Deer population control is important in wildlife management, because overabundance of deer is a problem worldwide. For practical deer population control, deer population dynamics and the factors that influence them need to be evaluated in low‐cost and time‐efficient ways. However, in traditional methods of estimation, such as cohort analysis, large numbers of deer need to be caught for many years, and the ages of the deer must be determined. We estimated deer population dynamics by using a Bayesian state‐space model with multiple deer abundance indices (seen deer per unit effort, pellet group count, and block count) and numbers of deer hunted and culled in Yamanashi Prefecture, central Japan. In the state process of our state‐space model, latent deer abundance at year t in location m (Dt,m), with m being each cell of a grid mesh covering Yamanashi Prefecture, was assumed to decrease annually through hunting and culling, to increase with the population growth rate of each mesh (rm; which was determined from the percentages of forest, evergreen forest, and artificial grassland), and to fluctuate stochastically. In the observation process, Dt,m was assumed to be correlated with the deer abundance indices and a Gaussian white noise in the deer abundance indices. The estimated Dt,m was correlated with each deer abundance index, but the correlation coefficient was the greatest for pellet group density. The percentage of hunted and culled deer needed to reach 30% to reduce the annual growth rate (Dt,m/Dt−1,m). Increasing the percentage of artificial grassland increased rm. Our results showed that 1) deer abundance could be estimated by using only deer abundance indices in addition to population growth rate and the percentage of hunted and culled deer; and 2) preventing the intrusion of deer onto artificial grassland and intensive culling on artificial grassland were important to decrease deer abundance. © 2013 The Wildlife Society.

Abstract. Wildlife managers are often asking for reliable information of population density across larger spatial scales. In this study, we examined the spatiotemporal relationships between moose density as estimated by cohort analysis and the density indices (1) harvest density (HD; hunter kills per km 2 ), (2) moose seen per unit effort (SPUE), seen moose density (SMD; seen moose per km 2 ), and density of moosevehicle accidents (MVA density; e.g., traffic kills per km 2 ) in 16 areas in Norway with 13-42 years of data. HD showed a close positive relationship with moose density both within and between regions. However, the temporal variation in HD was best explained as a delayed reflection of moose density and tended to overestimate its growth and decline. Conversely, SMD and SPUE were unable to predict the spatial variation in moose density with high precision, though both indices were relatively precise temporal reflectors of moose density. However, the SPUE tended to underestimate population growth, probably because of a decrease in searching efficiency with increasing moose density. Compared to the other indices, MVA density performed poor as an index of moose density within regions, and not at all among regions, but may, because of its independent source of data, be used to cross-check population trends suggested by other indices. Our study shows that the temporal trends in moose density can be surveyed over large areas by the use of cheap indices based on data collected by hunters and local managers, and supports the general assumption that the number of moose killed per km 2 provides a precise and isometric index of the variation in moose density at the spatial scale of our study.

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The abundance of Picea jezoensis, a major conifer tree species in Hokkaido, northern Japan, is currently decreasing due to the lack of suitable conditions for recruitment and intensive harvests. To contribute to the development of sustainable forest management in Hokkaido, suitable substrates for natural regeneration of P. jezoensis were evaluated during a 4-year experimental study using seed additions in a natural coniferous forest. The environmental conditions (moss height, log hardness, extent of the humus layer, and light conditions) of fallen logs were measured. Moss height was categorized into three groups: 0 mm, Bark; 0 - 20 mm, Mthin; and ≥ 20 mm, Mthick. The germination rates of P. jezoensis were highest on Mthin, intermediate on Bark, and lowest on Mthick. Survival rates were low on Mthick, did not differ between Bark and Mthin, and increased with enhanced light. Growth increased with light, but the root allocation of seedlings was not affected by any environmental conditions. From these results, we determined that fallen logs with no or thin moss cover under bright conditions were most suitable for P. jezoensis regeneration. We discussed the generality of our results in relation to a co-occurring tree species in Hokkaido and the results of other regions

To evaluate the effects of intraspecific hybridization of local and nonlocal genotypes on growth traits of progeny in Abies sachalinensis, we performed reciprocal crossing between nonlocal trees in a high-elevation zone (1,100-1,200 m asl) and local trees in a low-elevation zone (530 m asl) in Hokkaido, northern Japan, in 1979 and established a common garden experiment using local × local (female × male), local × nonlocal, nonlocal × local, and nonlocal × nonlocal progeny in the low-elevation zone in 1986. Survival, height, diameter at breast height (dbh), needle nitrogen content, specific leaf area (SLA), and needle area per shoot diameter (NA) of 25-year-old progeny were measured in 2005. The survival rate was consistently high (>85% on average). Reductions in height and dbh were apparent in F1 hybrids compared with local × local progeny. Furthermore, outbreeding depression was significant in height growth of nonlocal × local F1 hybrids and in dbh of both F1 hybrids. Reductions in growth traits may be related to morphological needle traits, such as the low values of SLA and NA. Elevation guidelines for A. sachalinensis seed zones are discussed to ensure the long-term viability of both restored and native populations.

Carrying capacity is 1 driver of wildlife population dynamics. Although in previous studies carrying capacity was considered to be a fixed entity, it may differ among locations due to environmental variation. The factors underlying variability in carrying capacity, however, have rarely been examined. Here, we investigated spatial heterogeneity in the carrying capacity of Japanese sika deer ( Cervus nippon ) from 2005 to 2014 in Yamanashi Prefecture, central Japan (mesh with grid cells of 5.5×4.6 km) by state-space modeling. Both carrying capacity and density dependence differed greatly among cells. Estimated carrying capacities ranged from 1.34 to 98.4 deer/km 2 . According to estimated population dynamics, grid cells with larger proportions of artificial grassland and deciduous forest were subject to lower density dependence and higher carrying capacity. We conclude that population dynamics of ungulates may vary spatially through spatial variation in carrying capacity and that the density level for controlling ungulate abundance should be based on the current density level relative to the carrying capacity for each area.

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