| Larix Principis-rupprechtii Mayr is the main tree species in the Liupanshan area,accounting for more than 90% of the area.In the context of global warming,it is important to explore the effects of climate and competition on L.principis-rupprechtii growth for the sustainable management of local plantations.Therefore,this study focuses on the subject of L.Principis-rupprechtii,combining dendrology method method and annual radial growth data and competition theory,trying to clarify influence a single influence factors on radial growth of trees,by the method of multi-factor model coupled radial growth of L.pricipis-rupprechtii model is set up,will provide a scientific basis for sustainable management of L.Principis-rupprechtii of Liupanshan area.The main results are as follows:(1)The increment of basal area of L.pricipis-rupprechtii with different competition grades had a certain difference,and the difference increased with the increase of tree age.In the region,the annual precipitation can promote the radial growth of trees,but when it exceeds 820 mm,the year increment tends to decline.The relationship between mean annual air temperature and annual tree growth is similar to annual precipitation.When the mean annual temperature was 6.7℃,the annual growth of L.pricipis-rupprechtii trees reached the maximum and the temperature continued to rise,but the annual growth of L.pricipis-rupprechtii trees decreased due to drought stress.Radial growth is also associated with competition,which significantly inhibits radial growth of trees.Finally,a multi-factor coupling annual growth model of L.pricipis-rupprechtii(BAI=(1.35E-5/(1+(Age/-5535243.76)~2))×(39205.68-139.97×P+0.075×P~2)×(-3371.4+1049.34×T-71.45×T~2)×(-0.15+0.41×HCL-0.33×HCL~2)).(2)The annual growth of trees showed a certain periodicity,which showed a periodicity of shrinkage during the day and expansion at night under sunny conditions.The change of trunk radius could be divided into three stages: contraction,recovery and growth.In cloudy days,the shrinkage of trunk radius was much lower than that in clear days,and there was a plateau period in which the trunk radius remained unchanged.Under rainy conditions,the radius of tree trunk continued to increase.The change of trunk radius in the growing season of 2021 can be divided into three periods,namely,the fast growing period from June 14 to July 18.Contractions affected by drought from May 1 to June 14 and from July 18 to August 16;Growth stability from August 16 to the end of the growing season.Similarly,the cumulative growth of trees subjected to low competitive stress was higher than that of trees subjected to high competitive stress.(3)According to the tree growth instrument data of L.Principis-rupprechtii,and through Pearson correlation analysis,the diurnal variation of tree radius was extremely significant positively correlated with precipitation and relative humidity,and extremely significant negatively correlated with solar radiation and vapor pressure deficit at the rapid growth stage.In the stable growth stage,the diurnal variation of tree radius was significant positively correlated with soil water content.Finally,through the multi-factor coupling method,established the radius of the trunk during the fast growth stage years growing season(DVTR=(5.71E-8-1.42E-9×H+8.65E-12×H~2)×(1.19-4.65×P+0.43×P~2)×(-22.33+92.86×VPD-64.96×VPD~2)×(-1351.89+16.27 × Sr-0.047 × Sr ~2)×(0.14-0.37 × HCL+0.43 × HCL ~2))and stable growth stage(DVTR=(18287.72-424.89×H+2.4×H~2)×(-0.046+0.062×P-1.37E-3×P~2)×(-1.81+8.46×VPD-8.6×VPD~2)×(-988.09+42.99×Sr-0.33×Sr~2)×(-62.76+477.55×Sw-904.7×Sw~2)×(-1.41E-5+2.04E-5×HCL-1.49E-5×HCL~2))of the radial growth model.In this study,the effects of competition and environmental factors on radial growth of L.pricipisrupprechtii at different time scales were analyzed,and finally,radial growth models of L.pricipis-rupprechtii at different time scales were established by multi-factor coupling method.The results of this study contribute to a deeper understanding of the impact of climate change on forest growth dynamics and are of great significance for the sustainable management of local plantation forests. |
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