Small-scale and multi-species approaches for assessing litter decomposition and soil dynamics in high-diversity forests

Premise of the Study: The relationship between tree species abundance and diversity and soil chemistry has been studied in several ecosystems and at different spatial scales. However, species-specific assessments have mainly been conducted in temperate ecosystems and in monospecific settings, calling for studies from diverse, mixed forests from different ecosystems. Methods: In a subtropical forest in southern China, under four dominant tree canopy species (Lithocarpus chintungensis, Castanopsis wattii, Schima noronhae, and Manglietia insignis), we assessed species’ effect on inter- and intraspecific percentages of litter mass loss, and the effect of species on soil nutrients and soil microbial biomass. Results: Our results show significant differences in litter decomposition for all four species; however, the percentage of litter mass loss was stable under different species. Microbial biomass and soil nutrients presented strong differences under different tree species. Species-specific differences in soil characteristics were seen for carbon-nitrogen-phosphorus relationships. Surprisingly, the correlations between carbon and phosphorus and between nitrogen and phosphorus showed opposite slopes in soils collected under different tree species. Discussion: Our results provide insights into the importance of tree species identity in providing variety to ecosystem processes occurring on the forest floor. We recommend this methodological approach—combining analysis of litter decomposition, soil nutrient concentrations, and microbial biomass—when dealing with species-rich forests.