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

合作研究：将木质部功能特征与加州丛林的生活史类型联系起来

• 批准号: 0131247
• 负责人: Frank Ewers
• 金额: $ 7万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-05-01 至 2005-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0131247&HistoricalAwards=false
• 关键词: Collaborative; Research; Linking; Xylem; Functional

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.

南加州的气候属于地中海型气候，特点是冬季温和、夏季持续干旱和周期性野火。 主要植被是灌木丛，它独特地适应夏季脱水和火灾。 灌木丛通过周期性火灾生存和持续存在三种策略：火灾后非发芽、火灾后兼性发芽和火灾后专性发芽。 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输送系统失效的脱水阈值来估计脱水耐受性。 这种失败是由严重水分胁迫下木质部栓塞形成引起的，即当植物的管道系统（木质部导管）被气泡堵塞时，切断了流向叶子的水流，导致枝条死亡。我们研究的主要目的是阐明不同物种灌木丛中木质部功能性状与生活史类型之间的联系机制。 我们假设木质部抗栓塞性、木质部传导效率和木质部机械强度之间存在权衡，这些取决于灌木丛物种应对野火的三种生活史策略。与经常发生的野火、水源保护、侵蚀控制、城市扩张和娱乐相关的问题在灌木丛地区比在加利福尼亚州任何其他类型的荒地中更为明显。 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当地机构，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。 这些发现将能够推广到更广泛的加利福尼亚丛林社区和世界其他四个地中海型气候地区。 拟议工作的结果将完善对下个世纪丛林分布和群落结构预期变化的预测，以应对预期的气候变化，加利福尼亚州将变得更加温暖、干燥，并伴有阵发性圣安娜风和野火的增加。