Joshua Schimel - sylwetka autora

My research is positioned at the intersection of ecosystem and microbial ecology, focusing on the pivotal role of soil microbes in regulating ecosystem processes. I am particularly intrigued by the interactions between plant and soil dynamics and how shifts in microbial community composition impact ecosystem functions on a larger scale. My current studies are centered on three diverse ecosystems: the Arctic tundra in Alaska and Greenland, the high-altitude systems in the Sierra Nevada, and the California annual grassland-oak savanna.

In the Arctic, my research delves into soil organic matter dynamics, a critical component in the context of global climate change. The Arctic's significance stems from its substantial carbon reservoirs and its rapid warming compared to the global average. An increase in temperatures could lead to more carbon being released into the atmosphere, creating a positive climate feedback loop. Conversely, the nutrients released from organic matter might boost plant growth, enhancing Arctic vegetation's ability to act as a carbon sink and thus providing a negative feedback on climate. The predominance of either process is influenced by the nature and bioavailability of soil organic matter and the fate of nutrients released through decomposition. Part of my projects investigates the bioavailability of carbon and nitrogen in tundra soils and their seasonal variations.

A key aspect of understanding the Arctic involves the winter season. Although long and cold, winter is far from biologically inactive. Winter activity significantly contributes to annual respiration and may account for all net annual carbon efflux. Additionally, nitrogen cycling beneath the snow potentially plays a crucial role in supplying nitrogen to plants. Our understanding of microbial activity controls in freezing and frozen soils is limited. This research is integrated into the ATLAS (Arctic Transitions in the Land-Atmosphere System) program, a component of the NSF Polar Programs focused on Land-Atmosphere-Ice Interactions, aiming to understand the Arctic as a cohesive system with interlinked physical and biological components.

In California, my research is part of a larger initiative aimed at deciphering the functioning of the state's annual grassland-oak savanna/woodland ecosystems. Within this scope, I am exploring two major areas. The first focuses on plant-soil interactions, examining how shifting plant communities influence soil processes, with an emphasis on nitrogen cycling. We particularly scrutinize the impact of annual grasses that invaded California over a century ago, investigating whether they thrive by altering soil conditions. Collaborating with Dr. Jim Reichman, Eric Seabloom, and Oliver Chadwick, we delve into these interactions.

The second area of my research in California investigates how stress factors, such as drying and rewetting, along with resource availability throughout the soil profile, regulate microbial diversity, community composition, and function. This fundamental study of microbial ecology employs molecular tools to examine the dynamics of specific microbial populations.