Coarse Woody Debris’ Invertebrate Community is Affected Directly by Canopy Type and Indirectly by Thinning in Mixed Scots Pine—European Beech Forests

Ximena Herrera-Alvarez,Gabriela Rivadeneira-Barba,J Bosco Imbert,Willin Alvarez,Juan A Blanco

doi:10.3390/f11090975

Abstract

Research Highlights: Thinning and tree species alter the forest floor microclimate by modifying canopy cover, radiation, wind, and humidity. Thus, forest management can directly influence the edaphic mesofauna responsible for decomposing coarse woody debris (CWD). Background and Objectives: This research was carried out in the Southwestern Pyrenees Mountains (Northern Spain) and aimed to determine the influence of forest thinning and canopy type (pure Pinus sylvestris L. or a mix of P. sylvestris and Fagus sylvatica L.) on CWD colonization by edaphic fauna. Materials and Methods: CWD samples were collected belonging to intermediate and advanced decomposition stages, approximately 10 cm long and 5 cm in diameter. Using a design of three thinning intensities (0%, 20%, and 40% of basal area removed), with three replications per treatment (nine plots in total), four samples were taken per plot (two per canopy type) to reach 36 samples in total. Meso- and macrofauna were extracted from CWD samples with Berlese–Tullgren funnels, and individuals were counted and identified. Results: 19 taxonomic groups were recorded, the most abundant being the mesofauna (mites and Collembola). Mixed canopy type had a significant positive influence on richness, whereas advanced decay class had a positive significant influence on total abundance and richness. In addition, there were non-significant decreasing trends in richness and abundance with increasing thinning intensity. However, interactions among thinning intensity, canopy type, and decay class significantly affected mesofauna. Furthermore, some taxonomic groups showed differential responses to canopy type. CWD water content was positively correlated with total invertebrate abundance and some taxonomic groups. Our results suggest that stand composition has the potential to directly affect invertebrate communities in CWD, whereas stand density influence is indirect and mostly realized through changes in CWD moisture. As mesofauna is related to CWD decomposition rates, these effects should be accounted for when planning forest management transition from pure to mixed forests.

Highlights

Coarse woody debris (CWD) are very important for forest ecosystems due to their multiple ecological functions, such as regulating carbon and nutrient cycles and providing different structuralForests 2020, 11, 975; doi:10.3390/f11090975 www.mdpi.com/journal/forestsForests 2020, 11, 975 properties to forest soils, such as affecting sediment transport storage and water retention [1,2].Previous works have emphasized the importance of coarse woody debris (CWD) for species diversity conservation.For example, brown bears (Ursus arctos L.) feed on carpenter ants (Camponotus herculeanus L.) that inhabit CWD [3]
To facilitate the release of nutrients from the fallen woody remains, it is necessary that such substrate is colonized by several taxonomic groups of invertebrates which, accompanied by microorganisms and abiotic factors, promote their total decomposition [6]
We registered a total of 8348 individuals belonging to 19 taxonomic groups in all different treatments combined (Table 3)

Summary

Introduction

Coarse woody debris (CWD) are very important for forest ecosystems due to their multiple ecological functions, such as regulating carbon and nutrient cycles and providing different structuralForests 2020, 11, 975; doi:10.3390/f11090975 www.mdpi.com/journal/forestsForests 2020, 11, 975 properties to forest soils, such as affecting sediment transport storage and water retention [1,2].Previous works have emphasized the importance of CWD for species diversity conservation.For example, brown bears (Ursus arctos L.) feed on carpenter ants (Camponotus herculeanus L.) that inhabit CWD [3]. Coarse woody debris (CWD) are very important for forest ecosystems due to their multiple ecological functions, such as regulating carbon and nutrient cycles and providing different structural. Previous works have emphasized the importance of CWD for species diversity conservation. The removal of biomass from CWD and standing dead trees decreases bird diversity and can even alter prey–predator relationships with insects and other taxonomic groups [5]. CWD increase soil microbial activity and fertility, depending on the decomposition of the wood that releases nutrients such as nitrogen and phosphorus. To facilitate the release of nutrients from the fallen woody remains, it is necessary that such substrate is colonized by several taxonomic groups of invertebrates which, accompanied by microorganisms and abiotic factors, promote their total decomposition [6]

Objectives

Results

Discussion

Conclusion