Wetland hydroperiod predicts community structure, but not the magnitude of cross-community congruence

Jody Daniel,Rebecca C Rooney

doi:10.1038/s41598-020-80027-4

Abstract

A major focus in community ecology is understanding how biological interactions and environmental conditions shape horizontal communities. However, few studies have explored whether cross-community interactions are consistent or non-stationary across environmental gradients. Using the relative abundance of birds, aquatic macroinvertebrates and plants, we examined how cross-community congruence varied between short and long-hydroperiod prairie pothole wetlands in southern Alberta. These wetlands are structured by their hydroperiod: the length of time that ponded water is present in the wetland. We compared the strength of cross-community congruence and the strength of congruence between each horizontal community and wetland hydroperiod in wetlands that typically contain ponded water throughout the year to wetlands that dry up every summer. The strength of cross-community relationships was similar between more permanent and more ephemeral wetland classes, suggesting that biological interactions have a near equivalent role in shaping community composition, regardless of hydroperiod. However, because cross-community congruence, measured as the Procrustes pseudo-R value, was, on average, 77% ± SE 12% greater than that between each horizontal community and measures of wetland hydroperiod, we concluded that community structure is not shaped by hydroperiod alone. We attribute the observed cross-community congruence to (1) plants and aquatic macroinvertebrates influence birds through habitat and food provisioning, and (2) birds influence plants and aquatic macroinvertebrates by dispersing their propagules.

Highlights

A major focus in community ecology is understanding how biological interactions and environmental conditions shape horizontal communities
Both environmental conditions and interactions between horizontal communities[1] are known to dictate which species will establish in a given habitat[2,3,4], and numerous studies have attempted to partition their relative influences on community composition[5,6,7,8]
Apart from examination of the stress gradient hypothesis among p lants[9,10,11] and predation-permanence gradient model with aquatic macroinvertebrates and their predators[12], only a few studies have explored whether the strength of biological interactions among multiple taxa is influenced by environmental conditions along a gradient[13,14,15] beyond gradients in space or time[16,17]

Summary

Introduction

A major focus in community ecology is understanding how biological interactions and environmental conditions shape horizontal communities. Apart from examination of the stress gradient hypothesis among p lants[9,10,11] and predation-permanence gradient model with aquatic macroinvertebrates and their predators[12], only a few studies have explored whether the strength of biological interactions among multiple taxa is influenced by environmental conditions along a gradient[13,14,15] beyond gradients in space or time[16,17] Questions arising from this gap include: (1) do relationships among horizontal communities change along environmental gradients, and (2) does the strength of cross-community relationships vary with environmental conditions? These comparisons are made between the relative abundance patterns evident in species belonging to different horizontal communities, commonly within a single taxon, to estimate the strength of inter-community interactions[27] or between the pattern of relative abundances in one horizontal community and environmental conditions[28,29] to estimate the strength of the dependency of a particular horizontal community on a given set of physicochemical factors

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Discussion

Conclusion