Drought decreases water storage capacity of two arboreal epiphytes with differing ecohydrological traits
Drought decreases water storage capacity of two arboreal epiphytes with differing ecohydrological traits
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DOI：
10.1016/j.scitotenv.2023.164791
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发表时间：
2023-06-27
影响因子：
9.8
通讯作者：
Gotsch，Sybil G.
中科院分区：
文献类型：
--
作者：
Moore，Althea F. P.;Antoine，Jalayna;Gotsch，Sybil G.
树附生植物，生长在树上的植物，可以显着增加雨水储存和蒸发（即，“拦截”）。干旱条件可能会影响这种水文作用，因为附生植物的生理反应会改变叶片的特性，从而影响水分保持。干旱引起的附生植物储水能力的变化可能会大大改变冠层水文，但还没有研究。我们测试了干旱对两种具有不同生态水文特征的附生植物：复叶蕨（Pleopeltis polypodioides）和西班牙藓（Tillandsia usneoides）的叶片和叶特性的储水能力（Smax）的影响。这两个物种在美国东南部的海洋森林中很常见，气候变化预计会减少春季和夏季的降水。为了模拟干旱，我们将叶片干燥至鲜重的75%、50%和~ 25%，并量化它们的Smaxin雾室。我们测量了相关的叶片特性：疏水性、最小叶片电导率（gmin;干旱条件下水分损失的衡量标准）和归一化差异植被指数（NDVI）。我们发现，干旱显着降低Smax和增加叶片疏水性的两个物种，表明较低的Smax可能是由于脱落的液滴。虽然整体减少在Smax没有两个物种之间的差异，他们表现出不同的干旱响应。脱水T.在干旱条件下，乌桕叶片的gmin较低，表明其具有限制水分流失的能力，而水龙骨科植物在脱水条件下的gmin增加，这与其非凡的抗水分流失能力相一致。脱水后，油松的NDVI下降，而油松的NDVI则没有下降。水龙骨科我们的研究结果表明，增加干旱可能有显着的影响冠层水分循环减少的Smax的附生植物。减少森林冠层的降雨截留和储存可能对水文循环产生广泛影响，因此了解植物干旱响应对水文的潜在反馈至关重要。这项研究强调了连接叶片尺度的植物响应与更广泛的水文过程的重要性。
Arboreal epiphytes, plants that grow on trees, can significantly increase rainwater storage and evaporation (i.e., “interception”) within canopies. Drought conditions may affect this hydrological role, as epiphytes' physiological responses change leaf properties that affect water retention. Drought-induced changes in epiphyte water storage capacity could substantially alter canopy hydrology, but have not been studied. We tested the effects of drought on the water storage capacity (Smax) of leaves and leaf properties of two epiphytes with distinct ecohydrological traits: resurrection fern (Pleopeltis polypodioides), and Spanish moss (Tillandsia usneoides). Both species are common in maritime forests of the Southeastern USA, where climate change is expected to decrease precipitation in spring and summer. To simulate drought, we dried leaves to 75 %, 50 %, and ~25 % of fresh weight, and quantified theirSmaxin fog chambers. We measured relevant leaf properties: hydrophobicity, minimum leaf conductance (gmin; a measure of water loss under drought), and Normalized Difference Vegetative Index (NDVI). We found that drought significantly reducedSmaxand increased leaf hydrophobicity for both species, indicating that lowerSmaxmay be due to shedding of droplets. While the overall reduction inSmaxdid not differ between the two species, they exhibited distinct drought responses. DehydratedT. usneoidesleaves had lower gmin, demonstrating the ability to limit water loss under drought.P. polypodioidesincreased gminwhen dehydrated, consistent with its extraordinary ability to withstand water loss. NDVI decreased with dehydration inT. usneoidesbut notP. polypodioides. Our results suggest that increased drought may have a dramatic effect on canopy water cycling by reducing theSmaxof epiphytes. Reduced rainfall interception and storage in forest canopies could have widespread effects on hydrological cycling, thus understanding the potential feedbacks of plant drought response on hydrology is crucial. This study highlights the importance of connecting foliar-scale plant response with broader hydrological processes.