current knowledge

The ecological consequences of biodiversity loss have aroused considerable interest and controversy during the past decade. Major advances have been made in describing the relationship between species diversity and ecosystem processes, in identifying functionally important species, and in revealing underlying mechanisms. There is, however, uncertainty as to how results obtained in recent experiments scale up to landscape and regional levels and generalize across ecosystem types and processes. Larger numbers of species are probably needed to reduce temporal variability in ecosystem processes in changing environments. A major future challenge is to determine how biodiversity dynamics, ecosystem processes, and abiotic factors interact.

/pdf/biodiversity-and-ecosystem-functioning-current-knowledge-and-252rku9qn3.pdf

Biodiversity and Ecosystem Functioning: Current Knowledge and Future Challenges

Understanding the negative and positive effects of agricultural land use for the conservation of biodiversity, and its relation to ecosystem services, needs a landscape perspective. Agriculture can contribute to the conservation of high-diversity systems, which may provide important ecosystem services such as pollination and biological control via complementarity and sampling effects. Land-use management is often focused on few species and local processes, but in dynamic, agricultural landscapes, only a diversity of insurance species may guarantee resilience (the capacity to reorganize after disturbance). Interacting species experience their surrounding landscape at different spatial scales, which influences trophic interactions. Structurally complex landscapes enhance local diversity in agroecosystems, which may compensate for local high-intensity management. Organisms with high-dispersal abilities appear to drive these biodiversity patterns and ecosystem services, because of their recolonization ability and larger resources experienced. Agri-environment schemes (incentives for farmers to benefit the environment) need to broaden their perspective and to take the different responses to schemes in simple (high impact) and complex (low impact) agricultural landscapes into account. In simple landscapes, local allocation of habitat is more important than in complex landscapes, which are in total at risk. However, little knowledge of the relative importance of local and landscape management for biodiversity and its relation to ecosystem services make reliable recommendations difficult.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1461-0248.2005.00782.x

Landscape perspectives on agricultural intensification and biodiversity – ecosystem service management

Understanding the negative and positive effects of agricultural land use for the conservation of biodiversity, and its relation to ecosystem services, needs a landscape perspective. Agriculture can contribute to the conservation of high-diversity systems, which may provide important ecosystem services such as pollination and biological control via complementarity and sampling effects. Land-use management is often focused on few species and local processes, but in dynamic, agricultural landscapes, only a diversity of insurance species may guarantee resilience (the capacity to reorganize after disturbance). Interacting species experience their surrounding landscape at different spatial scales, which influences trophic interactions. Structurally complex landscapes enhance local diversity in agroecosystems, which may compensate for local highintensity management. Organisms with high-dispersal abilities appear to drive these biodiversity patterns and ecosystem services, because of their recolonization ability and larger resources experienced. Agri-environment schemes (incentives for farmers to benefit the environment) need to broaden their perspective and to take the different responses to schemes in simple (high impact) and complex (low impact) agricultural landscapes into account. In simple landscapes, local allocation of habitat is more important than in complex landscapes, which are in total at risk. However, little knowledge of the relative importance of local and landscape management for biodiversity and its relation to ecosystem services make reliable recommendations difficult.

http://biologie.uni-bayreuth.de/toek1_pop/de/pub/pub/60936/EcolLetters2005%2C8_857-874.pdf

REVIEWS AND SYNTHESES Landscape perspectives on agricultural intensification and biodiversity - ecosystem service management

The links between plant diversity and ecosystem functioning remain highly controversial. There is a growing consensus, however, that functional diversity, or the value and range of species traits, rather than species numbers per se, strongly determines ecosystem functioning. Despite its importance, and the fact that species diversity is often an inadequate surrogate, functional diversity has been studied in relatively few cases. Approaches based on species richness on the one hand, and on functional traits and types on the other, have been extremely productive in recent years, but attempts to connect their findings have been rare. Crossfertilization between these two approaches is a promising way of gaining mechanistic insight into the links between plant diversity and ecosystem processes and contributing to practical management for the conservation of diversity and ecosystem services.

