Riyou Tsujino

Effects of sika deer on tree seedlings in a warm temperate forest on Yakushima Island, Japan

High-density herbivore species often play an important role in forest regeneration. Native sika deer (Cervus nippon yakushimae) inhabit a high density (51.5–63.8 head/km2, estimated by a pellet count method) area in the western part of a lowland natural forest on Yakushima Island, Japan. To test experimentally the impact of sika deer on the mortality and the survivability of current-year seedlings, which are at a more vulnerable stage than the later stages, we constructed fenced exclosures, planted seeds of nine sapfruit tree species and compared the mortality and the survivability of current-year seedlings between fenced and unfenced quadrats. Large seeded species had significantly greater survivability in fenced quadrats than in unfenced quadrats. However, the survivability disagreed with feeding preferences. Sika deer activity increased seedling mortality of large-seeded species more than that of small-seeded species, and did not decrease much seedling survivability of not-preferred species. We found that the physical disturbance by the high density of sika deer resulted in mortality for both preferred and not-preferred species, and that deer herbivory was important for preferred species.

Modelling the global distribution of fungal species: new insights into microbial cosmopolitanism

Microbes are usually believed to have cosmopolitan distributions. However, for estimating the global distributions of microorganisms, discriminating among cryptic species and eliminating undersampling biases are important challenges. We used a novel approach to address these problems and infer the global distribution of a given fungal ecological guild. We collected mushroom‐forming fungi from Yakushima, Japan. We sequenced the internal transcribed spacer 2 (ITS2) from these samples and queried their sequences against GenBank. After identifying similar sequences, we tracked down the geographical origins of samples that yielded those sequences. We used Bayesian zero‐inflated models to allow for species whose DNA sequences have not yet been deposited in GenBank. Results indicated that the geographical distribution of ectomycorrhizal (ECM) fungi was strongly constrained by host specificity, resulting in the occurrence of these fungi intensively in the neighbouring regions. On the other hand, saprotrophic (SAP) fungi were less constrained by climatic conditions, resulting in a much broader distribution range. We inferred that differences in constraints during colonization between ECM and SAP fungi were responsible for the different geographical distribution ranges. We hypothesize that the degree of host/habitat specificity and the degree of isolation of potentially suitable habitats determine microbial biogeographic patterns.

Topography‐specific seed dispersal by Japanese macaques in a lowland forest on Yakushima Island, Japan

1. We investigated patterns of seed dispersal (i.e. dispersal distances and topography of seed-deposition sites) via the cheek pouches of Japanese macaques (Macaca fuscata yakui) during three seasons in a lowland forest on Yakushima Island, Japan. 2. The mean seed-dispersal distances were 16.7, 26.1, 41.8, and 32.4 m from the trunks of mother trees of Myrica rubra, Persea thunbergii, Neolitsea sericea, and Litsea acuminata, respectively. 3. We assessed the possible effect of macaque foraging patterns and the spatial distribution of fruiting trees on topography-specific seed dispersal. The topography of the locations of macaques differed across seasons, likely because the spatial distribution of fruiting trees determined the seasonal foraging patterns of macaques. 4. In early summer, macaques foraged on a ridge and fed on fruits of M. rubra and P. thunbergii, which were primarily distributed and dispersed within this area. In contrast, during the winter, macaques foraged within a valley and fed on fruits of L. acuminata, which were chiefly distributed and dispersed within the valley. 5. Seeds of M. rubra, P. thunbergii, and L. acuminata were directly dispersed to the specific topographic areas in which adult trees were distributed and in which juveniles have a predictably high probability of survival relative to random sites.

Variation in tree growth, mortality and recruitment among topographic positions in a warm temperate forest

