Forests litter dynamics and environmental patterns in the Indian Himalayan region

Abstract

Litter production and its decomposition are major drivers of soil carbon input and nutrient cycling in forest ecosystems. The litterfall patterns and decomposition rate still need to be explored in the geographically diverse Himalayan region. The study aims to investigate the factor affecting litterfall and its decomposition patterns in tropical, subtropical, and temperate forests by synthesizing a comprehensive database for the Indian Himalayan Region (IHR). We compiled a large dataset of annual litterfall, litter decomposition rate (k), and litter quality data from 102 published research articles and explore its relationship with environmental factors using a linear mixed effect model. Mean annual litterfall in the IHR ranged between 0.26 and 13.4 Mg ha−1 yr−1 and k-values varied from 0.006 to 4.71 yr−1. The study shows greater annual litterfall (5.89 Mg ha−1 yr−1) and k-values (2.47 yr−1) in tropical forests while litter C:N ratio (48) and lignin content (20.2%) were significantly higher in subtropical forests. The data distribution indicates higher but insignificantly different litterfall (5.45 Mg ha−1 yr−1) and mean k-values (1.86 yr−1) in the 1000–2000 m altitudinal range. Both litterfall and k-values were greater at higher temperatures (20–30 °C; 4.72 Mg ha−1 yr−1, 1.81 yr−1) and moderate precipitation (1000–2000 mm; 5.57 Mg ha−1 yr−1, 1.60 yr−1). The linear mixed effect model revealed a significant effect of moisture and precipitation on annual litterfall patterns, while aridity and precipitation significantly influence litter decomposition rate. Our study concluded that tropical forests have greater annual litterfall and k-values but subtropical forests have higher litter quality. The present study suggests environmental factors and forest types instead of litter quality in the IHR mainly control litter decomposition. The outcome of the study can be used to predict the forest carbon and nutrient cycle in future climate change scenarios.