Litter accumulation and decomposition in secondary forests of the southern Sierra Madre of Chiapas, Mexico

Abstract

Litter accumulation and decomposition processes affect organic matter input and cycling of nutrients in forest ecosystems. Forest restoration may enhance these two processes reducing soil erosion and the risks of landslides on steep slopes. The main objective of this study was to identify factors determining litter accumulation and decomposition in degraded secondary forests from the upper part of the Grijalva River watershed (Chiapas, Mexico). We assessed litter accumulation over a period of 290 days on tilted (52-104 % slope) and horizontal collecting surfaces, and litter decomposition of Alnus acuminata, Quercus segoviensis and Pinus tecunumanii ("litter bag" method) in six localities (≥ 5 replicate 1,000 m² plots). We used analysis of variance to compare vegetation and soil attributes among forest fragments, and we fitted multiple linear regression models to identify explanatory variables of litter accumulation and decomposition. Litter accumulation on both types of collecting surfaces was higher in SW-faced slopes, and with lower tree density and soil fertility. Litter decomposition of A. acuminata (40-56 %) was faster than in the other two species, and was higher in more humid sites at higher elevations, with higher canopy cover and in mountainsides with SW slope-aspect. We propose planting juveniles of A. acuminata (followed by Q. segoviensis) in the initial stages of a forest restoration program aimed at improving the structure and stability of soils.