The Productivity Of Taiwania Flousiana Plantation

Taiwania flousiana, introduced and studied for years, has well-adapted ability, growing fast. It grew the same fast as Chinese fir provided with suitable condition. Its wood quality was good with less pests and diseases. It is an important extension species in high altitude area, and is adopted as the excellent renewed species on the cut over land of Chinese fir. It is important to study the productivity of T. flousiana so as to provide scientific data for the afforestation in southern China, and provide the fundamental data so as to protect and develop the rare germplasm T. flousiana.Biomas is used to measure the forest ecosystem function, indicating the change of forest structure and function. It is the foundation for the study of ecosystem carbon sink and carbon cycle, and irreplaceable for the study of carbon cycle and global climate change. In this study, the plantation biomass, productivity, and the contents of carbon and nitrogen of T. flousiana were analysed. The relationship between the age and tree height, DBH or volume were carried out, followed the scientific cultivation measures were set out, which promoted the forest quality.In this paper, the standard plot survey method, the stem analysis method, plot harvest and layered harvest method were used to study the biomass, productivity, the growth regularity, and the distribution pattern of carbon and nitrogen pool of T. flousiana in Dehua Gekeng National Forest Farm. The results were as the followings:1. The average biomass per individual was 202.56 kg in 20-year-old T. flousiana plantation. The aboveground biomass and underground biomass were 167.74 kg and 34.81 kg, accounting for 82.81% and 17.19% of individual total biomass, respectively. The order of biomass: stem >ground root > leaf > branch > thick root > fine root > moderate root. The total biomass of T. flousiana plantation was 177.75t·hm-2, among of which the total biomass of tree layer was 176.23t·hm-2, accounting for 99.14% of the total stand biomass; the proportion of the litter biomass was very small, 1.52 t·hm-2 only, accounting for 0.86%.2. The productivity of 20-year-old T. flousiana plantation was 11.87t·hm-2·a-1. The order of organ productivity: trunk > leaf > root > branch. From the view of the organ productivity distribution of T. flousiana, firstly the ration of the trunk productivity to total productivity was low; secondly, the total productivity proportion was higher than that of other species because of the large leaf differentiation. By analysis, it might be the T. flousiana was still in the fast-growing period, and did not reach the age of quantitative maturity.3. By the analysis of the growth process of T. flousiana that its maximum successive annual increment of DBH appeared on the 6th year, the maximum average growth increment appeared in 6th year also, and the intersecting time of the average growth increment and annual growth increment appeared in the 8th year; the maximum tree height growth increment appeared in the 5th year, the average growth increment appeared in the 6th year, there were four intersecting time of the average growth increment and the annual growth increment, and after 13 years old, the annual growth increment was less than the average growth increment; in the early stage, T. flousiana grew slowly in volume, after 11 years old it grew fast, but it did not reach the quantitative maturity plantation until 19 years old.4. The carbon accumulated amount per individual was 96.1kg in the fast-growing stage, and the nitrogen accumulated amount was 0.679 kg.The order of the carbon pool of different organs mainly: stem > ground root > leaf > branch > thick root > moderate root > fine root. The carbon pool in roots increased with the increase of root diameter. The order of the nitrogen pool of different organs mainly: stem > leaf > root > branch >thick root > fine root > moderate root. The total carbon and total nitrogen storage of 20-year-old T. flousiana plantation were 84.29 t·hm-2 and 0.6 t·hm-2, respectively. the tree layer carbon storage and nitrogen storage were much larger than that of the layer of vegetation, accounting for 99.19% of total stand carbon storage and 98.33% of total stand nitrogen storage, respectively. The carbon and nitrogen storage of tree layer overground were much larger than that of the underground, accounting for 83.23% the of total tree layer carbon storage and 88.14% of total tree layer nitrogen storage, and accounting for the total 82.56% of total stand carbon storage and 86.67% of total stand nitrogen storage, respectively, of which the carbon and nitrogen storage mainly concentrated in the trunk, providing 56.17 t·hm-2 and 0.33 t·hm-2, accounting for 80.72% and 63.46% of the tree layer, respectively.