Mapping LAI of different plant communities in arid and semi-arid northwestern China

Abstract

Leaf area index (LAI) is an important characteristic of vegetation and a critical vegetation parameter for the global and regional scale studies of the climatic and environmental change. There are many methods that can be used to get LAI, generally, they belong to the three types: filed measurement; empirical and modeling methods. In this paper, we try to get one method that can be used in Arid and Semi-arid Northwestern China to derived LAI in the case of lack of LAI measurements. The empirical method was selected to derive LAI for different type vegetation from SPOT-VGT and landuse data. The study area was the Heihe River basin that has a large-scale area and diverse vegetation types. There were 7 types of vegetation to be mapping LAI using the methodology. They were irrigated, dry, forest, shrub, dense grass, moderate-dense grass and alkaline lands. The parameters of vegetations were modified based on the study area and vegetation types. The results were compared with the whole China LAI map and filed measured LAI. The results suggested that the method was feasible in arid and semi-arid northwestern China. And the results could be greatly improved if using big scale vegetation class map or plant function type data, and the parameters were derived based on the vegetation types in their own region.