RUI: Xylem Embolism in Drought-hardy Shrubs of California

美国干旱地区木本植物的生存和生长取决于它们在干旱期间抵御组织脱水的能力。特别重要的是，负责将水分从土壤输送到叶片的细胞（木质部血管）保持功能，水柱不被气泡（栓塞）破坏。在高等植物中，将气泡引入木质部导管会导致水运输的阻塞，如果范围足够大，则会杀死植物。室内实验表明，长时间干旱造成的严重水分胁迫是木质部栓塞的主要原因之一。然而，人们对栓塞的发生及其在自然界中的意义知之甚少。没有旱地植物的数据，那里的组织水分胁迫很大，因此栓塞可能是最显著的。本研究的目的是提供木质部栓塞在植物生长、生产力和干旱地区植物生存中的作用的第一个信息，特别是加利福尼亚本土的灌木。该项目将揭示灌木林植被的水关系动态，特别是在野火后恢复的早期阶段。这方面的知识可能有助于改善对灌木丛的管理，将其作为分水岭，作为野生动物的海湾和牲畜的觅食地，防止土壤侵蚀/山体滑坡。

The survival and growth of woody plants in dryland regions of the United States depends on their ability to withstand tissue dehydration during drought. It is particularly important that the cells specialized in transporting water (xylem vessels) from the soil to leaves remain functional and that the water column not be disrupted by air bubbles (embolism). In higher plants the introduction of air bubbles into xylem vessels results in a blockage of water transport and, if extensive enough, kills the plant. Laboratory experiments indicate that one of the major cases of xylem embolism is severe water stress during extended periods of drought. However, very little is known about the occurrence and significance of embolism in nature. No data are available for dryland plants where tissue water stress is great and thus where embolism may be the most significant. The objective of this proposed study is to provide the first information on the role of xylem embolism in plant growth, productivity, and survival of dryland plants, specifically chaparral shrubs indigenous to California. This project will shed light on the dynamics of water relations in chaparral vegetation, especially during the early phases of recovery after wildfire. This knowledge could potentially lead to an improved management of chaparral as a water shed, as a deterrent of soil erosion/landslides as a cove for wild animals and as a browse for livestock.