LTER Cross-Site: Contrasts of Global Change and Ecotonal Shifts: Buffering Effects of Mycorrhizae and Nurse Plants and Increased Sensitivity due to Herbivores and Mistletoe

LTER 跨站点：全球变化和生态转移的对比：菌根和护士植物的缓冲作用以及食草动物和槲寄生引起的敏感性增加

• 批准号: 0087017
• 负责人: Catherine Gehring
• 金额: $ 30万
• 依托单位: Northern Arizona University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-10-01 至 2004-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0087017&HistoricalAwards=false
• 关键词: LTER; Cross; Site; Contrasts; Global

0087017Gehring Global change models predict an increase in the frequency of intense drought in the continental interior of the US, and recent field studies have shown that semiarid ecosystems can be highly sensitive to this type of abiotic stress. For example, in the 1950's a severe drought in New Mexico resulted in high tree mortality that shifted ecotones by 2 kilometers in less than five years. Rapid, sustained ecotonal shifts depend on to processes: high rates of mortality of one or more of the dominant plant species in the ecosystem, and lack of recruitment of the dominant plant species following the mortality event. This LTER cross-site research will test the hypothesis that the probability that an ecotonal shift will occur depends on the degree of abiotic stress, and on the relative effects of positive and negative biotic associations on the dominant plant species. Positive associations, such as mycorrhizal associations and nurse plants, could buffer communities from major ecotonal shifts while negative associations with herbivores and parasites could increase sensitivity to global change. This study will focus on pinyon pine growing at the southern edge of their distribution in New Mexico and Arizona. Pinyon is an ideal candidate for global change studies because it is a dominant member of the third largest vegetation type in North America. Both paleoecological and recent studies show that pinyon is highly sensitive to environmental change. Much is known about the interactions among pinyon pine and its associated community, including is co-dominant tree associate and the bacteria, fungi, invertebrates and vertebrates that live in close association. This knowledge of broader interactions will allow a more accurate prediction of the effects of pinyon mortality on other members of the community and on ecosystem processes.

0087017 Gehring全球变化模型预测，美国大陆内陆的严重干旱频率将增加，最近的实地研究表明，半干旱生态系统对这种非生物胁迫高度敏感。例如，在20世纪50年代，新墨西哥州的严重干旱导致树木死亡率很高，在不到五年的时间里将生态交错区转移了2公里。快速、持续的生态带转移取决于以下过程：生态系统中一种或多种优势植物物种的高死亡率，以及死亡事件后优势植物物种缺乏补充。这LTER跨站点研究将测试的假设，即生态区转移的概率将发生取决于非生物胁迫的程度，以及对优势植物物种的积极和消极的生物协会的相对影响。正相关性，例如菌根相关性和保育植物，可以缓冲社区免受重大生态区变化的影响，而与食草动物和寄生虫的负相关性可能会增加对全球变化的敏感性。这项研究将集中在松树生长在其分布在新墨西哥州和亚利桑那州的南部边缘。Pinyon是全球变化研究的理想候选者，因为它是北美第三大植被类型的主要成员。古生态学和近期的研究都表明，松属植物对环境变化高度敏感。关于松及其伴生群落之间的相互作用，包括共同优势的树木伴生物和生活在密切关系中的细菌、真菌、无脊椎动物和脊椎动物，已经有了很多的了解。这种知识的更广泛的相互作用将允许一个更准确的预测松死亡率对社区的其他成员和生态系统过程的影响。