哈尼梯田对厄尔尼诺极端干旱事件的响应及其机制分析

为探讨自然环境要素对典型干旱事件的响应与路径,以2019年厄尔尼诺极端干旱事件为背景,在气象站观测数据基础上识别出1个干旱年份(2019年)和1个正常年份(2013年),使用landsat8影像反演了哈尼梯田区2个年份的地表温度(TEM)、土壤水分(TVDI)、植被覆盖(NDVI)、地表水体(NDWI)等自然环境要素数据,进一步探讨了哈尼梯自然环境要素对极端干旱事件的响应状态、相互作用、影响路径等问题。结果表明:哈尼梯田区在极端干旱事件下气温增加了约2℃,植被指数下降了约0.04,土壤水分指数增加了约0.07,水体面积下降了40.2%;地表温度与植被覆盖、地表水体为显著负相关(p0.05),与土壤水分为显著正相关(p0.05);植被覆盖与土壤水分为显著负相关(p0.05),与地表水体为显著正相关(p0.05);土壤水分与地表水体为显著负相关(p0.05);地表温度、土壤水分、植被覆盖、地表水体均发生了显著变化(p0.05),且形成了正反馈路径,加剧了区域的干旱。研究结果可高效合理地预防和减缓干旱对社会和自然环境的影响具有重要科学和现实意义。     

干旱区典型绿洲土壤有机质的反演及影响因素研究

为了大面积、高精度地反演土壤有机质含量,为农业可持续发展提供数据支撑。以新疆渭干河-库车河三角洲绿洲为研究区,采用波段平均法将实测高光谱窄波段拟合为Landsat 8 OLI遥感影像的宽波段,建立土壤有机质含量的估算模型,并将最优估算模型应用到经过波段校正的Landsat 8OLI遥感影像中。结果表明:(1)反射率进行倒数、对数、平方、一阶微分等数学变换后与有机质含量的相关性显著提高;(2)土壤有机质的高光谱估算模型拟合度较高,最优估算模型的决定系数R2为0.852,采用比值法对多光谱波段反射率进行校正,校正后的遥感影像反演结果得到了较大提高,检验样本的决定系数R2从0.711提升至0.849。从反演结果来看,将高光谱估算模型应用到经过订正的多光谱影像,土壤有机质反演模型的精度得到了大幅度提高,运用此方法可以实现高精度的土壤有机质区域化反演。(3)有机质的分布受土地利用类型、土壤颗粒组成、土壤质地的影响,其中土壤质地对有机质的空间分布影响最为显著。     

Long‐term changes in the distribution and core habitat use of a coastal delphinid in response to anthropogenic coastal alterations

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