Collaborative Research: Linking Xylem Functional Traits to Life-History Type in California Chaparral

加州南部的气候属于地中海型气候，其特点是温和的冬季，持久的夏季干旱和周期性的野火。 主要的植被是查帕拉尔，这是独特的适应夏季脱水和火灾。 查帕拉尔通过三种策略在周期性火灾中生存和持续：火灾后的非萌芽，火灾后的兼性萌芽和火灾后的专性萌芽。 我们假设这三种策略与脱水耐受性相关。 我们将通过确定导致植物水分运输系统失败的脱水阈值来估计脱水耐受性。 这种失败是由于木质部栓塞形成严重的水分胁迫下，也就是说，当管道系统（木质部导管）的植物成为由气泡堵塞，切断水流到叶子，导致shootdeath.The我们的研究的主要目的是阐明木质部功能性状的机制，生活史类型之间的不同种类的查帕拉尔灌木。 我们假设，有权衡之间的木质部栓塞电阻，木质部的传导效率和木质部的机械强度，这些取决于三个生活史的策略，查帕拉尔物种在响应wildfire.Issues有关的经常性野火，水资源保护，侵蚀控制，城市扩张和娱乐的查帕拉尔地区比任何其他类型的野生土地在加州更明显。 研究结果将广泛传播给负责管理和保护圣莫尼卡山脉自然资源的地方机构，以及教育团体，包括州立公园管理局和国家公园管理局的讲解员。 研究结果将允许推广到更广泛的查帕拉尔社区的加州和其他四个地中海型气候地区的世界。 从拟议的工作结果将细化预测的预期变化，在查帕拉尔分布和社区结构在下一个世纪，以应对预期的气候变化，一个温暖，干燥的加州增加情节圣安娜风和野火。

The climate of southern California is a Mediterranean-type, characterized by mild winters, protracted summer drought, and periodic wildfire. The dominant vegetation is chaparral, which is uniquely adapted to summer dehydration and fires. There are three strategies by which chaparral survive and persist through periodic fire: non-sprouters after fire, facultative sprouters after fire, and obligate sprouters after fire. We hypothesize that these three strategies are coupled to dehydration tolerance. We will estimate dehydration tolerance by determining the threshold in dehydration that causes the water transport system of plants to fail. This failure is caused by xylem embolism formation under severe water stress, that is, when the plumbing system (xylem conduits) of plants become blocked by air bubbles, cutting off water flow to leaves, leading to shoot death.The primary objective of our research is to elucidate the mechanisms linking xylem functional traits to life history type among diverse species of chaparral shrubs. We hypothesize that there are trade-offs among xylem embolism-resistance, xylem conductivity efficiency and xylem mechanical strength and these depend on the three life history strategies that chaparral species have in response to wildfire.Issues related to recurrent wildfire, water conservation, erosion control, urban expansion and recreation are more pronounced in regions of chaparral than in any other type of wild land in California. Results from the research will be disseminated widely to local agencies responsible for management and conservation of natural resources in the Santa Monica Mountains, and to educational groups including docents for the State Park Service and the National Park Service. The findings will allow generalizations to the broader chaparral community of California and to the other four Mediterranean-type climate regions of the world. Results from the proposed work will refine predictions of expected shifts in chaparral distribution and community structure over the next century in response to an anticipate climate change to a warmer, drier California with increased episodic Santa Ana winds and wildfire.