Resource information
Monoculture plantations with rapidly growing trees are often used for reforestation schemes on abandoned land. There is evidence that in some cases, reforestation facilitates forest succession toward natural species composition. However, the success of a scheme varies according to site conditions, and systematic investigations are required for adaptive management. Monoculture plantations were used to reforest abandoned pastures at the study site in Hokkaido, northern Japan. At the study site—a 40-year-old nonnative larch (Larix kaempferi) plantation—the effects of thinning and deer-browsing exclusion treatments on the demography of understory saplings were analyzed to achieve appropriate management planning for reforestation. After deer-browsing exclusion, saplings of various species became established, and species composition corresponded closely to that of a natural conifer–broadleaved mixed stand. Saplings of shade-tolerant species, such as Abies sachalinensis and Acer mono, were abundant. Thinning influenced the demography of saplings over an 8-year period and significantly affected the height growth rate of A. sachalinensis saplings, which show strong variations in response to varying light conditions. There were also negative effects of thinning, such as increased mortality and decreased height growth rate of broadleaved saplings, the growth of which was suppressed by facilitated growth of A. sachalinensis. Thus, treatments used for reforestation must take into account differences in demographic traits of tree species by including long-term monitoring.
