Abstract: A series of techniques including the variance analysis (VR), χ²-test, the association co-efficient（AC）, the percentage of co-ocurrenc (PC) consulting the association indices（OI、DJ、JI）were used together with a 2×2 contingency table to analyze the interspecific associations of natural Nitraria tangtorum population and its main companion species in Ulanbuh Desert Inner Mongolia. Result: In the natural Nitraria tangtorum population，the association of 8 dominant species showed no correlation. By the calculation results, in the all 28 species-pairs, there are 15 species-pairs which revealed positive association, and 13 species-pairs revealed negative association. Most of the species-pairs revealed little significant association except Nitraria tangtorum–Artemisia ordosica. Nitraria tangtorum–Artemisia ordosica revealed significant negative association.. Nitraria tangtorum-herbage and other herbaceous species-pairs distributions trend to be independent. The result is very important to construct steady desert plant community, reconstruct desert plant community and regulate ecological pattern in theory.

Key words: Natural Nitraria tangtorum, interspecific associations, population, Ulanbuh Desert