Effects Of Different Slope Positions On Spatial Structure And Competition Of Cotinus Coggygria

Cotinus coggyria,belonged to Cotinus,Anacardiaceaeis,has been widely planted in Europe and the eastern and northwestern parts of China,which is an important ornamental red leaf species.The studies about the specie obsess a great scientific research value,such as the studying on effects of site conditions,spatial structure and intensity of competition on the morphological characteristics of Cotinus coggyria,which is of vital for the cultivation of artificial forests in northern China.With the Cotinus coggyria in the Red Leaf Valley of Beijing as the respondent,this study was conducted to compare the effects of different slope positions on trunk shape,crown shape,crown shape,important value,stand density,crowding degree,mixed degree,aggregation index and competition intensity of Cotinus coggyria and then analyse the relationship between spatial structure and competition with the individual morphological traits of Cotinus coggyria,aiming at providing an important reference value for the seed selection of Cotinus coggyria in Red Leaf Valley in Beijing.The primary conclusions listed as follows:(1)The individual morphology of Cotinus coggyria at different slope positions:The height of tree diameter,crown and trunk structure were affected by different slope positions significantly,while the crown width,important value and dominance degree were not altered significantly by it.More specifically,the tree height,diameter at breast height,height-to-diameter ratio,important value and dominance were all ranked as valley>uphill>downhill>mountain ridge,while the crown width,crown diameter ratio,crown height ratio were all ranked as ridge>downhill>uphill>valley.The spatial structure of Cotinus coggyria at different slope positions:the mixed degree,density,aggregation index,and crowding degree of Cotinus coggyria were affected by different slope positions significantly.The mixed degree,aggregation index and crowding degree were all ranked as ridges>downhill>uphill>valley and the density was ranked as valley>downhill>uphill>ridge.The competition index of Cotinus coggyria at different slope positions:the competition index of Cotinus coggyria was affected by different slope positions significantly.Stand competition index,canopy competition index and Lorimer competition index were ranked as ridges>downhill>uphill>valley.(2)The individual morphology of Cotinus coggyria in different spatial structure:The mixed degree had a significant negatively correlation with the trunk morphology and aspect ratio,a significant positively correlation with the crown width,crown diameter ratio and a quiet positively correlation with crown height ratio.The aggregation index of Cotinus coggyria in forest had a significant negatively correlation with the height-diameter ratio.Cotinus coggyria had a positive correlation with the trunk shape,crown width,crown diameter ratio and crown height ratio,and only the height of tree was not affected significantly.When the aggregation index R was above 0.15,the exponential growth of DBH and crown width were the most significantly.The density of forest had a significantly positive correlation with the height-diameter ratio,a negative correlation with the trunk morphology,crown width,crown diameter ratio and crown height ratio and a significant influence on DBH,crown width,and crown diameter ratio,as well as a significant effect on crown height ratio.When the forest density was above 300 plants/hm2,the diameter of DBH was decreased most significantly.The crowding degree of forest had a significant positive correlation with the height of tree,DBH,and height-to-diameter ratios,a significant negatively correlation with crown width,crown diameter ratio and crown height ratio.While the crown width and crown diameter ratio were affected by it significantly.When the stand density k was under 1,the crown width decreased faster than any others,when k was between 1 and 3,the crown diameter ratio was declined at the fastest rate.(3)The indexes of Hegyi competition,crown competition and Lorimer competition of Cotinus coggyria were negatively correlated with the trunk shape,crown shape and crown shape.The individual morphological traits of Cotinus coggyria were all affected by Lorimer competition index significantly.When the Lorimer competition index was above 1,the falling speed of tree height and crown width reached the maximum.When the Lorimer competition index was between 1 and 3,the aspect ratio was not altered.The DBH,ratio of height to diameter,ratio of coronary diameter,tree height,crown width and crown height ratio were all affected by Hegyi competition index significantly.When the Hegyi competition index was above 3,the falling speed of crown height ratio reached the maximum.In addition to crown-to-height ratio,other indicators were all affected by crown competition index significantly.When the crown competition index was above 4,the falling speed of diameter reached the maximum.when the crown competition index was between 4 and 12,the aspect ratio was not altered.