Collaborative Research: Understanding spatiotemporal dynamics of plant-soil feedbacks: Consequences for shrub-grass interactions in a dryland ecotone

由于人类造成的环境变化速度很快，了解允许物种迁徙到新的合适栖息地的因素变得越来越迫切。该项目结合野外和实验室实验，评估植物-植物和植物-微生物相互作用如何影响杂酚油迁移到邻近草原。杂酚油是北美温暖沙漠(索诺兰、奇瓦瓦和莫哈韦)最常见和最重要的灌木之一。以牺牲草原为代价的木本植物扩张，这种现象被称为灌木侵蚀，这是一种全球性的现象，预计在未来气候变暖和大气中二氧化碳含量上升的情况下，这种现象会加速。生活在植物根部及其附近的微生物可能在影响灌木侵蚀率方面发挥关键作用，但它们对灌木建立和迁徙成功的影响尚未得到检验。为了预测植物-微生物和植物-植物(在这种情况下是灌木/草)的相互作用将如何在未来的气候中推动或减缓植物种群的扩张，需要评估这些相互作用发生的空间和时间尺度。利用田间和实验室实验以及数学模型，该项目将能够预测植物-植物和植物-微生物相互作用如何在其地理分布的限制下重塑灌木和草物种的丰度和分布。灌丛-草原动态影响生态系统储存的碳量，推动牧场管理决策，影响保护生物多样性的战略，仅北美就有超过3.3亿公顷的土地。该项目对学生进行多层次的培训，并与利益相关者和管理人员建立伙伴关系，以确保知识转让造福社会。科学和艺术的合作也被嵌入到研究活动中，包括设计和创造3D打印的植物模型和植物形态的艺术解释。博物馆将展出这些模型和微生物与植物的相互作用，以扩大公众覆盖面，并创造微生物和植物相互关系的美学表达。拟议的研究将阐明植物根和土壤中与微生物相关的微生物如何在环境变化下影响植物物种范围的移动。研究活动包括获取关于决定范围扩散的关键参数的新的定量数据：植物影响其微生物环境的空间范围和时间速度，以及相对于植物/植物竞争相互作用的微生物/植物反馈的相对强度。野外观测实验将通过解决以下问题来确定植物-微生物相互作用的潜在机制：(1)在范围限制发生碰撞的交错带上，基础物种之间的植物-土壤反馈的空间范围是多少？这个问题将通过空间显式配对田间和温室实验来解决，以量化植物/微生物反馈的空间范围，因为它们影响草和灌木的性能。(2)二氧化碳浓度升高如何影响这些交错带的微生物反馈和基础物种之间的共存？这个问题将通过生长室实验来解决，以对比环境和高浓度二氧化碳下草和灌木之间的微生物反馈和竞争。(3)随着时间的推移，植物物种通过什么机制培养独特的微生物群落？将通过田间实验来解决这一问题，以评估土壤和植物微生物改良的潜在机制以及每种机制的时间尺度。最后，将利用这些实验和观测的数据开发定量模型，以解决以下问题：(4)土壤微生物如何促进范围扩大、收缩或在物种范围限制下稳定，以及增加的二氧化碳将如何改变范围限制动态？该项目取得了新的突破，在空间和时间背景下评估植物/土壤反馈，使用了一个有良好记录的、具有生态重要性和实验上易于处理的范围转移：C3木质灌木对美国西南部C4草原的侵蚀。灌木入侵可以显著改变生物多样性和生态系统过程，包括碳储存。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Understanding factors that allow species to migrate into new suitable habitats has become increasingly urgent because of the rapid pace of human-caused environmental change. This project combines field and lab experiments to evaluate how plant-plant and plant-microbe interactions influence the migration of creosote, one of the most common and important shrubs of the warm deserts of North America (Sonoran, Chihuahuan and Mojave), into adjacent grasslands. The expansion of woody plants at the expense of grassland, a phenomenon called shrub encroachment, is global in scale and expected to accelerate under future warmer climates and elevated atmospheric CO2. The microbes that live in and near plant roots (the plant microbiome) likely play key roles in affecting the rate of shrub encroachment but their influence on shrub establishment and migration success has not yet been examined. To predict how plant-microbe and plant-plant (in this case shrub/grass) interactions will drive or slow plant population expansion in future climates requires evaluating the spatial and temporal scales at which these interactions occur. Using both field and lab experiments and mathematical models, this project will enable forecasts of how plant-plant and plant-microbe interactions reshape the abundance and distributions of shrub and grass species at the limits of their geographic distributions. Shrubland-grassland dynamics affect the amount of carbon stored by an ecosystem, drive rangeland management decisions, influence strategies to conserve biodiversity, and extend over 330 million hectares of North America alone. This project trains students at many levels, and builds partnerships with stakeholders and managers to ensure knowledge transfer to the benefit of society. A science-art collaboration is also embedded in the research activities, including the design and creation of 3D-printed plant models and artistic interpretations of plant morphologies. A museum exhibit of these models and microbe plant interactions will be created to expand public outreach and create an aesthetic expression of the inter-relationships of microbes and plants.The proposed research will elucidate how plant root and soil associated microbes influence plant species range movements under environmental change. Research activities include the acquisition of novel quantitative data on key parameters that determine range spread: the spatial extent and temporal speed at which plants influence their microbial environment and the relative strength of the microbe/plant feedbacks compared to plant/plant competitive interactions. Experiments on field observations will determine the underlying mechanisms of plant-microbe interactions by addressing the following questions: (1) What is the spatial extent of plant-soil feedback between foundation species at ecotones where range limits collide? This question will be addressed using spatially-explicit paired field and greenhouse experiments to quantify the spatial extent of plant/microbe feedbacks as they influence both grass and shrub performance. (2) How does elevated CO2 affect microbial feedbacks and coexistence between foundation species at these ecotones? This question will be addressed using a growth chamber experiment to contrast microbial feedbacks and competition between grass and shrubs under ambient versus elevated CO2. (3) By what mechanisms do plant species cultivate unique microbial communities through time? This will be addressed with a field experiment to evaluate mechanisms underlying soil and microbial modification by plants and the temporal scale of each mechanism. Finally, quantitative models will be developed using the data from these experiments and observations to address the question, (4) How do soil microbes contribute to range expansion, contraction, or stabilization at species range limits, and how will elevated CO2 change range limit dynamics? The project breaks new ground ni evaluating plant/soil feedbacks in a spatial and temporal context using a well-documented, ecologically important, and experimentally tractable range shift: the encroachment of C3 woody shrubs into C4 grasslands in the American Southwest. Shrub encroachment can dramatically alter biodiversity and ecosystem processes, including carbon storageThis award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.