Past research demonstrating the importance plant-microbe interactions as drivers of ecosystem suc... more Past research demonstrating the importance plant-microbe interactions as drivers of ecosystem succession has focused on how plants condition soil microbial communities, impacting subsequent plant performance and plant community assembly. These studies, however, largely treat microbial communities as a black box. In this study, we sought to examine how emblematic shifts from early successionalssp.(Sitka alder) to late successional(Sitka spruce) in primary succession may be reflected in specific belowground changes in bacterial community structure and nitrogen cycling related to the interaction of these two plants. We examined early successional alder-conditioned soils in a glacial forefield to delineate how alders alter the soil microbial community with increasing dominance. Further, we assessed the impact of late-successional spruce plants on these early successional alder-conditioned microbiomes and related nitrogen cycling through a leachate addition microcosm experiment. We show ...
Environmental conditions within a catchment vary by slope aspect, and hence slope aspect provides... more Environmental conditions within a catchment vary by slope aspect, and hence slope aspect provides a means of observing their controls on critical zone structure and function. We summarize water, biogeochemistry, soil, and weathering on opposing slope aspects in Gordon Gulch, a headwater catchment in the Front Range of Colorado. These observations show that water and energy delivery to the lower critical zone are the most important climate characteristics involved in the evolution of critical zone architecture.
The architecture of the Critical Zone, including mobile regolith thickness and depth to the weath... more The architecture of the Critical Zone, including mobile regolith thickness and depth to the weathering front, is first order controlled by advance of a weathering front at depth and transport of sediment at the surface. Differences in conditions imposed by slope aspect in the Gordon Gulch catchment of the Boulder Creek Critical Zone Observatory present a natural experiment to explore these interactions. The weathering front is deeper and saprolite more decayed on north-facing than on south-facing slopes. Simple numerical models of weathering front advance, mobile regolith production, and regolith transport are used to test how weathering and erosion rates interact in the evolution of weathered profiles. As the processes which attempt are being made to mimic are directly tied to climate variables such as mean annual temperature, the role of Quaternary climate variation in governing the evolution of Critical Zone architecture can be explored with greater confidence.
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Papers by Patrick Kelly