Abstract

A new indicator for the accounting effect of landcover is defined based on the integration of thermodynamics (exergy analysis) and ecology (net primary production (NPP)). The indicator NPPEX allows quantifying and assessing the impacts of landuse changes, in spatial and temporally dimensions. This study is focused on the effect of landuse changes on NPP-based exergy for the south-central of Chile from 2000 to 2014. The exergy-based spatially characterization factor (NPPEX) was estimated based on the time series of NPP extracted from MODIS and exergy conversion factor. Finally, the dynamic of NPPEX changes by the transition of each landuse type was studied for identifying the driver force influencing on biomass productivity. Results confirmed the important influence of forestry policy on land use changes, in particular, the forest transitions during the two last decade, which exhibit a cover increase of 28% between 1994 and 2014 established mainly on land destined to crops, native forest, and shrubs. In consequences, the highest land efficiency (NPPEX) was obtained for exotic tree plantations (88.25-91.4 MJex m(-2)yr(-1)) during all studied period, due to high carbon stock per square meter associated to its intensive forest management. From the transition of landcover changes point of view, there was produced a positive effect on NPPEX, being the exotic tree plantation expansion the main driver of gains of NPPEX. Nevertheless, this expansion has carried out severe local environmental impacts (i.e., ecosystem fragmentation, biodiversity loss, topsoil compaction, losses of Biobio Basin's morpho-sedimentary regulation capacity, etc.).