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Measuring the landscape pattern from a three-dimensional perspective is of great significance for comprehensively revealing the complex spatial characteristics of island ecosystems. However, the archipelago composed of rocky islands has received little attention as its three-dimensional landscape characteristics are difficult to quantify. This study took the largest archipelago in China, the Zhoushan Archipelago, as the study area and constructed an island landscape pattern evaluation model from a dual-three-dimensional (dual-3D) perspective. The model divided the island into upper and lower layers, namely the surface landscape based on topography and the landscape elements above the surface (i.e., vegetation and buildings), and then evaluated their landscape patterns from a three-dimensional perspective, respectively. The landscape pattern model based on a dual-3D perspective and multiple scales achieved excellent results in the archipelago. First, the island landscape pattern was evaluated from three-dimensional perspectives, including human interference, landscape fragmentation, vegetation space, and building space. Second, landscape indices such as the human interference three-dimensional index (HITI), the landscape fragmentation three-dimensional index (LFTI), the vegetation three-dimensional index (VTI), and the building three-dimensional index (BTI) established at multiple spatial scales revealed spatial heterogeneity within and between islands. Environmental factors such as elevation, slope, and island area exhibited significant correlations with them. There were significant differences in landscape pattern indices between the two-dimensional (2D) and the three-dimensional (3D) perspectives, and high values were mainly distributed in areas with significant topographic changes and larger islands. In addition, as the evaluation unit increased, the landscape indices increased, and HITI became more responsive to the transitions from 2D to 3D, while LFTI was the opposite. Therefore, the multiscale landscape pattern measurement of China's largest archipelago based on high-resolution remote sensing was carried out from three-dimensional perspectives to accurately reveal the spatial heterogeneity. [ABSTRACT FROM AUTHOR]

Total suspended particulate matter (TSM) in estuarine and coastal regions usually exhibits significant natural variations. The understanding of such variations is of great significance in coastal waters. The aim of this study is to investigate and assess the diurnal and seasonal variations of surface TSM distribution and its mechanisms in coastal waters based on Geostationary Ocean Color Imager (GOCI) data. As a case study, dynamic variations of TSM in the macro-tidal Yalu River estuary (YRE) of China were analysed. With regard to diurnal variability, there were usually two peaks of TSM in a tidal cycle corresponding to the maximum flood and ebb current. Tidal action appears to play a vital role in diurnal variations of TSM. Both the processes of tidal re-suspension and advection could be identified; however, the diurnal variation of TSM was mainly affected by a re-suspension process. In addition, spring-neap tides can affect the magnitude of TSM diurnal variations in the YRE. The GOCI-retrieved TSM results clearly showed the seasonal variability of surface TSM in this area, with the highest level occurring in winter and the lowest in summer. Moreover, although river discharge to the YRE was much greater in the wet season than the dry season, TSM concentrations were significantly higher in the dry season. Wind waves were considered to be the main factor affecting TSM seasonal variation in the YRE. [ABSTRACT FROM AUTHOR]

• Ecological importance and tenacity were proposed to represent the specialty of islands. • Two new indices, EII and ETI, were used to quantify the importance and tenacity, respectively. • The combination of EII and ETI provided an effective method to conduct island protected area zoning. • The optimum scheme of island protected area zoning could be obtained using the method. • Targeted island protected area zoning greatly contributes to the island sustainable development. Island protected area zoning is highly significant for maintaining the biodiversity and achieving the island sustainable development. Ecological importance and tenacity were proposed in this study for the island protected area zoning. The ecological importance was composed of three components, namely, landscape, soil, and vegetation; the ecological tenacity was evaluated based on the ecological importance and considering three types of influences, i.e., anthropogenic, topographic, and marine influences. Two new indices, namely, ecological importance index (EII) and ecological tenacity index (ETI), were established, and remote sensing and field data were integrated to serve as the data source and realize the spatial exhibitions. Then, the island protected area zoning was conducted based on the spatial distributions of EII and ETI, and six schemes for different protection and development purposes were designed. An island chain in Dongtou Archipelago in South China was used as the study area. Results indicated that the ecological importance and tenacity showed spatial heterogeneities across islands and within the islands. The islands with higher proximities to the mainland and larger areas generally possessed lower ecological importance and tenacity. Of the six schemes, Scheme B was the recommended scheme because of its reasonable area assignments for different protected areas, the optimum compatibility with island uses, and the balance of protection and development. The demonstration of the method validated the advantages of the EII and ETI in revealing the spatial characteristics of island ecological importance and tenacity, as well as the effectiveness of the method in the island protected area zoning. [ABSTRACT FROM AUTHOR]