干旱导致树木死亡机制研究进展
摘要：
随着全球气候变化，气温上升，干旱发生的可能性增加，干旱导致树木死亡现象的发生也越来越普遍，但干旱导致树木死亡确切的生理学机制还未完全解决，目前仍是研究的热点。近来提出的干旱导致树木死亡的假说主要有：水力学失败假说，认为干旱导致的低水势阻碍植物体内水分的长距离运输，使植物因组织脱水干燥而死亡；碳饥饿假说，认为干旱过程中发生的气孔关闭会限制碳摄取，导致植物体内可利用碳的耗竭；生物攻击假说，认为干旱中的植物易受生物因子（昆虫和病原体）的攻击而死亡。3种假说各自都能解释一定的现象，但又都存在缺陷，主要问题是不能解释所有干旱导致树木死亡的现象。近来的研究越来越关注这些机制之间的共同作用或相互作用，水力学失败、碳饥饿和生物因子之间会相互影响而加重干旱对植物的作用，尤其是水力学失败和碳饥饿相耦合已得到越来越多的认可。本文主要综述这几种致死机制的试验证据及存在的问题，同时综述当前研究存在的局限性，并讨论了未来可能的研究方向。
关键词: 生物源杀虫剂, 生命表, 西花蓟马, 亚致死浓度, 发育历期
Abstract: Warming and drought will occur with increased frequency and intensity along with global climate change. In recent years, extensive tree mortality and forest declines have been reported in response to drought and rising temperature. Despite an enormous body of empirical evidence, the underlying physiological mechanisms of the changes still remain unclear. At present, the study on the drought-induced tree mortality mechanisms is still a hot spot. Three hypotheses concerning the physiological mechanisms leading to tree mortality during drought have been proposed: hydraulic failure hypothesis, proposing that low water potential due to drought impedes long-distance water transport within plants and results in dehydration of plant tissues; carbon starvation hypothesis, suggesting that a prolonged stomatal closure during drought constrains carbon uptake and leads to a depletion of available carbohydrats; and biotic attack hypothesis, considering that trees subjected to drought are prone to attacks by insects and pathogens. Each of the hypotheses can interpret certain phenomena of drought-induced tree mortality, but cannot universally interpret all phenomena of drought-induced tree mortality under whatever drought conditions. Lately more attention has been paid to the combined action or interaction of the different mortality mechanisms, especially the coupling of hydraulic failure and carbon starvation. This paper mainly reviewed experimental evidence and existing problems of the three hypotheses. Meanwhile, the limitations of current researches and possible research direction in the future in this field were also discussed.
Key words: Frankliniella occidentalis, life table, developmental duration, sublethal concentration, biopesticide
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