Abstract Questions: Do the population dynamics of trees differ among topographic positions and, if so, how does topographic position affect the population dynamics of species that are distributed in a topography-specific manner? Which is the most important life stage in determining vegetation patterns? Location: Primary and secondary warm temperate evergreen broad-leaved forest (40 - 280 m a.s.l.) on the western part of Yakushima Island, Japan. Methods: Mortality, recruitment, DBH growth and distribution of stems (≥ 5 cm DBH) in a 2.62-ha plot were surveyed in 1992 and 2002 to determine the relationships between population parameters and (1) topography and (2) distribution patterns of 17 common tree species. Results: Common species (n = 17) were classified into three distribution pattern groups: group A, distributed mainly on convex slopes; group B, on concave slopes, and group C, not aggregated with respect to topographic position. Stem mortality, recruitment and DBH growth were greater in group A than in group B within each topographic class. The hierarchy of stem mortality among topographic classes for groups A and B was convex > planar > concave. Stem recruitment density was relatively high on the convex and concave slopes, respectively, for groups A and B. Conclusions: The topographical positions of adult trees were not always most suited for adult survival and growth. For group A, the distribution pattern of adults was determined in the juvenile stage, while this was not the case for group B. Studies of juvenile stages are important for understanding the demographic basis of vegetation distribution patterns. Nomenclature: Mitsuta & Nagamasu (1984). Abbreviations: AIC = Akaikes information criterion; BA = Basal area; IC = Index of Convexity; G = DBH growth; M = Stem mortality; R = Stem recruitment.

Dietary adaptations of temperate primates : comparisons of Japanese and Barbary macaques

Habitat, diet and leaf chemistry are compared between Japanese and Barbary macaques to reveal the similarities and differences in dietary adaptations of temperate primates living at the eastern and western extremes of the genus Macaca. Tree species diversity and proportion of fleshy-fruited species are much higher in Japan than in North Africa. Both species spend considerable annual feeding time on leaves. Japanese macaques prefer fruits and seeds over leaves, and Barbary macaques prefer seeds. These characteristics are adaptive in temperate regions where fruit availability varies considerably with season, since animals can survive during the lean period by relying on leaf and other vegetative foods. The two species are different with respect to the higher consumption of herbs by Barbary macaques, and the leaves consumed contain high condensed and hydrolysable tannin for Barbary but not for Japanese macaques. Barbary macaques supplement less diverse tree foods with herbs. Because of the low species diversity and high tannin content of the dominant tree species, Barbary macaques may have developed the capacity to cope with tannin. This supports the idea that digestion of leaves is indispensable to survive in temperate regions where fruit and seed foods are not available for a prolonged period during each year.

Distribution Patterns of Five Mammals in the Jomon Period, Middle Edo Period, and the Present, in the Japanese Archipelago

Abstract. We compared the distribution patterns of five mammals in the Jomon period (12,000– 2,400 years before present time), middle Edo period (1730s), and the present (ca. 1978–2000) using three existing databases. Cervus nippon was widely distributed from Hokkaido to Kyushu during the Jomon and Edo, but absent from most of northern Honshu in the present age. Sus scrofa was widely distributed from southern Hokkaido to the Ryukyu Islands in the Jomon, but absent from Hokkaido in the 1730s and from northern Honshu in the present age. Macaca fuscata was distributed from the northern-most region of Honshu to Kyushu in the Jomon and Edo periods, but diminished in northern Honshu and exhibits a fragmented distribution in the present age. Ursus arctos and/or U. thibetanus were distributed from Hokkaido to Kyushu in the Jomon and 1730s, but greatly diminished in Kyushu in the present age. The distribution patterns of these five mammals changed little from the Jomon to the Edo periods, but were greatly diminished between the Edo and present periods. We suggest that the distribution of mammals changed due to direct (hunting) and indirect (habitat alteration) humanmammal interactions.

A proposal of the method of deer density estimate without fecal decomposition rate: a case study of fecal accumulation rate technique in Japan

The accuracy of estimating deer density using the fecal pellet count method is greatly limited by variability of the fecal decomposition rate. The fecal accumulation rate technique can avoid the issue of decomposition rate. However, the precision of this technique is not clear when the decomposition rate is relatively high, such as in Japanese forests. We estimated deer population densities on Yakushima Island by the fecal accumulation rate technique and compared them between seasons. The estimated densities were similar to reported estimates, and did not differ seasonally, in accord with reports that deer on Yakushima do not migrate seasonally. Thus, we conclude that the fecal accumulation rate technique is applicable in Japanese forests.

Ecosystem impacts of folivory and frugivory by Japanese macaques in two temperate forests in Yakushima.

