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Biodiversity and ecosystem functioning in dynamic landscapes

The Royal Society
Philosophical Transactions B
Authors:
Ulrich Brose at Friedrich Schiller University Jena
Ulrich Brose
Helmut Hillebrand at Carl von Ossietzky Universität Oldenburg
Helmut Hillebrand
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Abstract

The relationship between biodiversity and ecosystem functioning (BEF) and its consequence for ecosystem services has predominantly been studied by controlled, short-term and small-scale experiments under standardized environmental conditions and constant community compositions. However, changes in biodiversity occur in real-world ecosystems with varying environments and a dynamic community composition. In this theme issue, we present novel research on BEF in such dynamic communities. The contributions are organized in three sections on BEF relationships in (i) multi-trophic diversity, (ii) non-equilibrium biodiversity under disturbance and varying environmental conditions, and (iii) large spatial and long temporal scales. The first section shows that multi-trophic BEF relationships often appear idiosyncratic, while accounting for species traits enables a predictive understanding. Future BEF research on complex communities needs to include ecological theory that is based on first principles of species-averaged body masses, stoichiometry and effects of environmental conditions such as temperature. The second section illustrates that disturbance and varying environments have direct as well as indirect (via changes in species richness, community composition and species’ traits) effects on BEF relationships. Fluctuations in biodiversity (species richness, community composition and also trait dominance within species) can severely modify BEF relationships. The third section demonstrates that BEF at larger spatial scales is driven by different variables. While species richness per se and community biomass are most important, species identity effects and community composition are less important than at small scales. Across long temporal scales, mass extinctions represent severe changes in biodiversity with mixed effects on ecosystem functions. Together, the contributions of this theme issue identify new research frontiers and answer some open questions on BEF relationships in dynamic communities of real-world landscapes. © 2016 The Author(s) Published by the Royal Society. All rights reserved.
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Introduction
Cite this article: Brose U, Hillebrand H. 2016
Biodiversity and ecosystem functioning
in dynamic landscapes. Phil. Trans. R. Soc. B
371: 20150267.
http://dx.doi.org/10.1098/rstb.2015.0267
Accepted: 22 February 2016
One contribution of 17 to a theme issue
‘Biodiversity and ecosystem functioning in
dynamic landscapes’.
Subject Areas:
ecology, environmental science,
theoretical biology
Keywords:
disturbance, species richness, varying
environmental conditions, food webs,
meta-communities, spatial and temporal scales
Author for correspondence:
Ulrich Brose
e-mail: ulrich.brose@idiv.de
Biodiversity and ecosystem functioning
in dynamic landscapes
Ulrich Brose1,2 and Helmut Hillebrand3
1
German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e,
04103 Leipzig, Germany
2
Institute of Ecology, Friedrich Schiller University Jena, Dornburger Strasse 159, 07743 Jena, Germany
3
Institute for Chemistry and Biology of Marine Environments (ICBM), Carl-von-Ossietzky University Oldenburg,
Schleusenstrasse 1, 26382 Wilhelmshaven, Germany
The relationship between biodiversity and ecosystem functioning (BEF) and
its consequence for ecosystem services has predominantly been studied by
controlled, short-term and small-scale experiments under standardized
environmental conditions and constant community compositions. However,
changes in biodiversity occur in real-world ecosystems with varying environ-
ments and a dynamic community composition. In this themeissue, we present
novel research on BEF in such dynamic communities. The contributions are
organized in three sections on BEF relationships in (i) multi-trophic diversity,
(ii) non-equilibrium biodiversity under disturbance and varying environ-
mental conditions, and (iii) large spatial and long temporal scales. The first
section shows that multi-trophic BEF relationships often appear idiosyncratic,
while accounting for species traits enables a predictive understanding. Future
BEF research on complex communities needs to include ecological theory that
is based on first principles of species-averaged body masses, stoichiometry and
effects of environmental conditions such as temperature. The second section
illustrates that disturbance and varying environments have direct as well as
indirect (via changes in species richness, community composition and species’
traits) effects on BEF relationships. Fluctuations in biodiversity (species rich-
ness, community composition and also trait dominance within species) can
severely modify BEF relationships. The third section demonstrates that BEF
at larger spatial scales is driven by different variables. While species richness
per se and community biomass are most important, species identity effects
and community composition are less important than at small scales. Across
long temporal scales, mass extinctions represent severe changes in biodiversity
with mixed effects on ecosystem functions. Together, the contributions of this
theme issue identify new research frontiers and answer some open questions
on BEF relationships in dynamic communities of real-world landscapes.
1. Introduction
Twenty-five years of research on the role of biodiversity in ecosystem processes
and services has yielded an impressive body of literature. Generalizing over
several hundred studies, there is clear evidence that the loss of biodiversity
from a certain trophic group of species results in their reduced biomass pro-
duction, associated with reduced efficiency of resource capture [1 – 3]. This
relationship has been primarily observed in communities of autotrophs such
as plants [4–7], but also holds in consumers of plant or animal resources
[8–10] and decomposers feeding on dead organic material [11,12]. In fact, the
loss of biodiversity across trophic levels has been predicted to show even stron-
ger effects owing to the strong connection between consumer – resource energy
fluxes and ecosystem processes [2,13,14]. The primary focus of BEF research has
been on bivariate relationships between biodiversity and a single ecosystem
process [1,4], but recent studies have provided strong evidence that the real
functional importance of biodiversity lies in maintaining multiple ecosystem
processes across environmental fluctuations in time or space [5,15]. The effects
of biodiversity loss are rapidly seen when multiple functions are monitored
&2016 The Author(s) Published by the Royal Society. All rights reserved.
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Most research on the effects of environmental change in freshwaters has focused on incremental changes in average conditions, rather than fluctuations or extreme events such as heatwaves, cold snaps, droughts, floods or wildfires, which may have even more profound consequences. Such events are commonly predicted to increase in frequency, intensity and duration with global climate change, with many systems being exposed to conditions with no recent historical precedent. We propose a mechanistic framework for predicting potential impacts of environmental fluctuations on running-water ecosystems by scaling up effects of fluctuations from individuals to entire ecosystems. This framework requires integration of four key components: effects of the environment on individual metabolism, metabolic and biomechanical constraints on fluctuating species interactions, assembly dynamics of local food webs, and mapping the dynamics of the meta-community onto ecosystem function. We illustrate the framework by developing a mathematical model of environmental fluctuations on dynamically assembling food webs. We highlight (currently limited) empirical evidence for emerging insights and theoretical predictions. For example, widely supported predictions about the effects of environmental fluctuations are: high vulnerability of species with high per capita metabolic demands such as large-bodied ones at the top of food webs; simplification of food web network structure and impaired energetic transfer efficiency; and reduced resilience and top-down relative to bottom-up regulation of food web and ecosystem processes. We conclude by identifying key questions and challenges that need to be addressed to develop more accurate and predictive bio-assessments of the effects of fluctuations, and implications of fluctuations for management practices in an increasingly uncertain world.
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