Effects of thinning intensities on litterfall characteristics and decomposition in the natural secondary lowland forests of Southeastern Taiwan

ABSTRACT Research Highlights: This study presented novel evidence of the optimal level of forest thinning to maintain nutrient cycling and achieve management objectives. Background and Objectives: Litter dynamics play a vital role in balancing forest nutritional dynamics, which may be related to forest productivity. This study aimed to examine the influence of thinning intensity on litter quantity and quality in a secondary forest (a natural tropical secondary forest in southeastern Taiwan). Materials and Methods: Five different thinning treatments were implemented, and forest dynamics were measured. The litterbag method was used to assess the initial status of litter decomposition. Results: The rate of litter accumulation without thinning ranged from 5.14 to 5.63 t ha−1 yr−1. Thinning altered the litter decomposition rate. A 20% thinning intensity resulted in the fastest litter decomposition, with an annual litter loss of 22.4% compared with the control area. However, at >60% thinning intensity, the rate of litter decomposition slowed down, and the annual loss increased to 42.5%. Conclusions: Thinning changes the litter decomposition rate mainly by influencing soil humidity and temperature. A thinning intensity of 20% in secondary forest thins the forest, improves litter status, accelerates litter decomposition, and promotes nutrient cycling.