Evaluating Landscape Degradation Along Climatic Gradients During the 1930s Dust Bowl Drought From Panchromatic Historical Aerial Photographs, United States Great Plains
Evaluating Landscape Degradation Along Climatic Gradients During the 1930s Dust Bowl Drought From Panchromatic Historical Aerial Photographs, United States Great Plains
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DOI：
10.3389/feart.2018.00153
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发表时间：
2018-10-12
影响因子：
2.9
通讯作者：
Forman, Steven L.
中科院分区：
文献类型：
--
作者：
Bolles, Kasey C.;Forman, Steven L.
美国大平原（USGP）是全球最多产的牧场之一，也是大气中重要的碳汇，但草原对降水的反应是高度可变的，并且随着时间和空间的变化而受到的约束很少。USGP有丰富的历史航空摄影记录，提供了无与伦比的过去景观视图，并允许评估地表对干旱的反应，超出卫星记录，例如在20世纪30年代的沙尘暴干旱（DBD）期间。这项研究从20世纪30年代末从分布在USGP生态区的六个县获得的辐射校正和地理校正数字化航空底片的无缝拼接中分类了地表剥蚀的程度和位置。在子午线100度以东的地点，退化的主要来源是耕地和河流沉积物，这与木本植被对未开垦地区水分供应的反应有关。在西部，被剥蚀的地表主要是风沙和沙丘，这与干旱条件的强度和植物多样性的减少有关。干旱的离散空间特征不仅在传统的南部沙尘区，而且在北部和中部平原。站点变异性的统计分析表明，景观对DBD的响应受干湿分水岭、降水和温度异常严重程度的影响最大。随着预计21世纪干旱的增加，风成过程在西部草原上层叠，就像沙尘暴一样，可能会对未来的尘埃颗粒排放以及土地和碳储存管理产生重大影响。
The United States Great Plains (USGP) are some of the most productive rangelands globally and a significant carbon sink for the atmosphere, but grassland response to precipitation is highly variable and poorly constrained over time and space. There is a rich historical aerial photographic record of the USGP which provides an unparalleled view of past landscapes and allows for evaluation of surficial response to drought beyond the satellite record, such as during the 1930s Dust Bowl Drought (DBD). This study classified the extent and loci of surficial denudation from seamless mosaics of radiometrically corrected and georectified digitized aerial negatives acquired in the late 1930s from six counties distributed across USGP ecoregions. The dominant sources of degradation found for sites east of the 100th meridian are cultivated fields and fluvial deposits, associated with woody vegetation response to water availability in uncultivated areas. For sites to the west, denuded surfaces are predominantly eolian sandsheets and dunes, correlated with intensity of drought conditions and reduced plant diversity. Discrete spatial signatures of the drought are observed not only within the classically recognized southern Dust Bowl area, but also in the northern and central plains. Statistical analyses of site variability suggest landscape response to the DBD is most strongly influenced by the arid-humid divide and severity of precipitation and temperature anomalies. With a projected increase 21st century aridity, eolian processes cascading across western grasslands, like during the Dust Bowl, may significantly impact future dust particle emission and land and carbon storage management.