Genetic diversity, stand structure and sex ratio of Populus euphratica floodplain forests at the Tarim River, Xinjiang, NW China

点击翻译按钮获取中文摘要

Watered by rivers draining glaciers of the surrounding mountain ranges, the so-called Tugai forests in the extremely arid Tarim basin of Chinas Xinjiang province are made up mainly by a single tree species, the dioecious Populus euphratica. Although germinating exclusively at riverbanks after high floods, adult trees can survive up 10 m ground water depth and produce root suckers up to 30 m apart from the mother tree. The proposed project aims to investigate the spatial and genetic structure of these forests, addressing the following questions:1. Meandering rivers have stands ranging from seedlings to dying old trees. What is the time scale of stand development; how can a contiguous forest develop from germination rows?2. Does spatial mapping of trees and their sexes allow an estimation of clone size (to be calibrated by molecular analyses)? Can we identify pockets of high genetic diversity in the forests by using this method at a landscape scale?3. How depends the large-scale genetic structure of Tugai forests from past river movements, and can we predict the genetic diversity of the forests from landscape features?4. Forests under drought stress seem to have a male-biased sex ratio. What are the reasons, and does an even sex ratio indicate more suitable growth conditions?