Assembly processes of waterbird communities across subsidence wetlands in China: A functional and phylogenetic approach

Abstract

Aim Although assembly processes have been studied in a wide range of taxa, determining assembly rules remains controversial, particularly in assemblages consisted of species with strong dispersal capacities. Moreover, few studies focused on communities in recently human‐created habitats. We tested two prevailing but opposing hypotheses, environmental filtering and limiting similarity, in waterbird communities across subsidence wetlands created by underground coal mining in China, with an aim to better understand assembly processes in communities composed of highly mobile species in human‐dominated landscape. Location The North China Plain. Methods We quantified taxonomic, functional and phylogenetic diversity of the waterbird assemblages in different seasons and compared the mean pairwise distances (MPD) and the mean nearest taxon distances (MNTD) with null models to examine whether co‐occurring species were clustered or overdispersed on the functional dendrogram or phylogenetic tree. Independent contributions of multi‐scale habitat variables therein were determined using a hierarchical partitioning method. Results We showed asynchronous patterns of seasonal dynamics among the multiple diversity metrics, with highest species diversity during autumn migration. Generally, the co‐occurring species were functionally and phylogenetically clustered. Habitat variables had stronger effects on the functional structure than on the phylogenetic structure of the communities. The degree of functional clustering increased in older and larger wetlands, while the assemblages shifted from functional clustering to overdispersion with increasing habitat diversity, landscape connectivity and human disturbance. Main conclusions The waterbird assemblages were mainly structured by environmental filtering, and the assembly processes were significantly affected by habitat variables, with stronger effects on functional diversity. Our study highlights the importance of environmental filtering and habitat variables in structuring assemblages dominated by species with high dispersal capacities and suggests that increasing habitat diversity and reducing disturbances will contribute to waterbird conservation in this human‐dominated landscape.

Changes in functional composition and diversity of waterbirds: The roles of water level and submerged macrophytes

“…Environmental filtering would result in negative SESFRic and SESFDis values by allowing only a set of species with certain functional traits to persist and by forcing most of the biomass into a small trait space (Liu, Swenson, Zhang, & Ma, 2013;Mason et al, 2005). These findings were also in concordance with some of the previous studies on waterbirds that reported functionally clustered waterbirds communities (the western populations in Che et al, 2018;summer season in Che et al, 2019;Li et al, 2019).…”

“…For organisms like waterbirds, which have high-dispersal capabilities and can respond to changes in the environment quickly, priority effects (Chase, 2003) and stochastic processes (Hubbell, 2001) are less likely to be dominant players in community assembly (Daniel et al, 2019;Fukami, 2015;Li et al, 2019). One may argue that highly mobile taxa such as birds should rely on larger landscapes and should be exposed to filtering at the landscape scale (Rooney, Bayley, Creed, & Wilson, 2012).…”

“…One may argue that highly mobile taxa such as birds should rely on larger landscapes and should be exposed to filtering at the landscape scale (Rooney, Bayley, Creed, & Wilson, 2012). However, most waterbirds depend strongly on wetlands and have strong habitat associations, which means that environmental filtering can also be a strong force in community assembly at local scale (Li et al, 2019), especially during times of the year when environmental stress is high such as winter in our study region (summer season in Che et al, 2018). Furthermore, in permanent and large lakes such as our study lakes, environmental filtering is expected to be more prominent in community assembly as compared to smaller and temporary wetlands, where stochastic events and priority effect are expected to be major determinants of assembly (Daniel et al, 2019;Li et al, 2019).…”

“…However, most waterbirds depend strongly on wetlands and have strong habitat associations, which means that environmental filtering can also be a strong force in community assembly at local scale (Li et al, 2019), especially during times of the year when environmental stress is high such as winter in our study region (summer season in Che et al, 2018). Furthermore, in permanent and large lakes such as our study lakes, environmental filtering is expected to be more prominent in community assembly as compared to smaller and temporary wetlands, where stochastic events and priority effect are expected to be major determinants of assembly (Daniel et al, 2019;Li et al, 2019). However, it should also be noted that there have been other studies reporting neutrally assembled waterbird communities (spring and autumn populations in Che et al, 2019; populations of temporary wetlands in Daniel et al, 2019;de Arruda Almeida et al, 2019) and functionally over-dispersed waterbird communities (the eastern populations in Che et al, 2018;winter populations in Che et al, 2019).…”

“…Community assembly can be influenced by processes operating at both local and metacommunity scales (Leibold et al., 2004). Species sorting metacommunity perspective is expected to apply at the metacommunity scale for organisms such as birds that are highly mobile, capable of quickly responding to environmental changes and have strong habitat associations (Li et al., 2019; Özkan, Svenning, & Jeppesen, 2013; Spasojevic, Copeland, & Suding, 2014). In this perspective, assemblies are determined chiefly by local interactions (Leibold et al., 2004), and at the local scale, communities can be shaped by stochastic processes, environmental filtering, limiting similarity, fitness equalising, priority effects, or any combination of these (Spasojevic & Suding, 2012).…”