A Synthesis is Emerging between Biodiversity–Ecosystem Function and Ecological Resilience Research: Reply to Mori

Abstract

A recent paper by Mori [1] states the need for a unification of studies of 'engineering' and 'ecological' frameworks of resilience. Engineering resilience focuses on the capacity of a system to recover to equilibrium following some kind of perturbation, whilst ecological resilience explicitly recognizes multiples stable states and the capacity for systems to resist 'regime shifts' between alternate states. We find Mori's argument somewhat surprising given the number of recent biodiversity--ecosystem functioning studies (B--EF) that incorporate aspects of both resistance and recovery [e.g. see references in 2, 3]. We would argue that a synthesis is well underway and that apparent discrepancies are more due to differences in the spatial, temporal and systems scale of focus, and ambiguities in defining this study context, rather than any fundamental incompatibilities in conceptual frameworks.With regards to our recent review on the mechanisms which underpin the resilience of ecosystem functions [3], Mori states: "To avoid confusion, resilience in this case should be explicitly termed as recovery or defined as the analogy of engineering resilience". We clearly consider both recovery and resistance mechanisms that promote the resilience of ecosystem functions. It is unclear what would be the benefit of narrowing the focus to recovery or engineering resilience.Mori appears to feel that although there is some consideration of resistance in recent B--EF research (red text in his Box 1), it does not adequately embrace some of the concepts in the 'ecological resilience' definition, such as the potential for alternative stable states. We clearly define resilience at the level of an individual function, specifically as "the degree to which the ecosystem function can resist or recover rapidly from environmental perturbations, thereby maintaining function above a socially acceptable level" [3]. This definition does not preclude the existence of alternative stable states of the underlying system, and, indeed, we include the potential to shift to alternate states that provide lower function delivery as one of several mechanisms underpinning the provision of resilient ecosystem functions. However, there are many other factors that operate at finer scales of biological organisation, such as the species--level (e.g. genetic variability, sensitivity to environmental change, adaptive phenotypic plasticity, Allee effects) and the community--level (e.g. correlation between response and effect traits, functional redundancy, network interaction structure). Most importantly, we feel that a focus on system state (relative to an assumed equilibrium) is not particularly helpful. The ecological resilience literature is somewhat vague with regards to what aspects of the system should be resistant in the face of an environmental perturbation. The relevant response is varyingly defined as the system 'state', the 'persistence of relationships among state variables within the system', or the 'ways of functioning ' [4]. In our review, we promote ...

Plant diversity maintains long‐term ecosystem productivity under frequent drought by increasing short‐term variation

“…Whether biodiversity-driven buffering occurs in other systems over the long-term, or where thresholds are reached that lead to reductions in biodiversity itself, deserves further exploration. Overall, our results provide novel empirical insights into the importance of the timing and temporal scale at which the effects of environmental perturbations are observed to influence diversity-productivity or diversity-stability relationships (Peterson et al 1998, Oliver et al 2016.…”

“…, Mori , Oliver et al. ), here it quantifies the proportion of drought‐induced reduction of summer productivity that was recovered again the following spring. For instance, in Fig.…”

“…The two measures parallel the index of stability by dividing the temporal mean (l) by the average absolute difference from the mean (i.e., similar to r) allowing for resistance, recovery and stability to be readily compared among each other and with other studies on a common relative scale. Although previous definitions and calculations of ecosystem resilience vary and have generated some debate (Schl€ apfer and Schmid 1999, Hodgson et al 2015, Mori 2016, Oliver et al 2016, here it quantifies the proportion of drought-induced reduction of summer productivity that was recovered again the following spring. For instance, in Fig.…”

“…, Oliver et al. , ). However, understanding how short‐term resistance and recovery responses maintain the long‐term productivity of an ecosystem still requires long‐term empirical observations (Oliver et al.…”

The contrasting roles of host species diversity and parasite population genetic diversity in the infection dynamics of a keystone parasitic plant

“…The value of biodiversity can be considered both economically, in terms of the monetary value of the services that the biotic world provides to us “for free” (Constanza et al, ), and philosophically, in terms of its inherent value to the world and our responsibility towards maintaining it (Ehrlich & Ehrlich, ; Randall, ). Biologically, the relative importance of biodiversity for maintaining ecosystem function has been a topic of debate for at least the past 40 years (see Grime, for overview and Loreau et al, for a synthesis of findings), and continues to be so (Mori, ; Oliver et al, ). Evidence appears to be mounting, however, that there is a broadly positive relationship between species biodiversity and ecosystem services and functions, albeit dependent on experimental system, specific function, and the focal level of organization (i.e., population or community) (Balvanera et al, ; Lefcheck et al, ; Weisser et al, ), and that there is a tendency for these relationships to strengthen over time (Meyer et al, ).…”