The long-term impacts of residue retention on soil quality, tree nutrition and productivity of an exotic pine (Pinus elliottii var.) plantation in southeast Queensland, Australia

Abstract

A study was conducted to assess the long-term impacts of the on-site retention of residues following clear-felling on soil quality, tree nutrition and productivity of a second rotation F1 hybrid exotic pine, Pinus elliottii var., plantation. Soil was investigated for total carbon (C), total nitrogen (N), microbial biomass carbon (MBC), microbial nitrogen (MBN), hot-water extractable carbon (HWEC) and hot-water extractable total nitrogen (HWETN). Foliage and litter total N, P, K, Ca, Mg, and d13C and d15N isotopic compositions were determined. Results showed that soil organic matter quality, as indicated by the labile C and N pools, was greater where harvest residues were retained. Residue retention also improved tree growth. However, foliar and litter analysis showed no significant differences in treatments, except for K and d 13C, which were positively correlated with tree diameter at breast height (DBH) (r2 = 0.67; p<0.005), suggesting greater water use and photosynthetic rates by trees where residues were retained.