Response of Vegetation FPAR in Growing Season to Climate Change in Hengduan Mountains, China

Abstract:

Hengduan Mountains (HM), located in the transition zone between the first and second steps of China's terrain (Fig.1a) is an important ecological barrier in China (Fig.1b). It is important to evaluate the ecosystem service function to obtain the vegetation health status. The Fraction of Absorbed Photosynthetically Active Radiation (FPAR) directly reflects the energy absorbed and capturing capacity of vegetation canopy. Thus, it has been used as one of the important indices to monitor the health of vegetation. At present, there are few studies on characteristics of vegetation FPAR change and its response to climate factors in the growing season (May to September). The spatial differentiation law of FPAR and its response to climate factors were studied based on the data of MOD15A2H/FPAR in HM from 2001 to 2018. The value of FPAR was high in the south and the northeast, and low in the northwest of HM (Fig. 1c). The correlation analysis showed that the positive correlation area between air temperature and vegetation FPAR was mainly distributed in TianQuan - ShiMian - EBian (Fig. 1d) with broad-leaved and coniferous forest, and the negative correlation areas distributed mainly in the south of HM with low altitude with the main vegetation types of crops. The areas where vegetation FPAR is negatively correlated with precipitation were mainly distributed in the middle and high altitude areas of coniferous forest and grassland, and the area with positive correlation was mainly located in the low altitude region of HM (Fig. 1e). The area where vegetation FPAR is positively correlated with sunshine duration was mainly located in the southern low altitude area and the northern high altitude area of mainly broad-leaved forest and grassland, and the area with negative correlation was mainly located in the low altitude area in the south of HM (Fig. 1f). The correlation analysis through significance test (p < 0.05) of vegetation FPAR with air temperature, precipitation, and sunshine duration in the growing season showed an area proportion of 10.95%, 29.21% and 27.13%, respectively, indicating that the vegetation FPAR had a strong response to precipitation and sunshine duration, but relatively weak response to air temperature.