Key Message

Frost-sensitive and frost-resistant Cerrado tree species differ in their morphological and physiological traits, which are linked with their resprout strategies and can affect their persistence under recurrent frost events.

Abstract

Although fire is the most common disturbance affecting neotropical savannas, frost events are locally common and are sometimes severe enough to cause dieback of savanna trees at their southern limit of distribution. However, it is yet to be elucidated how physiology and morphology determine which species are frost sensitive. In this study, we evaluated morphological and physiological responses of trees to controlled low temperatures and to a severe frost event that occurred in 2016 at savanna sites of Southeastern Brazil. We determined the degree of bud protection, branch bark thickness, resprout strategies, and recovery of height and biomass 1 year after frost occurrence, and we performed an experiment to measure the photosynthetic capacity of leaves after exposure to low temperatures. We found that frost-sensitive species had unprotected buds, but were able to recover their lost biomass 1 year after frost. Frost-resistant species had buds with a greater degree of protection and maintained higher photosynthetic capacity under sub-zero temperatures. We did not find any differences in bark thickness between frost-resistant and frost-sensitive species. Frost-resistant and frost-sensitive species had different strategies to persist under frost events; however, if frost were more frequent, it could severely affect the height and carbon gain of sensitive species.

中文翻译：

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形态生理特征在新热带稀树草原树木抗冻性中的作用

关键信息

对霜敏感和抗霜冻的塞拉多树种的形态和生理特征不同，这与其再发芽策略有关，并会影响它们在反复霜冻事件下的持久性。

抽象的

尽管火灾是影响新热带稀树草原的最常见干扰，但霜冻事件在当地很常见，有时严重到足以导致热带稀树草原树木在其分布的南部边界枯死。然而，生理学和形态学如何决定哪些物种对霜冻敏感还有待阐明。在这项研究中，我们评估了树木对受控低温和 2016 年巴西东南部稀树草原地区发生的严重霜冻事件的形态和生理反应。我们确定了霜冻发生后 1 年的芽保护程度、枝皮厚度、再发芽策略以及高度和生物量的恢复，并进行了一项实验，以测量暴露于低温后叶片的光合能力。我们发现对霜敏感的物种有未受保护的芽，但能够在霜冻后 1 年恢复失去的生物量。抗冻物种的芽具有更高的保护程度，并在零下温度下保持更高的光合能力。我们没有发现抗霜和霜敏感物种的树皮厚度有任何差异。抗霜冻和对霜冻敏感的物种在霜冻事件下有不同的生存策略；然而，如果霜冻更频繁，可能会严重影响敏感物种的高度和碳增加。抗霜冻和对霜冻敏感的物种在霜冻事件下有不同的生存策略；然而，如果霜冻更频繁，可能会严重影响敏感物种的高度和碳增加。抗霜冻和对霜冻敏感的物种在霜冻事件下有不同的生存策略；然而，如果霜冻更频繁，可能会严重影响敏感物种的高度和碳增加。