Forest management effects on carbon sequestration and Nitrous Oxide release

Abstract

Forests not only produce timber and sequestrate carbon dioxide (CO2) but also release nitrous oxide (N2O) to the atmosphere. The sequestration of CO2 and release of N2O plays a crucial role in climate change. The importance of their impact to the environment has been recognised during 1990s and different policies have been formed to reward the benefits of forest resources. Forest management practices are changed to optimise the environmental services of forest resources. Forests in Central Europe have a long and dynamic management history. The litter raking, fuel wood extraction and small diameter timber production in the forest during preindustrial age has been replaced by large diameter timber production due to industrial development. Further, forest management changed to address the climate change issues. In Austria, Quercus rubur/petraea a coppice system with repeated clear cuts at intervals of 20 years was practiced until the end of the 19th century. Later coppice systems were replaced either by high forests or a coppice with standards system. In this study, the Biome BGC model was used to assess the forest dynamics in two forest management systems practiced in Austria. Daily meteorological data and site characteristics were used as model input. Model outputs on net primary production (kgC.ha-1), carbon sequestration (kgC.m-2) and nitrogen volatilisation (kgN.m-2) were analysed. Model results show that high forest and coppice with standards systems significantly vary on production and eventually the contribution to global warming. Increasing production and C sequestration is also linked with increasing N2O emissions from the forest. Only considering the management effects on carbon sequestration will be misleading. Based on this study, it is suggested that trade-off between carbon sequestration and nitrogen volatilisation should be considered to assess the impacts of forest management.