Assessing the importance of species and their assemblages for the biodiversity‐ecosystem multifunctionality relationship

Abstract

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.

Nitrogen availability and plant functional composition modify biodiversity‐multifunctionality relationships

“…At the same time, some slow species had only negative effects on functioning, meaning that on average monocultures of slow species had low multifunctionality. These results highlight that species vary in their effects on multifunctionality and that negative effects are possible (Mori et al, 2023). However, we extend previous findings to consider how similar species are in the functions they drive and whether this varies between fast and slow species.…”

“…Biodiversity generally increases the ability of an ecosystem to simultaneously deliver many functions at high levels (i.e. multifunctionality; Gamfeldt et al., 2008; Hector & Bagchi, 2007; Isbell et al., 2011; Lefcheck et al., 2015; Meyer et al., 2018; Mori et al., 2023; van der Plas, 2019). However, studies find substantial variation in the direction and strength of the biodiversity‐multifunctionality relationships, which suggests that these relationships depend on the biotic and abiotic environmental context (Balvanera et al., 2006; Soliveres et al., 2016; van der Plas, 2019).…”

“…Therefore, slow species might drive different sets of functions than fast ones; however, it remains unknown whether diversity plays a larger role in driving functioning in fast vs. slow dominated communities. Extending to multifunctionality, it has been shown that species vary substantially in their effects and differ in their degree of multifunctional redundancy (Mori et al., 2023) but whether fast and slow species differ in multifunctional redundancy is not known. Species richness, fast‐slow functional composition, and functional diversity are typically correlated in observational studies (Allan et al., 2015), meaning that new experimental approaches are needed to assess their individual and interactive effects.…”

Hill–Chao numbers allow decomposing gamma multifunctionality into alpha and beta components

“…Since the foundational paper by Hector and Bagchi (2007), a number of multifunctionality measures have been proposed, discussed and debated. Previous measures include the overlap method (Hector & Bagchi, 2007), the averaging approach (Maestre et al, 2012), multivariate modelling (Dooley et al, 2015) and the threshold method (Byrnes et al, 2014;Gamfeldt et al, 2008;Meyer et al, 2018;Mori et al, 2023). Each of these different approaches has its strengths and limitations.…”

The architecture of multifunctional ecological networks

“…quantify the relationship between biodiversity and ecosystem multifunctionality 6,7 , its connection has been done mainly conceptually, due to challenges measuring different interactions and establishing their relevance across multiple niche dimensions 8,9 . Such lack of quantitative studies therefore limits our ability to determine which species and interactions are important to maintain the multiple functions of ecosystems 10 . Here we develop a framework -derived from a resource-consumer-function tensor analysis-that bridges these gaps by framing biodiversity-ecosystem multifunctionality in terms of multilayer ecological network theory.…”