This special feature, “Challenging information gaps in conservation science,” is based on a symposium at the 63rd annual meeting of the Ecological Society of Japan. Its focus is on gaps in the process of information use in conservation science, which represents an important barrier between science and practical conservation. Four papers have been contributed. First, Amano (2017) reviews two types of gap in conservation science; namely, gaps in the availability of information, and the research-implementation gap. Amano proposes three practical approaches for resolving these problems. Osawa (2017b) explores in further detail gaps in information availability, focusing in particular on problems in Japan. Ishihama (2017), on the other hand, reviews practical modelling techniques that use presence-only data, as an example of using statistical approaches to make the best of imperfect data. Finally, Ohsawa (2017a) provides a thorough opinion piece on gaps and barriers between conservation science and policy-making in Japan.

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The contribution of science to halting ongoing biodiversity loss is a crucial aspect of conservation. Those engaged in conservation science usually collect and analyse data, and apply the findings to conservation practices and policies. However, several “gaps” exist in this process of information use, representing barriers between science and conservation. This paper reviews the details of these gaps. For example, the amount of existing data varies greatly with space, time, taxa, and data types because survey efforts are determined not only by conservation demands but also by a variety of other factors, such as the ease of data collection, scientific interests, and other constraints. The research implementation gap, that is, science not being used in conservation practices and policies, is another well-known gap in conservation science, and is often the result of differences between the knowledge provided by scientists and that required by practitioners and policymakers, and the inaccessibility of scientific information for those decision-makers. This paper concludes with three types of potential solution: increasing the amount of scientific data, using statistical modelling to make the best use of imperfect data, and transcending barriers between science and practice.

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Presence-only data are distribution records without absence information, such as museum specimens and chance observation data obtained in civil surveys. Recently established open databases, such as the Global Biodiversity Information Facility (GBIF), have promoted the use of presence-only data to estimate species distributions for various conservation purposes. However, the lack of absence data may bias distributions estimated only with presence-only data. To apply species distribution models with presence-only data for conservation purposes, we require a detailed understanding of the logic behind the model and data handling, and should consider factors such as sampling biases pertaining to the area and time of surveys, pseudo-absence data in relation to sampling biases, the validity and reliability of the estimated distribution, and how to assess accuracy and precision evaluation indices. Here, I review international reports and introduce recent advances in species distribution modelling using presence-only data.

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In the field of conservation science, the availability of data and databases is a critical factor for successful research and practical work. Conservation researchers and practitioners should work towards addressing the existing deficiencies in data and database availability. In this review, I address the “data gap” in conservation science, focusing on three types of data: taxonomic, spatial and temporal. I then analyse “S-Net,” a widely used biodiversity database, to evaluate current data gaps in Japan. Finally, I discuss several approaches to overcoming these challenges.

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The gap between science and practice has historically been a major topic in the field of conservation biology. In this article, I review this gap at both the international and domestic level, and subsequently discuss what types of scientific knowledge and insight are required to promote practical conservation, particularly in Japan. At the international level, scientific evidence is needed, for instance, to provide a rationale for the Aichi Biodiversity Target and to measure the extent to which the target has been achieved. At the national level, various questions emerge in the practice of policy-making. Furthermore, certain sub-fields dictate what types of scientific information are lacking. To facilitate the development of research that addresses such gaps, I also discuss the scientific information that should be provided by researchers to aid policy-making decisions, as well as how this it should be provided. Furthermore, I discuss how researchers can identify this type of information.

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Forest area has dramatically decreased with agricultural development in Tokachi, Hokkaido, Japan. The remaining riparian forests provide suitable habitats for various wildlife species, including sika deer (Cervus nippon), which seriously damage agricultural crops, and red foxes (Vulpes vulpes), which can transmit echinococcosis. We used 37 infrared cameras to examine the local- and landscape-scale factors affecting the frequency of riparian forest use by sika deer and red foxes in Tokachi from May 2011 to December 2012. In summer and autumn, the capture frequency of deer was positively correlated with areas of forest and farmland, as well as riverine areas within a 300-400 m buffer zone from each camera. Deer also preferred dense understorey vegetation in autumn. The factors influencing the capture frequency of foxes varied with season; it was negatively correlated with forest area within a 200 m buffer zone in spring, positively correlated with relative abundance of small birds in summer, and positively correlated with urban areas within a 200 m buffer in winter.

