Institute of Ecology and Biodiversity, School of Life Sciences, Shandong University, 72 Binhai Road, Qingdao 266237, China.
Shandong Provincial Engineering and Technology Research Center for Vegetation Ecology, Shandong University, 72 Binhai Road, Qingdao 266237, China.
Tree Physiol. 2023 May 12;43(5):737-750. doi: 10.1093/treephys/tpad005.
Ongoing global climate change is increasing the risk of drought stress in some areas, which may compromise forest health. Such drought events also increase outbreaks of insect herbivores, resulting in plant defoliation. Interactions between drought and defoliation are poorly understood. In a greenhouse experiment, we selected a native species, Quercus acutissima Carr. and an alien species, Quercus rubra L. to explore their physiological responses to drought and defoliation treatments. After the treatments, we determined the seedlings' physiological responses on Days 10 and 60. Our results showed that the defoliation treatment accelerated the carbon reserve consumption of plants under drought stress and inhibited the growth of both seedling types. Under the drought condition, Q. rubra maintained normal stem-specific hydraulic conductivity and normal growth parameters during the early stage of stress, whereas Q. acutissima used less water and grew more slowly during the experiment. Sixty days after defoliation treatment, the stem starch concentration of Q. acutissima was higher than that of the control group, but the stem biomass was lower. This indicates that Q. acutissima adopted a 'slow strategy' after stress, and more resources were used for storage rather than growth, which was conducive to the ability of these seedlings to resist recurrent biotic attack. Thus, Q. acutissima may be more tolerant to drought and defoliation than Q. rubra. The resource acquisition strategies of Quercus in this study suggest that the native Quercus species may be more successful at a long-term resource-poor site than the alien Quercus species.
持续的全球气候变化正在增加某些地区干旱胁迫的风险，这可能会损害森林健康。此类干旱事件还会增加昆虫食草动物的爆发，导致植物落叶。干旱和落叶之间的相互作用还不太清楚。在温室实验中，我们选择了一种本地物种麻栎和一种外来物种栓皮栎，以探究它们对干旱和落叶处理的生理响应。处理后，我们在第 10 天和第 60 天测定了幼苗的生理响应。结果表明，落叶处理加速了干旱胁迫下植物的碳储备消耗，并抑制了两种幼苗类型的生长。在干旱条件下，栓皮栎在胁迫早期维持了正常的茎部比水力导率和正常的生长参数，而麻栎在实验过程中用水量较少，生长较慢。落叶处理 60 天后，麻栎的茎淀粉浓度高于对照组，但茎生物量较低。这表明麻栎在受到胁迫后采用了“缓慢策略”，更多的资源用于储存而不是生长，这有利于这些幼苗抵抗反复的生物攻击的能力。因此，麻栎可能比栓皮栎更能耐受干旱和落叶。本研究中栎属的资源获取策略表明，本地栎属物种在长期资源匮乏的地点可能比外来栎属物种更成功。
