High Heterogeneity in Canopy Temperature Among Co‐occurring Tree Species in a Temperate Forest
High Heterogeneity in Canopy Temperature Among Co‐occurring Tree Species in a Temperate Forest
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温带森林共生树种冠层温度的高度异质性
DOI：
10.1029/2020jg005892
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Yang, Xi
中科院分区：
文献类型：
--
作者：
Yi, Koong;Smith, Jake W.;Jablonski, Andrew D.;Tatham, Elizabeth A.;Scanlon, Todd M.;Lerdau, Manuel T.;Novick, Kimberly A.;Yang, Xi
树木通过蒸腾作用调节树冠温度（Tc）以维持最佳温度范围。在不同的森林中，如美国东部的森林，不同物种对变化的环境条件的敏感性可能不同，反映了水力特征的广泛差异。然而，在成熟的森林中，这些联系并没有得到很好的理解，在那里，历史上很难获得数据。热成像仪（tic）的最新进展使以前难以接近的高大树木的测量成为可能。通过利用TIC和树液通量测量，我们研究了共生树木(栎，Q。falcata，和pinus virginia)等树种在气温（Ta）和大气VPD （VPDa）变化的影响下，会改变其冠层表面的温度和蒸汽压差（VPDc）。我们发现，在干燥条件下，对气孔功能调节最强烈的物种的冷却效应较弱(等水；P。virginiana)。其中，下午松林的Tc（最高1.3°C）和VPDc（最高0.3 kPa）较高，∆T（=Tc - Ta）和∆VPD （=VPDc - VPDa）对气候变化的敏感性较小。此外，在树冠的阳光照射部分和遮荫部分之间，温度和vpdc的显著差异暗示了对调节的非蒸发效应。具体来说，松林冠层内的碳含量更为均匀，这反映了叶片形态的差异，这使得冠层对太阳辐射的透射率更高。物种间的变率（高达1.3°C）与之前报道的不同土地覆盖类型的地表温度差异（1°C至2°C）相当，这意味着物种组成变化可能对局部/区域地表温度产生重大影响。
Trees regulate canopy temperature (Tc) via transpiration to maintain an optimal temperature range. In diverse forests such as those of the eastern United States, the sensitivity ofTcto changing environmental conditions may differ across species, reflecting wide variability in hydraulic traits. However, these links are not well understood in mature forests, whereTcdata have historically been difficult to obtain. Recent advancement of thermal imaging cameras (TICs) enablesTcmeasurement of previously inaccessible tall trees. By leveraging TIC and sap flux measurements, we investigated how co‐occurring trees (Quercus alba,Q. falcata, andPinus virginiana) change theirTcand vapor pressure deficit near the canopy surface (VPDc) in response to changing air temperature (Ta) and atmospheric VPD (VPDa). We found a weaker cooling effect for the species that most strongly regulates stomatal function during dry conditions (isohydric;P. virginiana). Specifically, the pine had higherTc(up to 1.3°C) and VPDc(up to 0.3 kPa) in the afternoon and smaller sensitivity of both∆T(=Tc−Ta) and∆VPD (=VPDc− VPDa) to changing conditions. Furthermore, significant differences inTcand VPDcbetween sunlit and shaded portions of a canopy implied a non‐evaporative effect onTcregulation. Specifically,Tcwas more homogeneous within the pine canopy, reflecting differences in leaf morphology that allow higher canopy transmittance of solar radiation. The variability ofTcamong species (up to 1.3°C) was comparable to the previously reported differences in surface temperature across land cover types (1°C to 2°C), implying the potential for significant impact of species composition change on local/regional surface temperature.
影响因子：
6.2
作者：
Young-il Kim;C. Still;D. Roberts;M. Goulden
通讯作者：
Young-il Kim;C. Still;D. Roberts;M. Goulden
植物维持恒定的叶片温度——I.假设限制的恒温
影响因子：
5.7
作者：
J. Mahan;D. R. Upchurch
通讯作者：
D. R. Upchurch
影响因子：
11.6
作者：
Quan Zhang;M. Barnes;M. Benson;E. Burakowski;A. Oishi;A. Ouimette;Rebecca Sanders‐DeMott;P. Stoy;M. Wenzel;L. Xiong;K. Yi;K. Novick
通讯作者：
Quan Zhang;M. Barnes;M. Benson;E. Burakowski;A. Oishi;A. Ouimette;Rebecca Sanders‐DeMott;P. Stoy;M. Wenzel;L. Xiong;K. Yi;K. Novick