Influence of input litter quality and quantity on carbon storage in post-mining forest soil after 14 years of reclamation

Abstract

Reclamation of post mining soils by planting trees is of great research interest due to its potential to stabilize mine soils and sequester atmospheric carbon (C). However there are knowledge gaps regarding the effect of different litter quality and biomass on the C sequestration vis-à-vis molecular characterization of soil organic carbon (SOC) in reclaimed mine soils. Hence, an experiment was conducted to determine the effect of litter quality, quantity, and leaf litter decomposition rate on the quality and quantity of carbon sequestered after 14 years of restoration by three representative plant species (Azadirachta indica, Dalbergia sissoo, and Gmelina arborea) which have been frequently used for revegetation of post-mining sites in India. Results indicate that significant amounts of carbon accumulated under different tree species (47.44, 42.34, and 20.17 Mg C ha−1 under A. indica, D. sissoo, and G. arborea plantations resepctively) as compared to recent dump. Decomposition rate constant had a significant relationship with C/N ratio and nitrogen (N) content and therefore tree species (A. indica) with high C/N, lignin/N ratios, and low N content had a significantly lower decomposition rate constant thereby sequestering more carbon, making it the tree species of choice. Among the three tree species studied, G. arborea witnessed the highest litterfall (4635 kg ha−1 yr−1) but had the lowest SOC stock due to the highest decomposition rate constant (0.00229), which established the fact that composition of leaf litter rather than total litterfall played a significant role in carbon sequestration. Furthermore, spectroscopic methods (UV–vis and FTIR) could clearly distinguish differences in functional groups and molecularity of the humic acids derived from plant species of different resource quality and hence can be effectively used in studying the quality of C sequestered.