People and Nature Lab Seminar: Astrid Volder (UC Davis)

Astrid Volder

Vice Chair for teaching in the Department of Plant Sciences.Chair for the Horticulture and Agronomy graduate group at University of California, Davis

BIO Dr. Astrid Volder received her B.S. in Biology from Utrecht University in The Netherlands. As an undergraduate student she worked on diurnal nitrogen uptake in grasses and on flowering of plants growing in tidal marshes in the South of France. She then moved to the University of Washington (Seattle) where she received an MS in Botany, followed by a PhD from Utrecht University, working on the nitrogen economy of polar desert plants. This was followed by postdoctoral projects at Penn State University (nitrogen uptake of plants as affected by root age), CSIRO/Australian National University in Canberra (root/growth dynamic of pasture grass in response to elevated CO2 and diurnal warming patterns), and Texas A&M University (belowground tree-grass interactions in oak-savannah grassland in response to changes in precipitation patterns). She then took a faculty position at Texas A&M University in Horticultural Landscape Ecology (green roofs, but also Pecan root dynamics) and eight years later moved to the University of California, Davis to exclusively work on root and rhizosphere questions in various ecosystems. She is now a full professor and served as graduate chair for the Horticulture and Agronomy graduate group and currently serves as vice chair for teaching in the Department of Plant Sciences.

ABSTRACT In spite of huge improvements in root phenotyping in controlled environment settings, we still know surprisingly little about root x environment interactions, particularly in perennial plants. This is because roots are very difficult to observe in their natural environment, but also because the root system is complex and very responsive to environmental conditions. Analogous to the aboveground system, root systems have a long-lived component - "the stem and large branches" - and a short-lived component "the leaves". Fine roots are akin to the leaves, except more complicated as the finest roots are dependent on less fine roots and so forth - there is a strong hierarchy within the root system. This could be considered akin to "twigs", however, compared to the aboveground system, there are many more root orders that are still considered fine. Substantial variation in age, function and lifespan occurs within the finest root classes. As the most dynamic part of the root system they are also most affected by short term environmental fluctuations (e.g., light, water availability, nutrient heterogeneity, shoot management), as compared to the coarser (long lived) part of the root system which is more strongly affected by long term characteristics of the environment (e.g., compacted layers, soil texture, climate). This informal talk will focus on this framework and provide field examples that demonstrate the differential responses of fine root orders to management decisions that alter the root environment on a short term basis and will include some data on how this in turn feeds back to the rhizosphere microbiome.