关键词: 荒漠河岸林, 胡杨种群结构, 分布格局, 地下水埋深, 浅层土壤含水率, 塔里木河下游

Abstract: The study on population structure and spatial distribution pattern of P. euphratica was conducted in degradation regions of desert riparian forest at lower reaches of Tarim River, Xinjiang. The results showed that the population density followes a tendency of decreasing with the degradation level, with the greatest decease at the level from heavy degradation region to extremely degradation region. Meanwhile the number of accompanying species in the P. euphratica plot decreases with the increasing level of degradation. The distribution of the P. euphratica population was uneven. There relatively lack seedlings and saplings, but middle tree and old tree are rich. Individual P. euphratica population formed different distribution patterns under different environment conditions. Along with the degradation level increasing, the number of seedling and sapling of the P. euphratica population decrease, but the number of the middle and old tree increase. The distribution pattern of the P. euphratica population was generally in cluster, and the aggregation intensity increased with the degradation level increasing. The distribution pattern of the seedlings and saplings shifted from cluster to random. It is groundwater depth other than the shallow water content of soil that influences the structure and distribution pattern of the P. euphratica population.

Key words: desert riparian forests, Populus euphratica, population structure, spatial distribution pattern, groundwater depth, soil shalow water content