Effects of Thinning on the Diversity, Composition, and Spatial Structure in a Mixed Temperate Forest

Abstract

structure in a temperate mixed forest.

Design/methodology/approach: Data were collected in a 1 ha research plot. Five scenarios were evaluated through computer simulations: no thinning (T1), thinning with removal of 25% of basal area (Gha^-1), (T2), thinning with removal of 25% of Gha^-1 (T3), thinning with removal of 45% of Gha^-1 (T4), and thinning with removal of 70% of Gha^-1 (T5). The importance value index, alpha diversity, Pretzsch's A index and structural complexity index were estimated. A spatial distribution analysis was performed using the pair-correlation function g(r). 

Results: Pinus douglasiana and Quercus resinosa were the species of highest ecological value. Due to the removal effect, no significant changes in tree diversity were observed in the applied thinning scenarios. However, as thinning became more intense, at least one species (Quercus candicans) was lost. Thinning from below affected the oaks and thinning from above affected the pine species, which is also reflected in the spatial distribution of the remaining trees.

Limitations on study/implications: The analysis is static; therefore, it is recommended that a long-term study be conducted under varying ecological conditions.

Findings/conclusions: The effect of thinning on forest diversity, composition and structure depends on the type of thinning, condition of the structure, initial composition and intensity of removal. Thinning of less than 25% of the basal area, in the immediacy, allows timber harvesting without generating changes in the diversity, structure and composition of the temperate mixed forest under study.