| As a long time on deforestation and the enormous pressure of population growth, we have no time to wait for a new management system to maintain the ecosystem value we expected. In the absence of a long concrete examples of the results of the case, the emergence and applications of the models provided us some possibilities for the response of the ecosystems to disturbances. In this paper we usedFORECAST model to simulate the impacts of different rotations for the carbon storage of Chinese fir and spruce to provide some basic data for further study in China and the global carbon cycle of forest ecosystems,as well as to help forest managers to develop reasonable management strategies. Our results support that the shorter rotation (≤25 year) has the higher carbon storage, but carbon sequestration capacity is lower and soil organic carbon seems to decline. If the rotation length is too long(>50 year) ,it may cause lower carbon storage and in rich site its carbon sequestration capacity has the downward trend. It will get the most stem biomass but do not maintain the sustainable develop of soil organic carbon when the rotation is 25 year. When the rotation is 50 year, it can maintain the sustainability of the ecosystem carbon storage. So we considered that longer rotation (25 year~50 year) is relatively reasonable to keep the sustainable production in Chinese fir plantation based on the results. Results about spruce suggest that the accumulation of stem carbon and total tree carbon get to themaxium when the rotation length is 80 years,but it will consume more soil fertility.In the case of forest clear-cutting,no matter which rotation we choose,the soil carbon storage showed a downward trend,but with the rotation of the extension (not more than 160 years), the reducing proportion declines. When rotation is not more than 160 years, the average annual amount of carbon sequestration increased as the rotation length gets longer. And a better site for carbon storage and carbon sequestration is higher than worse ones. Therefore, from the perspective of rotation and site, maintaining long-term site productivity should choose a longer rotation periods (120-160 years) and better site. From the perspective of the harvesting styles, the extensive harvesting more conducive to the accumulation of carbon stocks and carbon fixation is higher than that intensive harvesting. At present, the forest economy changes to intensive economic ,and no doubt extending the rotation length can reduce the gap between the two harvesting styles, and can reduce the loss site.The simulation results of two stands are very similar. From the economic, the mid-level rotation length is conducive to the greatest economic benefit, but will consume the most serious soil fertility, it also highlights the contradiction between the economic benefits and ecological benefits. Selecting a longer rotation period can be reflected the concept of forest sustainable development, and longer rotation has higher carbon sequestration capacity, and has a certain contribution in the global problem of climate change. |
