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个物种共存和随之而来的物种多样性的主要决定因素。 然而，生物体本身可以通过其自身的可变繁殖和扩散过程，通过竞争等相互作用，以及通过不同生物体局部改变其环境并增加异质性的方式，促进物种共存。 外部环境和生物体本身在决定物种共存和多样性方面的作用的平衡在生态学中是一个很大的开放问题。 本项目将使用一种新的实地实验，以检查这个问题的草地系统在堪萨斯。 该实验将利用土壤混合物来控制环境的异质性，并将通过以不同方式种植不同的物种混合物来引入生物效应的差异。 计算机模拟模型将补充实验，以探索各种过程的细节。 这项工作将有助于增进关于维持植物群落物种多样性的知识，这对于管理自然和改良（此处指牧场）植物群落以维持生态系统服务十分重要。 该项目还通过培养研究生和本科生以及与当地一所高中建立良好的联系，促进下一代科学家的发展。该研究将探讨外源性和内源性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。外源性空间异质性是指土壤的空间异质性，内源性异质性是指空间异质性对扩散限制、人口随机性、竞争相互作用和生物-环境反馈的响应所产生的条件，这些条件导致了独立于底层环境梯度的种群和群落的内源性空间结构。 一个新的实验将比较混合和未混合的土壤在块设计。 将播种不同的物种聚集模式和物种库（通过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可以模拟实验设计的模拟模型来补充。 模拟将允许考虑其他尺度的异质性。 通过将实验与模型相结合，这项工作将缩小理论与实证工作之间的差距。 该研究将通过一个副科学家计划扩展到教育领域，该计划涉及当地高中生，他们将直接参与数据收集和分析。 研究生将参加培训本科生和高中生。 这项工作将有助于保护通过了解植物群落简化的影响。

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.