Gap Dynamics In A Secondary Coniferous Forest Of Guandi Mountain

This thesis mainly studies the natural secondary coniferous forests in Guandi Mountain. First analyse the formation of gap, as well as the factor of characteristics by sample survey and mathematical statistics; then have a comparative study between the gap and the non-gap species on the diversity, the number, the diameter of the contacted surface between the tree and the ground,as well as the tree height; finally analyse the regular number of filled in gaps. The results are as follows:1,Among the 54 gaps investigated, the formation of gap is mainly by man-made cutting and main stems breaking. The number of the formation wood focuses on between 1 to 2 plants. The diameter and height of formation wood respectively focuse on 20cm ~ 40cm and 10m ~ 30m. The size of forest canopy gaps and expanded gaps are mainly concentrated in between 0m2 ~ 100m2, 50m2 ~ 100m2.2,The author is fitting forest canopy gaps and expanded gaps by Normal model, Lognormal model and weibull model, then comes the result that Lognormal model is the best according to the Model Fit.3,With species diversity of the gap and non-gap, the number of species at all levels and the comparative analysis of tree height and the diameter for main saplings,we can get as followings:The forest gap can increase communities species in Guandi Mountain. Judging from the density, the gap is still greater than the non-gap. The differences are significant of tree height and the diameter between the three kinds of stand-gaps and non-gap.4, The author also analyzes the relationship between the number of filled, the size of gap and the sensitivity of expanded gap. The results: There is a positive correlation between the number of filled and the both two. To the linear relations with the sensitivity of expanded gap, the positive correlation of North China larch is obvious, followed by oil pine and spruce forest the weakest.