Impacts of nitrogen additions and harvest residue management on chemical composition of soil carbon in a plantation forest

摘要

Soils are the major pool of terrestrial C globally that, if carefully managed, can be used to offset rising atmospheric C02. An important consideration for the forestry sector is how forest management practices might impact on the forest soil C stock.An experiment has been set up to determine how long-term fertilisation and harvest residue management will affect soil C stocks and the relative abundance of biochemically resistant compounds in soil organic C. The early results suggested that soil C concentration has not been affected by fertilisation and harvesting methods. The following results were achieved in the light fraction of soil organic matter (SOM): long-term fertilisation increased alkyl C and alkyl-to-O-alkyl ratio; the abundance of cutin-derived compounds was greater in fertilised soil C than in non-fertilised soil C; major carbohydrates (mannose, glucose and sucrose) decreased in the fertilised plot despite greater forest litter inputs. Also, in the light fraction of SOM, the stem only harvesting treatment had a greater amount of cutin-derived compounds and carbohydrates, compared with whole tree harvest treatment. The project will eventually lead to a better understanding of forest management impacts on both quantity and quality ofsoil C in New Zealand forests.