Collaborative Research: RUI: how landscape fragmentation interferes with plant-pathogen interactions that maintain local plant diversity

由于土地利用的变化，如郊区的扩张，许多自然区正在被分割成更小的碎片。与较大的碎片相比，小碎片通常是极端的环境，因为它们会经历更高的温度、更多的光照和更低的土壤水分等压力。这项研究着眼于生活在不同大小碎片中的植物如何受到病原体的影响。植物与病原体之间的相互作用很重要，因为尽管病原体最为人所知的是它们造成的破坏，但它们也有助于保护生物多样性。这是因为每一种植物都有自己独特的一组专门针对它的病原体，它们会减缓生长或只杀死它们感染的植物。这可以防止任何单一的植物物种在一个地区占据主导地位。然而，并不是所有的病原体都能在小片的极端环境中茁壮成长。可能在小斑块中，不同类型的病原体更常见，这些病原体减缓生长或不分青红皂白地杀死多种植物物种。如果是这样的话，与大片土地相比，它们可能会减少植物多样性。通过揭示植物和病原体如何在不同的斑块大小中相互作用，这项工作将与理解破坏自然区域的生物多样性后果相关，并可能影响自然景观的管理。该项目的两位首席研究人员都是本科院校的职业早期教师，他们将把本科生纳入这项工作的所有方面，包括社区外展。将进行三项平行研究，以评估景观破碎化如何改变植物与病原体的相互作用，特别是真菌病原体。首先，研究人员将在堪萨斯州的碎裂地点将12种植物的种子埋在不同大小的地块中，使种子能够被潜在的病原体定居，并进行测试，看看种子在埋藏一年后是否仍然活着。这将决定真菌病原体导致的种子死亡是否最受生态因素的影响，这些因素随斑块大小而变化，如植物寄主密度、植物物种丰富度和小气候条件(如温度和土壤湿度)。其次，这些埋藏的种子中的真菌群落将使用基于培养的方法和独立于培养的分子工具进行表征。这将决定真菌群落结构是否可预测地随斑块大小、寄主身份和寄主密度而变化。最后，温室和田间试验的结合将检验这样一种假设，即负反馈(当植物在根部周围的土壤中“培养”寄主特定的病原体时)在大斑块的内部最强，而不是在大斑块的边缘或小斑块。据预测，边缘和小斑块上的高温压力环境将有利于通用型真菌，减少维持多样性的反馈对较小片段的影响。总体而言，这些研究将个别植物与真菌的相互作用与植物多样性中观察到的景观模式联系起来。

Many natural areas are being broken up into smaller fragments due to land-use changes such as suburban sprawl. Compared with larger fragments, small fragments are often extreme environments because they can experience stresses like higher temperatures, more light, and lower soil moisture. This research looks at how plants living in different sized fragments are affected by their pathogens. Interactions between plants and their pathogens are important because although pathogens are best known for the damage they cause they can also help preserve biological diversity. This is because each plant species has its own unique group of pathogens that specialize on it, and slows growth or kills just the plants they infect. This can keep any single plant species from dominating in an area. However, not all pathogens can thrive in the extreme environments found in small patches. It may be that in small patches, different types of pathogens that slow growth or kill multiple plant species indiscriminately are more common. If this is the case, they could decrease plant diversity compared with large patches. By uncovering how plants and pathogens interact in different patch sizes this work will be relevant for understanding the biodiversity consequences of breaking up natural areas, and may affect management of natural landscapes. Both lead researchers for this project are early-career faculty at undergraduate colleges, and will incorporate undergraduate students into all aspects of this work, including community outreach.Three parallel studies will be conducted to assess how plant-pathogen interactions are altered by landscape fragmentation, focusing on fungal pathogens in particular. First, researchers will bury seeds of twelve plant species in patches of different sizes at the Kansas Fragmentation Site, allowing the seeds to be colonized by potential pathogens and testing to see if the seeds remain viable after a year of burial. This will determine if seed mortality due to fungal pathogens is most influenced by ecological factors that vary with patch size, such as plant host density, plant species richness, and microclimatic conditions (such as temperature and soil moisture). Second, the fungal community from these buried seeds will be characterized using both culture-based methods and culture-independent molecular tools. This will determine whether fungal community structure varies predictably with patch size, host identity, and host density. Finally, a combination of greenhouse and field experiments will test the hypothesis that negative feedbacks (when plants "culture" host-specific pathogens in the soil surrounding their roots) are strongest in the interiors of large patches, rather than on the edges of large patches or in small patches. It is predicted that thermally stressful environments on edges and small patches will favor generalist fungi, reducing the influence of diversity-maintaining feedbacks on smaller fragments. Collectively, these studies link individual plant-fungal interactions to observed landscape patterns in plant diversity.