| In order to understand the stand structure of Larix gmelinii var.principis-rupprechtii,reveal the law of dynamic change in quantity,and to study the Larix gmelinii var.principis-rupprechtii in Guandi mountain,then lay 10 30 m x 30 m standard slots in Woniuping and Badaogou,check the trees in the standard area to reach the diameter scale,and analyze the spatial analysis of the spatial lys ingress ational parameters of the forest fractional scale,size ratio,mixed correlation,point pattern function and reveal the spatial;At the same time,Weibull function,normal distribution,negative exponential function and finite mixed Weibull function were used to study the diameter distribution law of Larix gmelinii var.principis-rupprechtii natural forest composed of different species in the standard ground,and the test parameters were used to test.The main research results of this paper are as follows:(1)the growth trend of Larix gmelinii var.principis-rupprechtii is in the middle.Among them,the distribution of pure forest samples was more random,followed by the cluster distribution,and there was no uniform distribution.Among the trees in mixed forest,there was interval competition,but the larch of north China did not show an absolute leading position in the competition,but the stand space structure did not reach a reasonable state.(2)in the pure forest,the spatial pattern correlation of Larix gmelinii var.principis-rupprechtii in different scales showed no obvious rule,but more positive correlation and random distribution,indicating that the north China larch in this stand occupied an absolute advantage and formed a stable top-level community structure.(3)the correlation between Larix gmelinii var.principis-rupprechtii and other tree species in mixed forests has an obvious rule: at the scale of 0-3m,north China larch and other tree species are mostly unrelated and randomly distributed.When the scale is larger than 3m,the correlation is mostly positive.As the proportion of larch in stand increased,the correlation became weaker and weaker.(4)the 1-6 plots were pure forests of Larix gmelinii var.principis-rupprechtii,and the 1,2and 4 plots presented a normal distribution,indicating that the stand diameter structure was relatively simple,and the three-parameter Weibull model had a good fitting effect.The no.3,no.5and no.6 plots showed asymmetric single peak or multi-peak curves,and were secondary heterophyletic forests.The 8-10 sample plot is mixed forest,and the 8 sample plot is an approximate bimodal curve.The fitting effect of the finite mixed Weibull distribution model is good.Samples no.9 and no.10 presented an inverse j-shaped curve with a relatively complex diameter structure,which was consistent with the law of mixed-age forests.The negative exponential model presented a better effect. |
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