基于多源遥感和多分支时空特征融合网络的高标准农田建设地块形态变化

    Morphological variation in well-facilitated farmland parcels after construction using multi-source remote sensing and dual branch spatiotemporal fusion network

    • 摘要: 农田地块是农业耕作管理和经营生产的基本单元。近年来,在高标准农田建设推进下,中国农田地块空间结构发生了显著变化。然而,当前尚缺乏一套系统完备的农田地块变化分析方法,制约了高标准农田地块整治成效的评估及其效益的可持续发挥。该研究以长江中游典型高标准农田建设区为案例,基于国产高分二号和哨兵二号遥感影像,结合多分支时空特征融合的深度学习模型,提取农田建设前后的地块矢量化边界。然后,选取平均地块面积、形状指数、分维数指数、边缘密度、地块密度和标准距离指数6项景观指标,系统刻画农田地块空间形态变化特征。结果表明,研究区内“小田变大田”趋势明显(平均地块面积从0.80 hm2增长至0.84 hm2),农田地块的几何形状趋于规则(形状指数从1.53下降至1.51、分维数指数从1.48下降至1.46、边缘密度下降约7%),田块空间聚集程度提高(地块密度从0.82降至0.72,标准距离指数离散程度变小)。多数区域表现出集约化、宜机化发展特征,少数区域受到配套设施建设或地形因素限制,地块整治效果不够显著。综上,该研究构建的基于多源遥感影像、深度学习算法和多维景观指标的地块变化分析与评估方法,能够有效表征高标准农田地块时空变化特征,为其动态监管与整治优化提供了科学的方法支持和理论依据。

       

      Abstract: A cropland parcel is one of the most basic units in agricultural production. Its spatial structure has also changed significantly in China in recent years, particularly with the advancement of well-facilitated farmland construction. However, it remains unclear on the spatial morphological variations in the cropland parcels after well-facilitated farmland construction. It is still lacking in the evaluation of construction and long-term benefits. In this study, a systematic and efficient monitoring was proposed to timely detect the cropland changes. Several typical regions of the well-facilitated farmland construction were also selected in the middle reaches of the Yangtze River. Sentinel-2 and GF-2 imagery data were integrated with deep learning (Dual branch SpatioTemporal Fusion Network, DSTFNet). The vectorized boundaries of cropland parcels were extracted after construction. Six landscape metrics—mean parcel size, shape index, fractal dimension index, edge density, parcel density, and standard distance index—were employed to characterize the spatial morphological features of the cropland parcels after construction. Furthermore, the Cropland Parcel Spatial Morphology Index (CPSMI) was developed to evaluate the interannual variations in the cropland use intensification. There was a trend of “small parcels larger” after construction, according to the high-accuracy cropland parcel boundary data (with over half of the accuracy metrics exceeding 90%). The mean parcel size increased from 0.80 to 0.84 hm². Contiguous cropland facilitated faster land transfer and then enhanced labor efficiency throughout agricultural production. In addition, the geometric shape of the parcels was more regular: the area-weighted mean shape index decreased from 1.53 to 1.51, the mean fractal dimension declined from 1.48 to 1.46. These indicators collectively confirmed that the shape regularity and simplified boundaries were improved after the cropland consolidation. Mean parcel density also decreased from 0.82 to 0.72, indicating a more concentrated spatial distribution. While the mean standard distance index remained unchanged, its dispersion was reduced for intensive agricultural production. Overall, the spatial morphology of well-facilitated farmland parcels in the study area tended toward greater mechanization and intensification. The CPSMI of well-facilitated farmland parcels also decreased from 0.378 to 0.357. Moreover, several challenges were presented in the well-facilitated farmland construction in agricultural modernization. There was an urgent need to optimize the site selection of cropland parcels and supporting facilities within the construction region. Rational planning was essential to consider the natural and production conditions in the local regions. The supporting facilities were expanded to encroach on the cropland resources, leading to a reduction in cropland. It was crucial to strike a balance between the production efficiency of cropland parcels and supporting facilities, particularly for the stable and high grain production. In conclusion, the cropland parcel assessment—using multi-source remote sensing imagery, deep learning, and landscape metrics—can provide an effective tool to track the spatial variations in cropland morphology. The valuable data support and theoretical foundations can also be offered to monitor, regulate, and optimize the well-facilitated farmland construction. The finding can greatly contribute to more scientifically grounded and data-driven decision-making on modern agriculture.

       

    /

    返回文章
    返回