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浙江省2000—2022年植被覆盖时空动态及其驱动力

The Spatiotemporal Dynamics and Driving Forces of Vegetation Coverage in Zhejiang Province from the Year 2000 to 2022

  • 摘要: 浙江省是国家战略发展布局中的关键区域,森林覆盖率高但生产力较低,探究其植被覆盖度(Fractional Vegetation Cover,FVC)动态及其驱动力对区域生态修复和可持续发展具有重要指导意义。本研究基于Google Earth Engine平台,以Landsat Collection 2为数据源,采用NDVI最大值合成法、像元二分法和Sen + Mann-Kendall检验法探究浙江省2000—2022年植被覆盖度时空动态,利用最优参数地理探测器模型定量分析植被覆盖度的驱动因子,并结合转移矩阵和土地利用变化图谱探究土地利用与植被覆盖度关系,旨在为区域生态保护与管理提供科学依据。结果表明:(1)时间动态上,2000—2022年研究区植被覆盖度呈波动增长趋势,增速达0.30%·a−1。(2)空间格局上,浙江省整体植被覆盖状况普遍较好,以较高和高覆盖度为主。FVC显著和极显著改善区域占比分别为10.28%和25.34%,显著和极显著退化区域占比分别为3.28%和4.35%。FVC变化趋势具有明显的空间异质性:海拔高和坡度大的地区通常FVC较高且显著改善,而浙北平原区、沿海地区、衢江和金华江沿线通常FVC较低且显著退化。(3)驱动因子分析表明,人为活动因子的影响强于自然因子,其中土地利用类型、夜间灯光指数、海拔和坡度是影响植被覆盖度的主导因子,且q值均大于0.28。(4)交互作用中,土地利用类型与其他因子的交互作用占主导地位,q值均大于0.53,且土地利用类型与夜间灯光指数交互影响力最强,q值达0.553。揭示了最适宜研究区的植被生长驱动因子类型或范围。(5)土地利用变化上,耕地转为不透水地表最为突出,其分布范围与FVC极显著退化区基本一致,表明城镇化扩张是区域植被退化的主要驱动力;同时耕地与林地表现为相互转化。

     

    Abstract: Zhejiang Province is a key area in China’s strategic development layout with high forest coverage but low productivity, therefore, it is of great significance to explore the dynamics of fractional vegetation cover (FVC) and the driving forces for regional ecological restoration and sustainable development. Landsat Collection 2 data on the Google Earth Engine platform being the basis, the NDVI maximum synthesis method, pixel dichotomy method, and Sen trend analysis and Mann-Kendall test were adopted to investigate the spatiotemporal dynamics of FVC in Zhejiang Province from the year 2000 to 2022. The optimal parameter geographic detector model was employed to quantitatively analyze the driving factors of FVC, and the transition matrix and land use change map were incorporated to explore the relationship between land use and FVC dynamics, aiming to provide a scientific basis for regional ecological protection and management. The results showed that: (1) Temporally, the FVC in the study area showed a fluctuating upward trend from 2000 to 2022, with a growth rate of 0.30% per year. (2) Spatially, the overall vegetation coverage in Zhejiang Province was generally in a better condition, dominated by medium-high and high FVC. Areas with significant and extremely significant improvement in FVC accounted for 10.28% and 25.34% respectively, while those with significant and extremely significant degradation accounted for 3.28% and 4.35%, respectively. The changing trend of FVC had obvious spatial heterogeneity: Areas with high elevation and steep slopes generally had higher FVC and significant improvement, whereas the northern plains of Zhejiang Province, coastal areas, and areas along the Qujiang River and Jinhua River usually had lower FVC and significant degradation.(3) Analysis of driving factors revealed that the impact of anthropogenic factors was stronger than that of natural factors, in which land use type, nighttime light index, elevation and slope were the dominant factors affecting FVC, with q values all exceeding 0.28. (4) The interaction analysis demonstrated that the interaction between land use types and other factors played a dominant role, with q values greater than 0.53. The interaction between land use types and nighttime light index had the strongest influence, with a q value reaching 0.553. This study revealed the types or ranges of driving factors most suitable for vegetation growth in the study area. (5) The land use change analysis revealed that the conversion of cropland to impervious surfaces was most prominent, with its spatial distribution closely coinciding with areas of extremely significant degradation in FVC, which demonstrated that urban expansion was the primary driving force of regional vegetation degradation, concurrently, bidirectional conversion between cropland and forestland was observed.

     

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