黄土高原地区土地覆盖类型的时空格局

[目的] 构建黄土高原地区长时序、高精度的土地覆盖数据集，对该区2001—2020年土地覆盖的时空格局进行分析，并为该地区生态环境保护和可持续发展提供科学依据。[方法] 利用多源、多时期土地覆盖产品和地面特征数据构建训练样本，并使用谷歌地球引擎（Google Earth Engine，GEE）平台和随机森林分类模型生成黄土高原地区土地覆盖（land cover of Loess Plateau，LCLP）数据集。在此基础上，通过空间分析和一元线性回归模型对黄土高原地区土地覆盖类型的时空格局进行分析。[结果] 基于随机森林验证集的结果显示，LCLP产品的总体精度和kappa系数均高于90%。基于独立验证集的精度验证结果显示，LCLP的总体精度较现有产品提高了0.58%～20.23%。同时，耕地、林地、草地、不透水面和裸地的分类精度均得到了提升。[结论] 本研究构建的LCLP数据集分类精度相较于其他产品有了显著提升，适用于反映黄土高原地区土地覆盖的变化。2001—2020年，黄土高原地区耕地和灌木呈现下降趋势，而林地、水体和不透水面呈现为极显著的上升趋势。从土地覆盖的变化情况来看，耕地和草地是其他土地覆盖类型新增的主要来源。

Spatiotemporal Pattern of Land Cover Types on Loess Plateau

[Objective] A long-term and high-precision land cover dataset was constructed for the Loess Plateau. The spatiotemporal pattern of land cover in 2001 and 2020 was analyzed in order to provide a scientific underpinning for initiatives concerning ecological environmental preservation and sustainable development within the region. [Methods] Training samples were constructed using multiple sources of land cover products and ground feature data from various time periods. The Google Earth Engine (GEE) platform and a random forest classification model were used to generate the land cover of Loess Plateau (LCLP) dataset. Spatial analysis and a univariate linear regression model were then used to analyze the spatiotemporal pattern of land cover types on the Loess Plateau. [Results] According to the validation set built using random forest, LCLP exhibited an overall accuracy and kappa coefficient greater than 90%. Moreover, based on the independent verification set, LCLP demonstrated an overall accuracy ranging from 0.58% to 20.23% higher than existing products. Additionally, the accuracy of the classification of various land cover types, including cultivated land, forest land, grassland, impervious surface, and bare land, was increased. [Conclusion] Compared with other datasets, LCLP significantly improved classification accuracy and is suitable for accurately reflecting land cover changes for the Loess Plateau region. During 2001-2020, there has been a decreasing trend in cultivated land and shrubs in the Loess Plateau region, while forest land, water bodies, and impervious surfaces have shown a significant increasing trend. From the perspective of land cover changes, cultivated land and grassland were the primary sources of newly added land cover types.