Abstract: In this paper, the methods such as V/m ratio t-test, negative binomial parameter, clump index, mean crowding intensity, index of patchiness, dispersion coefficient, and two-term local variance (TTLV) were used to analyze the spatial distribution pattern and interspecific association of Populus euphratica and Tamarix ramosissima seedlings populations in the middle and lower reaches of the Tarim River. The results showed that the spatial distribution pattern of the two populations all presented significantly aggregative at a block size of 16 m². Based on 2×2 contingency table, the interspecific associations of the two species were examined by means of χ²-test, together with the association coefficient and percentage co-occurrence. The results indicated that the two species showed significantly positive association. It was suggested that the two populations in the study area were in stable distribution pattern, and the two species coexisted and held the common ecological niche.

Key words: Quercus liaotungensis, Tilia paucicostata, Natural secondary stand, Evapotranspiration, Forest structure