Collaborative Research: Interactive Effects of Exogenous and Endogenous Spatial Heterogeneity on Plant Diversity

特定区域内物理环境的空间异质性可能是多种物种共存以及由此产生的物种多样性的主要决定因素。然而，生物本身可以通过它们自己的可变繁殖和扩散过程，通过竞争等相互作用，以及不同的生物局部改变环境和增加异质性的方式，促进物种共存。在决定物种共存和多样性方面，外部环境和有机体本身的作用的平衡在很大程度上是生态学中一个悬而未决的问题。这个项目将使用一个新颖的野外实验来研究堪萨斯州的一个草原系统的这个问题。该实验将使用土壤混合物来操纵环境的异质性，并通过以不同的方式种植不同的物种混合物来引入生物影响的差异。计算机模拟模型将作为实验的补充，以探索各种过程的细节。这项工作将有助于在植物群落中保持物种多样性的知识，这对于管理天然和改良(在这种情况下是牧场)植物群落以维持生态系统服务是有价值的。该项目还通过培训研究生和本科生以及与当地高中建立良好的联系来促进下一代科学家的发展，让学生参与到研究中来。这项研究将检验外源和内源空间异质性在调节草原群落物种共存和多样性方面的优势。外源空间异质性被认为是土壤中的空间异质性，内源异质性是空间异质性对扩散限制、人口随机性、竞争相互作用和生物-环境反馈的响应，从而导致种群和群落的内生空间结构独立于下层环境梯度。一项新的实验将在区块设计中比较混合和未混合的土壤。种子将被播种，以改变物种聚集模式和物种池(根据功能和系统发育多样性)。一组较小的实验将集中在植物-土壤反馈上。这些实验将通过开发一个模拟实验设计的模拟模型来补充。该模拟将允许考虑更多的异质性尺度。通过将实验和模型相结合，这项工作将缩小理论和实证工作之间的差距。这项研究将通过一个由当地高中生参与的副科学家项目扩展到教育领域，他们将直接参与数据收集和分析。研究生将参加本科生和高中生的培训。这项工作将通过了解植物群落简化的影响来促进保护。

The spatial heterogeneity of the physical environment within a given area may be the primary determinant of the coexistence of multiple species and consequent species diversity therein. However, organisms themselves can contribute to species coexistence through their own processes of variable reproduction and dispersal, through interactions such as competition, and through ways that different organisms modify their environment locally and increase heterogeneity. The balance of the roles of the external environment and the organisms themselves in determining coexistence and diversity of species is a largely open question in ecology. This project will use a novel field experiment to examine this question for a grassland system in Kansas. The experiment will manipulate environmental heterogeneity using soil mixtures and will introduce differences in the effects of organisms by planting different mixtures of species in different ways. A computer simulation model will complement the experiment to explore the details of various processes. This work will contribute to knowledge on the maintenance of species diversity in plant communities, which is valuable in managing natural and modified (in this case, rangeland) plant communities to maintain ecosystem services. The project also contributes to the development of the next generation of scientists through training of graduate and undergraduate students and a well-developed connection to a local high school that involves students in the research.This research will examine the strengths of exogenous and endogenous spatial heterogeneity in mediating species coexistence and diversity in grassland communities. The exogenous spatial heterogeneity is taken here as the spatial heterogeneity in soils, and the endogenous heterogeneity is taken as the conditions created by spatial heterogeneity in response to dispersal limitation, demographic stochasticity, competitive interactions, and organism-environment feedbacks resulting in endogenous spatial structuring of populations and communities independent of underlying environment gradients. A novel experiment will compare mixed and unmixed soils in a block design. Seeds will be sown to vary species aggregation pattern and species pools (by functional and phylogenetic diversity). A smaller set of experiments will focus on plant-soil feedbacks. The experiments will be complemented by the development of a simulation model that can mimic the experimental design. The simulation will allow additional scales of heterogeneity to be considered. By combining experiments with models, the work will close a gap between theory and empirical work. The research will be extended to education through an associate scientist program involving a local high school students who will participate directly in data gathering and analysis. Graduate students will participate in training undergraduates and the high school students. The work will contribute to conservation through an understanding of the effects of plant community simplification.