Consequences of changing biodiversity

Abstract

Human alteration of the global environment has triggered the sixth major extinction event in the history of life and caused widespread changes in the global distribution of organisms. These changes in biodiversity alter ecosystem processes and change the resilience of ecosystems to environmental change. This has profound consequences for services that humans derive from ecosystems. The large ecological and societal consequences of changing biodiversity should be minimized to preserve options for future solutions to global environmental problems.

A safe operating space for humanity

“…The current and projected rate of biodiversity loss constitutes the sixth major extinction event in the history of life on Earth -the first to be driven specifically by the impacts of human activities on the planet (Chapin et al 2000). Previous extinction events such as the Tertiary extinction of the dinosaurs and the rise of mammals caused massive permanent changes in the biotic composition and functioning of Earth's ecosystems.…”

Functional traits in agriculture: agrobiodiversity and ecosystem services

“…For instance, although it is currently well established that intercropping can increase crop yields through niche complementarity [29], understanding of intercropping comes from examples of particular species interactions in particular contexts, rather than from principles that can be generally applied across different species compositions and environmental conditions. The statement that intercropping maize with cowpeas increases yield is less generalizable than the finding that, under conditions where plant-available NO 3 À concentrations are lower than a certain threshold, intercropping facultative N 2 -fixing species increases staple grain seed set and protein content. The latter statement refers to well-defined, measurable traits (categorical: N 2 fixation; continuous: biomass or grain protein content), while the former refers to taxonomic affiliations that group multiple traits, thereby masking the mechanisms of how intercropping increases yield.…”

“…These differences increase ecosystem functioning by increasing the odds of including more productive species when diversity increases (sampling effect, see Glossary), increasing the complementarity in how species use resources (resource partitioning), and/or in how they modify their surrounding environment in ways that impact other species (facilitation; the latter two mechanisms are referred to together as 'niche complementarity' [2]). The functional characteristics of species (i.e., their traits) influence ecosystem functioning directly by mediating changes in biotic controls (e.g., predation or competition) and indirectly through responses to changes in local environment (e.g., microclimates or disturbance regimes) [3]. Traits govern not only the impacts of species on the environment, but also the response of species to the environment and, thus, their fitness [4].…”

“…The latter statement refers to well-defined, measurable traits (categorical: N 2 fixation; continuous: biomass or grain protein content), while the former refers to taxonomic affiliations that group multiple traits, thereby masking the mechanisms of how intercropping increases yield. Both approaches predict that intercropping increases yield, but the approach referring to functional traits can guide management strategies over a broad gradient of environmental conditions by pinpointing the general controls, such as abiotic (e.g., soil [NO 3 À ]) and biotic (e.g., nematode inhibition of symbiosis between legumes and N 2 -fixing microorganisms [30]), on rates of soil nutrient cycling (e.g., N 2 fixation) and human nutrition (e.g., crop yield or protein content).…”

Ecological Impacts of Genetically Modified Crops: Ten Years of Field Research and Commercial Cultivation

“…Substantial scientific data on environmental effects of the currently commercialized GM crops are available. Independent from the use of GM crops, modern agricultural systems have considerable negative impacts on global biodiversity [6][7][8][9][10][11]. On a global scale, the most direct negative impact is due to the considerable loss of natural habitats, which is caused by the conversion of natural ecosystems into agricultural land [9,12].…”