关键词: 集约经营, 化学计量, 毛竹, 粗放经营, 氮沉降

Abstract: Based on the MODIS NDVI data of 250m resolution during the period of 2000-2013, the mixed pixel decomposition model was employed to calculate vegetation coverage and evaluate vegetation degradation situation in Shaanxi Province, in order to analyze the main factors causing the degradation of vegetation and to provide a basis for ecological construction and the planning of urban construction. The results showed that: 1) The degradation areas of vegetation in Shaanxi Province were mainly distributed in the Guanzhong urban agglomeration, especially in Xi’an City and the desert belt in the north of Yulin City. Xi’an City was the city with the greatest vegetation degradation area, followed by Yulin City, and Ankang City had the least area. 2) The vegetation was mainly improved or not significantly changed, accounting for 48.03% and 49.10% of the total land area, respectively. The vegetation degradation area was smaller, accounting for 2.87% of the total land area, of which the areas of mild, moderate and severe degradation accounted for 1.39%, 0.56% and 0.92% of the total land area, respectively. 3) Vegetation degradation occurred mainly in the farmland, accounting for 54.36% of the total degradation area. 4) The relationship between the vegetation degradation area and newly increased built area reached a significant level, indicating that the continuous development of urbanization came with the occupation of the farmland, forest and grassland with high degrees of vegetation coverage, thus directly leading to the degradation of vegetation. Therefore, attention should be paid on green space landscape construction in urban planning. Some vegetation in the desert region of the north of Yulin City continued to degrade, and desertification control should be continuously maintained.

Key words: nitrogen deposition, intensive management., stoichiometry, Moso bamboo, conventional management