101-7
Water, Temperature, and Defoliation Effects On Perennial Grassland Respiration.

Monday, November 4, 2013: 11:35 AM
Tampa Convention Center, Room 19, First Floor

R. Howard Skinner, Pasture Systems and Watershed Management Research Unit, USDA-ARS, University Park, PA
Changes in respiration can have a profound effect on ecosystem C balance. This talk will present results from eddy covariance studies describing environment and management effects on ecosystem C flux from cool- and warm-season perennial grasslands. In addition, stable C isotope studies that partitioned belowground respiration between the rhizosphere and free-living soil organisms will provide estimates of whole-plant respiration in undisturbed field plots. Although respiration and photosynthesis can be closely coupled at the whole-field scale, changes in respiration rather than photosynthesis drive the net ecosystem C balance in many ecosystems and often less than 20% of assimilated C is harvested from perennial grasslands. During much of the year, respiration can be greater than photosynthetic uptake resulting in a net loss of C from the ecosystem. Ecosystem respiration tends to be less susceptible than photosynthesis to drought stress whereas both are equally responsive to N fertilization. Implications of changes in respiration rate on yield and ecosystems services such as soil C sequestration will be discussed.
See more from this Division: C02 Crop Physiology and Metabolism
See more from this Session: Symposium--Crop Respiration - The Other Half of the Carbon Balance

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