Abstract:

In this paper Ulmus pumila populations in two habitats of fixed sand dunes and low land between dunes in the Otindag sandy land were targeted and, the spatial distribution patterns and the associations of different developmental stages of the populations by using point pattern analysis. The results showed that the whole population in sandy lands between dunes had a clumped distribution at the scales <10 m. The young trees and middle-aged trees had random spatial distributions at a greater scale,however the mature trees had a clumped distribution. The spatial associations between different developmental stages exhibited at a smaller scale. With increasing scales,the spatial association between different developmental stages turned to be feeble. The whole population on fixed sand dunes had a clumped distribution at a smaller scale. With increasing scales,the population tended to have random spatial distributions. The spatial association of middle-aged trees and mature trees was positively correlated with each other. The spatial associations of different developmental stages were weak.

Key words: Otindag sandy land, Ulmus pumila, population pattern, point pattern analysis, spatial association