Biological, structural and functional responses of tropical forests to environmental factors

Abstract

As compared to temperate and boreal forests, the majority of tropical forests are biodiverse, structurally-complex and high-functioning ecosystems, yet their potential attributes are vulnerable to anthropogenic disturbances and environmental factors. Here, we hypothesize that the biological, structural and functional attributes of tropical forests respond to water-related climatic and soil nutrient-related factors. Thus, we quantified 27 forest attributes and 20 environmental factors across 189 plots of Sri Lankan tropical forests. Our results suggest that environmental conditions were characterized by both water-related and temperature-related factors, and as such, both coarse-textured and compacted-structured soils determined soil conditions. Forest conditions were characterized by high species-functional diversity, structural complexity and aboveground biomass-related functions. We found strong positive effects of water-related climatic factors (particularly mean annual precipitation) followed by temperature-related climatic factors (i.e., growing degree days) but negligible positive to negative effects of textured-related (i.e., gravel contents) and nutrient-related (i.e., bulk density) soil factors on most of the biological, structural and functional attributes. Overall the biodiversity and carbon stocks of Sri Lankan tropical forests are likely to increase with water-energy balance and improved soil conditions, and thus, studied forests could offset a substantial quantity of anthropogenic carbon emissions to achieve carbon neutrality which can have both regional and global significance if protected from anthropogenic disturbances. Broadly, this study suggests that conservation practices should consider multiple environmental and biotic attributes of the tropical forests during forest management which can have a win-win situation for biodiversity conservation and climate change mitigation.