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We surveyed hierarchical spatial patterns of plant species diversity in 15 Chagusaba (semi-natural grasslands that are mown regularly) and two terraced paddy levees in Shizuoka Prefecture, Japan. Additive diversity partitioning indicated that both between-habitat type β-diversity and between-patch (within habitat type) β-diversity contributed largely (31% and 46%, respectively) to the observed native species richness. Non-metric multidimensional scaling (NMDS) indicated a clear difference in species composition between the Chagusaba and the terraced paddy levees. Tall perennials dominated in the Chagusaba, which are mown once per year, whereas annuals and small perennials were frequently found on the terraced paddy levees, which are mown five times per year. The variability of species composition within these habitat types can be explained by species-specific responses to soil conditions, such as moisture, nitrate-nitrogen, and calcium. Terraced paddy levees often include two microhabitat types: levee slopes and flat parts. Small perennials occurred in relatively high numbers on the levee slopes, which are managed by frequent mowing, whereas annuals dominated in the flat parts, which are influenced by repairing of the levees. Our results emphasize the importance of various management activities and the variability of local environmental conditions for maintaining overall species diversity in agricultural landscapes.

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Unionid mussel is a key taxon for conservation of freshwater biodiversity. Four species of unionids, Nodularia douglasiae nipponensis, Pronodularia japanensis, Sinanodonta lauta, and S. japonica, inhabit the Matsuyama Plain of Ehime Prefecture, Japan. The distributions of three taxa (N. douglasiae nipponensis, P. japanensis, and Sinanodonta spp.) were investigated in 2013-2014 and compared with those recorded in 1988-1991. The habitat conditions and reproductive status (abundance of egg-incubating females and host fish infected by glochidia) of P. japanensis were also investigated. Nodularia d. nipponensis and Sinanodonta spp. were found at only two and one of the 96 sites, respectively, and a comparison with the previous record showed drastic decreases in their distributions. Although P. japanensis was found at several sites, its distribution area had also decreased to less than half of that previously recorded, and its maximum density decreasing from 58 to 2.7 individuals/m2 over 25 years. Furthermore, no P. japanensis with shell lengths below 51.5 mm were found, suggesting that no recruitment had occurred during the past decade. These results reveal that the unionids in the Matsuyama Plain are under high risk for extinction. A habitat analysis of P. japanensis indicated that its present distribution was limited to downstream of weirs, which could prevent upstream dispersal of their larvae, and P. japanensis preferred fine sediments containing sand with the rate of <38.8%. Egg-incubating P. japanens is females and their host fish infected with glochidia were found at high frequencies, suggesting that their recruitment is inhibited at the settlement and/or early survival stages of their juveniles.

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The population of endangered species, Blakiston’s fish owl Ketupa Blakistoni, has been increasingly recovering with conservation activities. The next conservation target is to expand their distribution that currently concentrates in the eastern Hokkaido. In this study, we first built a static distribution model of the fish owl in the region where the owl has stable populations. Based on the static model, we projected the future range expansions of the owl using dynamic distribution modeling under the scenarios with varied conservation activities and land-use changes. The static distribution model suggested that the regions with large amounts of natural riparian forests and river length are suitable areas for the owl. Future projection of the owl ranges indicated that an increase in the breeding success would greatly contribute to the range expansion. It was also indicated that population dispersal from the eastern-most (Konsen) population is restricted, and that the existing populations are likely to expand the ranges into the central Hokkaido (Yubari Mountains). However, there were large unexplained variations in the static distribution model and large uncertainties in the projection of range expansion, suggesting that conservation activities should be flexibly planned according to the actual range expansion processes of the Blakiston’s fish owl.

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Global warming is causing the distributions of many species to shift towards higher latitudes or altitudes. The white-spotted char (Salvelinus leucomaenis), a cold-water adapted stenothermal fish, is potentially vulnerable to ongoing climatic warming. We therefore evaluated the extent to which the areas protected by national parks cover current and future potential habitats of S. leucomaenis under various climate-warming scenarios. Species distribution models using MaxEnt predicted that catchment area, slope inclination, distance to the river mouth, and estimated ground water temperature were key factors for potential habitats of anadromous and landlocked populations, and that 28.4% of potential habitats would be lost with a 3°C increase in the annual average air temperature. Potential habitats at lower latitudes, in particular, are likely to be affected, and most river basin habitats would disappear if the average temperature were to increase by 2°C. Although potential habitats in higher latitudes are less vulnerable to climate warming, the current national park system would not be able to protect these refuges. There is thus an urgent need for the development of conservation measures to mitigate the potential impact of global warming on white-spotted char habitats.

