Ecological Research最新文献

The genetic structure and demographic history of the Asian black bear (Ursus thibetanus) in Japan were investigated using Double digest restriction-site associated DNA sequencing (ddRADseq). Analysis of 83 individuals revealed seven regional populations with clear geographic structure. Bayesian clustering and principal coordinate analysis showed low genetic differentiation in central populations and higher divergence in peripheral populations. The fluctuation of effective population size (Ne) inferred from SNP data showed an initial decline until around 200,000 years ago, followed by two additional reductions in most populations, with no evidence of recovery. These declines likely correspond to migration from the continent, habitat loss during the Last Glacial Maximum, and human expansion. Nuclear data suggest male-biased gene flow across mitochondrial DNA lineage boundaries. Isolated populations exhibited low heterozygosity and high genetic differentiation, emphasizing the impact of habitat fragmentation. This is the first large-scale population genomic study of Asian black bears and provides important insights for conservation and future genomic research.

Satoyama is a traditional heterogeneous Japanese landscape complex including semi-natural ecosystems such as farmland, grassland, and secondary forests. In Satoyama, abandonment of farmland is increasing, contributing to the mosaic structure of these landscapes by introducing new components. However, previous research on Satoyama has largely overlooked this perspective. Spiders serve as valuable biodiversity indicators in mosaic landscapes and provide ecosystem services, such as pest control. This study presents spider collection data as an indicator of abandoned farmland's impact on surrounding biodiversity, considering it a factor in enhancing landscape mosaic complexity. Specimens were collected from different Satoyama landscape components, including dry fields, paddy fields, abandoned dry fields, and abandoned paddy fields, in Machida City, Tokyo, over four periods during June–October 2023. The resulting dataset included 629 individuals representing 94 taxa identified at the following levels: 55 species, 31 genera, 1 subfamily, and 7 families. All data were deposited in the Global Biodiversity Information Facility (GBIF) through its Japan Node and are accessible via the GBIF portal under the Creative Commons Attribution 4.0 International license (https://www.gbif.org/dataset/259d6519-f92d-4291-adb0-04a925be0d33). The detailed Metadata for this abstract is available in MetaCat in JaLTER at https://doi.org/10.20783/DIAS.JLE.92.

Forest plantations can impact animal communities that depend on grazing and detritus food webs. In this study, we investigated this distinction by analyzing Aculeata bees and wasps that feed on different food resources in natural deciduous broadleaved forests and in two coniferous plantations, Cryptomeria japonica (“Sugi”) and Chamaecyparis obtusa (“Hinoki”), in a mountainous region of southern Kyushu, Japan. Analysis of samples collected with yellow pan traps revealed that Aculeata abundance and species richness significantly declined in plantations, and that the communities exhibited greater reliance on detritus-based food chains. This suggests that detritus-dependent species are more resilient to the conversion of natural forests to plantations than grazing-dependent species. Moreover, species in plantations tended to have longer seasonal durations, indicating a lower seasonal segregation of food resources. They also tended to have larger body sizes, suggesting wider foraging ranges. We also observed differences between the Sugi and Hinoki plantations. Compared with Sugi plantations, Hinoki plantations were inhabited by only a few large species with wide feeding ranges. Overall, our findings highlight that land modification profoundly alters food web structure and aboveground Aculeata communities. Maintaining the detritus food web and enhancing the grazing food web could increase biodiversity in plantations.

There has been a growing interest in integrating geological and ecological processes for sustainable river management and restoration. Lotic systems are shaped by diverse physical processes, including geology, geomorphology, hydrology, and interactions with terrestrial processes. However, restoration practices often prioritize specific habitats or river forms without fully considering the underlying physical processes that support biological communities and ecosystem functions. In this paper, we synthesize studies that integrally examine geological and ecological processes across different scales and components of riverscapes, including geohydrological processes, which have been less investigated in riverscape studies. We begin by examining processes at broader spatial scales, including river–watershed and river–riparian interactions, and gradually narrow our focus to the dynamics that occur among habitats within river channels, through which we highlight the significance of conceptualizing rivers as dynamic “networks” rather than linear features. Finally, we identify both scientific and practical challenges that can be addressed to bridge the gap between basic-science implications and their implementation in riverscape restorations.

Ungulates have become dominant and changed natural ecosystems in the modern era. They browse or graze unevenly on palatable plants, causing a shift to the vegetation of unpalatable species. Ungulate palatability is a key plant trait in the plant community assembly process. The browsing pressure at a site can be defined as the threshold palatability value between browsed and unbrowsed plants at the site, and it should be used for ungulate population management to conserve endangered and culturally important plants and to maintain regeneration of forests with palatable trees. Estimation of palatability and browsing pressure is a key technique for ecosystem management. We compared four methods to estimate palatability based on browsing scar surveys and estimated palatability for 195 plant species from boreal to warm-temperate zones in Japan. A browsing pressure map for planning regional ecosystem management was also constructed based on the estimated palatability. The four methods examined produced similar results, although simple logistic regression caused outliers for extremely palatable and unpalatable plants. The type of survey data restricts the applicable method; the species-to-species comparison matrix method accepts broad data types. In contrast, the distance likelihood and Bayesian logistic regression methods require a countable number of examined plants. The plant species listed in the results can serve as indicator species for determining browsing pressure in field surveys. These methods for estimating palatability and browsing or grazing pressure will contribute to future plant community studies and advances in ungulate management.

Predator–prey interactions in tropical dry forests remain understudied, despite their central role in the top-down regulation of insect herbivory, a key process influencing plant fitness, community composition, and nutrient cycling in these threatened ecosystems. This study assessed how predation by invertebrate and vertebrate predators on insect herbivores is affected by habitat type, vegetation structure, elevation, and prey color (white vs. terracotta) in a tropical dry forest. We used plasticine caterpillars to quantify predation rates and to identify predator groups across forest and silvo-pastoral systems at two elevations. Local vegetation structure was characterized by canopy cover and vegetation density. Chewing arthropods accounted for the majority (81.1%) of predation events. Arthropod attacks were more frequent in forests than in silvo-pastures, while the opposite was true for birds. Overall, the probability of predation was higher at 600 m a.s.l. compared to 1200 m a.s.l. Notably, canopy cover had contrasting effects depending on habitat type: in forests, predation increased with canopy cover, whereas in silvo-pastures it decreased. This interaction between canopy cover and habitat type was largely driven by predation exerted by arthropods. Prey color did not affect predation rates. Our results suggest that predator communities respond differently to canopy cover depending on habitat type, likely due to differences in tree species composition and in resource availability for prey or predators. These findings emphasize that top-down control in a tropical dry forest landscape is shaped by interactions between vegetation structure and habitat type, underscoring the need to consider habitat-specific mechanisms when predicting ecological processes across heterogeneous environments.