Review: Monitoring of land cover changes and plant phenology by remote‐sensing in East Asia

Abstract

To achieve a sustainable society and solve the problems caused by climate change and socioeconomic activities, it is necessary to monitor the spatial and temporal variability of ecosystem functions, services, and biodiversity at both regional and global scales. During the last decade, we have seen rapid and significant improvement in satellite and near-surface remote-sensing technologies. In this review, we describe how remote-sensing observations are being used to effectively evaluate the spatial and temporal variability of land use and cover types and of plant phenology in East Asia. We discuss the current status, uncertainties, problems, and future perspectives for terrestrial ecosystem and

Perspective: Improving the accuracy of plant phenology observations and land-cover and land-use detection by optical satellite remote-sensing in the Asian tropics

“…Takeuchi et al (2021) emphasized the necessity of satellite observations that provide the academic perspectives and evidence needed to implement natural ecosystem conservation policies. We further encourage the use of in situ observed data to improve the accuracy and precision of analyses of satellite observations and reinforcing the networking of research communities working with in situ and satellite observations in the Asian tropics (Dronova and Taddeo, 2022;Shin et al, 2023).…”

“…How can we detect the characteristics of phenology in tropical rain forests consisting of evergreen broad-leaved trees, with seasonality much less clear than that of deciduous trees, with optical sensors on board satellites? Previous studies reported that the RGB composite images observed by the Sentinel-2A/2B-MSI satellites, with the highest spatial resolution among the optical sensors on board public satellites, detected the color change on the canopy surface of Castanopsis sieboldii, Castanopsis cuspidate, and Lithocarpus edulis (evergreen oak tree species) caused by leaf flush (light green) and successive flowering (cream) in Japan (Nagai et al, 2020b;Shinohara and Nasahara, 2022;Shin et al, 2023) during a general flowering in 2019. These results indicate the possibility that satellite-based observations may be used to track the phenological timing and patterns of various tree species in tropical rain forests in tandem with ground-truth information.…”

“…Satellite remote-sensing by optical sensors is useful for evaluating the spatiotemporal variation of plant phenology, land cover, and land use over a broad scale (Muraoka et al, 2012;Nagai et al, 2020a;Shin et al, 2023). Since 1972 when Landsat-1 was launched, 2 satellite optical sensors that observe visible and near-infrared regions of the electro-magnetic spectrum have continuously monitored the state of the ground surface from plot to global scales (Table 1 shows a summary of the specification of optical sensors on board satellites shown in this perspective paper).…”

“…In the latter half of the 2010s, the spatiotemporal resolution of optical sensors on board public satellites remarkably progressed with the launch of the Multispectral Instrument (MSI) on board the Sentinel-2A/2B satellites, with a 10-m spatial resolution at 5day intervals (; e.g., Nomura and Mitchard, 2018;Persson et al, 2018;Vrieling et al, 2018;Chang et al, 2021), 5 and the Advanced Himawari Imager (AHI) on board the Himawari-8 geostationary satellite, with a 1,000-m spatial resolution at 10-min intervals (at 2.5-min intervals around Japan; Miura et al, 2019;Yan et al, 2019;Miura and Nagai, 2020). 6 Although these optical sensors do not satisfy the need for simultaneous high spatial, temporal, and wavelength resolutions, these optical sensors will be expected to provide much more accurate and precise satellite observations, along with a reduction of uncertainties and systematic noise in land-cover and land-use detection and phenology observations (Shin et al, 2023). Continuous and extensive satellite observations by these optical sensors will be also expected to develop spatiotemporally interpolating and extrapolating in situ observed data on ecosystem functions and biodiversity in each tropical observation field.…”

Perspective and review: how to develop our understanding of temporal changes in the relationship between people and the landscape under societal and climate change in Northeast Asia?

“…It can detect the spatio-temporal variability of land surface changes in the landscape at a large scale (from local to regional) on a scale of seasons to decades. Recent technological developments have dramatically increased the spatial resolution and temporal frequency of satellite observations (Moon et al, 2021;Wu et al, 2021;Shin et al, 2023a;2023b;Wang et al, 2023). When a disaster occurs, detailed data on damage caused by landslides, floods, and tsunamis can be obtained with optical sensors and synthetic aperture radar (SAR) onboard satellites (Rao and Lin, 2011;Huyck et al, 2014;Boschetti et al, 2015;Miura and Nagai, 2020;.…”