The Effects of Grazing on Reproductive Allocation of Elm (Ulmus Pumila) in Sparse Grassland of Horqin Sand Land, North-eastern China

摘要

To estimate effects of grazing intensity and age classes on reproductive allocation of Ulmus pumila, a common tree in sparse tree grassland, elm trees of different intensity regions and different age classes were selected. The modules produced in current year such as branches, leaves and seeds were collected and weighted, because of whose biomass representing the resource devoted to allocation or growth. It was found that the grazing improved the ratio of resource allocated to reproductive allocation. However, effects of grazing intensity were not obvious according to our study. The prime adult trees devoted more resource to reproduction than that of fresh adult trees and ojd adult trees. It was concluded that the elm produced more seeds to escape from distributed habita.