Beaver creates early successional hotspots for water beetles

Petri Nummi,John Loehr,Juliette Van Der Schoor,Wenfei Liao

doi:10.1007/s10531-021-02213-8

Petri Nummi, John Loehr + Show 2 more

Open Access

https://doi.org/10.1007/s10531-021-02213-8

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Abstract

Beavers (Castor spp.) are ecosystem engineers that induce local disturbance and ecological succession, which turns terrestrial into aquatic ecosystems and creates habitat heterogeneity in a landscape. Beavers have been proposed as a tool for biodiversity conservation and ecosystem restoration. So far, most research has compared biodiversity in beaver wetlands and non-beaver wetlands, but few studies have explored how beaver-created succession affects specific taxa. In this study, we investigated how water beetles responded to different successional stages of wetlands in a beaver-disturbed landscape at Evo in southern Finland. We sampled water beetles with 1-L activity traps in 20 ponds, including: 5 new beaver ponds, 5 old beaver ponds, 5 former beaver ponds, and 5 never engineered ponds. We found that beaver wetlands had higher species richness and abundance than non-beaver wetlands, and that new beaver wetlands could support higher species richness (321%) and abundance (671%) of water beetles compared to old beaver wetlands. We think that higher water beetle diversity in new beaver ponds has resulted from habitat amelioration (available lentic water, shallow shores, aquatic vegetation, and low fish abundance) and food source enhancement (an increase of both dead and live prey) created by beaver dams and floods. We conclude that using beavers as a tool, or imitating their way of flooding, can be beneficial in wetland restoration if beaver population densities are monitored to ensure the availability of newly colonizable sites.

Highlights

Habitat heterogeneity is an essential factor in creating biodiversity at the landscape level (Turner et al 2001; Hammill et al 2018)
14 species were only found in new beaver ponds (Fig. 1), three in old beaver ponds, and Hydroporus obscurus only in a never beaver engineered pond
Our GLMM results showed that new beaver ponds had significantly higher water beetle species richness and abundance than old beaver ponds and non-beaver ponds

Summary

Introduction

Habitat heterogeneity is an essential factor in creating biodiversity at the landscape level (Turner et al 2001; Hammill et al 2018). In a landscape with a high degree of environmental heterogeneity, landscape level diversity is high even if the patch level diversities “α” do not differ. Heterogeneous landscapes have higher turnover “β” and landscape level diversity “γ” than homogeneous landscapes. Higher levels of species turnover “β” may be associated with increased ecosystem functioning in heterogeneous landscapes, as communities may perform different functions under varying environmental conditions (Thompson and Gonzales 2016). The presence of functionally dominant species can have major impacts on ecosystem function since they can push ecological systems to a different state (Naeem et al 2012; Hammill et al 2018). In northern boreal and temperate environments, beavers cause patch disturbance, which consequentially leads to a successional mosaic in a landscape (Remillard et al 1987; Johnston 2017; Kivinen et al 2020)

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