Natural Regeneration Characteristics And Influencing Factors Of Larix And Quercus In Yaoxiang Forest Farm Of Shandong Province

Forest resources provide humanity with the necessary material foundation and are an important guarantee for the development of human society.With the continuous progress of social development,forest resources are becoming increasingly scarce.The shortage of forest resources has led to an increasing number of environmental problems,and improving the intensity of forest resources is crucial.Natural forest regeneration is an important way to improve the comprehensive intensity of forest resources.In order to investigate the characteristics and influencing factors of natural regeneration of Larix and Quercus forests in Shandong Province,two long-term observation plots with an area of 80m×80m and100m×100m were established according to the topography in this study,taking Yaxiang Forest in Shandong Province,where larch and sagebrush forests are widely distributed,as the study site.Firstly,the stand structure characteristics of larch and sesquicentennial oak forests were analyzed;Secondly,g(r)function was used to analyze the spatial distribution characteristics of trees with different life histories and the intra-species distribution relationship,and g12(r)function was used to analyze the association between trees of different diameter classes of each species.Finally,the dominant factors among the stand factors and other influencing factors were selected by random forest method,and on this basis,Pearson correlation analysis was used to investigate the influence of each factor on the regeneration of larch and Quercus robur forests in Yaxiang Forestry.The main results are as follows:(1)A total of 677 trees were surveyed in the larch forest of Medicine Township Forestry.The main species were larch and Diospyros lotus L..The diameter level structure of the larch forest is normally distributed.It was found that there was no larch regeneration under the larch forest,and there was a large number of natural regeneration of junipers.The distribution of Diospyros lotus L.is inverted "J" type,and the diameter distribution is continuous.A total of 1,083 trees were investigated in the Yaoxiang forest,and the main species was Quercus robur.The diameter distribution of Quercus robur is bimodal,with a large number of 2cm diameter and a large number of 24 cm diameter.(2)According to the results of g(r)function,the larch sample plot was aggregated and distributed at a small scale,and tended to be randomly distributed with the growth of small trees to large trees,and was aggregated and distributed at 14-16 m scale and then turned to be randomly distributed;the overall distribution of the larch sample plot was mainly randomly distributed.In the small scale of 0-3m,the distribution of hemp oak forest was aggregated with the increase of scale to random distribution,and the small trees were basically aggregated in the whole spatial scale.According to the results of the g12(r)function,there was basically no correlation or positive correlation between the life history stages of larch sample sites,and in general,large trees were positively correlated with young saplings and small trees at small scales,and medium trees and young saplings were positively correlated at the scales of 0-3m and 15-20 m.Small trees and seedlings were positively correlated on small scales,but not on the rest of the scales;there was basically no correlation between the life history stages in the hemp oak sample site,and overall there was a negative correlation trend between medium trees and small trees;small trees and medium trees were positively correlated on the 0-1 m scale.(3)The overall regeneration of both larch and Quercus robur forests in Yaxiang Forestry is moderate.The dominant factors in the evaluation of larch forest renewal are the growth condition and density of renewed trees,followed by the distribution pattern;the dominant factors in the evaluation of larch forest renewal are: the growth condition and density of renewed trees are the dominant factors affecting the renewal of larch forest,followed by the distribution pattern.(4)The random forest algorithm revealed that the average thickness of dead sediment(MES12.41%)and grass and scrub cover(MES7.53%)were the main factors influencing the regeneration of larch forest in Yaxiang Forestry;the degree of depression(MES14.65%)and grass and scrub richness(MES12.70%)were the main factors influencing the regeneration of hemlock forest in Yaxiang Forestry.In addition,according to Pearson correlation analysis,the sample site regeneration in the larch sample site was highly significantly and positively correlated with the thickness of dead wood(p<0.001)and negatively correlated with the cover of grass and scrub layer(p<0.01);in the sagebrush sample site,the sample site regeneration was highly significantly and positively correlated with the degree of depression(p<0.01)and with the abundance of grass and scrub layer,elevation,soil(p<0.05)and slope(p<0.05).