Doctoral Dissertation Research: Dynamics in Montane Grasslands: The Invasion of an Exotic Species in Rocky Mountain National Park

国家公园管理局和其他以保护为导向的组织历史上一直试图保持公园土地和荒野地区的自然条件，但外来物种的入侵往往改变了本地植物群落。 固氮植物改变地球化学过程，促进未来外来入侵。 这篇博士论文的研究项目解决了空间和资源竞争的外来物种，黄甜三叶草（Melitotus officinalis），在落基山国家公园的山地草原的影响。 初步分析表明，M.药用植物入侵蔓延到本地社区，并导致物种组成的改变，从降低养分供应和土壤小气候变化。 继续的研究将集中在假设本地物种将受益于规定的燃烧和氮的操纵，而M。药用植物的蔓延和密度将下降。 本项目采用的研究方法包括在受入侵和未受入侵斑块的重复扰动地点取样土壤和植被。 初步结果表明，M.在整个季节中，药用植物扩展到原来的地图边界，物种组成在斑块之间是不同的。 土壤分析表明，低氮的有效性，净矿化，和土壤水分的斑块占据M。药用植物 历史航空照片、全球定位系统和地理信息系统将被用来绘制外来入侵的地图。 项目后期阶段的实地方法将包括在几个地点进行规定的焚烧和沿沿着斑块边缘进行氮处理。 该项目将为生物入侵和改变化学过程的过程提供新的见解。 除了产生关于这些地理学和生物地球化学过程的基本知识外，该项目还将为土地管理人员提供实用信息，特别是因为它涉及规定的火灾和氮处理在保护自然植被群落方面可能发挥的作用。 作为博士论文研究改进奖，该奖项还将提供支持，使有前途的学生建立一个强大的独立的研究生涯。

The National Park Service and other conservation-oriented organizations historically have tried to maintain park land and wilderness areas in their natural conditions, but the invasion of exotic species often has altered indigenous plant communities. Nitrogen-fixing plants alter biogeochemical processes and facilitate future exotic invasions. This doctoral dissertation research project addresses spatial and resource competitive effects of an exotic species, yellow sweet clover (Melitotus officinalis), in montane grasslands in Rocky Mountain National Park. Preliminary analyses show that M. officinalis invasion spreads into native communities and induces an altered species composition from lowered nutrient availability and soil microclimate changes. Continued research will focus on the hypotheses that native species will benefit from prescribed burning and nitrogen manipulations while M. officinalis spread and density will decrease. Research methods to be used in this project include sampling soil and vegetation in replicate disturbed sites of invaded and non-invaded patches. Preliminary results show that M. officinalis expanded past original mapped boundaries throughout the season, and species composition is different between patches. Soil analysis shows lower nitrogen availability, net mineralization, and soil moisture in patches occupied by M. officinalis. Historical aerial photographs, global positioning systems, and geographic information systems will be used to map exotic invasion. Field methods during the latter stages of the project will incorporate prescribed burning in several sites and nitrogen manipulations along patch edges. This project will provide new insights into the processes of biological invasions and altered chemical processes. In addition to generating fundamental knowledge about these biogeographic and biogeochemical processes, this project will provide practical information for land managers, especially as it relates to the role that prescribed fires and nitrogen manipulations may play in the preservation of natural vegetation communities. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.