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• A multiscale model is built to analyze the suitable habitats for Siberian cranes. • The hydraulic model is combined with remote sensing to determine habitat features. • The impacts of the Poyang Lake Hydraulic Project on habitat suitability are revealed. • Water level regulation reduces the fragmentation degree of highly suitable habitats. • The spatial characteristics of habitats can guide habitat protection and management. Poyang Lake is located in the middle and lower reaches of the Yangtze River in China. It is the most important wintering area for the endangered Siberian cranes. Identifying the scale characteristics of habitat selection for Siberian cranes is essential for habitat conservation. In this study, a habitat suitability index (HSI) model based on multiscale habitat features was developed to assess the distribution and fragmentation degree of the suitable habitat for Siberian cranes before and after the construction of the proposed Poyang Lake Hydraulic Project (PLHP). The habitat of the entire lake area was divided into four ranks on the basis of HSI values. 2D shallow-water equations (SWEs), combined with remote sensing and geographic information system technology, were utilized to determine the key habitat features. Results indicated that the established HSI model could effectively recognize the potentially suitable habitats for Siberian cranes in Poyang Lake. The highly suitable habitat in the wet year was larger than that in the dry year, and the complexity of patch shapes and patch fragmentation increased. The influence of the PLHP on the suitable habitat for cranes mainly depended on its regulated water level, and this project could promote the formation and reduce the fragmentation degree of the suitable habitat under a properly regulated water level in the dry year. However, a higher regulated water level may cause a considerable negative impact on the distribution of suitable habitats in both years. This study provided a quantitative method to evaluate the potentially suitable habitats for Siberian cranes, and it could serve as a reference for the water level management of the proposed PLHP. [ABSTRACT FROM AUTHOR]

• A conceptual model is proposed to study the evolution of vegetation patches. • The relationship between final coverage and initial vegetation patches is revealed. • The longitudinal dispersion is usually enhanced during the vegetation evolution. • The effects of critical bed shear stress on the vegetated landscape is explored. Hydrodynamic conditions are important controlling factors in the evolution of vegetation and ecosystems, especially aquatic ecosystems. This study established a conceptual vegetation evolution model to explore the succession law of vegetation patches in the effective area of a channel, including the evolution of vegetation coverage (C e) and the corresponding longitudinal dispersion coefficient (K e). 2D shallow-water equations were implemented to calculate flow variables, and the equivalent Manning coefficient was used to reflect the effects caused by vegetation patches. New vegetation emerged in regions where the bed shear stress is lower than the critical bed shear stress, whereas the original vegetation was removed in regions where the bed shear stress is higher than the critical value. Two typical cross-sections and two initial C e were considered to better understand the succession trend of vegetation patches under different external conditions. The findings showed that C e and K e increased to a constant value with increasing simulation duration, whereas a higher critical bed shear stress, defined by the threshold value (TV), was linked to a higher final vegetation coverage (C f) and final longitudinal dispersion coefficient (K f). Furthermore, different initial vegetation distributions, including coverage and position, caused little effect on the C f in the rectangular channel, but the C f in the parabolic channel was linearly affected by the averaged bed shear stress at the initial patches. The maximum K f in both channels occurred with regularly distributed initial patches on one side of the bank. The vegetation patches in all scenarios evolved from block-shaped to strip-shaped and finally formed a stable vegetated landscape. This conceptual vegetation evolution model will improve our understanding of the influence of hydrodynamic conditions on the vegetation evolution in aquatic ecosystems. [ABSTRACT FROM AUTHOR]