An official website of the United States government
Biodiversity changes, such as decline in species richness and biotic homogenization, can have grave consequences for ecosystem functionality. Careful investigation of biodiversity–ecosystem multifunctionality linkages with due consideration of conceptual and technical challenges is required to make the knowledge practically useful in managing social–ecological systems. In this paper, we introduced different methods to assess perspectives regarding the issue of diversity‐multifunctionality, including a possible multifunctional redundancy/uniqueness, and the influences of the number and identity of functions on multifunctionality. In particular, we aimed to align methods with detecting the mechanisms underpinning diversity‐multifunctional relationships that are free from statistical biases. Based on a set of novel methods that excluded analytical biases resulting from differences in the number and identities of multiple functions considered, we found that a substantial portion of species disproportionately supported ecosystem functions and that the diversity effects on multifunctionality were more markedly observed when more functions were considered. These results jointly emphasize that individual species are, to some extent, both functionally unique as well as redundant, highlighting the complexity and necessity for managed assemblages to retain high levels of diversity. We also observed that the relative magnitude of uniqueness or redundancy can differ between species and functions and therefore should be defined in a multifunctional context. We further found that only a small subset of species was identified as significantly less important, especially at low levels of multifunctionality. Taken together, given the low level of multifunctional redundancy we identified, we stress that unraveling the hierarchical roles of biodiversity at different levels, such as individual species and their assemblages, should be a high research priority, in both theory and practice.
more »
« less
Understandable multifunctionality measures using Hill numbers
In ecology, multifunctionality metrics measure the simultaneous performance of multiple ecosystem functions. If species diversity describes the variety of species that together build the ecosystem, multifunctionality attempts to describe the variety of functions these species perform. A range of methods have been proposed to quantify multifunctionality, successively attempting to alleviate problems that have been identified with the previous methods. This has led to a proliferation of more‐or‐less closely related metrics which, however, lack an overarching theoretical framework. Here we borrow from the comprehensive framework of species diversity to derive a new metric of multifunctionality. Analogously to the effective number of species used to quantify species diversity, the metric we propose is influenced both by the number of functions as well as, crucially, the evenness of performance levels across functions. In addition, the effective multifunctionality also considers the average level at which the functions are performed. The result is a measure of the cumulative performance of the system were all functions provided equally. The framework allows for the inclusion of the correlation structure among functions, thus allowing it to account for non‐independence between functions. We show that the average metric is a special case of the newly proposed metric when all functions are uncorrelated and performed at equal levels. We hope that by providing a new metric of multifunctionality anchored in the rigorous framework of species diversity based on effective numbers, we will overcome the considerable skepticism that the larger community of ecologists has built against indices of multifunctionality. We thereby hope to help popularize this important concept which, like biological diversity, describes a fundamental property of ecosystems and thus lies at the heart of ecology.
more »
« less
- Award ID(s):
- 1637630
- PAR ID:
- 10485024
- Publisher / Repository:
- Oikos
- Date Published:
- Journal Name:
- Oikos
- Volume:
- 2023
- Issue:
- 2
- ISSN:
- 0030-1299
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
1. Ecosystem restoration often focuses on re‐establishing species richness and diversity of native organisms. However, effective restoration requires re‐establishment of ecosystem functions and processes by all trophic levels. Functional trait descriptions of communities, including decomposer communities, may provide more comprehensive evaluations of restoration activities and management than taxonomic community metrics alone. 2. We examined species and functional trait composition of dung beetle (Coleoptera: Scarabaeidae, Geotrupidae) communities across a 3–31 yearchronosequence of restored prairies, in which sites varied in the presence of re‐introduced bison and prescribed fire. We calculated functional diversity metrics and community‐weighted mean trait values using behavioural and morphological measurements. We also performed a dung decomposition experiment to measure an ecosystem function driven by these insects. 3. Bison presence doubled beetle abundance and increased richness by 50%. Shannon diversity increased with restoration age, nearly doubling from the youngest to oldest restorations. Functional diversity was unchanged by site characteristics, except functional richness, which was reduced by bison and fire presence. Beetles were, on average, smaller in older restorations, although this pattern was weaker when bison were present. 4. Dung decomposition was unaffected by site characteristics but increased with community weighted mean beetle mass. Dung decomposition was better predicted by mean trait values, suggesting that supporting large‐bodied species may be more important than species diversity in settings where maximizing decomposition function is a goal. 5. Restoration managers should consider dung beetle communities and their functional characteristics when making management decisions, particularly where large grazers are a component of management strategies.more » « less
