Large-diameter hail is unusual in the lowland tropics; consequently, its impact on water flux responses of trees and lianas due to foliage loss is unknown. In December 2012, Xishuangbanna Tropical Botanical Garden (21°55′N) in southern Yunnan, China, experienced the most severe hailstorm in approximately 30 years, with hailstones of 8- to 17-mm diameter falling for 10–30 min. We assessed the effect of this hailstorm on sap flux density (SFD) in response to foliage loss in six tree and three liana species. Among the trees, for a given atmospheric vapour pressure deficit (VPD), Tectona grandis and Dipterocarpus tuberculatus showed a significant reduction in sap flux density and water use during the post-hailstorm week in comparison to pre-hailstorm week. In contrast, a liana Ventilago calyculata showed a significant increase in SFD during the first post-hailstorm week, whereas the other tree and liana species showed no significant change in their SFD and water use. T. grandis also showed visible wilting during the first 5 days post-hailstorm. However, this tree species showed recovery from wilting and also no more reduction in SFD after ~7–9 days. D. tuberculatus also showed SFD recovery a week post-hailstorm. We conclude that the impact of a heavy hailstorm on the water flux of tropical trees and lianas was mild or neglectable. Our study documented a rare severe hailstorm occurrence and its impact on ecosystem processes of tropical forest and enhances our understanding about water flux of tropical woody species exposed to hailstorm.

中文翻译：

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热带树木和藤本植物对强冰雹造成的树叶损失的水通量响应

大直径冰雹在低地热带地区并不常见；因此，由于树叶损失，它对树木和藤本植物的水通量响应的影响是未知的。2012 年 12 月，云南南部西双版纳热带植物园（北纬 21 度 55 分）遭遇了近 30 年来最严重的冰雹，直径 8 至 17 毫米的冰雹持续 10 至 30 分钟。我们评估了这场雹暴对 6 种树木和 3 种藤本植物叶子损失的响应对树液通量密度 (SFD) 的影响。在这些树木中，对于给定的大气蒸汽压差 (VPD)，与冰雹前一周相比，在冰雹后一周内，Tectona grandis和Dipterocarpus tuberculatus 的树液通量密度和用水量显着降低。相比之下，藤本Ventilago calyculata在冰雹后的第一个周显示 SFD 显着增加，而其他树木和藤本植物的 SFD 和用水量没有显着变化。T. grandis在冰雹后的前 5 天也表现出明显的萎蔫。然而，该树种在大约 7-9 天后显示出从枯萎中恢复并且 SFD 不再减少。D. tuberculatus也显示SFD恢复一周后冰雹。我们得出的结论是，强冰雹对热带树木和藤本植物的水通量的影响是轻微的或可以忽略的。我们的研究记录了罕见的严重冰雹的发生及其对热带森林生态系统过程的影响，并加深了我们对暴露于冰雹的热带木本物种水通量的理解。