This study is design to define the roles of forest and to find the optimized management schemes if the value of carbon abatement is included in existing forest stands. Mitigation schemes to climate change by forest include reforestation, afforestation and efficient forest management to maximize carbon absorption. Many Annex I industrialized countries try to establish various policies for forest carbon abatement, which can be approved as permissions or credits of carbon emission from Kyoto Protocol. They prefer to focus on forest management rather than expensive reforestation or afforestation. These countries take forest management under Convention on Climate Change as forest management schemes. These efforts to get permissions or credits for carbon emission, however, do not consider the efficiency of forest management, which includes socioeconomic values. Each country needs to account carbon relevant to forest management as a whole, but schemes for each stands are required to enhance carbon absorption.
Therefore this study finds optimal forest management schemes. The rotation period is extended if the value of carbon absorption as well as the timber values are considered for the stands of pine trees and Korean pine trees. The current management method is also analyzed and compared with the optimal scheme. The result says that for the case of pine trees the rotation period is optimal with the current method. But the rotation period decreases and the function value(objective value) increases if the optimal scheme is applied. The reasons are that the late execution of the second thinning brings about slow progress of volume increment and extends rotation period. By the longer rotation period the present value from stands are discounted more seriously. To enhance the value of stands the current rotation should be shorten, and the thinning should be executed at a time.
For the case of Korean pine trees the current rotation period is too short, and it is not optimal even under current management method. Under the optimal management scheme, however, the rotation period becomes shorter than the current method. This happens because the current method includes four times of silvicultural treatments, and they last until 35 years after plantation. The costs for the treatments could not be recovered until after 100 years of plantation. Hence it is required to reduce the number as well as the age of the last application of silvicultural treatments.
The results of simulation says that the rotation period becomes shorter if the discount rate increases. And it becomes longer if the price of carbon dioxide increases.
It is well known that the rotation period lengthens if public values are added to the stands. It is also possible to find optimal management scheme, however, by adjusting the number and the age of silvicultural treatments. Consequently, it could not be an optimal method of forest management to apply long and flat rotation period even some public values are added, but it is required to adjust and apply various rotation period according to the treatment numbers and ages for each species.
The current effort to protect forest fire does not satisfy optimal conditions. The social value of forest increases if we put more efforts on fire protection. Consequently it is necessary to extend the efforts on fire protection by increasing the government budget.

Researchers: Sang-Min Lee; Kyeong-Duk Kim and Seong-Hwan Song
E-mail address: smlee@krei.re.kr