RESUMEN
The potential for species to shift their ranges to avoid extinction is contingent on the future availability and accessibility of habitats with analogous climates. To develop conservation strategies, many previous researchers used a single method that considered individual factors; a few combined 2 factors. Primarily, these studies focused on identifying climate refugia or climatically connected and spatially fixed areas, ignoring the range shifting process of animals. We quantified future habitat availability (based on species occurrence, climate data, land cover, and elevation) and accessibility (based on climate velocity) under climate change (4 scenarios) of migratory birds across the Yangtze River basin (YRB). Then, we assessed species' range-shift potential and identified conservation priority areas for migratory birds in the 2050s with a network analysis. Our results suggested that medium (i.e., 5-10 km/year) and high (i.e., ≥ 10 km/year) climate velocity would threaten 18.65% and 8.37% of stable habitat, respectively. Even with low (i.e., 0-5 km/year) climate velocity, 50.15% of climate-velocity-identified destinations were less available than their source habitats. Based on our integration of habitat availability and accessibility, we identified a few areas of critical importance for conservation, mainly in Sichuan and the middle to lower reaches of the YRB. Overall, we identified the differences between habitat availability and accessibility in capturing biological responses to climate change. More importantly, we accounted for the dynamic process of species' range shifts, which must be considered to identify conservation priority areas. Our method informs forecasting of climate-driven distribution shifts and conservation priorities.
Priorizar los esfuerzos de conservación en función de la disponibilidad y accesibilidad futura de hábitats ante el cambio climático Resumen El potencial de las especies para desplazar sus rangos y evitar la extinción depende de la disponibilidad y accesibilidad futura de hábitats con climas análogos. Para desarrollar estrategias de conservación, muchos investigadores anteriores utilizaron un solo método que consideraba factores individuales; algunos combinaron 2 factores. Principalmente, estos estudios se centraron en identificar refugios climáticos o áreas climáticamente conectadas y espacialmente fijas, ignorando el proceso de desplazamiento de rangos de los animales. Cuantificamos la disponibilidad futura de hábitats (basada en la presencia de especies, datos climáticos, cobertura terrestre y elevación) y la accesibilidad (basada en la velocidad climática) bajo el cambio climático (4 escenarios) de aves migratorias en la cuenca del río Yangtsé (YRB). Luego, evaluamos el potencial de desplazamiento de rangos de las especies e identificamos áreas prioritarias de conservación para las aves migratorias en la década de 2050 mediante un análisis de redes. Nuestros resultados sugieren que una velocidad climática media (es decir, 5−10 km/año) y alta (es decir, ≥ 10 km/año) amenazarían el 18.65% y el 8.37% del hábitat estable, respectivamente. Incluso con una velocidad climática baja (es decir, 0−5 km/año), el 50.15% de los destinos identificados por la velocidad climática eran menos disponibles que sus hábitats de origen. Basándonos en nuestra integración de la disponibilidad y accesibilidad de hábitats, identificamos algunas áreas de importancia crítica para la conservación, principalmente en Sichuan y en las partes media e inferior del YRB. En general, identificamos las diferencias entre la disponibilidad y accesibilidad de hábitats en la captura de respuestas biológicas al cambio climático. Más importante aún, tuvimos en cuenta el proceso dinámico de los desplazamientos de rangos de especies, lo cual debe considerarse para identificar áreas prioritarias de conservación. Nuestro método contribuye a la predicción de cambios en la distribución impulsados por el clima y las prioridades de conservación.
RESUMEN
There is a growing recognition of the broader environmental significance of exploring the relative importance of climate change and anthropogenic impacts on hydrologic fluctuations in river-lake systems. In the case of Dongting Lake, the typical river-lake system, we collected the water level from 1990 to 2019, spanning before and after the operation of the Three Gorges Dam (TGD) in 2003. This study was conducted to detect water level fluctuations in Dongting Lake and to quantify the relative influence of climate, land cover and dam construction on water levels. We defined the impact of the dam construction as the three inlets inflow of Yangtze River (In-YR), and four waters inflow of Hunan (In-HN). The Mann-Kendall (M-K) test revealed the trends and change points of water level fluctuations. Structural Equation Model (SEM) was used to detect the direct and indirect effects of these factors on water level and quantify their relative importance. The MIKE21 hydrodynamic model reflected the spatial-temporal variability of water levels under the action of key driver. The results showed that the water level appeared a downward trend during 1990-2019 and the change point appeared in 2003; During 1990-2002, the significant factors were: precipitation (V = 0.469, P = 0.013), evaporation (V = -0.424, P = 0.029), non-agricultural cover (V = -0.334, P = 0.025), and agricultural cover (V = 0.235, P = 0.033); During 2003-2019, the significant factors were: In-YR (V = 0.436, P = 0.007), In-HN (V = 0.431, P = 0.012), and precipitation (V = 0.349, P = 0.045); The In-YR was the key factor affecting the changes of the water level during 1990-2019; Under the influence of In-YR, the most obvious fluctuation of water level was in the flood adjustment period (Jun-Aug) and the impoundment period (Sep-Nov) when the average declined by about 0.50 and 0.67 m, respectively. Our findings provide a new insight into how to better maintain the stability of river-water system water resources under the influence of multiple factors.