Comparison On Vegetation Diversity And Biomass Of Cunninghamia Lanceolata And Pinus Massoniana Plantation Under Natural Thinning

By investigating Cunninghamia lanceolata and Pinus massoniana plantation growing in Experimental Center of Tropical Forestry, this paper analyzes their vegetation diversity and biomass, in addition to the growing pattern. The results are shown as below.(1) The composition of family, genus and species shows no significant difference. In Cunninghamia lanceolata plantation, there are 39 families,52 genus and 63 species, while there are 33 families,53 genus and 68 species in Pinus massoniana plantation. Species in arboreous layer are the least in both plantation with only 8 species, respectively. Species of herbaceous layer in Cunninghamia lanceolata plantation,25 species, are more than Pinus massoniana plantation,15 species. For both plantation, species of shrub layer are the most, with 46 species in Cunninghamia lanceolata plantation and 37 species in Pinus massoniana plantation.(2) Under natural thinning, species richness of herbaceous layer of the two plantation are significantly different, with 18 species in Cunninghamia lanceolata plantation and 10 species in Pinus massoniana plantation. SP and SW index of Cunninghamia lanceolata plantation are significantly higher than that of Pinus massoniana plantation. In addition, evenness index, Pielou, shows that the evenness in arboreous and shrub layer of Cunninghamia lanceolata plantation are higher than Pinus massoniana plantation, while it's similar in herbaceous layer.(3) The result shows that there is significant difference for the biomass, with the value are 261.38t/hm2 and 239.53t/hm2 in Cunninghamia lanceolata plantation and Pinus massoniana plantation, respectively. Biomass distribution in tree organs are different as well. For Cunninghamia lanceolata, tree trunk has the highest biomass, followed by root, while for Pinus massoniana, the highest is also tree trunk, but followed by tree branch. Except for root, the biomass in tree organs of Cunninghamia lanceolata are lower than that of Pinus massoniana.(4) The number of natural regenerated trees in arboreous layer of Cunninghamia lanceolata plantation is 61 trees/hm2, while that of Pinus massoniana plantation is 100 trees/hm2. However, the average diameter at breast height and average height of tree of Pinus massoniana plantation are smaller than that of Cunninghamia lanceolata plantation. What's more, the biomass of natural regenerated trees in arboreous layer of Cunninghamia lanceolata plantation is higher than that of Pinus massoniana plantation on the whole.(5) As for the biomass in each layer of under-tree, there are also differences. In Cunninghamia lanceolata plantation, the total biomass is 34.65t/hm2, with litter layer being the highest and followed by herbaceous layer. The total biomass of these two layer is 99.2% of the total biomass of the whole. In Pinus massoniana plantation, the total biomass is 5.58t/hm2, with litter layer being the highest and followed by shrub layer and herbaceous layer.(6) After the process of natural thinning, average diameter at breast height of Cunninghamia lanceolata plantation isl7.8cm,the same as Pinus massoniana plantation,but preservation rate and average height is significantly higher than that of pinus massoniana plantation. Preservation rate of Cunninghamia lanceolata plantation is 62.7% and preservation rate of Pinus massoniana plantation is only 34.7%.Analyzing the stand diameter order different growth indicators,the degree of dispersion of diameter at breast height is greatly different, with that of Cunninghamia lanceolata plantation is rather wide, while that of Pinus massoniana plantation concentrates between 14cm-26cm. The changing trend of biomass is similar to stand volume. For both plantations, the highest biomass are mainly those trees of 16cm,20cm and 24cm, which occupies 86% and 92% of the total biomass of both plantation. The percentage of stand volume are the same.