Difference Study On The Relationship Between The Radial Growth Of Larix Principis-rupprechtii And Meteorological Factors At Different Altitudes And Slopes In Guandishan

Larix principis-rupprechtii is one of the main tree species for forestation and afforesting barren hills in North China in recent decades.Study on the response model and mechanism of tree radial growth and regional climate in different slopes and altitudes which is contribute to reveal the internal mechanism of tree radial growth change caused by the difference of site factors.To collect standard wood cores,we selected 4 different altitudes and 2 different slopes to set up Larix principis-rupprechtii plantation sample plots in the Xiaowen Forest Farm of Guandishan Forest Region and Pangquangou National Nature Reserve.We used the dendroecological method to got two radial growth indexes names Basal area increment and Ring width index,and then we used the Redundancy analysis to know the relationship between the Basal area increment and annual average temperature,precipitation and Palmer Drought Severity Index,and used the correlation analysis to konw the relationships between Ring width index and monthly average temperature,precipitation and Palmer Drought Severity Index.Through the analysis,we got the following main conclusions:(1)In the different altitudes and slope directions of Larix principis-rupprechtii plantation plots in this study,the response of the Basal area increment of sample trees to the drought stress was obvious.By studying the Basal area increment of Larix principis-rupprechtii and its rising rate in different site conditions,we concluded that the growth of Larix principis-rupprechtii is more suitable in sunny slope than in shady slope.(2)On the sunny slope of Guandishan forest region,the climate information of sample trees at low altitude is more abundant than that at high altitude,and the sensitivity of tree Ring width index to the response of meteorological factors is higher than that of high altitude.On sunny slope,the altitude of 2200 m is the critical altitude for the change of response mechanism of radial growth of sample trees to precipitation and Palmer Drought Severity Index.By establishing the multiple regression model of tree ring width index and meteorological factors,it can be concluded that temperature plays a leading role in the radial growth of Larix principis-rupprechtii on the sunny slope.(3)On the shady slope of Guandishan forest region,the climate information of sample trees at high altitude is more abundant than that at low altitude,and the sensitivity of tree Ring width index to the response of meteorological factors is higher than that of low altitude.On shady slope,The altitude of 2000 m,is the critical altitude for the transformation of the coupling effect of temperature and precipitation on the radial growth of Larix principis-rupprechtii.The multiple regression model of tree ring width index and meteorological factors of four altitudinal gradients in shady slope has correspond well with the previous correlation analysis.which shows that these models can accurately guide the management of local Larix principis-rupprechtii plantation.(4)In the process of slope changing from shady slope to sunny slope,the change of site factors lead to the threshold altitude of the correlation transformation between Ring width index and precipitation of Larix principis-rupprechtii in shady become 2,000 meters and the sunny slope rises to 2,200 meters.In addition to the threshold altitude,the response of ring width index to precipitation and Palmer Drought Severity Index was synchronism.The sensitivity of the radial growth of trees to the response of meteorological factors is reversed in vertical zonality due to the difference of slope direction.On the whole,the sensitivity of radial growth of trees on sunny slope to climate is better than that on shady slope.