The Impact Of Human Disturbances On Red-crowned Cranes Habitat Suitability Of Songnen Plain

Under the background of global change and the increasing of human disturbances,it is important to clarify the influencing factors of rare and endangered waterfowl habitats for the protection and management of wetland wild animals.Red-crowned crane is the national level protected animal and the world's endangered species.The Songnen Plain has an important wetland ecological type in the northeastern part of China and a national nature reserve that protects rare waterfowl such as cranes.Due to the increase of human disturbance activities,the number of rare waterfowl populations such as red-crowned cranes in the Songnen Plain region has decreased drastically,and the suitable habitat area is shrinking and biodiversity is seriously damaged.Therefore,studying the effects of human disturbance activities on the suitability of red-crowned crane habitats in the Songnen Plain region has the great significance for protecting the biodiversity of wetland waterfowl and promoting the sustainable development of biological resources and ecological environment.Based on the 3S technology platform,this paper selects the Songnen Plain as a research area and uses remote sensing images such as Landsat TM,Landsat OLI and DEM in 1995,2000,2010 and 2016.Considered the habitat selection of Red-crowned cranes,this paper selects 8 habitat features to assess the habitat quality of the Red-crowned cranes,including land use type,distance to residents,distance to farmlands,distance to roads,slope,aspect,NDVI,and distance to open water,which reflects the human disturbances,food sources,hiding conditions,and topographical characteristics.It evaluates and predicts the suitable habitat of red-crowned cranes in the study area and analyzes the impact of aggravation of human disturbance on the red-crowned crane habitat in the Songnen Plain in 1995-2016 by using a data-driven niche model-the maximum entropy model(MaxEnt),combining Red-crowned crane geographical distribution data.The research results can provide technical support for the protection of red-crowned crane habitats in Northeast China,and provide a scientific basis for planning and formulating red-crowned crane protection policies in the future.The main findings of this paper are as follows:(1)This paper constructs a habitat suitability evaluation model for four periods from 1995 to 2016.The results of the MaxEnt model were evaluated using the ROC curve.The values of the training set and the verification set AUC were both greater than 0.9.The evaluation results obtained in this paper have reached a high level,which proves that the MaxEnt model has higher prediction accuracy.It is excellent in predicting the distribution of suitable habitats of species,the weight analysis of environmental variables,and the quantitative analysis of the effects of environmental variables on the suitability of species habitats.(2)This paper combines the geographical distribution data and environmental variable data of red-crowned cranes,and uses Jackknife method to calculate the importance of each environmental variable.It analyzes the distribution of suitability of red-crowned crane habitat under the influence of human disturbance.Based on the analysis of the results of the four-stage model simulation,the most influential factor for the suitability of red-crowned crane habitat is the human disturbances factor,and the cumulative contribution rates are 58.09%,70.69%,78.73%,and 78.14%,respectively.The next influencing factors are food source factors,topographic factors,and concealed feature factors.In addition,the suitable habitat area of red-crowned cranes in the Songnen Plain is decreasing with the increase of farmlands,construction land and road network density.The suitable habitat area of red-crowned crane decreased by 16749km~2 from 1995to 2016,and decreased 6.7%on the percentage of the study area.It shows that the habitat quality of red-crowned cranes has been greatly affected by human activities.(3)Combined with the actual situation of the study area and the analysis of this study,we found that the suitable habitats of red-crowned cranes were concentrated in the western Songnen Plain,near the large-scale river beach and marsh wetlands.The area is relatively abundant in water and food,and is relatively concealment high and is far from human disturbance.The response curve of each human disturbances factor to the probability of emergence of red-crowned cranes is shown.The suitable habitat area for red-crowned cranes is in marsh wetlands 1.3km away from roads,1.4km away from cultivated land and 2.1km away from resident areas.It is the best place for red-crowned cranes to hide,forage and breed.