Five decades of monitoring data (1974-2022) at the acidified, acid-sensitive forested catchment of Langtjern in southern Norway document strong chemical recovery and browning of surface water, related to changes in sulfur (S) deposition. We used the process-oriented model MAGIC to simulate water chemistry from 1860 to 2100 using historical and projected deposition and climate. New in MAGIC is i) a solubility control of dissolved organic carbon (DOC) from S deposition, which allows inclusion of the changing role of organic acids in chemical recovery, and ii) climate-dependency of weathering rates. MAGIC successfully described measured chemical recovery and browning, and the change towards organic acid dominated acidification status. Hindcasts of pH suggested lower preindustrial pH than previously modelled with MAGIC, simulated without sulfate-dependency of DOC solubility. Climate scenarios indicated substantially wetter climate, leading to increased base cation losses and slight reacidification of the surface waters. A sensitivity analysis of weathering rates revealed that a doubling of weathering rates is needed to reach pre-industrial ANC in 2100, given that S deposition is expected to be reduced to a minimum. We conclude that impacts of climate change are most likely to lead to slight reacidification of surface waters, and that enhanced weathering rates could partly compensate this trend.

Excessive anthropogenic nitrogen fixation alters the nitrogen cycle and increases nitrogen deposition, leading to nitrogen saturation, which leads to forest decline and nitrate leakage into stream waters. Kureha Hill in Toyama Prefecture, Japan, is considered to be in nitrogen saturation, since many streams have contained high concentrations of nitrate for more than 20 years. This study verified the latest status of nitrogen saturation by comparing the latest data with 20-year observational data. Results showed that the current nitrate concentration in stream water is lower than that observed 20 years ago. However, the C/N ratio of the soil between 12 and 18, indicates that nitrogen saturation could take place. In addition, the net nitrogen mineralization and net nitrification rate showed no significant change from the past data. Based on the nitrogen leakage to the stream water, Kureha Hill’s nitrogen saturation was found to be less intense; however, its potential to produce nitrate has been unchanged for 20 years.

For 40 years MAGIC has been used to simulate the acidification of soils and waters due to acid deposition. The original model has now been updated and re-implemented in the C++ Mobius platform and is available as open source. New features include multipoint calibration, forest growth, and a soil carbon module. The Mobius platform facilitates automatic optimisation of calibrated parameters and multiple-calibrations using Monte-Carlo routines. The usefulness of MAGIC is demonstrated by application to the 50-year data series for deposition and runoff at Birkenes, a small, calibrated catchment in southern Norway. Acid deposition has declined dramatically at Birkenes since the peak in the 1970s. Sulphate is 90% lower. Stream water has recovered strongly. Decreased concentrations of sulphate have led to increased acid neutralising capacity, pH and reduced concentrations of toxic aluminium. These changes are well-simulated by MAGIC. The new features added as part of Mobius improve the simulations. The MAGIC-Mobius modelling tool is now available for applications to scenarios of land-use and climate change.

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.

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.

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.