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Many species of freshwater fish are known to inhabit irrigation ditches in Japan, which are thus regarded as an important fish habitat. Conserving and restoring the ditch environments preferred by fish is essential to the conservation of endangered freshwater fish and maintenance of biodiversity in farming areas. The objective of this study was to undertake a conservation-oriented review of the literature on the ecology of fish in Japanese irrigation ditches. Many studies have examined the relationships between fish distribution and physical characteristics of ditches, providing detailed information on habitat requirements for growth, spawning, and wintering. The effects of chemical environments and water temperature on fish distribution have also been well explored. However, the effects of biotic interactions on the distribution of fish in ditches are poorly understood. In addition, field experiments and model analyses considering spatial factors are needed to support the empirical knowledge accumulated by research. Adaptive management will also be critical in planning conservation strategies.

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The distribution patterns of Oryzias latipes, was revealed in Marugame, Kagawa in 2001-2003 and 2011. Between the surveys, O. latipes did not decrease significantly, though a land conversion of rice field into the residential zone had progressed. The presence probability of O. latipes was predicted using the land use, river system, the distance from the nearest pond, elevation and slope. As the result, the area of the mainstream and ponds within 100 m of a sampling site negatively affected the presence probability of O. latipes. The area of rice field and residential zone within 100 m of a sampling site positively affected the presence probability. The results indicated the possibility that the boundary zone between the rice field had become suitable as a habitat for O. latipes.

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Protaeti pryeri, a scarab beetle from the subfamily Cetoniinae (Coleoptera, Insecta), was recently found at Port of Tokyo Wild Bird Park, nature preserve located on reclaimed land in Tokyo, Japan. As this species originates from the Nansei Islands in southern Japan, and is not native to the Tokyo area, it is referred to as a “domestic alien”. Two additional domestic alien Cetoniinae species (Cetonia pilifera, P. brevitarsis) may have been observed in the park. If any of these species expands their range from the coast to inland Tokyo, severe ecosystem disturbance and genetic introgression could occur. We investigated the prevalence and resource use of five Cetoniinae species in the park. We found high numbers of P. pryeri adults and larvae. In the soil layer, where a lot of larvae were particularly abundant, their excretions tended to replace the soil itself. This phenomenon may negatively affect the soil ecosystem and alter decomposition. In addition, abnormal outbreaks of adult Gametis jucunda, C. pilifera, and P. brevitarsis, as well as P. pryeri, were found on flowers and tree saps from multiple plant species. Continued monitoring, rearing them, and DNA-based research are recommended in order to manage the spread of domestic alien Cetoniinae species.

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In this study, we used Landsat images to observe changes in the distribution of Trapa L., which has a tendency to overgrow in Japanese lakes. Six Japanese lakes in different locations were chosen as study areas (Lakes Sirarutoro, Takkobu-numa, North Inba-numa, South Inba-numa, Suwa and Mikata). The extraction algorithm for Trapa L. was developed based on the Normalized Difference Water Index (NDWI), which uses short-wave infrared and green reflectances, instead of the more commonly used Normalized Difference Vegetation Index (NDVI); NDVI cannot distinguish between Trapa L. and cyanobacterial blooms due to their similar spectral characteristics at near infrared and red bands. Satellite-derived and in-situ estimates of Trapa L. distribution corresponded closely (R2=0.82, N=8). Seasonal observation in Lakes Sirarutoro, North Inba-numa and Mikata revealed that Trapa L. was absent from February to May, rapidly increased in July, with subsequent numbers maintained through September, and rapidly decreased in October. Changes in the distribution of Trapa L. over the past 25 years showed a tendency toward expansion in most lakes.

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We conducted a flora survey in the post-mined Sphagnum peatland, Sarobetsu Mire, northern Hokkaido, to investigate the invasion status of alien plant species. The survey area covered a parking space and trails that were used during the mining operation, in addition to 21 mined sites. The effects of peat mining on invasion of alien species was assessed by comparing the species recorded before and after the peat mining and those of the un-mined peatland. In total, 123 species including 22 alien species and five red-listed species were recorded. Nine of the alien species are considered to have established due to peat mining because these species were not recorded either before peat mining or in the un-mined sites. The distribution of alien species was limited to the parking space and the trails; however, three species (Rumex acetosella L. subsp. pyrenaicus (Pourret ex Lapeyr.) Akeroyd, Rumex obtusifolius L., and Hypochaeris radicata L.) have established also in two mined sites where ground water level was relatively low. Rumex acetosella subsp. pyrenaicus and R. obtusifolius are known for their large ecological impacts, and have a potential to threaten endangered species and vegetation recovery after peat mining. Continuous monitoring would be necessary to avoid damage to native flora and landscape by alien species.

