Effects of Biodiversity on Ecosystem Functioning: A Consensus of Current Knowledge

Abstract

Effects of biodiversity on ecosystem functioning: a consensus of current knowledge AbstractHumans 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 relationship 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 structured, 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.Based on our review of the scientific literature, we are certain of the following conclusions:1)Species' functional characteristics strongly influence ecosystem properties. Functional characteristics operate in a variety of contexts, including effects of dominant species, keystone species, ecological engineers, and interactions among species (e.g., competition, facilitation, mutualism, disease, and predation). Relative abundance alone is not always a good predictor of the ecosystem-level importance of a species, as even relatively rare species (e.g., a keystone predator) can strongly influence pathways of energy and material flows.2)Alteration of biota in ecosystems via species invasions and extinctions caused by human activities has altered ecosystem goods and services in many well-documented cases. Many of these changes are difficult, expensive, or impossible to reverse or fix with technological solutions.3)The effects of species loss or changes in composition, and the mechanisms by which the effects manifest themselves, can differ among ecosystem properties, ecosystem types, and pathways of potential community change.4)Some ecosystem properties are initially insensitive to species loss because (a...

Food webs: reconciling the structure and function of biodiversity

“…When normalized by L/S, degree distributions have a general exponential-type shape [20] indicating that most paths of energy flow through food webs go through relatively few species. This is consistent with species removal experiments in BEF studies, which have suggested a small sub-group of species disproportionately influences productivity [9].…”

“…The interplay between intraspecific (e.g., closely related taxa tend to share trophic relationships) and inter-specific (e.g., strong interactions between predators and prey, and plants and pollinators) interactions will have profound effects on food-web structure [63], and the balance of these can determine the occurrence and strength of niche partitioning effects on ecosystem functioning [9]. Most studies have considered food webs as a fixed suite of species with no variation in patterns of connectivity through evolutionary time [64].…”

“…In the 1980s biodiversity-ecosystem function (BEF) studies attempted to bridge this gap. These studies initially focused on concerns over the consequences of species loss for ecosystem productivity and stability [9]. Early studies relating biodiversity to functions such as primary productivity, decomposition, pollination, and fisheries production were necessarily simple and primarily focused on single trophic levels ( [9] for a review).…”

“…Early studies relating biodiversity to functions such as primary productivity, decomposition, pollination, and fisheries production were necessarily simple and primarily focused on single trophic levels ( [9] for a review). The limitations of this approach have been widely described [9,10], and there is a growing recognition that BEF studies would benefit from a framework that considers effects of changes in biodiversity across trophic levels on multiple ecosystem processes [9][10][11].…”

Phylogenetic constraints on ecosystem functioning

“…There is today a consensus that biodiversity losses will result in declining EF if species perform different roles in ecosystems, in other words if they have different functional traits [1][2][3] . Understanding the mechanisms that shape the distribution of species traits within species assemblages has thus become central to the biodiversity-EF research agenda.…”