Forest management strategy affects saproxylic beetle assemblages: A comparison of even and uneven-aged silviculture using direct and indirect sampling.

Klara Joelsson,Heloise Gibb,Joakim Hjältén,Danilo Russo

doi:10.1371/journal.pone.0194905

Klara Joelsson, Heloise Gibb + Show 2 more

Open Access

https://doi.org/10.1371/journal.pone.0194905

Copy DOI

Abstract

Management of forest for wood production has altered ecosystem structures and processes and led to habitat loss and species extinctions, worldwide. Deadwood is a key resource supporting forest biodiversity, and commonly declines following forest management. However, different forest management methods affect dead wood differently. For example, uneven-aged silviculture maintains an age-stratified forest with ongoing dead wood production, while even-aged silviculture breaks forest continuity, leading to long periods without large trees. We asked how deadwood-dependent beetles respond to different silvicultural practices and if their responses depend on deadwood volume, and beetles preference for decay stages of deadwood. We compared beetle assemblages in five boreal forest types with different management strategies: clearcutting and thinning (both representing even-aged silviculture), selective felling (representing uneven-aged silviculture), reference and old growth forest (both uneven-aged controls without a recent history [~50 years] of management, but the latter with high conservation values). We collected beetles using window traps and by sieving the bark from experimental logs (bolts). Beetle assemblages on clear-cuts differed from all other stand types, regardless of trapping method or decay stage preference. Thinning differed from reference stands, indicating incomplete recovery after clear-cutting, while selective felling differed only from clear-cuts. In contrast to our predictions, early and late successional species responded similarly to different silvicultural practices. However, there were indications of marginal assemblage differences both between thinned stands and selective felling and between thinned and old growth stands (p = 0.10). The stand volume of early decay stage wood influenced assemblage composition of early, but not late successional species. Uneven-aged silviculture maintained species assemblages similar to those of the reference and old growth stands and might therefore be a better management option when considering biodiversity conservation.

Highlights

A vast majority of ecosystems across the globe are today shaped by anthropogenic activities rather than natural disturbances [1]
Since the large-scale introduction of even-aged forest management in Scandinavia in the mid20th century, the deadwood volume in managed forests has decreased to an average of 5–7 m3/ ha, compared with 70–100 m3/ha in natural forests [9, 10]
There were no significant differences in assemblages between thinning, selective felling or old growth stands

Summary

Introduction

A vast majority of ecosystems across the globe are today shaped by anthropogenic activities rather than natural disturbances [1]. Human use has extensively modified most of the world’s forests, often accompanied by the deterioration of environmental conditions [2, 3]. These changes in ecosystem structures and processes have led to habitat loss and species extinctions [4, 5]. Through simplification and homogenization of forest structure, even-aged silviculture (e.g., clear-cutting and subsequent thinning) has been linked to severe negative consequences for forest biodiversity [5, 6] for deadwood-dependent species [7, 8]. New management methods that better mimic natural disturbances and processes are needed to mitigate further loss of biodiversity [17, 18]

Results

Discussion

Conclusion