Effects of human disturbances on Korean pine coverage and age structure at a landscape scale in Northeast China

Korean pine ( Pinus koraiensis) is an important species of forests in Northeast China and the Russian Far East. In recent years, human disturbances have increasingly threatened the long-term population sustainability of Korean pine in Northeast China. Though the Chinese government has implemented various programs to restore and protect Korean pine, results have not been satisfactory. Economic income often conflicts with ecosystem function, so figuring out ways to balance ecologic and economic values is important for Korean pine sustainability and management. The effects of humans on Korean pine forest are complex and interact in ways that are difficult to predict at the landscape scale. In this paper, we used a simulation approach to examine multiple intensities of timber harvest and seed harvest on landscape-scale Korean pine coverage and age structure. We found that the influences of seed harvest became increasingly important over the simulation period. Seed harvest noticeably influenced the percent coverage of young (<60. yr) Korean pine. Young age classes of Korean pine disappeared when seed harvest intensity was high, even with a low timber harvest intensity. Except during high timber harvest intensities, Korean pine maintained its coverage and age structure to a certain extent under a medium seed harvest level. When seed harvest was prohibited, Korean pine coverage remained steady compared to initial conditions, regardless of the timber harvest intensity. Percent coverage of young and middle age (60-120. yr) Korean pine increased late in the simulation period. Our study showed that some level of seed harvest intensity combined with medium and low timber harvest intensities may be optimal for managers to maintain a viable economy together with ecosystem sustainability.