Soil Biodiversity as Affected by Different Thinning Intensities in a Pinus laricio Stand of Calabrian Apennine, South Italy

Adele Muscolo,Giovanna Settineri,Carmelo Mallamaci,Federico Romeo

doi:10.3390/f12010108

Abstract

Forest soil biodiversity, which drives natural ecosystem multifunctionality, can be altered by incorrect forestry management practices. Pinus laricio is the most representative and widespread conifer species in Calabria, South Italy, and appropriate management is needed to maintain Pinus laricio forest for its great economic and natural value. In Europe, thinning is considered the most effective silvicultural treatment to maintain/increase the ecological value of coniferous stands. In this study, moderate thinning (MT), intense thinning (HT), and clear cut (CC) treatments were used to manage Pinus laricio stands with the aim of identifying the thinning intensity that is less detrimental to soil biodiversity. The effects of the different thinning intensities were evaluated, in two contrasting seasons (summer and winter), on the abundance, and diversity of arthropods, fungi, and bacteria colonies as well as on selected soil properties (organic matter, humification index, bulk density, pH) related to soil habitability. Results evidenced that the abundance, species richness, and diversity of arthropods, as well as fungi, bacteria colonies, and soil properties, changed with the treatments and seasons. Under HT, the greatest biodiversity and the highest amounts of arthropods, fungi, and bacteria were found in both seasons. This study finds evidence for Connell’s intermediate disturbance hypothesis, highlighting that the greatest organic carbon content and humification index, as well as the lowest bulk density, found in HT reduced the likelihood of competitive exclusion between occurring species, thereby promoting high species richness and diversity. This study gives insights into ecological relationships between understory composition related to tree species abundance and soil community.

Highlights

Published: 19 January 2021Among forest management techniques used to preserve forests, thinning is the practice that removes a small number of trees from a stand [1,2] in order to make sites more productive, thereby driving the abundance and composition of undergrowth vegetation and increasing the economic value of forests
We found the greatest abundance of the above mentioned arthropods in HT plots (Table 4), and, surprisingly, we observed the appearance of other groups that were completely absent in plots of the other treatments (Chilopoda, Psocoptera, Symphyla, and Thysanoptera) in HT plots in summer (Tables 3 and 4)
Despite the complex nature of soil dweller interactions, we found that the soil community responses to forest management in coniferous forest depended on the provided higher resources and better habitat conditions for shade-intolerant species that thinning treatments established along with resident vegetation

Summary

Introduction

Published: 19 January 2021Among forest management techniques used to preserve forests, thinning is the practice that removes a small number of trees from a stand [1,2] in order to make sites more productive, thereby driving the abundance and composition of undergrowth vegetation and increasing the economic value of forests. Soil microorganisms have an essential role in soil organic matter decomposition [17] and in nutrient cycling and are considered early warning indicators of changes in soil properties on account of their high sensitivity to external perturbation [9]. Arthropods, with their 1.2 million species, are litter transformers and pulverizers [18,19], contributing to improving soil physical and chemical properties [20,21,22]

Methods

Results

Conclusion