Estimation Of Forest Biomass And Carbon Storage In Maoershan State Forest Farm And Analysis On Their Temporal And Spatial Change

Forest biomass and carbon storage, the most basic quantitative characteristics of forest ecological system and the base of the material and energy cycle, have always been an important part of the forest resources monitoring and forestry researches to achieve sustainable development and utilization of forest ecological system. Based on the forest resources investigation data of Maoershan forest farm in Heilongjiang province in 1983,1993 and 2004, stand biomass equations including biomass expansion factor(BEF) were used to estimate the forest biomass of the study area in the three periods; Paired-sample T test was carried out on the stand average biomass of subcompartments and average biomass of fixed plots in 2004, to verify the applicability of stand biomass equations including biomass expansion factor in the study area; the paper took the rate of a particular tree species in tree species composition as the weight factor of the carbon content rate for the species to obtain the average forest carbon content rate of each subcompartment, and then estimated forest carbon storage based on the biomass; According to the different forest types and age groups, the temporal dynamic change of forest biomass and carbon storage of the past 20 years was statistically analyzed and spatial distribution change was mapped by using GIS spatial analysis technology, the results showed that:(1) Based on the result of paired-sample T test, P> 0.05, the original assumption can’t be overturned, which showing that there is no significant difference between the two kinds of biomass estimation methods, and that the method of stand biomass equations including biomass expansion factor based on the forest resources investigation data was reasonable in the study area.(2) Form the temporal dynamic change of the biomass, carbon storage and carbon density, the total biomass and carbon storage of the study area in 1983 respectively were 2133566.17t,938769.2t, but in 1993 the total biomass decreased to 1995473.61t, the total carbon storage to 878008.2t. In 2004 the total biomass was 2719287.58t, and the total carbon storage was 1196487t. The trend of dynamic change of carbon storage was consistent with of that of biomass, decreasing first and then increasing. The total average carbon density reduced from 43.75996 t/hm2 to 40.72583 t/hm2, and then increased to 52.48487 t/hm2; There were great differences between forest biomass of different forest types, so as the carbon storage. The contribution rate of hardwood and softwood biomass and carbon storage was much higher than other forest types, playing a leading role in the total biomass and carbon storage in the three period. The biomass and carbon storage of middle-age forest have been the largest proportion of all age groups. The trend of biomass, carbon storage of different age groups was different, nearly mature forest and mature forest first decreasing and then increasing, mature forest and over mature forest increasing first and then decreasing, the young forest reducing all the time, because of trees natural growth to naturally promotion of the age group.(3) From the point of the spatial distribution change of biomass per unit area, carbon density, biomass per unit area of the most area of Maoershan in 1983 was 80-120t/hm2, the carbon density in the 30-45t/hm2. Biomass per unit area and carbon density decreased in 1993, due to deforestation and other causes. Biomass per unit area was generally 120-160t/hm2, and carbon density generally reached to 45-60t/hm2, forest biomass per unit area reaching 160t/hm2, and the carbon density more than 60t/hm2 in the northwest part of the study area with high quality forest; Hardwood and softwood forest was widely distributed in the entire study area, and coniferous forest was mainly distributed in the study area in south area. The distribution of biomass per unit and carbon density of different forest types was uneven in different three periods and the difference is bigger; In 1983, young forest and middle-aged forest mainly distributed in the western region, near mature forest and mature forest in the East. To 1993, near mature forest and mature forest in the eastern region has been almost cleared, the biomass per unit area and carbon density greatly reduced. In 2004 the young forest area decreased, while biomass per unit area and carbon density of the other age groups increasing.