Research Interests:
Trophic dynamics, Global climate change, Plant-soil interactions and Community structure & function.
Current Research Focus
My current research interests focus on plant carbon (C) allocation in grassland communities in Yellowstone National Park. Specifically, I am interested in belowground C partitioning between fine root biomass and root metabolism and the environmental factors than control these patterns.
Why Grasslands?
Grasslands comprise a third of the world’s terrestrial surface and are estimated to store one quarter of total C sequestered by terrestrial communities each year. Therefore, grasslands are a significant portion of the total global C budget and represent a large portion of global C, making them an important ecosystem for understanding global climate change.
The Carbon Economy
C is the source of energy for entire ecosystems. Ecosystem health and function are highly dependent upon exchange and storage of energy that makes up the C economy. Changes in C allocation influences species composition, food web structure, nutrient cycling, and soil C storage.
Why Roots?
Soils make up the largest land reservoir of C with grasslands accounting for approximately 30% of global soil C storage. C allocated to root biomass either remains in plant roots or is turned over and enters the soil food web community and soil C stores, whereas, C allocated to root metabolism is immediately lost from the system. In grasslands, upwards to 90% of total C stores are sequestered belowground in roots and soil. Fine roots are the predominant source of soil C in grasslands accounting for on average 83% of all root production. C partitioning between fine root biomass, the largest potential contributor to soil C, and root respiration is a critical controller in understanding terrestrial ecosystem C dynamics.
Trophic Dynamics in Grazing Ecosystems
Herbivore control and regulation of grassland productivity and ecosystem functioning has been well documented. Changes in C allocation to aboveground and belowground plant biomass directly affects herbivores and has potential top-down and bottom-up cascading trophic effects, and thus, positive or negative feedbacks on ecosystem productivity and functioning.
Publications:
Thorne, M. A. & D. A. Frank. (2009) Influences of simulated grazing and variable soil moisture on root respiration in temperate and tropical grass species. Plant Ecology 200: 205-215.
Anderson, T. M., W. T. Starmer & M. A. Thorne. (2007) Bimodal root diameter distributions in Serengeti grasses exhibit plasticity in response to defoliation and soil texture: Implication for nitrogen uptake. Functional Ecology 21:50-60. |
