Soil moisture and vapor pressure deficit controls of longleaf pine physiology: results from a throughfall reduction study
Soil moisture and vapor pressure deficit controls of longleaf pine physiology: results from a throughfall reduction study
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DOI：
10.1007/s00468-023-02423-3
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发表时间：
2023-06
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通讯作者：
Caren C. Mendonca;L. Samuelson;Tom A. Stokes;Michael R. Ramirez;C. Gonzalez-Benecke;Michael J. Aspinwall
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作者：
Caren C. Mendonca;L. Samuelson;Tom A. Stokes;Michael R. Ramirez;C. Gonzalez-Benecke;Michael J. Aspinwall
Key messageLongleaf pine表现出对土壤水分减少和VPD增加的一般抗性，但结果突出了可能引发长叶松功能和生产力下降的土壤和大气条件。AbstractLow土壤水分和高大气蒸汽压赤字（VPD）独立限制树木功能和森林生产力。然而，问题仍然是如何大，建立树木响应干燥的土壤和高VPD在较长的时间内。我们进行了为期3年的穿透雨减少实验在年轻（12-14岁）长叶松种植园在西格鲁吉亚（美国）。我们假设，穿透雨减少会降低土壤水分，叶尺度气孔导度（gs），净光合作用（Pnet），但增加内在水分利用效率（iWUE）。我们还假设，穿透雨减少将减少冠层电导（Gs）在参考VPD为1千帕和GS VPD的敏感性。此外，我们usedGsdata收集在两个治疗，以确定断点的相对控制土壤水分和VPD上Gs。降水量减少使土壤水分含量降低，使净光合速率（Pnet）和净光合速率（-21%，13%）略有下降，但对水分利用效率（iWUE）没有影响。正如预期的那样，减少穿透雨降低GsandGssensitivity VPD分别为20%和8%。尽管如此，穿透雨减少对树木生长或森林生产力的影响很小。重要的是，GS VPD的敏感性是相似的，在中等土壤水分，但最高和最低的土壤水分高于田间持水量和低于永久萎蔫点，分别。因此，我们可以确定阈值的相对控制土壤水分和VPD overGs。这些结果表明，长叶松人工林的一般阻力减少土壤水分和增加VPD，但突出的土壤和大气条件，可能会引发长叶松功能和生产力下降。
Key messageLongleaf pine demonstrated general resistance to reduced soil moisture and increased VPD, but results highlight the soil and atmospheric conditions that could trigger declines in longleaf pine function and productivity.AbstractLow soil moisture and high atmospheric vapor pressure deficit (VPD) independently limit tree function and forest productivity. However, questions remain about how large, established trees respond to dry soil and high VPD over longer time periods. We carried out a 3-year throughfall reduction experiment in a young (12–14-year-old) longleaf pine plantation in west Georgia (USA). We hypothesized that throughfall reduction would reduce soil moisture, leaf-scale stomatal conductance (gs), and net photosynthesis (Pnet), but increase intrinsic water-use efficiency (iWUE). We also hypothesized that throughfall reduction would reduce canopy conductance (Gs) at a reference VPD of 1 kPa andGssensitivity to VPD. In addition, we usedGsdata collected across both treatments to identify breakpoints in the relative control of soil moisture and VPD onGs. Throughfall reduction decreased soil moisture and caused small reductions ings( – 21%) andPnet( – 13%), but no change in iWUE. As expected, reduced throughfall decreasedGsandGssensitivity to VPD by 20 and 8%, respectively. Despite this, throughfall reduction had very little effect on tree growth or forest productivity. Importantly,Gssensitivity to VPD was similar at intermediate soil moisture, but highest and lowest at soil moistures above field capacity and below the permanent wilting point, respectively. Consequently, we could identify thresholds in the relative control of soil moisture and VPD overGs. These results demonstrate the general resistance of longleaf pine plantations to reduced soil moisture and increased VPD but highlight the soil and atmospheric conditions that could trigger declines in longleaf pine function and productivity.