Site Election And Growth Calculation Of Populus Afforestation Under Flooding Stress In Beach Land Of Dongting Lake

The seasonal flooding beach land was taken as the research object in this paper. The studies on the evalution of site quality, the growth pattern and calculation, and the economical effects of Populus plantation under flooding stress were developed.According to the water-level changes of 13 hydrological station during flooding season, the models on the correlation between the flooding time and the elevation of beach lands were set up. The site index and the site quality evalution of Populus in the seasonal flooding beach land were studied. The results showed that the annual flooding days was the main factor affecting the survival rate and the output of Populus plantation.Under different flooding condition, it had no obvious influence on the fiber length and width. However, there existed obvious differences on the ring width, the quantities of radial fiber cells and the basic density of wood. The ring width decreased while the flooding time increased, it was due to the reduce of fiber cell quantities which formed through the cambium cell division. Compared to higher beach land, the relative yield of Populus plantation in lower one increasingly improved as the age growing, this indicated that the anti-flooding ability of Populus was increasingly strengthened. Under flowing condition, the utilizations of beach land were specially classified into 3 kinds according to the annual flooding duration: <30 days-was suitable for the cultivation of Populus high-yield stand; 30~65 days-was suitable for the cultivation of middle-little diameter timberstand and ecological forest; >65 days-wasn't suitable for Populus afforestation. The studies on the growth model and calculation of Populus plantation were carried out according to the different flooding duration, site index and afforestation density.Based on the unified principle: the quantitive maturity, technological maturity, economical maturity and utmost profit, the analysis on the economical effect and cutting age of Populus plantation was done according to the planting density. The cutting age was 1 ~2 years earlier than the classical quantitive maturity age, and the annual net profit during wood productive period was improved.