/pdf/vive-la-difference-plant-functional-diversity-matters-to-4nj6gcnq41.pdf

Vive la différence: plant functional diversity matters to ecosystem processes

We evaluate the empirical and theoretical support for the hypothesis that a large proportion of native species richness is required to maximize ecosystem stability and sustain function. This assessment is important for conservation strategies because sustenance of ecosystem functions has been used as an argument for the conservation of species. If ecosystem functions are sustained at relatively low species richness, then arguing for the conservation of ecosystem function, no matter how important in its own right, does not strongly argue for the conservation of species. Additionally, for this to be a strong conservation argument the link between species diversity and ecosystem functions of value to the human community must be clear. We review the empirical literature to quantify the support for two hypotheses: (1) species richness is positively correlated with ecosystem function, and (2) ecosystem functions do not saturate at low species richness relative to the observed or experimental diversity. Few empirical studies demonstrate improved function at high levels of species richness. Second, we analyze recent theoretical models in order to estimate the level of species richness required to maintain ecosystem function. Again we find that, within a single trophic level, most mathematical models predict saturation of ecosystem function at a low proportion of local species richness. We also analyze a theoretical model linking species number to ecosystem stability. This model predicts that species richness beyond the first few species does not typically increase ecosystem stability. One reason that high species richness may not contribute significantly to function or stability is that most communities are characterized by strong dominance such that a few species provide the vast majority of the community biomass. Rapid turnover of species may rescue the concept that diversity leads to maximum function and stability. The role of turnover in ecosystem function and stability has not been investigated. Despite the recent rush to embrace the linkage between biodiversity and ecosystem function, we find little support for the hypothesis that there is a strong dependence of ecosystem function on the full complement of diversity within sites. Given this observation, the conservation community should take a cautious view of endorsing this linkage as a model to promote conservation goals.

https://faculty.washington.edu/elizaw/100/Schwartz_2000_BDEF.pdf

Linking biodiversity to ecosystem function: implications for conservation ecology

Th er ole of diversity in the maintenance of ecosystems has been studied widely in the past decade. By correlating richness and diversity with basic ecosystem processes, these investigations lend support to the hypothesis that species diversity significantly influences ecosystem functioning and, in turn, provide support for the conservation of biodiversity. Nonetheless, the majority of these investigations demonstrate that conservation of a relatively small number of generally dominant species is sufficient to maintain most processes. Indeed, there is remarkably little evidence to support the contention that less common species, those likely of highest conservation concern, are important in the maintenance of ecosystem functioning. Here we summarize studies, most employing alternative methodological strategies, wherein less common and rare species are demonstrated to make significant contributions to ecosystem functioning. Evidence exists among studies of keystone species, aggregate effects of less common species, and species turnover. Our findings suggest that (1) less common species can make significant ecosystem contributions; (2) further investigation into the effects of rare and less common species on ecosystem maintenance is sorely needed; (3) further investigation should embrace a variety of approaches; and (4) until further research is conducted a prudent conservation approach is warranted wherein the contribution of less common species to ecosystem functioning is assumed.

Rare Species and Ecosystem Functioning

The imminent decline in species diversity coupled with increasing exotic species introductions has provoked investigation into the role of resident diversity in community resistance to exotic species colonization. Here we present the results of a field study using an experimental method in which diversity was altered by removal of less abundant species and the resulting disturbance was controlled for by removal of an equivalent amount of biomass of the most common species from paired plots. Following these manipulations, the exotic grass, Lolium temulentum, was introduced. We found that exotic species establishment was higher in plots in which diversity was successfully reduced by removal treatments and was inversely related to imposed species richness. These results demonstrate that less common species can significantly influence invasion events and highlight the potential role of less common species in the maintenance of ecosystem function.

Rare Species Loss Alters Ecosystem Function – Invasion Resistance

http://web.ecologia.unam.mx/laboratorios/fmolina/images/stories/publicaciones/ArticulosJournals/Franklin-etal-2006.pdf

Buffelgrass (Pennisetum ciliare) land conversion and productivity in the plains of Sonora, Mexico

Buffelgrass is a non-indigenous, invasive, C4 grass that was introduced throughout much of southern Texas, the Southwestern United States, and northern and central Mexico to improve degraded rangelands. The successful introduction and spread of buffelgrass follows a trajectory similar to that of other invasive C4 grasses in arid and semiarid ecosystems. In the Plains of Sonora of the Sonoran Desert (Mexico) buffelgrass is favored by widespread removal of native vegetation and seeding, but, why, following initial introduction, the species persists remains unclear. In this study, we addressed two concerns associated with buffelgrass invasion in the Plains of Sonora. We hypothesized that under arid rangeland conditions, buffelgrass outcompetes native herbaceous species (1) through rapid acquisition of limiting nutrients (here assumed to be nitrogen) and (2) under conditions with high nitrogen input. In summer 2002, a 2 by 2 factorial experiment was established with buffelgrass removal and nitrogen a...

/pdf/community-and-ecosystem-effects-of-buffelgrass-pennisetum-3bsb7tvss2.pdf

Kelly G. Lyons

Papers

Linking biodiversity to ecosystem function: implications for conservation ecology

Rare Species and Ecosystem Functioning

Rare Species Loss Alters Ecosystem Function – Invasion Resistance

Buffelgrass (Pennisetum ciliare) land conversion and productivity in the plains of Sonora, Mexico

Community and Ecosystem Effects of Buffelgrass (Pennisetum ciliare) and Nitrogen Deposition in the Sonoran Desert