Abstract The introduction of exotic buffelgrass (Pennisetum ciliare) to the Sonoran Desert has modified the structure and fuel loads of desert scrub, creating a continuous fuel bed and altering fire frequencies and intensities. The damage to native vegetation has been widely acknowledged, but the mechanisms underlying the response have been little studied. Considering bark as one of the important characteristics to protect stems from fire, this study aimed to compare bark traits of two native Sonoran desert trees (Bursera microphylla and Olneya tesota) that may promote cambium survival from fire. Physical features of trees and fuel that influence fire behavior were analyzed, and bark characteristics were examined, including anatomy and chemical composition, to determine how these properties may influence their survival to fire. Surprisingly, drought-resistant traits of Bursera microphylla, such as thicker inner bark and greater stem water reserves make this species better able to survive fires, providing up to ten times more resistance to heat inputs from buffelgrass. In contrast, Olneya tesota has a dry and narrow inner bark, a flammable outer bark, fuel material accumulation under its crown, and large branches close to the soil surface, characteristics that increase fire intensity and give less protection to stem live tissues.

中文翻译：

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水牛草火灾对两种索诺兰沙漠树木的影响：树皮和结构分析

摘要 将外来水牛草（Pennisetum ciliare）引入索诺兰沙漠改变了沙漠灌木的结构和燃料负荷，创造了一个连续的燃料床并改变了火灾频率和强度。对原生植被的破坏已得到广泛承认，但对响应机制的研究却很少。考虑到树皮是保护茎免于火灾的重要特征之一，本研究旨在比较两种可能促进形成层在火灾中存活的本地索诺兰沙漠树木（Bursera microphylla 和 Olneya tesota）的树皮特性。分析了影响火灾行为的树木和燃料的物理特征，并检查了树皮特征，包括解剖结构和化学成分，以确定这些特性如何影响它们在火灾中的生存。出奇，Bursera microphylla 的抗旱特性，例如更厚的内皮和更大的茎水储备，使该物种能够更好地在火灾中生存，对来自水牛草的热量输入的抵抗力提高十倍。相比之下，Olneya tesota 的内树皮干燥而狭窄，外树皮可燃，树冠下有燃料物质，靠近土壤表面的大树枝，这些特征会增加火灾强度，但对茎活组织的保护较少。