Doctoral Dissertation Research: The Effects of Honeysuckle Encroachment on White Oak Savannas in Relation to Understory Light, Soil, and Dispersal Characteristics.

本博士论文项目研究了入侵物种在北美中部草原稀树草原优势物种减少中的作用。该研究的目的是通过减少侵略性的黑龙江金银花入侵物种来确定和开发刺激曾经占主导地位的白栎树的方法。橡树稀树草原曾经在北美中部覆盖了1000万到1300万公顷，但现在已经受到地理限制，变得罕见。白栎是一种不耐阴的树种，它的再生目前受到一种具有侵略性的耐阴入侵物种——黑龙江金银花的控制，这种入侵物种在过去70年里一直在橡树树冠下蔓延。如果不能更好地理解橡树是如何重新成为主导的，有效的土地管理将阻碍白橡树重新获得其在景观中的主导地位，并且预测白橡树将在未来几十年内失去其历史主导地位。这反过来又会进一步恶化中西部橡树稀树草原的残余，这一生态系统已经在其他方面受到威胁。本项目主要研究三个具体问题：(1)黑龙江金银花入侵对林下光环境和白栎树苗、树苗光合效率的影响；(2)金银花对白栎再生发育重要的土壤水分、土壤化学和土壤质量特征有何影响？(C)最后，如何了解入侵黑龙江金银花种群的时空分布模式（基因流）来设计有效的管理策略？为了回答这些问题，该项目的pi将在Nachusa草原进行生物地理研究，这是伊利诺伊州中北部的一个草原保护区。他们将分析光照有效性的空间差异、橡树和金银花地下土壤水分和土壤质量的差异，并对金银花的分散模式（基因流）进行分析。本研究结果将直接传达给Nachusa草原和其他类似保护区的土地管理者和管理员，以便为入侵物种管理和保护政策提供信息。来自代表性不足群体的学生将被招募参与该项目，其成果将被纳入北伊利诺伊大学的相关课程，以帮助学生将科学概念和方法应用于现实世界的情况。该项目也将被纳入NIU STEM与青年和社区团体的外展工作。此外，研究结果将在区域和国家学术会议上发表，并在重要期刊上发表。作为博士论文研究改进奖，该项目将为有前途的研究生建立独立的研究生涯提供加强培训和专业发展的支持。

This doctoral dissertation project investigates the role of an invasive species in the decline of a dominant savanna species in the grassland savanna landscape of central North America. The objective of the study is to identify and develop ways to stimulate the once dominant white oak by decreasing the aggressive Amur honeysuckle invasive species. Oak savannas once covered 10 to 13 million hectares throughout central North America, but have now become geographically restricted and rare. White oak is a shade-intolerant tree species, and its regeneration is currently impeded by the domination of an aggressive shade-tolerant invasive species, Amur honeysuckle, which has spread underneath oak canopies over the past 70 years. Without a better understanding of how oak trees can become dominant again, effective land management to help white oak regain its dominance in the landscape is hindered, and it is predicted that white oak will lose its historical dominance within the next few decades. This will, in turn, further deteriorate the Midwest oak savanna remnants, an ecosystem already threatened in other ways. This project addresses three specific research questions: (1) How does Amur honeysuckle encroachment effect understory light environments and photosynthetic efficiency of white oak seedlings and saplings? (2) What impact does Amur honeysuckle have on soil moisture, soil chemistry, and soil quality characteristics that are important to white oak regeneration and development? (C) Finally, how can understanding the temporal and spatial dispersion patterns (gene flow) of encroaching Amur honeysuckle populations be used to design effective management strategies? To answer these questions the PIs of this project will conduct a biogeographic study at the Nachusa Grasslands, a grassland conservation area in north-central Illinois. They will analyze the spatial differences in light availability, the differences in soil moisture and soil quality underneath oaks and honeysuckle, and conduct an analysis of the dispersion patterns (gene flow) of honeysuckle. Results from this research will be communicated directly to land managers and stewards at Nachusa Grasslands and other similar conservation areas in order to inform management and conservation policies regarding invasive species management. Students from underrepresented groups will be recruited to work on the project and results will be incorporated into relevant courses at Northern Illinois University to help students apply scientific concepts and methods to real world situations. The project will also be included in NIU STEM outreach efforts with youth and community groups. Additionally, findings will be presented at regional and national academic conferences, and published in key journals. As a Doctoral Dissertation Research Improvement award, this project will provide support for enhancing the training and professional development of a promising graduate student as she establishes an independent research career.