关键词: GF-2, 叶面积指数, Sentinel-2, 相对真值, Landsat-8, 空间代表性

Abstract: Ecological stoichiometry reflects the interactions of energy balance and multiple chemical elements in ecosystems. This study focused on the C, N, and P concentrations and the stoichiometry characteristics of leaves of dominant plant species and soil between grazed and enclosed grassland in Nagqu, Tibet, to explore the effects of different grassland utilization strategies on soil and plants and the interrelations between them. The results showed that soil pH of grazed grassland (7.30) was significantly higher than that of enclosed grassland (7.13). Foliar P concentration in grazed grassland was significantly higher than that in enclosed grassland (1.25 vs 1.05 g·kg^-1) but C∶P ratio in grazed grassland was significantly lower than that in enclosed grassland (335.21 vs 434.60). Foliar C concentration was significantly negatively correlated with N and P concentrations. Foliar N concentration had significantly positive correlation with P concentration. Leaf N concentration had no significant correlation with soil total N concentration, and leaf P concentration was significantly negatively correlated with soil total P concentration, suggesting that plants were probably limited by P availability in the grassland. Our results provide a scientific basis for the sustainable management of grassland in the Qinghai Tibetan Plateau.

Key words: GF-2, leaf area index, Sentinel-2, relativity of true values, Landsat-8, spatial representativeness.