Dynamics,Patterns and Structure of Major Population in Ulmus pumila var. sabulosa Sparse Forest in Hunshandake Sandland

In Hunshandake sandland,the dynamics,patterns and structuresof major populations in Ulmus pumila var.sabulosa sparse forest were studied.The results showed: ①Populations inUlmus pumila var.sabulosa on the inter-dunes lowland presented declining type,and that in the fixed sand dune had abundant sapling and young trees,and presented increasing type;②Spatial distribution patterns of populations in Ulmus pumila var.sabulosa presented aggregated distribution,and the congregated intensity presented decreasing trend along with scale increasing.③For populationsin Ulmus pumila var.sabulosa on the inter-dunes lowland in differently congregated intensity scales,themid trees and sapling presented decreasing trend along with pyramids of tree class increasing,and big tree presented a random distribution on plot size of 5m 5m.④The congregated intensity of mid tree and young trees of populations in Ulmus pumila var.sabulosa on the fixed sand dune at differently scalespresented increasing trend along with pyramids of tree class increasing,and big tree presented a random distribution on plot size of 10 m×10 m.This distribution patterns of the species are mainly related to their ecological and biological characteristics and habitat,and the managing area must be not lower than 25 m2.