| Forest spatial structure is an important feature of forest architecture,and there is a strong correlation with the realization of forest multifunctional.The scientific rationality of forest spatial structure is the core content of cultivating healthy and stable forest.At present,the planning and adjustment of forest spatial structure is a hotspot in the study of forest structures.In this study,the mixed forest of Jiangle County fir(Cunninghamia lanceolata)in Fujian province was studied,and the location information and basic properties of all living wood in 28 sample land were investigated and recorded.The spatial structure index of four kinds of spatial structure(mixing degree,angular scale,chest diameter size ratio and density)of Chinese fir Pure forest and mixed forest was analyzed.The spatial structure Evaluation index is constructed by multiplication and division method and 5 structural grades are divided,and the spatial structure characteristics of each sample land are evaluated.The Rings of all trees(368 in total)were randomly selected from 28 samples,and the average diameter growth of nearly 5 years was measured by 2 pieces(4 pieces)of each tree in the sample site of Chinese fir.The analysis of the average growth of thoracic diameter was influenced by spatial structure.The results show that the growth of fir diameter in mixed forest is significantly higher than that of pure forest.In order to improve the state of forest spatial structure and increase the growth of tree diameter,the spatial structure of forest is optimized by simulating and adjusting the mixing degree,and the thinning and replanting schemes are provided.The main conclusions are as follows:(1)Calculate the Spatial structure Evaluation index of each measured sample,it is found that most of the spatial structure of the ground space is rated as L1(very poor),L2(poor),and a few samples are L3(medium)grade.It shows that the spatial structure of pure forest and mixed forest of Chinese fir needs to be adjusted in time.(2)to analyze the relationship between spatial structure index and chest diameter growth,it is found that the average growth of diameter of Chinese fir in mixed forest is significantly larger than that of pure forest of fir.With the increase of mixing degree,the diameter growth of fir and Pinus massoniana increased,and the growth of Chinese fir was more obvious than that of Pinus massoniana.In mixed forest,the trend of Chinese fir changing with angular scale is more obvious.In the pure forest of Chinese fir,the trend of fir changing with the change of mixing degree is weaker,and there is no obvious in mixed forest.The average growth of the diameter of Chinese fir in the mixed forest was better than the average growth of the diameter of fir in the pure forest of fir,and the larger the average growth of the diameter of fir,with the greater the mixing degree of single wood.(3)in different age groups,5 pieces of space structure are randomly selected to L1 the pure forest samples of fir,and the spatial structures are simulated and optimized.Through the adjustment of the mixing degree of the sample,the evaluation index of the forest spatial structure rose from L1 to L3,which had 1 pieces,and there were 2 samples from L1 to L4,and 2 pieces from L1 to L5.The results show that the adjustment of mixing degree can significantly improve the spatial structure condition... |
PDF Full Text Request