Biomass And Growth Process Of Pinus Pumila In Daxing’an Mountains, Inner Mongolia

As one of the coniferous species in colder North China, Pinus pumila is also a rare small shrub-like tree among pine trees, with high exploitation and utilization value on economy, ecology and other aspects. One purpose of this article was to study the growth of Pinus pumila on different sites. Stem analysis was adapted to survey the growth of Pinus pumila in the ridge and valley, including radial growth (diameter growth and ring width growth) and elongation. Based on the models of trees and the characteristics of the datas, several growth models were established. Then the optimal models were selected from them. What’s more, whorled branch method was also used to research stem elongation, and the results from stem analysis and whorled branch method were compared. So did ring width growth by stem analysis and ring bar analysis.To clarify the aboveground biomass and its allocation pattern of Pinus pumila trees, felled trees or standing trees were surveyed using the nested regression method. Independent component biomass models were established with the allometric growth model, and model compatibility was dealt afterwards. Through field survey and ring analysis, combined with compatible biomass models for single trees, the aboveground biomass and biomass increment of Pinus pumila drawf forest were estimated.Results showed that the average width of individual rings, mean annual increment and current annual increment of ring width calculated by stem analysis were 3.70%,4.88% and 3.70% higher than that by ring bar analysis, respectively. Whether in the valley or ridge, binomial model was the best model to simulate stem elongation. For the growth of stem diameter and stem length-diameter regression relationship, power model and binomial model were the best in the valley and ridge, separately. The growth rates of stem length, stem diameter and ring width were all larger in the ridge than in the valley, which was not only in relation to the growth characteristics of Pinus pumila itself, but also depended on the environment. Compatible biomass models for individual trees were all significant, with determination coefficient larger than 0.80. The aboveground biomass for drawf forest was 62.54t-hm-2, and the biomass of wood, stem bark, branch and needle were 33.98,5.04,14.90 and 8.63 t-hm-2, separately. The biomass increment was a little lower, only 3.5It hm-2 yr-1 in recent five years. Supposing the carbon content rate was 50%, the aboveground biomass for Pinus pumila drawf forest in north Daxing’an Mountains (including Inner Mongolia and Heilongjiang) was 11.05 million tons, its carbon storage was 5.51 million tons and carbon density was 31.19t hm-2. In the northern cold region, the biomass reached quite a high level.