Scaling up from local plant - plant and plant-soil relationships to landscape level patterns of diversity and process

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My research program investigates how plant-plant and plant-soil interactions structure plant and soil community diversity and composition. My objectives for this grant are to 1) investigate how local-scale plant-microbial relationships interact with large scale abiotic and climate factors to structure landscape-level patterns in plant and soil microbial communities, and 2) to disentangle the mechanisms underlying fine-scale plant rooting patterns, particularly the roles of soil nutrient heterogeneity and plant root competition.***Plant-plant and plant-soil interactions are fundamentally local, occurring at scales of millimetres to centimetres. These fine-scale processes are well studied, yet comparatively little is known about how they influence broad-scale patterns in plant and soil communities. Scaling up to landscapes is challenging because many interacting ecological mechanisms need to be assessed. I propose to link the local scale of direct plant-soil relationships to community patterns and processes at scales ranging from the local plant community, mid-scale factors such as herbivory and topography, and landscape-scale factors such as climate and soil parent material. Spatial structural equation modeling will allow me to evaluate how the relative strength and importance of mechanisms changes across scale. This will allow me to disentangle how medium to larger scale factors such as environmental conditions and landscape history interact with fine scale biological interactions to structure communities. Through characterizing the local-scale multitrophic relationships between plant roots and soil microbiota across broad climatic and soil gradients, I will examine how the well understood plant root-microbe linkages structure broad-scale patterns of plant and soil community diversity and composition. Finally, I will experimentally examine how these relationships feed back to individual plants by examining how the rooting patterns of individual plants are affected by fine-scale soil conditions.***I will utilize a multi-scale field survey program to characterize the plant and soil eubacteria, archaea, and fungal communities across a 1000 km2 region of native prairie. Sampling will follow a spatially explicit design to capture process ranging from individual plant-soil interactions (<25cm) to soil parent material and climate effects (1-100km). A PhD. student will investigate how landscape-scale factors interact with fine scale plant-soil relationships to structure plant and soil community composition. An MSc. student will focus on how local and landscape-level factors influence patterns of plant root diversity and root placement. Finally, a selection of potential mechanisms driving fine-scale plant rooting patterns including the role of soil fertility, soil nutrient heterogeneity, and competing plant roots will be investigated by a second MSc. student.**