Estimation and Analysis of Net Primary Productivity in Wuling Mountainous Area Based on Remote Sensing
Using the Ecosystem Productivity Simulator (BEPS) model which combines remote sensing and ecosystem process simulations to quantify the terrestrial carbon and water cycle, we estimated the NPP of Wuling mountainous area in 2010.Based on the survey data of forest, statistical data of grain yield, MODIS NPP data, and the published estimated NPP and surveyed NPP data of each vegetation type, we validated the results of NPP simulation.After exploring the spatial pattern and monthly variation trends of NPP in 2010, the relations between annual NPP and primary terrain factors including altitude, slope and aspect were analyzed specifically.Results showed that: 1) The mean value of annual NPP over the whole study area in 2010 was 555.17 g C/(m2· a), and the total annual NPP was 92.96 Tg C.Compared with that of MODIS NPP, the spatial pattem of simulated NPP was more reasonable, and it reflected more accurate topographical information.2) Monthly NPP changed with seasons.The monthly NPPs of different vegetation types within our study area in 2010 all displayed bimodal distributions.Among them, the NPPs of shrub and evergreen broadleaf forest had the largest amplitude of variation in the year, while the NPP of crop had the smallest amplitude of variation.3) With the altitude increasing, NPP increased first and then decreased quickly.As to the slope, NPP increased with the slope when it is gentle, and then decreased slowly when the slope getting steeper, but when the slope is greater than a certain value, NPP began to increase again.Additionally, among all the aspects of the slope, the mean NPP on the south slope was the highest, while that on the north slope was the lowest.
net primary productivity (NPP)Wuling mountainous areaBEPS modelterrain factorsremote sensing
NETL
NSTL
万方数据
维普
