ABSTRACT Globally, countries have experienced substantial increases in farmland abandonment. Although vegetation phenology is a key factor for the classification of land use, understanding of the phenological change of abandoned farmland is lacking. Using harmonic analysis of NDVI and NDWI extracted from Landsat imagery, this study investigates the distinctive phenological characteristics of abandoned farmland, which contrasts with that of three other agricultural types (paddy, agricultural field, orchard) in the study site of Gwangyang City in Jeollanam Province, South Korea. The results suggest that abandoned farmland has higher overall greenness coverage and overall water content in vegetation than the other uses. In terms of both indices, abandoned farmlands changed with relatively less fluctuation than those of other uses, suggesting the existence of constant and unmanaged vegetation from ecological succession, which differs from crop fields that undergo cultivation procedures. The significant harmonic components differed among agricultural types and vegetation indices. In paddy, NDVI was explained with multiple, higher-order harmonic components, while in other types only first-order components met the 5% statistical significance level. With NDWI, land types were more clearly discernible, because of the different cultivation procedures involving water: wet-field method (paddy), dryland farming (orchard, agricultural field), and no cultivation (abandoned farmland). The analysis confirms that harmonic analysis could be useful in discerning abandoned farmland among areas of active agricultural use and shows that the statistical significance of harmonic terms can be employed as indicators of different agricultural types. The observed pattern of the geographic distribution of abandoned farmland has policy implications for the promotion of sustainable reuse of marginal farmland.

中文翻译：

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时间序列植被指数数据调和分析废弃农田植被物候循环差异：以韩国光阳市为例

摘要 在全球范围内，各国的农田弃耕率大幅增加。虽然植被物候是土地利用分类的关键因素，但对废弃农田物候变化的了解尚缺乏。本研究利用从 Landsat 图像中提取的 NDVI 和 NDWI 的调和分析，研究了与全罗南道光阳市研究地点的其他三种农业类型（稻田、农田、果园）相比，废弃农田的独特物候特征。 , 韩国。结果表明，废弃农田比其他用途具有更高的整体绿化覆盖率和整体植被含水量。从这两个指标来看，废弃耕地的变化幅度均小于其他用途，表明存在来自生态演替的恒定和未管理的植被，这与经过耕作程序的农田不同。不同农业类型和植被指数的显着谐波分量不同。在稻田中，NDVI 被解释为多个高次谐波分量，而在其他类型中，只有一阶分量满足 5% 的统计显着性水平。使用 NDWI，土地类型更清晰可辨，因为涉及水的耕作程序不同：湿地法（稻田）、旱地耕作（果园、农田）和不耕作（废弃农田）。分析证实调和分析可用于区分活跃农业利用区的废弃农田，并表明调和项的统计显着性可作为不同农业类型的指标。观察到的废弃农田地理分布模式对促进边际农田的可持续再利用具有政策意义。