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To evaluate the current status of non-native fishes in the Yodo River basin, in Japan, we conducted a field survey and literature review. Twelve non-native fish species introduced from foreign countries (Micropterus salmoides, Lepomis macrochirus macrochirus, Gambusia affinis, Channa argus, Monopterus albus, Mic. dolomieu dolomieu, Oreochromis niloticus, Atractosteus spatula, Onchorhynchus mykiss, Misgurnus dabryanus, Ictalurus punctatus, and C. asiatica) and two non-native fish species introduced from other regions of Japan (Tridentiger brevispinis and Hypomesus nipponensis) were collected from the basin. Mic. salmoides, L. m. macrochirus, and G. affinis were particularly common, found at 112, 104, and 26 sites, respectively, among 231 sites. Atractosteus spatula and Mis. dabryanus were recorded for the first time from the Yodo River basin and I. punctatus from the Yodo River, respectively. A review of current literature confirmed sampling records of four non-native fish species (Ctenopharyngodon idellus, Hypophthalmichthys molitrix, Aristichthys nobilis and Channa maculata). Micropterus salmoides and L. m. macrochirus were primarily collected from the main rivers and Wando pools, whereas G. affinis was frequently collected in satellite areas such as creeks and tributaries of the Yodo River.

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Rapid increases in sika deer (Cervus nippon) populations have recently begun to disrupt vegetation in wetland ecosystems in Japan. The Mizorogaike wetland in Kyoto, Japan, has sustained repeated invasions by sika deer. Research has indicated that the impacts of these invasions on wetland vegetation may be evaluated through the detection of deer traces by aerial photography. The use of unmanned aerial vehicles (UAVs), capable of taking repeated high-resolution aerial photographs in an inexpensive manner, would be a novel way to assess the consequences of sika deer invasion on wetland vegetation, which is often found in remote locations. To determine changes in deer traces over time, I analysed and compared aerial photographs taken by a UAV in the Mizorogaike Wetland on two dates: March 6, 2015, and February 26, 2016. Through object-based image analysis, I generated objects from the RGB colour values of orthochromatic images and a digital surface model (DSM), and then categorised these objects into deer traces and other zones. I calculated the density of deer traces by kernel density estimation, and determined the difference in deer trace density between 2016 and 2015, finding that deer trace density had increased toward the western periphery of the wetland. This result substantiated the effectiveness of this simple UAV-based method for the early detection of detrimental effects of deer inhabitation on wetland vegetation. We hope that the addition of UAV-based aerial photography to the library of ecosystem information will contribute to improved ecosystem management.

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We established a non-invasive DNA sampling method to assess the genetic diversity of the Japanese rock ptarmigan Lagopus muta japonica inhabiting Mt. Tateyama. We collected 102 fecal samples and, in 50, determined the haplotype of the mitochondrial DNA control region. The success of DNA isolation depended on the form and freshness of the fecal samples. We detected three haplotypes, including a novel haplotype, suggesting that the genetic diversity of the Mt. Tateyama population is comparable to or greater than that of other populations. Mismatch distribution analysis suggested that the Mt. Tateyama population experienced a recent sudden expansion, probably reflecting a bottleneck during a warmer era 6,000?9,000 years ago, followed by population recovery.

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In order to improve the foraging habitat of the Japanese golden eagle Aquila chrysaetos japonica in Japanese cypress forests on Mt. Chokai, line thinning was conducted using four different cut-over widths (5, 7, 10, and 15 m). We examined the effects of line-thinning width and brushing in autumn of the third year after thinning on the frequency of habitat use by the Japanese hares Lepus brachyurus angustidens. Habitat use of hares was assessed by RAI (the number of hares recorded by camera traps per 30 days) and total cross-sectional area of bite marks made by hares on trees. In the first year after the thinning, the numeric value of RAI and the total cross-sectional area of bite marks made by hares on trees were high in the wider (15 m) cut-over lines. In the second year and thereafter, these values were high in the narrower (5 and 7 m) cut-over lines. After brushing, the values were higher in brushing plots than in non-brushing plots, and were particularly high in narrower cut-over lines. These results suggest that brushing enhanced the attractiveness of cut-over lines (particularly narrow cut-over lines) to hares. We accordingly propose that line thinning using narrow cut-over lines is an effective strategy for long-term forest management.

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[in Japanese]

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