Effects of Thinning Practices on Soil Properties and Arbuscular Mycorrhizal Fungi in Natural Pure Oriental Beech Forests

Abstract

Thinning intensities in Fagus orientalis Lipsky. stands may influence the soil properties, arbuscular mycorrhizal (AM) fungi symbiosis, and their interaction through soil quality enhancement. We aimed to investigate the impact of four thinning intensities—control (no thinning); moderate (15%), moderately intense (35%), and intense thinning (55%)—implemented five years ago in pure oriental beech forests. In this context, the percentage indicates the proportion of trees removed by each thinning intensity, based on the total number of trees before thinning. Our focus encompassed soil physical–chemical properties, AM fungi community composition, and root colonization. At the intense thinning sites, the soil organic carbon, total nitrogen, available potassium, AMF spore density, and root colonization increased by 209.7, 88.9, 115.8, 404.9, and 448.5%, respectively, when compared to the control sites. This suggests a potential rise in AMF spore density and root colonization—a vital aspect for natural regeneration. These findings highlight the importance of considering management practices in forest systems that can enhance the root system in a sustainable manner to improve plant performance, soil fertility, and symbiosis with AM fungi.