Climate sensitivity of water use by riparian woodlands at landscape scales
Climate sensitivity of water use by riparian woodlands at landscape scales
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DOI：
10.1002/hyp.13942
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发表时间：
2020-11-09
影响因子：
3.2
通讯作者：
Nagler, Pamela
中科院分区：
文献类型：
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作者：
Mayes, Marc;Caylor, Kelly K.;Nagler, Pamela
半干旱河岸林地面临着来自世界各地不断增加的采掘用水需求和气候变化的威胁。为了从战略上管理水资源，以及为潜在的气候未来制定成功的生态系统保护和恢复计划，需要改进对河岸林地水资源使用(蒸散，ET)及其对气候变量的敏感性的景观尺度的了解。在这项工作中，我们评估了2014-2019年美国亚利桑那州东南部80公里圣佩德罗河走廊的杨树-柳树河岸廊道林地的时空变异性及其与植被结构和气候变量的关系。我们使用了公开可用的遥感、气候和水文数据集的新组合：用于ET(Google Earth Engine EEFlux)的基于云的Landsat热遥感数据产品、Landsat多光谱图像和基于野外数据的植被结构校准(叶面积指数，LAI)，以及开放源码的气候和水文数据。我们发现，在景观尺度上，日蒸腾速率(6-10 mm day(-1))和生长季节蒸腾总量(400-1400 mm)与已公布的田间数据相匹配，而模拟的河段尺度平均LAI(0.80-1.70)与已公布的田间数据的较低范围相匹配。6年来，总生长季ET值的空间变异性(CV=0.18)大于时间变异性(CV=0.10)，说明河段尺度植被和水文条件对ET值动态控制的重要性。常年河段和间歇河段的ET对气候的响应不同。在常年径流河段，ET与温度显著相关，而在间歇性径流站点，ET与降雨量和径流量显著相关。在详细研究的范围中，我们发现LAI和ET之间存在正的但不同的对数关系。通过记录ET值在流域尺度上的高度空间变异性模式，这些结果强调了准确考虑林地植被结构和水文条件的差异对评估水分利用需求的重要性。结果还表明，ET的气候敏感性可以作为地下水资源相对于植被需求的一个远程指标，也可以作为一个指示养护管理优先事项的指标。
Semi-arid riparian woodlands face threats from increasing extractive water demand and climate change in dryland landscapes worldwide. Improved landscape-scale understanding of riparian woodland water use (evapotranspiration, ET) and its sensitivity to climate variables is needed to strategically manage water resources, as well as to create successful ecosystem conservation and restoration plans for potential climate futures. In this work, we assess the spatial and temporal variability of Cottonwood (Populus fremontii)-Willow (Salix gooddingii) riparian gallery woodland ET and its relationships to vegetation structure and climate variables for 80 km of the San Pedro River corridor in southeastern Arizona, USA, between 2014 and 2019. We use a novel combination of publicly available remote sensing, climate and hydrological datasets: cloud-based Landsat thermal remote sensing data products for ET (Google Earth Engine EEFlux), Landsat multispectral imagery and field data-based calibrations to vegetation structure (leaf-area index, LAI), and open-source climate and hydrological data. We show that at landscape scales, daily ET rates (6-10 mm day(-1)) and growing season ET totals (400-1,400 mm) matched rates of published field data, and modelled reach-scale average LAI (0.80-1.70) matched lower ranges of published field data. Over 6 years, the spatial variability of total growing season ET (CV = 0.18) exceeded that of temporal variability (CV = 0.10), indicating the importance of reach-scale vegetation and hydrological conditions for controlling ET dynamics. Responses of ET to climate differed between perennial and intermittent-flow stream reaches. At perennial-flow reaches, ET correlated significantly with temperature, whilst at intermittent-flow sites ET correlated significantly with rainfall and stream discharge. Amongst reaches studied in detail, we found positive but differing logarithmic relationships between LAI and ET. By documenting patterns of high spatial variability of ET at basin scales, these results underscore the importance of accurately accounting for differences in woodland vegetation structure and hydrological conditions for assessing water-use requirements. Results also suggest that the climate sensitivity of ET may be used as a remote indicator of subsurface water resources relative to vegetation demand, and an indicator for informing conservation management priorities.