Although atmospheric nitrogen deposition due to throughfall has decreased in Tokyo metropolitan, the forested catchment which composed with Japanese cedar (Cryptomeria japonica), Japanese cypress (Chamaecyparis obtusa), and oak (Quercus serrata) was still nitrogen saturated. We aimed to elucidate effects of decrease in nitrogen deposition on aluminum (Al) dynamics in a forested Andisols. Throughfall and soil percolated water samples were taken under Japanese cedar stand and Japanese cypress stand in Hachioji, Tokyo (Field Museum Tamakyuryo). Major inorganic ions were determined by ion chromatography. Total Al concentrations were measured by atomic absorption spectrometry after concentrating under acidic condition. Aluminum concentrations were significantly correlated with nitrate (NO3-) concentration in both Japanese cedar stand and Japanese cypress stand. In case of Japanese cedar stand, Al concentrations tended to decrease with time. Acid load associated with N transformation ([H+]load), which was chosen as the sole factor for Al mobilization in Japanese cedar stand, has also decreased. Decrease in nitrogen deposition affected Al dynamics via decrease in [H+]load. It was suggested that the calcium (Ca) content in needles may promote recovery from soil acidification in Japanese cedar stand.

Since the first vascular plants appeared on land at least 430 million years ago, plant-soil feedback has started through the root-soil interface. Plant species have inherently specific and diverse root traits, but root functional and morphological plasticity is important to respond to soil changes or diversity in terms of nutrient forms and availabilities, especially in ecosystems with low plant species diversity. This paper synthesized how tree plasticity facilitates soil nutrient acquisition from the tropics to the Arctic. The fine roots of dipterocarp (Shore laevis) and rhizosphere microbes increase malate release in acidic soils for phosphorus solubilization, aluminum detoxification, and lignin degradation. The development of finer roots is a well-known strategy for the acquisition of limited nutrients, but the allocation of roots foraging “nutrient hotspots” in deeper soil is an alternative strategy. Scots pine increases the allocation of finer roots into the subsoil to solubilize P bonded to Al/Fe oxides in fine-textured podzol, but not in the coarse-textured podzol with deeper nutrient hotspots. The black spruce trees increase the biomass allocation to the belowground to acquire soil nitrogen, especially when black spruce roots absorb urea in the shallow soil on permafrost. Even in northern ecosystems with limited species diversity, a combination of functional plasticity and vertical plasticity of root system architecture facilitates soil phosphorus or nitrogen limitation.

Community assembly can change over time following variations in connectivity among habitats. Previous studies have demonstrated the influence of seasonal pulse floods on community structures by facilitating species dispersal, but the effects of short-term flash floods have been poorly investigated. We investigated fish community structures before and after a short-term flood in drainage ditches of paddy fields in the Kita River basin, Japan. The study sites were classified into three connectivity types, “Transient” (connected only during the flood, with a temporally-disappearing vertical gap between drainage ditches and downstream rivers), “Connected” (always connected, without the vertical gap), and “Disconnected” (always not connected, with the vertical gap). The abundance of Misgurnus anguillicaudatus, the only species that dispersed from paddy fields to drainage ditches, increased after the flood irrespective of the connectivity types, although the total abundance of the other species significantly increased after the flood only in the “Transient” sites. The dissimilarity of species composition between the (n-1)-th and n-th surveys at each site was consistently low in the “Connected” and “Disconnected” sites, whereas it rose just after the flood and gradually declined in the “Transient” sites. Species composition was significantly different among the connectivity types, indicating that some fish species need stable connectivity even during the non-flood period. The results showed that the short-term flood facilitated fish dispersal from paddy fields by the increased water discharge and that from downstream rivers by the temporary removal of vertical gap, emphasizing the importance of hydrological connectivity for biodiversity conservation in an agricultural landscape.

