Relationship Among Host Tree Species Diversity, Soil Fertility, and Carbon Availability in Maintaining Belowground Ectomycorrhizal Community Structure and Function

对植物、微生物和它们所栖息的土壤之间相互作用的综合研究对我们理解生态系统功能至关重要。本研究采用生物化学和分子遗传学相结合的方法，研究了人工采伐油松对油松纯林和油松/云杉混交林中菌根群落结构和功能的影响。在小规模干扰下，我们将只对红松纯林斑块和红松/黑松混交林斑块进行落叶处理。然后我们将确定落叶如何影响EM真菌群落结构、分解凋落物的酶的活性以及土壤真菌群落的酶功能。我们将在土壤肥力梯度上取样，该梯度是由相对营养丰富的富钙流纹岩通过冰川活动形成的过渡带过渡到营养贫乏的流纹岩而形成的。通过这样做，我们将首次确定流向根部的碳流、树种多样性和土壤肥力之间的相互作用如何影响外生菌根真菌的多样性和功能。我们来自该系统的初步数据表明，只有在松树/云杉混交林中的松树落叶才能1)显著影响旋毛松/云杉混交林的EM群落，2)影响未落叶云杉的EM。我们的数据还表明，土壤肥力在影响EM群落结构中起着关键作用，其他人的工作表明，土壤肥力可以缓解落叶和昆虫食草的影响。我们将首次研究碳流到根部的变化如何影响混交林中的EM群落结构、EM酶功能和地下功能，并首次将这些因素与土壤肥力结合起来。我们将在黄石国家公园进行这项研究，黄石国家公园是1100万英亩大黄石生态系统的中心，其中包括三个州的几个国家森林。通过结合使用生化和分子方法，我们将提供迄今为止关于生态系统功能的这些方面的最全面的图景。因此，我们将大大加深我们对一个原始的、经济上重要的和地理上占优势的生态系统的理解。我们的教育/推广和更广泛的影响将是深远的。例如，卡林斯是一家为拉美裔服务的机构的兼职人员，将在那里授课和举办研讨会，该机构的学生将被邀请参与研究。此外，卡林斯还是艾姆斯美洲原住民咨询委员会的成员，该委员会是NASA内部的一个教育/推广组织，致力于将科学教育带到保留地。Henson自愿担任ASM少数民族教育者/讲师12年，并一直担任NIH(InstitutionalStudents少数民族发展)和NSF(少数民族准入计划，Science and Engineering for All)少数民族教育补助金的导师。此外，在过去的10年里，她的实验室通过美国印第安人研究机会(AIRO)计划在校园内接待了美国原住民高中学生和教师。她的组织还帮助YNP公园的工作人员为公众制作微生物小册子和录像带，并维护一个网站，介绍他们在黄石公园的工作(www.montana.edu.hotfals)。Henson还参与了ASMS在线科学指导项目。所有专业的学生都将被招募参加这个项目。

Integrated studies of interactions among plants, microbes, and the soils they inhabit arecritical to our understanding of ecosystem function. We propose to use a combination ofbiochemical and molecular-genetic methods to determine effects of artificial defoliation ofPinus contorta (lodgepole pine) on structure and function of ectomycorrhizal (EM)communities in pure P. contorta and mixed P. contorta/Picea engelmannii (Engelmannspruce) stands. We will defoliate only the pine in both pure P. contorta and mixed P.contorta/P. engelmannii patches formed within mixed stands by small-scale disturbance. Wewill then determine how defoliation affects EM fungal community structure, activities ofenzymes that break down litter, and enzymatic function of soil fungal communities. We willsample across a soil fertility gradient created by a transition from relatively nutrient-richandesite, through a transition zone created by glacial activity, to nutrient-poor rhyolite. Bydoing so, we will determine how interactions among carbon flow to roots, tree speciesdiversity, and soil fertility influence ectomycorrhizal fungal diversity and function, for thefirst time.Our preliminary data from this system indicate that defoliation of pine only in a patch of mixedpine/spruce can 1) significantly affect the EM community of mixed P. contorta/P. engelmanniistands, and 2) affect the EM of non-defoliated spruce. Our data also show that soil fertility playsa pivotal role in influencing EM community structure, and the work of others demonstrates thatsoil fertility can moderate effects of defoliation and insect herbivory. We will be the first toinvestigate how alteration of carbon flow to roots affects EM community structure, EMenzymatic function, and below-ground function in a mixed tree species forest, and the first tocombine these factors with soil fertility. We will conduct this study in Yellowstone NationalPark, the centerpiece of the 11-million acre Greater Yellowstone Ecosystem, which includesseveral National Forests in three states. By using a combination of biochemical and molecularmethods, we will provide the most comprehensive picture of these aspects of ecosystem functionto date. Thus, we will add greatly to our understanding of a pristine, economically important, andgeographically dominant ecosystem.Our education/outreach and broader impacts will be far-reaching. For example, Cullings isadjunct at a Hispanic-Serving Institution and will teach classes and seminars there, and studentsfrom that institution will be invited to participate in the study. In addition, Cullings is a memberof the Ames Native American Advisory Council, an education/outreach organization withinNASA dedicated to bringing science education to reservations. Henson has volunteered for 12years as an ASM minority educator/lecturer, and has been a preceptor for NIH (InstitutionalStudent Minority Development) and NSF (Minority Access Program, Science and Engineeringfor All) minority education grants. In addition, and for the past 10 years her lab has hostedNative American high school students and teachers through the American Indian ResearchOpportunities (AIRO) program on campus. Her group also assists YNP park personnel with theirmicrobiology brochures and videotapes for the general public, and maintains a Web site abouttheir work in Yellowstone (www.montana.edu.hotfungi). Henson also participates in ASMs on-line science mentoring project. Students from all programs will be recruited to participate in thisproject.