Comparative Study on Structure and Special Pattern of Different Tsuga longibracteata Communities in Tianbaoyan National Nature Reserve

The community structure and spatial pattern of the Tsuga longibracteata pure forest, the forest of Tsuga longibrceata mixed with Rhododendron sp., the forest of Tsuga longibracteata mixed with Cryptomeria fortunei from Yong′an Tianbaoyan National Nature Reserve were studied by means of the Community Mathematics and Applied Statistics methods. The results showed that the number of individuals together with the share rate in the Tsuga longibracteata pure forest and the Tsug alongibracteata- Cryptomeria fortunei mixed forest were reduced continuously along with the DBH increase; while the number of individuals together with the share rate in the Tsuga longibracteata-Cryptomeria fortunei mixed forest changed with a doublepeak form, i.e., in up-down- up-down curve along with the increase of DBH scale. The heightscale distribution of the arbor tree layer in the three communities was similar. The share rate of the forest also changed with a doublepeak form, i.e., in up-down-up-down curve along with the increase of tree height, which reached to the largest value at IV height class. The share rate of Tsuga longibracteata pure forest changed in a doublepeak form, but it changed in a singlepeak form in the Tsuga longibracteata-Cryptomeria fortunei mixed forest and in the Tsuga longibracteata-Rhododendron sp. Mixed forest. The spatial distribution pattern of Tsuga longibracteata population in the pure forest under 10m×10m, 10m×20m and 10m×30m scales all showed the aggregated distribution pattern. But with the sampling scale increased, the Tsuga longibracteata population in the pure forest showed the scattered distribution pattern.