Abstract: A quantitative analysis was made on the spatiotemporal characteristics of vegetation net primary productivity (NPP) in Shaanxi Province, based on the 2000-2006 average annual vegetation NPP data of MOD17A3 dataset and by using GIS technology. In the Province, the annual NPP ranged from 340 to 434 g C·m^-2·a^-1, with an average of 383 g C·m^-2·a^-1. The average annual NPP was higher in the south and lower in the north part of the Province, and higher in the west and lower in the east part of central and south Shaanxi, being 0-200 g C·m^-2·a^-1 in the wind-eroded area along Great Wall, 200-300 g C·m^-2·a^-1 in the hilly and gully area of Loess Plateau, 300-400 g C·m^-2·a^-1 in the dry-farming area of Weibei plateau, 400-500 g C·m^-2·a^-1 in the forest area of central part, and 400-500 g C·m^-2·a^-1 in the forest area of Qinba mountains region. As compared with that in 2000, the annual NPP in most part of the Province in 2006 had an increase, and the area with increased annual NPP accounted for 90.52% of the territory of the Province. The increase of the annual NPP in the Province was mainly in linear type, and the area with an increment of >10% occupied 50.6% of the territory of the Province, mainly distributed in the north parts from Yan’an, which suggested that through the implementation of a series of ecological construction projects such as closing hill for forestation and restoring farmland into forestland, the vegetation in these parts was improved.

Key words: biological soil crust, nitrogen fixation, microbial diversity, mine wasteland, PCR-DGGE.