The impact of water supplement on habitat suitability for breeding red-crowned cranes

Abstract

With the increasing influence of climate change and human activities, water shortage in wetlands is becoming an urgent problem. In order to maintain waterfowl habitat and prevent wetland degradation, water management strategies have been implemented for many wetland reserves. However, there is often uncertainty concerning optimal water supply amount, especially during the breeding periods of endangered waterfowls. In this study, the MIKE 21 hydrodynamic model was used to simulate the impact of different water supply amounts on water depths in the Zhalong wetlands, China. The simulated water depths were utilized to evaluate the area of suitable habitat for breeding red-crowned cranes (Grus japonensis) based on the Maximum Entropy (MaxEnt) niche model. The optimal water supply amount was determined by maximizing the extent of suitable breeding red-crowned cranes habitat. Results suggest that for the Zhalong wetlands, water depth is the key habitat feature which determines the variability of suitable habitat extent. The optimal water supply amount for the Zhalong wetlands in 2014 was 1.13 × 108 m3, producing a suitable breeding habitat area of 237.25 km2 at the end of the water supply period, 50% greater than the suitable habitat extent with the existing water supplement scenario. The proposed method, combining a hydrodynamic model with the MaxEnt niche model, has the potential to determine optimal water supply amount to any semi-closed floodplain. The results of the current study can not only provide an evidence base for wetland water management, but also provide a scientific basis for the study of wetland eco-hydrological processes and their impact on wetland biological diversity conservation.