Plant Root Contributions to Carbon Sequestration on the Northern Tablelands of New South Wales, Australia

Abstract

Root contributions to the soil carbon (C) budget vary depending on botanical composition, land-use and management, soil characteristics and prevailing environmental and climatic conditions. How these factors interact to influence the distribution of C and nitrogen (N) stocks with soil depth is not well understood. A two-phased study was conducted to evaluate root contributions to depth distribution of C and N stocks in an Alfisol on the Northern Tablelands of New South Wales (NSW), Australia. Phase 1 evaluated the impact of land-use on: (i) distribution of fine root biomass and associated root functional traits to a maximum depth of 1.0 m, (ii) accumulation of root and soil C and N stocks within the 1.0 m soil profile in relation to the root traits investigated and (iii) decomposability of root litters from improved pastures, native pastures and woodlands. In phase II, a one-year field experiment was conducted to address objectives (i) to (iii) above under three native grasses of NSW: 'Austrodanthonia richardsonii' (C3 sun-adapted), 'Chloris ventricosa' (C4 sun-adapted) and 'Microlaena stipoides' (C3 shade-adapted) across growing seasons at 0% and 75% shading.