Efficacy of Low and High Complexity Vegetation Treatments for Reestablishing Terrestrial Arthropod Assemblages during Montane Wetland Restoration

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Abstract

Assessments of faunal reassembly during wetland restorations have typically been derived from relatively benign, lower-elevation environments. We investigated recovery of terrestrial arthropod assemblages in conjunction with restoration of a montane wet meadow in Sequoia National Park (Sierra Nevada, California, U.S.A.). Our goal was to assess response of arthropod assemblages to wetland restoration in this winter-dominated environment, including comparison of faunal reassembly in (1) areas of sparse plugs (planted over several years) and (2) dual-density plantings with additional heterogeneity, complexity, and connectance to source habitats provided by high-density bands running through sparsely planted habitat (final study year only). Results across all restoration treatments indicated varying levels of faunal reassembly, but convergence of faunal assemblages with reference habitat had not occurred after recovery periods as long as 5 years. Similarity indices and multivariate compositional results indicated a slower recovery than did univariate trends for assemblage metrics and abundances for some individual taxa, highlighting the utility of assessments using a range of taxa and analytical approaches. Faunal recovery did not appear to lag behind that of vegetation structure, despite the short growing season. The dual-density plantings indicated faster recovery after 1 year, across almost all metrics, than was observed after several years for the sparse plantings. Restoration configurations that increase habitat complexity, heterogeneity, and/or connectance may disproportionately increase rates of passive faunal reassembly and prove to be cost-effective approaches for promoting recovery of ecosystem function.

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