陕北黄土高原生态脆弱性时空变异及驱动因素分析

Spatiotemporal variation and driving factors of ecological vulnerability in the Loess Plateau of northern Shaanxi

在多源数据的支撑下,基于敏感性-恢复力-压力模型构建评估指标体系,分析生态恢复工程实施前后(1997年和2021年)陕北黄土高原不同行政区、不同生态功能区和不同坡度的生态脆弱性时空分异规律及驱动机制。结果表明:(1)陕北黄土高原生态脆弱性明显改善,生态脆弱性指数均值从41.74下降至32.96,减幅21.0%;生态脆弱性等级也整体下降,已由中脆弱和低脆弱性占主导转化为低脆弱性占主导的格局。生态脆弱性存在明显地带性分布特征,从南到北生态脆弱性等级逐步提高。(2)1997—2021年,51.2%的区域生态脆弱性有所改善,以中脆弱改善到低脆弱为主;4.6%的区域生态脆弱性有所增加,以一般脆弱增加至低脆弱、低脆弱增加至中脆弱为主。铜川市、延安市和榆林市辖区内生态脆弱性指数和等级均在下降,其中铜川市生态脆弱性最低,榆林市最高。3个生态功能区生态脆弱性指数和等级均在显著下降,降幅表现为:退耕还林区>风沙区>黄桥林区。(3)符合退耕条件的区域,高等级脆弱性大幅转化为低等级脆弱性,生态脆弱性得到明显改善,工程取得了较为显著的成效。(4)剖析驱动机制可以发现,人为因素和自然因素的驱动力各占83.1%和16.9%,说明生态恢复工程是区域生态脆弱性显著改善的主要驱动力。研究结果可为该区域生态恢复工程成效评估和生态可持续性修复提供科学的参考数据。

Studying spatiotemporal changes in ecological vulnerability in the Loess Plateau region of northern Shaanxi before and after the implementation of an ecological restoration project helps to understand the impact of the project implementation on regional ecological vulnerability and provides a scientific reference for the sustainable restoration of regional ecology.This study aims to provide a scientific foundation for the sustainable restoration of the ecology in this region by leveraging multisource data and an evaluation index system built around the sensitivity-resilience-stress model.The analysis encompasses the spatiotemporal variation of ecological vulnerability in different administrative regions,diverse ecological function areas,and varying slopes in the region before and after the implementation of the project(1997 and 2021)is analyzed with the driving mechanism.The results show the following key insights:(1)The ecological vulnerability in the Loess Plateau,China,was improved substantially.The mean regional ecological vulnerability index decreases from 41.74 to 32.96,a decrease of 21.0%.This shift transforms from medium and low vulnerability to a predominantly low vulnerability pattern.(2)Ecological vulnerability in the study area exhibits a zonal distribution,and the ecological vulnerability in the south is better than that in the north.From 1997 to 2021,51.2%of the regional ecological vulnerability in the study area was improved,mainly from medium to low vulnerability,accounting for 75.3%of the total area improved,predominantly concentrated in farmland to forest and sandstorm areas.The second notable improvement involves the shift from low to general vulnerability,accounting for 16.9%of the improved areas,mainly within the Huangqiao forest area.Conversely,4.6%of the regional ecological vulnerability increases in the study area,with general vulnerability rising to low and low vulnerability rising to medium,accounting for 52.9%and 45.6%of the increased area of ecological vulnerability,respectively.These increases are scattered in the sandstorm areas and Huangqiao forest areas.Among the administrative units,Tongchuan City is the lowest ecologically fragile,while Yulin City is the highest,with the most vulnerable areas concentrated in Yulin City.However,the ecological vulnerability index and grade declined in the three municipal districts.Similarly,the ecological vulnerability index and grade of the three ecofunctional areas considerably decreased,with the largest decrease in the area of returning farmland to forest,followed by the wind-sand areas,and finally,the Huangqiao forest area.(3)In designated cropland-to-forest conversion zones,high-grade vulnerability largely transforms into low-grade vulnerability,leading to noticeable regional ecological improvement.(4)Analysis of the driving mechanism reveals that the driving forces of human and natural factors account for 83.1%and 16.9%,respectively.This result shows that ecological restoration projects are the main driving force for the profound improvement of regional ecological vulnerability.