Comparing animal consumption to plant primary production provides a means of assessing an animals impact on the ecosystem and an evaluation of resource limitation. Here, we compared annual fruit and leaf consumption by Japanese macaques (Macaca fuscata) relative to the annual production of these foods in the lowlands and highlands of Yakushima Island, Japan. We estimated consumption by macaques by the direct observation of macaque groups for 1 year in each habitat. We estimated leaf production as the sum of leaf litter fall (corrected for the effect of translocated organic and inorganic matter) and folivory by insects (assumed to be 10%) and by macaques. We estimated fruit production as the sum of fruit litter fall and consumption by birds (estimated by the seed fall) and macaques. The impact of macaque folivory at the community level was negligible relative to production (∼0.04%) compared with folivory by insects (assumed to be 10%); however, for some species, macaque folivory reached up to 10.1% of production. Tree species on which macaques fed did not decline in abundance over 13 years, suggesting that their folivory did not influence tree species dynamics. For the three major fleshy‐fruited species in the highland site, macaques consumed a considerable portion of total fruit production (6–40%), rivaling the consumption by birds (32–75%). We conclude that at the community level, macaque folivory was negligible compared with the leaf production, but frugivory was not. Am. J. Primatol. 76:596–607, 2014.

Factors affecting forest area change in Southeast Asia during 1980-2010

While many tropical countries are experiencing rapid deforestation, some have experienced forest transition (FT) from net deforestation to net reforestation. Numerous studies have identified causative factors of FT, among which forest scarcity has been considered as a prerequisite for FT. In fact, in SE Asia, the Philippines, Thailand and Viet Nam, which experienced FT since 1990, exhibited a lower remaining forest area (30±8%) than the other five countries (68±6%, Cambodia, Indonesia, Laos, Malaysia, and Myanmar) where forest loss continues. In this study, we examined 1) the factors associated with forest scarcity, 2) the proximate and/or underlying factors that have driven forest area change, and 3) whether causative factors changed across FT phases (from deforestation to net forest gain) during 1980–2010 in the eight SE Asian countries. We used production of wood, food, and export-oriented food commodities as proximate causes and demographic, social, economic and environmental factors, as well as land-use efficiency, and wood and food trade as underlying causes that affect forest area change. Remaining forest area in 1990 was negatively correlated with population density and potential land area of lowland forests, while positively correlated with per capita wood production. This implies that countries rich in accessible and productive forests, and higher population pressures are the ones that have experienced forest scarcity, and eventually FT. Food production and agricultural input were negatively and positively correlated, respectively, with forest area change during 1980–2009. This indicates that more food production drives deforestation, but higher efficiency of agriculture is correlated with forest gain. We also found a U-shaped response of forest area change to social openness, suggesting that forest gain can be achieved in both open and closed countries, but deforestation might be accelerated in countries undergoing societal transition. These results indicate the importance of environmental, agricultural and social variables on forest area dynamics, and have important implications for predicting future tropical forest change.

Effective spatial scales for evaluating environmental determinants of population density in Yakushima macaques.

Population densities of wildlife species tend to be correlated with resource productivity of habitats. However, wildlife density has been greatly modified by increasing human influences. For effective conservation, we must first identify the significant factors that affect wildlife density, and then determine the extent of the areas in which the factors should be managed. Here, we propose a protocol that accomplishes these two tasks. The main threats to wildlife are thought to be habitat alteration and hunting, with increases in alien carnivores being a concern that has arisen recently. Here, we examined the effect of these anthropogenic disturbances, as well as natural factors, on the local density of Yakushima macaques (Macaca fuscata yakui). We surveyed macaque densities at 30 sites across their habitat using data from 403 automatic cameras. We quantified the effect of natural vegetation (broad‐leaved forest, mixed coniferous/broad‐leaved forest, etc.), altered vegetation (forestry area and agricultural land), hunting pressure, and density of feral domestic dogs (Canis familiaris). The effect of each vegetation type was analyzed at numerous spatial scales (between 150 and 3,600‐m radii from the camera locations) to determine the best scale for explaining macaque density (effective spatial scale). A model‐selection procedure (generalized linear mixed model) was used to detect significant factors affecting macaque density. We detected that the most effective spatial scale was 400 m in radius, a scale that corresponded to group range size of the macaques. At this scale, the amount of broad‐leaved forest was selected as a positive factor, whereas mixed forest and forestry area were selected as negative factors for macaque density. This study demonstrated the importance of the simultaneous evaluation of all possible factors of wildlife population density at the appropriate spatial scale. Am. J. Primatol. 77:152–161, 2015.