重庆石漠化和非石漠化区植被绿度时空变化特征

目的] 为研究重庆岩溶石漠化和非石漠化地区植被绿度时空变化特征及其对土地利用类型的响应,有利于指导岩溶地区植被生态恢复的影响。方法] 基于植被叶面积指数(LAI)及土地利用类型数据,采用趋势分析和Hurst指数分析石漠化和非石漠化地区植被绿度的时空演变特征,利用土地利用转移矩阵定量分析土地利用变化对植被绿度的影响。结果] (1)石漠化和非石漠化地区的植被绿度整体呈增加趋势,分别在2007年和2012年达到最大绿度,绿度值为1.36和1.69,年平均增速为0.014和0.012。(2)石漠化和非石漠化地区植被绿度动态变化趋向良好,改善趋势面积占比分别为86.84%,87.04%,反持续改善趋势面积占比分别为52.82%,80.29%,是未来植被绿度主要变化趋势。(3)石漠化和非石漠化地区主要的土地利用类型是林地和耕地,且林地转化的耕地是植被绿度退化的主要发生区,耕地、灌木和草地转化的林地是植被绿度改善的主要发生区。(4)高LAI的土地利用类型转化为较低LAI土地利用类型导致LAI减小,降低植被绿度,较低LAI土地利用类型转化为高LAI土地利用类型,导致LAI增加。石漠化和非石漠化地区林地LAI转出总量减少最多,分别为11 902.01和4 442.18,转入总量增加最多分别为14 983.78和17 109.46;建设用地、水域和裸地面积较小,对LAI总量的影响不明显。结论] 研究结果有助于揭示生态脆弱区植被绿度的变化特征及对土地利用变化的响应机制,为重庆市岩溶地区石漠化治理、生态安全和经济可持续发展提供科学依据。

Spatial and Temporal Variation Characteristics of Vegetation Greenness in Rocky Desertification and Non-rocky Desertification Areas of Chongqing

Objective] The investigation of temporal and spatial variations in vegetation greenness and its response to different land use types in karst rocky desertification and non-rocky desertification areas in Chongqing is crucial for guiding ecological restoration efforts in karst regions. Methods] This study utilized vegetation leaf area index (LAI) data and land use type information to conduct a trend analysis and Hurst index calculations, aimed at analyzing the temporal and spatial evolution characteristics of vegetation greenness in both rocky desertification and non-rocky desertification areas. Additionally, a land use transfer matrix was employed to quantitatively assess the impact of land use changes on vegetation greenness. Results] (1) Vegetation greenness exhibited an increasing trend in both rocky desertification and non-rocky desertification areas, reaching maximum values of 1.36 and 1.69 respectively, with average annual growth rates of 0.014 and 0.012. (2) The dynamic changes observed in vegetation greenness within these areas demonstrated positive trends, with improvement trends accounting for 86.84% (rocky desertification) and 87.04% (non-rocky desertification). Furthermore, anti-continuous improvement trends were observed at rates of 52 .82% (rocky desertification) and 80.29% (non-rocky desertification), indicating the primary change trajectory for future vegetation greenness. (3) The main land use types in both rocky and non-rocky desertification areas were woodland and cropland, and cropland converted from woodland was the main occurrence of degradation of vegetation greenness, while woodland converted from cropland, shrubs and grassland was the main occurrence of improvement of vegetation greenness. (4) The conversion of land use types with high leaf area index (LAI) to those with low LAI resulted in a decrease in LAI and vegetation greenness, while the conversion from low LAI land use types to high LAI land use types led to an increase in LAI. In areas affected by stony desertification and non-stony desertification, the maximum reduction in total LAI transfer was 11 902.04 and 4 442.18 respectively, whereas the maximum increase was 14 983.78 and 17 109.46 respectively. The impact on total LAI from construction land, water area, and bare land area was minimal and not significant. Conclusion] These research findings contribute to understanding the change characteristics of vegetation greenness and its response mechanism towards land use changes in ecologically fragile areas. Furthermore, they provide a scientific basis for controlling rock desertification, ensuring ecological security, and promoting sustainable economic development in karst areas of Chongqing.