RESUMO
Spatial distribution pattern of Populus euphratica and P. pruinosa clonal ramets at three sites was studied, including natural mixed forest of P. euphratica and P. pruinosa in Awati County located in the downstream of Yarkant River, natural P. pruinosa forest in Group 16 of Nongyishi in the Tarim River upstream area, and natural P. euphratica forest in Luntai County located in the middle reach of the Tarim River. The clonal ramets of the three sites showed a cluster distribution pattern at eight sampling scales, i.e., 5 mx5 m, 5 mx10 m, 5 mx15 m, 10 mx10 m, 10 mx15 m, 15 mx15 m, 15 mx20 m, and 20 mX20 m. This pattern revealed that the cluster distribution was a basic property in the spatial distribution pattern of P. euphratica and P. pruinosa populations. At 5 mx5 m scale, negative binomial parameter was minimum, while Cassie index, patchiness inex and aggregation strength were maximum for the two ramet populations at the three sites.