Past landscape structure drives the functional assemblages of plants and birds

Lucie Lecoq,Aude Ernoult,Cendrine Mony

doi:10.1038/s41598-021-82851-8

Abstract

Landscape structure is a major driver of biodiversity in agricultural landscapes. However, the response of biodiversity can be delayed after landscape changes. This study aimed to determine the effect of current and past landscape structure on plant and bird assemblages. We used a trait-based approach to understand their responses to landscape simplification and habitat fragmentation. We quantified landscape structure at three different years (1963, 1985, 2000) and sampled current plant and bird assemblages in twenty 1 km2 landscape windows located along the Seine Valley (France). For each window, we calculated plant and bird species richness, Community Weighted Variance (CWV), and Community Weighted Mean (CWM) of five functional traits related to dispersal capacity, reproduction, and life-cycle. We detected non-random patterns of traits for both taxa. Plant and bird species richness was lower in simple landscapes. The functional variance of plant traits was higher in landscapes simple in configuration. Both plant and bird assemblages strongly responded to past landscapes, especially their traits related to reproduction and life-cycle. It suggests that landscapes of the Seine valley will face a functional extinction debt. Further research is needed to better predict the delayed response of biodiversity expected to occur after landscape structure changes.

Highlights

Values indicating a divergence[22]
A decrease in heterogeneity in agricultural landscapes could lead to a convergence of trait values toward high dispersal potential, whether in space or time, or a high reproduction rate resulting in a greater mass e ffect[24]
We examined the independent effects of landscape simplification characterized by compositional and configurational heterogeneity (i.e. Shannon index and mean patch area respectively) and habitat fragmentation characterized by habitat amount and isolation of both plant habitat types on species richness, trait ranges (CWV) and mean values (CWM)

Summary

Introduction

Values indicating a divergence[22]. The indices based on functional traits and used to describe biodiversity aim to be independent of species richness. Low compositional or configurational heterogeneity has been shown to reduce functional variance (i.e. reduce the range of dispersion trait values around the mean) by selecting for specific s trategies[12,16]. Assemblages can display a time-lagged response (i.e. relaxation time32) and can include a certain number of species predicted to become extinct (i.e. extinction d ebt33) as the assemblage reaches a new equilibrium after these environmental changes. These two processes have been identified across several taxa[34,35] but few studies have investigated the question in the light of functional traits (but s ee[36,37,38]). Beginning of flowering (month) Mean value at the beginning of flowering by species Flowering duration (month) Mean flowering duration measured by species

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Discussion

Conclusion