| With the acceleration of industrialization and urbanization,the shortage of land resources has become a key problem that restricts regional development.With the increasing conflicts between human beings and land resource,the excessive deforestation and land reclamation activities of human beings have led to the sharp decrease of forest area,the serious destruction of forest ecosystem and a series of ecological problems such as soil erosion and desertification.In order to solve these problems,Chinese government launched the Grain foe Green Project to mitigate soil erosion and improve ecological environment.However,the implementation of the Grain for Green Project is mainly based on patch scale.The reforestation regions are selected only considering the function of water and soil conservation with the factor of habitat protection ignored.On account of ignoring considerations to landscape connectivity,it is limited to species development and the biodiversity protection.Therefore,to ensure the successful implementation of the Grain for Green Project,a model that integrates ecological network method and landscape connectivity analysis is urgently needed.This study proposes a reforestation area identification optimization model that considering landscape connectivity from the view of species habitat protection.As for the nodes selection of the ecological network,the ecological source habitat patches area selected from the current forest areas by the Morphological Spatial Pattern Analysis.The potential reforestation areas are identified not only based on the evaluation and analysis of soil erosion sensitivity and cropland suitability that previous researches do,but also considering landscape connectivity.And then,we construct the ecological networks and analyze the network connectivity indexes to identify the optimal and important reforestation patches.Additionally,we design four different reforestation strategies according to the patch importance,patch size and spatial position to compare the behaviors of different reforestation sequences,which can guide the decision of optimal reforestation strategy.In this study,Wanzhou district of Chongqing City is selected as a case study.The results of our study shows as follows:(1)The highly soil erosion sensitive area is789.92 km~2,accounting for 22.85%of the total area of Wanzhou district.The extremely soil erosion sensitive area is 352.27 km~2,accounting for 10.19%of the total area of Wanzhou.(2)As for the cropland suitability,the marginal suitable area is1126.64 km~2,accounting for 32.59%.The unsuitable area is 520.28 km~2,accounting for 15.05%.(3)176 core habitat areas(ecological source patches)are extracted by the Morphological Spatial Pattern Analysis method,with a total area of 407.38 km~2.317potential reforestation patches are extracted based on the soil erosion sensitivity analysis and cropland suitability assessment,with a total area of 73.08 km~2.For four different bird species,the important potential reforestation areas are selected by the delta Probability of Connectivity index are 7.16 km~2,8.68 km~2,14.08 km~2and 8.20km~2.The numbers of optimal reforestation patches for four bird species are 250,244,234 and 230.These patches’total area is 63 km~2.(4)By the behaviors of four different strategies,we can conclude that for species with poor or medium migration capacity,the first strategy which based on the descending order of patch importance is the most optimal strategy.And for species with strong migration ability,the second strategy which based on the increasing order of patch size is the most optimal strategy.(5)By employing the landscape pattern indexes to compare the behaviors of the traditional slope scheme and optimal reforestation scheme,we can find that the optimal reforestation scheme is better than the traditional slope scheme. |
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