Coupling of remote sensing, field campaign, and mechanistic and empirical modeling to monitor spatiotemporal carbon dynamics of a Mediterranean watershed in a changing regional climate

The aim of this study was to simulate impacts of regional climate change in the 2070s on carbon (C) cycle of a Mediterranean watershed combining field measurements, Envisat MERIS and IKONOS data, and the Carnegie Ames Stanford Approach model. Simulation results indicated that the present total C sink status (1.36 Mt C year(-1)) of Mediterranean evergreen needleleaf forest, grassland and cropland ecosystems is expected to weaken by 7.6 % in response to the climate change in the 2070s (Mt=10(12) g). This decreasing trend was mirrored in soil respiration (R-H), aboveground and belowground net primary production (NPP), NEP, and net biome production (NBP). The decrease in NEP in the 2070s was the highest (21.9 %) for mixed forest where the smallest present C sink of 0.03 Mt C year(-1) was estimated. The average present net ecosystem production (NEP) values were estimated at 110 +/- 15, 75 +/- 19, and 41 +/- 25 g C m(-2) years(-1) in forest, grassland, and cropland, respectively, with a watershed-scale mean of 95 +/- 30 g C m(-2) years(-1). The largest present C sink was in grassland, with a total C pool of 0.55 Mt C year(-1), through its greater spatial extent.