Dynamics And Succession Of Pinus Yunnanensis Community Five Years After Fire In Central Yunnan

In order to provide a scientific base for successful management of Pinus yunnanensis forests after fire, we studied regeneration dynamics and succession of the plant communities in Tuanjie Zhen, cenral Yunnan. We established 20 plots (each plot area:20m x 20m) in Tuanjie Zhen, including five plots in the Pinus yunnanensis community after fire, fifteen plots in the unburned plant communities. Important values were used for similarity cluster analysis. Plant communities were delineated and possible correspondences between environmental factors (soil properties and the degrees of disturbance intensity) and plant communities were analyzed using canonical correspondence analysis (CCA). The results are below:1) We grouped twenty field plots into five plant Communities using floristic similarity cluster analysis. Each community is named after the dominant tree species. They are Pinus yunnanensis shrubland, Pinus yunnanensis community, Lithocarpus mairei-Pinus yunnanensis communtiy, Lithocarpus dealbatus-Castanopsis orthacantha community, and Castanopsis orthacantha community.2) The frequency distribution of P. yunnanensis in the P. yunnanensis shrubland and P. yunnanensis community was in an inverse-J type (good in regeneration). In the L. mairei-P. yunnanensis community, the L. mairei population was in an inverse-J type, P. yunnanensis population was in an unimodal type (poor in regeneration). In L. dealbatus-C. orthacantha community, L. dealbatus and C. orthacantha populations were in a sporadic type (unstable in regeneration). In C. orthacantha community, C. orthacantha population was in an inverse-J type (good in regeneration).3) The saplings and seedlings of P. yunnanensis were found in the P. yunnanensis shrubland and the P. yunnanensis community, but not in the other three plant communities.4) On the basis of CCA ordination analysis, the available P (AP) of soil and the degrees of disturbance intensity (DIST) strongly correlated with the P. yunnanensis shrubland. Total P (TP) showed a positive correction with the P. yunnanensis community. The total N (TN) showed a positive correction with the C. orthacantha community. 5) We used space-for-time substitution to obtain an understanding of the directions and pathways of the succession of the P. yunnanensis communities five years after fire. The approximate successional trends were from P. yunnanensis shrubland to P. yunnanensis community, then to L. mairei-P. yunnanensis community, and finally to L. dealbatus-C. orthacantha community or C.orthacantha community.6) Species richness and species diversity of the P. yunnanensis'community and L. mairei-P. yunnanensis community in the middle successional stage had higher values than the P. yunnanensis shrubland in the early successional stage and the C. orthacantha community, L. dealbatus-C. orthacantha community late successional stage.