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Josh Grinath
Board Member
Office: Life Sciences 420 & 421
Assistant Professor
Community and Global Change Ecology
My research addresses broad questions about the processes that determine ecological community structure and ecosystem functioning. Specifically, I am interested in understanding how drivers of global change such as atmospheric pollution, climate change and species invasions, restructure communities and impact ecological dynamics from plants to predators. My work primarily occurs in grassland ecosystems that include plants and animals of conservation concern and that provide vital ecosystem services to humans. Using field experiments and modeling, I study systems that contain multiple types of species interactions, such as predation, mutualism, and ecosystem engineering. While many ecologists study ecological networks composed of single types of species interactions, for example food webs or mutualistic webs, most ecological systems are composed of multiple interaction types that must be considered together to fully understand the consequences of global change. Overall, my goal is to conduct research that is relevant to managing current and future environmental challenges and that can inform conservation efforts.
One of my primary research goals has been to understand how atmospheric nitrogen (N) deposition and the cascading effects of predators restructure a plant-arthropod community in a Colorado sagebrush steppe ecosystem. Through field experiments and network analysis, I discovered that ant-eating black bears indirectly benefit plants by suppressing an ant-herbivore mutualism, which should be considered in the management of bears. However, I also found that simulated low-level N deposition weakens this cascade of effects, which suggests that current widespread rates of N deposition have altered resource versus consumer control of ecological structure in other ecosystems as well. I have maintained this N manipulation for twelve years now and am revisiting this experiment to assess the long-term repercussions of low-level N deposition. This project provides a unique opportunity to not only assess the effects of chronic N deposition on plants, like most previous studies, but on animals and plant-animal interactions.
I have also conducted research on how an annual grassland community in California is structured by precipitation and a dominant, burrowing herbivore – the federally endangered giant kangaroo rat. I led studies on the ecosystem engineering effects of these rodents on soil properties (soil moisture and N dynamics) and plant-arthropod communities. In addition, I have used a combination of field experiments and herbarium records to study ‘cedar glade’ grassland responses to climate change, invasive insects, and restoration efforts in Tennessee.
My current research is focused on understanding how the combination of changes in N deposition and climate impact plant-animal communities and ecosystem functioning, particularly in sagebrush steppe ecosystems of the Intermountain West. Plant growth is commonly limited by both N and water availability and respond synergistically to simultaneous changes in these resources. However, animal responses to these dynamics are poorly understood, as are the repercussions for ecosystem functioning.
Please see my personal website (jbgrinath.wordpress.com) for further details.