The Japan Verified Emission Reduction (J-VER) Scheme began in 2008 and includes three forest-management-related projects. Various projects have recently started, primarily involving prefectural governments, municipal offices, and private enterprises; the projected area is generally large. However, the size of typical farm forests in Japan is generally small. The objective of this paper is to determine the current problems in carbon offsetting programs related to the organization of forest owners' cooperatives at the prefectural level. This investigation was conducted in Hyogo and Osaka prefectures. The following problems were identified. First, it is difficult to plan and conduct carbon-offsetting projects with forest owners' cooperatives alone due to the need to sell credits. An offset provider or prefectural trading scheme is also necessary. Second, because the J-VER Scheme is connected to the Kyoto Protocol, uncertainty after the first commitment period would influence further expansion of projects before 2012. Uncertainty in the future calculation method for the carbon sink and in the carbon price will also affect projects. Third, forests that are suitable for projects under the J-VER Scheme are limited because a forest-practice plan under the Forest Act or forest certification is needed as a precondition. To increase the forests that satisfy this criterion, forests that are owned by multiple small-scale owners must be gathered. For these reasons, the rapid adoption of forest-management projects among local forest owners' cooperatives will be limited. Through expansion of various carbon-offsetting projects, an increase in forests with forest-practice plans is expected.

Fruit set of Litsea cubeba, a range-expanding dioecious small tree species, was measured for females with different population densities in Tottori prefecture. The ratio of mature fruits to flowers of females in low density site was significantly lower than in high density site. Distance to the nearest male tree was significantly longer for females in low density site than in high density site, while stem diameter, growth rate of stem diameter and relative growth rate of stem diameter were not significantly different between females in low and high density sites. These results suggested the density-dependent fruit set and pollen limitation in a lower density population of Litsea cubeba.

Evergreen arboreal Quercus glauca and shrubby Eurya japonica are the common species in secondary forest in warm temperate broad-leaved forest in Japan. To clarify the effect of light condition on water transport properties in these species, we studied xylem transport property, xylem structure, leaf mass and diurnal course of gas exchange for saplings grown under contrasting light conditions: full, 10 and 3% sunlight. For Q. glauca, not large diameter but double number of vessel was found under full sunlight condition while xylem hydraulic conductivity (K_s) was not different between full sunlight and shaded condition. Total leaf area per a plant tended to be smaller and leaf specific hydraulic conductivity (LSC) tended to be larger in full sunlight than in shading. Daytime depression in stomatal conductance (g_s) was observed in Q. glauca under full sunlight, contributing the avoidance of daily drought stress. For E. japonica, vessel diameter, vessel density and K_s were restricted under full sunlight while total leaf area was smaller, leading higher LSC. Less depression in g_s was observed at daytime under full sunlight for this species. Results reveals that Q. glauca under high irradiance maintain leaf water supply without remarkable restriction of leaf biomass by both xylem structure and diurnal stomatal regulation, whereas, E. japonica adjusted to full sunlight by limiting leaf biomass rather by acclimating xylem structure to retain leaf water supply.