In the context of initiatives focused on captive breeding and reintroduction of endangered animal species, it is crucial to minimize any bias in reproductive success during the reintroduction phase in order to preserve genetic diversity. One population of Tachysurus ichikawai, a critically endangered bagrid catfish endemic to Japan, faces a threat from the construction of a dam. To address this, a captive breeding program followed by translocation is being implemented. Multiple breeding families are involved in this process; however, if there is a bias in reproductive success among them after release, it will result in a decline in genetic diversity. To identify potential biases in breeding lineages, we conducted kinship analysis between individuals born at the release site and breeding individuals. Because there were no samples available from the released individuals themselves, we examined distant kinship relationships, such as grandparent–grandchild and uncle–aunt–nephew–niece relationships, using a substantial number of single-nucleotide polymorphisms obtained from the whole genome re-sequence. Our findings indicate no bias between lineages in the first year after reintroduction, but a significant bias in the second year, emphasizing the need for continuous management and monitoring of reintroduced populations. This study demonstrates that monitoring kinship after reintroduction can correct lineage bias, which is critical for the prompt restoration of genetic diversity.

Globally, around half of all tropical forests are secondary communities which are recovering from previous disturbances. In these communities, dominant pioneers play a critical role in the successional dynamics due their ability to modify the environment, and thus to facilitate or hinder the performance of other species. In this study, we examined the population dynamics of the dominant pioneer species, Mimosa acantholoba var. eurycarpa, in a tropical dry forest during the process of secondary succession. We collected data from permanent plots over a period of 13 years and used integral projection models to analyze the vital rates and changes in population size. Most vital rates were negatively related to successional age, with resprouting, survival and recruitment of individuals responding more strongly, and individual growth rate more weakly. These vital-rate trends translated into significant variation of population size over succession, with a maximum size at year four and a rapid decline thereafter. Overall, our findings suggest that this species benefits from its ability to display a large number of resprouts in very early stages of succession, contributing to the rapid increase in population density. However, as succession unfolds, a lack of resprouting and a decline in survival reduce its population size, to the point of local extinction. These results highlight the importance of resprouting in the early dynamics of tropical dry forest communities recovering from disturbance.

The use of artificial intelligence (AI) and machine learning (ML) has significantly enhanced ecological research in Asia by improving data processing, analysis, and pattern extraction. Analyzing 1550 articles, I show an overview of the use of AI and ML for Asian ecological research. Following the last 20 year trend, I found that the topics in Asian ecological research have transitioned from technical perspectives to more applied issues, focusing on biodiversity conservation, climate change, land use change, and societal impacts. Non-Asian countries, on the other hand, have focused more on theoretical understanding and ecological processes. The difference between Asian and non-Asian regions may have emerged due to the ecological challenges faced by Asian countries, such as rapid economic growth, land development, and climate change impacts. In both regions, deep learning related technology has been emerging (e.g. big data collection including image and movement). Within Asia, China has been the Asia-leading country for AI/ML applications followed by Korea, Japan, India, and Iran. The number of computer science education programs for education in China has been increasing 3.5x times faster than that in the U.S., indicating that a nationwide strategy for computer science development is key for ecological science with AI. Overall, the adoption of AI and ML technologies in ecological studies in Asia has propelled the field forward and opened new avenues for innovative research and conservation practices.

Flowering phenology of alpine plant communities and seasonal dynamics of flower visitors have been scarcely studied in the tropical/subtropical alpine regions. We report flowering phenology, flower production, and flower-visiting insects in the alpine site of central Taiwan. Throughout the research period (2017–2018), we recorded flowering phenology of 130 plant species, flower production of 81 species, and 15,127 insects visiting alpine flowers. Most of the alpine plants were visited by dipteran insects and/or hymenopteran insects. The seasonal patterns of flowering were more apparent in bee-visited plants compared to fly-visited plants in which the flowering of bee-visited plants clearly increased as the season progressed. About 63% of flower visitors were dipteran insects (syrphid and non-syrphid flies), and 30% were hymenopteran insects (mostly bumble-bee workers). Although the seasonal trend in fly abundance was less clear between years, bumble-bee abundance consistently increased in the middle to late seasons, reflecting colony development. There was a positive correlation between bee abundance and the number of flowering species of bee-visited plants, but there was no correlation between fly abundance and the number of flowering species of fly-visited plants throughout the season. These results suggest that the flowering phenology of subtropical alpine communities is influenced by the seasonal availability of pollinators. Bumble bees, syrphid flies, and non-syrphid flies had wide ranges of foraging flowers, but their niche overlap was relatively small. Because cold-adapted bumble bees are threatened by climate change in Taiwan, plant–pollinator interactions may be disturbed by global warming.

