The international community has set ambitious targets for restoring degraded landscapes and forests at the global level following the increased recognition of the various roles of forests. However, the factors driving deforestation and forest degradation, such as population growth, economic development, and the increased global demand for raw materials, such as food, fiber and energy, have not been well addressed. Long-term planning and adaptive management at the landscape level are needed to receive various ecosystem services from restored forests. Activities to restore forest landscapes will succeed only when the factors driving deforestation and forest degradation are controlled. Thus, restoring forest landscapes should not be rushed.
We compared the leaf properties of four tree species (Japanese cedar, hinoki cypress, and two deciduous hardwood species) at sites in Tsukuba (a high nitrogen-deposition area) and Katsura (a low nitrogen-deposition area) in the Kanto district of Japan. Nitrogen concentration in fresh leaves of Japanese cedar did not differ between the two sites, whereas those for the other three species were higher at Tsukuba than at Katsura. Leaf mass per area of hinoki cypress and the two deciduous hardwood species was lower at Tsukuba than at Katsura, but the effects on leaf nitrogen content per area varied among tree species. The nitrogen resorption efficiency of Japanese cedar was lower at Tsukuba than at Katsura, but there was no clear difference in the other three species. The nitrogen isotope ratio in all species was higher at Tsukuba than at Katsura, but the carbon isotope ratio did not differ between the two sites. These results suggested that the effects of nitrogen deposition on leaf properties varied among tree species and that Japanese cedar at Tsukuba was in a more nitrogen-saturated condition than were the other three species.
After the Sapporo branch of the Forest Experiment Station (the present Hokkaido Research Center, Forestry and Forest Products Research Institute) was moved to Hitsujigaoka, Sapporo, the Hitsujigaoka Experimental Forest was developed. At almost the same time, meteorological observations were initiated mainly for nursery management. These observations may not be sufficiently accurate; however, longterm observations at the wide green area are valuable, considering there are not many observation sites with no influence of the urbanization. In this article, we report observation results for 1973–2013. Mean air temperature, vapor pressure, and annual maximum snow depth were 7.5 °C, 9.6 hPa, and 98 cm, respectively. The mean annual precipitation was 952 mm; however, it was likely that the observations were underestimated, mainly in winter. Wind velocity had declined with the growth of the planted trees around the field.