Assessment On Forest Health Of Planted Cotinus Coggygria Scenic Forest In Beijing

The scenic forest of Cotinus coggygria is a significant part of the mountain landscape forest in Beijing, however, growth declination and quality degradation have emerged in the scenic forest of Cotinus coggygria in recent years. Taking scientific and reasonable management measures to ensure the healthy and sustainable development of Cotinus coggygria forest has become a serious scientific issue. Our research was based on the investigation of Cotinus coggygria forest, using Principal Component Analysis, Descriminant Analysis and Factor Analysis to evaluate the forest stands quality of Cotinus coggygria scenic forest, the health degree of individual tree of Cotinus coggygria and the health condition of Cotinus coggygria forest stand, respectively. And the study was carried out to provide a theoretical foundation for scientific management of Cotinus coggygria scenic forest. The results are as follows:(1) The species composition of Cotinus coggygria forest was very simple and the forest stand was too dense, and clustered Cotinus coggygria trees were in large quantity. The forest with a density of> 1750 plants/ha took up 45% while the forest with a density of>3000 plants/ha accounted for 55%.(2) The soil of Cotinus coggygria forest was barren and poor, because 19.5% of the soil layer thickness in our investigation was less than 15 cm, and their nutrient contents were lower than the other soil types in mountain district of Beijing. Also, slope position, slope aspect and slope degree had a significant influence on the soil physical and chemical properties.(3) In the light of results of comprehensive evaluation on Cotinus coggygria forest land quality, the forest land quality were divided into 3 levels, in which the first and the second level took up 24.4% and 31.7%, respectively, and the third level was of the worst quality.(4) The slope position, slope aspect, slope degree and soil layer thickness had a significant effect on growth of Cotinus coggygria trees. The trees on moderate slope position exhibited good growth status, and the growth of trees on sunny slope and half-sunny slope were better than those on shaded slope, moreover, trees living on steep slope and very thin soil were in poor growth condition.(5) The health prediction model of individual tree of Cotinus coggygria was appropriate for health prediction because the accuracy was up to 90%. In this research, the general health of Cotinus coggygria forest was very poor, and the percentage of health of Cotinus coggygria trees in the third level or even more lower levels reached 67.32%.(6) Health degree and tree size had significant effects on root structure of Cotinus coggygria trees. As health degree dropping down and trees becoming aging, the root developmental capacity of Cotinus coggygria trees gradually became weakening, and health trees in small size had the most dynamic root developmental capacity, nevertheless, the capacity of unhealthy trees in large size were the weakest.(7) On the whole, the investigated Cotinus coggygria forest were in poor health condition, and the number of forest plots in the third health level and more lower levels achieved the percentage of 82.93% of all the study area.