[Assessment of ecological vulnerability in multi-scale and its spatial correlation: A case study of Bailongjiang...

The study of ecological vulnerability is of great significance to regional ecological environment protection and sustainable development. Bailongjiang Watershed (BLJW) of Gansu Pro-vince is a vital area for water conservation and environmental fragile in the upper Yangtze River. Therefore, it is necessary to understand the ecological vulnerability of BLJW for local sustainable development. Based on the sensitivity-recovery-pressure (SRP) model, landscape pattern index and the typical ecosystem type, we constructed the assessment system of ecological vulnerability by taking township as the spatial unit to analyze the spatiotemporal pattern of ecological vulnerability from the township, county, watershed scales in BLJW of Gansu Province in 2002 and 2014 via the auxi-liary regression, entropy weight, synthetic index, and spatial autocorrelation methods. The results showed that from the view of the township scale, the townships of severe or extreme vulnerability were concentrated in the northwestern Tanchang and most of Wudu in 2002 and 2014. The ecological vulnerability in the watershed had changed from moderate vulnerability to light vulnerability at township scale. At the county scale, the change of ecological vulnerability in Zhouqu was relatively stable, while that of Wudu, Wenxian, Tanchang and Diebu were relatively violent from 2002 to 2014. The ecological vulnerability of Wudu, Wenxian and Diebu improved to a certain extent, while that of Tanchang was deteriorating gradually. On watershed scale, the average value of ecological vulnerability index in the watershed were 0.2976 and 0.2904 in 2002 and 2014, respectively, showing a small downward trend, indicating that the ecological vulnerability in the watershed decreased in the past 12 years. The coefficients of variation were 0.3905 and 0.4358, respectively, with an increasing trend, suggesting that the spatial pattern of ecological vulnerability in the watershed developed in an unbalanced way. In 2002, the Moran I of ecological vulnerability index in the watershed was 0.5460, implying that the ecological vulnerability in the watershed was spatially agglomerated. Specifically, the areas of high-high were mainly distributed in the northern and central Wudu, and northwestern Tanchang. In 2014, the Moran I of ecological vulnerability index in the watershed increased to 0.5635, which indicated that the spatial agglomeration was more significant, and the areas of high-high were concentrated in central Wudu and northwestern Tanchang.