-
Abstract To advance understanding of biodiversity and ecosystem function, ecologists seek widely applicable relationships among species diversity and other ecosystem characteristics such as species productivity, biomass, and abundance. These metrics vary widely across ecosystems and no relationship among any combination of them that is valid across habitats, taxa, and spatial scales, has heretofore been found. Here we derive such a relationship, an equation of state, among species richness, energy flow, biomass, and abundance by combining results from the Maximum Entropy Theory of Ecology and the Metabolic Theory of Ecology. It accurately captures the relationship among these state variables in 42 data sets, including vegetation and arthropod communities, that span a wide variety of spatial scales and habitats. The success of our ecological equation of state opens opportunities for estimating difficult-to-measure state variables from measurements of others, adds support for two current theories in ecology, and is a step toward unification in ecology.more » « less
-
Abstract Human impacts on ecosystems are resulting in unprecedented rates of biodiversity loss worldwide. The loss of species results in the loss of the multiple roles that each species plays or functions (i.e., “ecosystem multifunctionality”) that it provides. A more comprehensive understanding of the effects of species on ecosystem multifunctionality is necessary for assessing the ecological impacts of species loss. We studied the effects of two dominant intertidal species, a primary producer (the seaweedNeorhodomela oregona) and a consumer (the shellfishMytilus trossulus), on 12 ecosystem functions in a coastal ecosystem, both in undisturbed tide pools and following the removal of the dominant producer. We modified analytical methods used in biodiversity–multifunctionality studies to investigate the potential effects of individual dominant species on ecosystem function. The effects of the two dominant species from different trophic levels tended to differ in directionality (+/−) consistently (92% of the time) across the 12 individual functions considered. Using averaging and multiple threshold approaches, we found that the dominant consumer—but not the dominant producer—was associated with ecosystem multifunctionality. Additionally, the relationship between abundance and multifunctionality differed depending on whether the dominant producer was present, with a negative relationship between the dominant consumer and ecosystem function with the dominant producer present compared to a non‐significant, positive trend where the producer had been removed. Our findings suggest that interactions among dominant species can drive ecosystem function. The results of this study highlight the utility of methods previously used in biodiversity‐focused research for studying functional contributions of individual species, as well as the importance of species abundance and identity in driving ecosystem multifunctionality, in the context of species loss.more » « less
-
Abstract Generalization is difficult to quantify, and many classifications exist. A beta diversity framework can be used to establish a numeric measure of generalist tendencies that jointly describes many important features of species interactions, namely spatiotemporal heterogeneity. This framework is promising for studying generalized symbiotic relationships of any form.We formulated a novel index, turnover importance (T).Tdescribes spatiotemporal heterogeneity in interactor assemblages, an inherent feature of generalist relationships that is not captured by available metrics. We simulated the behaviour ofTrelative to other available metrics, calculatedTfor native North American orchid‐insect relationships, and tested correlations betweenTand eco‐geographic variables. We performed case studies to demonstrate applications ofTfor conservation and eco‐evolutionary studies.Tbehaves predictably across simulations, and dynamically interacts with site number, gamma diversity, and species range sizes.Tis moderately sensitive to sampling depth. Orchids with higherTscores occupy larger ranges and broader climatic niches.Alternative interactor‐specific measures of generalism are best employed for local‐level community networks over short timespans. While these interactor metrics can assess use versus availability in local communities,Tcan be used to measure spatiotemporal patterns of variation in interactor assemblages across a focal species' range. This study provides a roadmap for future work focused on better understanding the patterns and consequences of generalized relationships.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1111/oik.09402
