Beyond the single index: Investigating ecological mechanisms underpinning ecosystem multifunctionality with network analysis

Abstract

Ecosystems simultaneously deliver multiple functions that relate to both the activities of resident species and environmental conditions. One of the biggest challenges in multifunctionality assessment is balancing analytical simplicity with ecosystem complexity. As an alternative to index‐based approaches, we introduce a multivariate network analysis that uses network theory to assess multifunctionality in terms of the relationships between species' functional traits, environmental characteristics, and functions. We tested our approach in a complex and heterogeneous ecosystem, marine intertidal sandflats. We considered eight ecosystem function, five macrofaunal functional trait groups derived from 36 species, and four environmental characteristics. The indicators of ecosystem functions included the standing stock of primary producers, oxygen production, benthic oxygen consumption, DIN (ammonium and NOx efflux) and phosphate release from the sediments, denitrification, and organic matter degradation at the sediment surface. Trait clusters included functional groups of species that shared combinations of biological traits that affect ecosystem function: small mobile top 2 cm dwellers, suspension feeders, deep‐dwelling worms, hard‐bodied surface dwellers, and tube‐forming worms. Environmental characteristics included sediment organic matter, %mud, %shell hash, and %sediment water content. Our results visualize and quantify how multiple ecosystem elements are connected and contribute to the provision of functions. Small mobile top 2 cm dwellers (among trait clusters) and %mud (among environmental characteristics) were the best predictor for multiple functions. Detailed knowledge of multifunctionality relationships can significantly increase our understanding of the real‐world complexity of natural ecosystems. Multivariate network analysis, as a standalone method or applied alongside already existing single index multifunctionality methods, provides means to advance our understanding of how environmental change and biodiversity loss can influence ecosystem performance across multiple dimensions of functionality. Embedding such a detailed yet holistic multifunctionality assessment in environmental decision‐making will support the assessment of multiple ecosystem services and social‐ecological values.

Plant diversity and ecosystem multifunctionality of different degraded grasslands in alpine meadows of Maqu

“…When studying the relationship between plant diversity and EMF, maintaining a detailed exploration of the functional relationship between diversity indices and each component of the EMF is essential for understanding the complex functional mechanisms of alpine meadow ecosystems (Siwicka et al, 2021). In this study, six of the eight selected ecological function indicators were significantly and positively correlated with both taxonomic diversity indices, functional diversity indices (except FDiv and FEve), phylogenetic PD index (Figure 8), and species richness (SR), functional richness (FRic) and Faith's PD (PD) all showed significant positive correlations with EMF as well (Figure 9).…”

Conservation in coastal soft‐sediment ecosystems: valuing places and recovery

“…The concept of multifunctionality acknowledges that ecological functions interact with and can be dependent on one another. There are numerous studies that explore methods for calculating multifunctionality, which involves measuring functions and assessing them together under a framework of multifunctionality (e.g., Alsterberg et al 2014; Dooley et al 2015; Archana & Baker 2020; Siwicka et al 2020; Siwicka et al 2021; Zhang et al 2021).…”

The architecture of multifunctional ecological networks

“…Integrating several ecological functions, thus, represents both a necessity and a challenge 28 given the difficulties imposed by data collection and standardisation, and their subsequent translation into appropriate modelling paradigms. As a result, there is a lack of quantitative studies connecting biodiversity-ecosystem multifunctionality to ecological networks 8,29 .…”