The recovery of mammalian species in the US Midwest through natural recolonization constitutes a conservation success story, yet management remains challenging due to many unknowns related to population dynamics and abundance. Abundance is a critical parameter for management decisions, and estimating the density and abundance of elusive species, such as terrestrial carnivores, remains challenging despite recent technological advances. In this study, we evaluated density and abundance of a recovering carnivore species, the bobcat (Lynx rufus) in two areas of Ohio using non-invasive DNA from scat. The target areas in eastern and southern Ohio have been shown to have uneven dynamics and recolonization success and we expected that this would be reflected in differences in density and abundance. We collected 298 bobcat scats between July 2018 and April 2019 on 150 km of repeated transects. Of these, 102 scats were successfully genotyped, and 55 individuals were identified (33 in eastern Ohio and 22 in southern Ohio). Using Spatially Explicit Capture-Recapture models, we estimated 17.9 ± 4.3 and 11.3 ± 2.9 bobcats/100 km2 in eastern and southern Ohio study areas, respectively. Our results support prior telemetry data which indicated that bobcats in eastern Ohio had smaller home-ranges than bobcats in southern Ohio, and thus could support a higher density of individuals. The higher densities were similar to other eastern US populations and are much higher than other Midwestern recovering populations. Our results provide a snapshot of the population status and can be used to determine sustainable management strategies for Ohio’s bobcat population

A subtropical mangrove along the Miyara River in Ishigaki Island, Japan was studied for evaluating the carrying capacity for biomass of the monospecific stands. Rhizophora stylosa and Bruguiera gymnorrhiza were dominant in the downstream area whereas B. gymnorrhiza in the upstream. The stem diameter D, stem height H, fine roots mass were measured and, aboveground biomass AGB, belowground coarse root biomass BGBcoarse were estimated. The AGB, BGBcoarse and fine root mass were estimated as 128.46 Mg ha-1, 31.01 Mg ha-1 and 12.75 Mg ha-1 in the R. stylosa; 269.82 Mg ha-1, 93.68 Mg ha-1 and 11.13 Mg ha-1 in the downstream B. gymnorrhiza; and, 227.94 Mg ha-1, 81.05 Mg ha-1 and 6.35 Mg ha-1 in the upstream B. gymnorrhiza plots, respectively. The AGB did not differ among the plots, meanwhile BGBcoarse was significantly lower and fine root mass was significantly higher in the R. stylosa plots than in the downstream B. gymnorrhiza plots. Significantly lower mean individual phytomass wt specific to tree density  of R. stylosa plots than B. gymnorrhiza plots in the  – wt relationship was found, which denoted the lower carrying capacity for AGB of R. stylosa than that of B. gymnorrhiza. The results rejected our hypothesis that the stressful edaphic conditions, such as high soil salinity and low pH at the downstream, limit biomass and potential canopy height Hmax of mangrove along a river gradient but partly supported another hypothesis that biomass and Hmax differs between different mangrove species at the same edaphic environment.

Plants, as immobile organisms, depend on their roots to access soil resources efficiently and cost-effectively. To achieve this goal as well as develop more productive crops and adapt to variable challenging conditions plants rely on root phenotypic plasticity. This includes changes in root morphology, growth angles, diameter, elongation, branching density, and rotation rate. In simpler terms, a plant root system is a dynamic structure that can change its branching structure in response to changes in biotic and abiotic conditions such as water availability, soil mineral nutrient content, soil compaction, salinity, and the formation of symbiotic relationships with other organisms or anchored in the substrate. However, the complexity of these responses and their impact on plant fitness are not well understood. In this study, we have reviewed different aspects of the morphological plasticity of the root system. The results show that root flexibility can greatly help plant adaptation. Thus, gaining a comprehensive understanding of root plasticity can lead to improved and sustainable plant production.