Special feature Long-term monitoring and research in Asian university forests: towards further understanding of environmental changes and ecosystem responses

Forests cover 593 million hectares of land in Asia (FAO 2016), with high biodiversity and supplying multiple ecosystem services to human society. Meanwhile, the influence of global warming becomes apparent, and extreme weather events frequently occur in the region, posing threats to forest ecosystems and serious damages to people’s lives. To sustain, conserve, and manage Asian forests, it is an important and urgent challenge to understand long-term environmental and ecosystem changes in the forests and to provide robust scientific knowledge on how the ecosystems respond to those changes.

For forests, the detection of environmental changes and ecosystem responses requires baseline datasets based on long-term (e.g., 10¹–10² years) observations. University forests refer to forested areas owned or managed by universities and devoted primarily to research and teaching programs in forest-related sciences (Straka 2010). Such institutions have been collecting, managing, and analyzing long-term data of meteorological, hydrological, biological, and geographic information under an organizationally stable observation system.

With funding from the Core-to-Core Program (B. Asia-Africa Science Platforms) of the Japan Society for the Promotion of Science (JSPS), the University of Tokyo Forests initiated a 3-year research exchange project in 2016 entitled “Developing a network of long-term research field stations to monitor environmental changes and ecosystem responses in Asian forests” (Project Coordinator: Prof. Naoto Kamata). The project was implemented in collaboration with core institutions in five countries (Japan, Korea, Taiwan, Thailand, and Malaysia) that hold or manage university forests and research sites in different climates and vegetation zones of the Asian monsoon region. We aimed to promote the development of long-term research field stations for stable and continuous monitoring and to establish a multilateral research cooperation network among the core institutions through close collaborations. In 2019, the JSPS Core-to-Core Program further awarded the University of Tokyo Forests another 3-year research exchange project. We invited three new universities from China, Indonesia, and Sri Lanka, to strengthen and expand our multilateral research cooperation network that has been established through the previous research exchange project.

To disseminate various long-term data and research results from university forests in Asia, the Editorial Board of the Journal of Forest Research proposed a special feature entitled, “Long-term monitoring and research in Asian university forests: towards further understanding of environmental changes and ecosystem responses.” We invited authors to contribute original articles regarding the latest scientific findings from university forests in Asian countries towards the realization of adaptive forest management and conservation based on a comprehensive understanding of environmental changes and ecological responses.

This special feature consists of a total of 12 articles from researchers participating in the JSPS Core-to-Core Program. Among them, two articles address the research topic of climate and water with long-term meteorological and hydrological data. Lai et al. (2020) classified the current climate types of university forests in Japan, Korea, Taiwan, Thailand, and Malaysia, and projected changes in the classification results under future climate scenarios. The author used temperature and precipitation data observed for 15–54 years at 15 weather stations. Im et al. (2020) determined Soil Conservation Service (SCS) curve number values using rainfall and runoff data measured for 6–17 years in Japan, Korea, Taiwan, and Thailand. The curve number procedure was developed by the U.S. SCS to estimate storm runoff volume on ungauged forest watersheds.

Six articles deal with forest ecosystems in Asia using long-term biological and ecological data. Kamata et al. (2020a) determined developmental periods for bud break and leaf opening of Quercus crispula by developing a growing degree days model with leafing phenology data over 10 and 53 years in central and northern Japan. Cheng et al. (2020) collected monthly litterfall data in 2012–2019 in coniferous and broadleaf plantations to examine the effects of typhoon disturbances on seasonal and interannual patterns of litterfall in central Taiwan. Jung et al. (2020) conducted a tree-ring analysis with monthly climate data over 50 years to examine the differences in climate and drought response of three introduced conifers (Abies firma, Cryptomeria japonica, and Chamaecyparis obtusa) in southern Korea. Kamata et al. (2020b) used trapping data collected between 1994–2003 and 2013–2014 to investigate factors influencing the number of species and abundance of bark and ambrosia beetles captured by traps in a cool temperate forest in central Japan. Sanguansub et al. (2020) captured insects every two weeks using ethanol bait traps in 2014–2016 to analyze the influence of seasonality and weather on captures of wood-boring beetles in a seasonal tropical forest of northern Thailand. Jeong et al. (2020) investigated the annual change of egg-laying dates for varied tits (Poecile varius) in response to spring pre-breeding period temperatures by monitoring nest boxes and climate data over 13 and 36 years in Korea and Japan.

Four articles are contributions from the research field of forest growth and mensuration based on long-term plot measurement and remote sensing data. Lam and Guan (2020) used tree census data repeatedly measured between 1950–2015 at a Sugi (Cryptomeria japonica) spacing trial in central Taiwan with initial densities of 400–2500 trees ha⁻¹. The authors employed a mixed-effects modelling approach to quantify Sugi stand basal area growth under different planting densities with acceptable prediction accuracy. Hiroshima et al. (2020) fitted Richards growth functions with time-series diameter at breast height data of planted Sugi trees between 14 and 108 years old in long-term growth observation sites in central Japan and confirmed that a longer observation period can improve the accuracy of growth prediction in old Sugi plantations. Moe and Owari (2020) used long-term measurement data between 1968 and 2016 from permanent plots in northern Japan to predict the individual tree growth of high-value timber species and to determine the time required to reach marketable size. To facilitate the biomass assessment of reforestation sites, Wei et al. (2020) examined the relationships between standing stock, leaf area index (LAI), and normalized difference spectral index (NDVI) in southern Taiwan, by using plot measurement records, hemispherical photos, and SPOT satellite images obtained annually between 2011 and 2015.

We hope that this special feature provides an overview of what the JSPS Core-to-Core research exchange programs have accomplished.

Acknowledgments

We wish to thank Dr. Masahiro Takagi for his careful manuscript check with huge efforts as the Coordinating Editor of this special feature. Our acknowledgements also extend to Prof. Satoshi Ito, Editor-in-Chief of the Journal of Forest Research, and Ms. Yoko Machida at the Editorial Office, for their dedicated support during the editorial process.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Japan Society for the Promotion of Science [JPJSCCB20190007].