Takuhiko Murakami

Change in habitat selection by Japanese macaques (Macaca fuscata) and habitat fragmentation analysis using temporal remotely sensed data in Niigata Prefecture, Japan

Abstract The aim of this study was to evaluate changes in macaque habitat selection during a 29-year period. We focused on the 1970s, when little crop damage was caused by Japanese macaques ( Macaca fuscata ), and the 2000s, when the damage became remarkable. Landsat/MSS from 1978 and ALOS/AVNIR-2 from 2007 were employed for land-cover mapping. For the 2007 land-cover classification, we applied an object-oriented image classification and a classification and regression tree. The Kappa coefficient of the 2007 land-cover map was 0.89. For the 1978 land-cover classification, change detection using principal component analysis and object-oriented image classification were applied to reduce resolution difference errors. The Kappa coefficient of the 1978 land-cover map was 0.84. We applied a Random Forest model for machine learning and data mining to predict the habitat selection of macaques. Several important environmental factors were identified for macaque habitat selection: the ratio of coniferous forest to farmland, distance to farmland, and maximum snow depth. The Random Forest model was extrapolated to the 1978 land-cover map. Over the 29-year period, coniferous forest changed to broad-leaved forest and/or mixed forest within the macaque habitat area. Coniferous forests were not selected as food resources by Japanese macaques. Furthermore, large-scale patches of farmland were used as food resources over the 29-year period. These changes indicated that habitat selection by Japanese macaques changed over the study period. The results show that the home range of macaques expanded, and macaques may now be distributed over a wider area as a result of changes in landscape configuration. Thus, forest planning, such as sustainable management of artificial conifer forests, is important for reducing crop damage.

Effects of environmental factors on the density of three species of peracarid crustaceans in micro-tidal sandy shores in Japan

The swash zone of sandy shores is a transitional habitat between the sea and land where the physical environment is the primary factor influencing the distribution of shore macrofauna. We constructed cumulative logit models using Bayesian inference to predict the ranked abundance of three species of peracarid crustaceans (Haustorioides japonicus, Excirolana chiltoni, and Archaeomysis kokuboi) that dominate the sandy shores of the Niigata coastline, Sea of Japan. Additionally, we estimated the importance of 14 environmental factors at explaining the variation in abundance. The environmental factors were grouped into three categories: swash zone, landward, and offshore. Optimum models were selected among the null model, the basic model (swash zone factors only), and additional models with landward and/or offshore factors. The optimal model for each of the three species was obtained when landward and/or offshore factors were added to the basic model, suggesting the importance of these regional factors. Combinations of significant factors differed between the three peracarid species. Some differences can be explained by accounting for life history characteristics. The slope of the offshore seafloor was the only common significant factor for the three species. Therefore, a decrease in the size of the shallow area off the sandy shore was associated with a decrease in the density of the three species. Because the peracarid crustaceans play an important role in trophic links in sandy shore ecosystems, our study results predict that an increase of coastal erosion leading to change of near-shore bathymetry will reduce the ecological function of the swash zone.

Historical logging and current successional status of old-growth Cryptomeria japonica forest on Yakushima Island

ABSTRACT Estimation of the current successional status of long-lived coniferous forests is difficult especially after several hundred years of human disturbance. However, in Cryptomeria japonica forest on Yakushima Island, the stumps generated by logging activities from the seventeenth to nineteenth centuries remain almost intact without intense rotting. From an inventory of these stumps and long-term monitoring of current stands for more than 25 years, we estimated the forest condition before logging and evaluated the current status of secondary succession. The size structure of Cr. japonica stumps suggested the stumps were composed of two different generations: the stumps of trees present before initiation of logging; and those of trees that regenerated after initiation of logging. In the current forest, the stem number of canopy species is decreasing and that of understory broad-leaved species is increasing. Regenerating Cr. japonica individuals are rare. Before the logging, the forest contained a larger number of larger Cr. japonica trees than the current forest. The results of monitoring the current forest suggested that all coniferous species, including Cr. japonica, were still undergoing self-thinning. The current Cr. japonica forest is in an intermediate stage of secondary succession, but the processes of succession are markedly different between the study plots, depending on their location or previous logging intensity.