RUI: Xylem Embolism in Drought-hardy Shrubs of California

木本植物在美国干旱地区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，专门负责从土壤向叶片输送水分的细胞(木质部导管)保持正常运转，水柱不被气泡破坏(栓塞症)。在高等植物中，气泡进入木质部导管会导致水分运输受阻，如果足够广泛，就会杀死植物。实验室实验表明，木质部堵塞的主要原因之一是长期干旱期间的严重水分胁迫。然而，人们对栓塞症的发生和意义知之甚少。没有旱地植物的数据，这些植物的组织水分压力很大，因此栓塞症可能是最严重的。这项拟议研究的目的是提供有关木质部栓塞在植物生长、生产力和旱地植物存活中的作用的第一个信息，特别是加州原产的查帕尔灌木。该项目将阐明查帕尔植被中水分关系的动态，特别是在野火后恢复的早期阶段。这一知识可能会改善对查帕拉的管理，将其作为分水岭，作为对土壤侵蚀/山体滑坡的威慑，作为野生动物的海湾和作为牲畜的觅食。

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.