OOS 32 - Seeking Conceptual Equity In Forest Carbon Balances: Looking Beyond NPP

Wednesday, August 8, 2012: 1:30 PM-5:00 PM
B113, Oregon Convention Center
Robert M. Scheller, Portland State University
Mark E. Harmon, Oregon State University
Robert M. Scheller, Portland State University
Projections of forest carbon dynamics under a changing climate are predicated on empirical relationships among net primary productivity, detritus generation, heterotrophic respiration, and the residence times of various soil organic carbon components. These relationships are incorporated into models of succession and disturbance to enable the simulation of longer-term (multiple decades) forest carbon dynamics. Excellent progress has been made in measuring and modeling net primary productivity. However, other barriers to robust estimates of carbon trajectories under climate change remain. Most estimates of forest carbon dynamics are drawn from relatively short duration observations, a particular problem for large coarse woody debris and soil pools. Models of forest dynamics often neglect critical interactions such as successional or climate-driven changes in tree species composition and changing disturbance dynamics. An improved understanding will require that we move beyond carbon models driven primarily by net primary productivity. In our session, we will highlight the latest methods, approaches, and applications to the challenges of projecting forest carbon. The solicited talks span a broad range from innovative approaches for measuring soil residence times via C14 analysis to regional modeling that integrates multiple drivers of forest carbon change. Our goal is to summarize the current state of the science; identify areas of understanding and disagreement; and guide future research through the exchange of ideas and information. Our session will be broken out into five principle sections: 1) Woody detritus. Key points: Consideration of woody detritus needs to move beyond downed material and include all forms of detritus; the importance woody detritus legacies following disturbance; the general state of knowledge of controls; and the next critical steps in research. 2) Non-wood Litter: Key points: There is a limited understanding of long-term dynamics; mass loss versus respiration losses; the fate of leachates; abiotic losses are important in many ecosystems; reexamining lignin as the key driver of substrate quality. 3) Soil dynamics: Key points: The balance of auto- versus heterotrophic contributions; residence times and heterogeneity; temperature sensitivity; substrate versus other controls (e.g., physical protection). 4) Modeling Heterotrophic Respiration: Key points: Heterogeneity in space and time is critical to address (including shifts caused by changes in life-forms and species); disturbances are key to understanding carbon balances at all spatial and temporal scales. 5) Regional Analysis: Key points: Disturbances must be considered; legacy effects at regional scales must be recognized; the effects of (past history; possible lags between disturbances and C release.
1:50 PM
 Attributes of dead wood carbon stocks across forests of the U.S.
Christopher W. Woodall, USDA Forest Service; Grant M. Domke, USDA Forest Service, Northern Research Station; James E. Smith, US Forest Service, Northern Research Station
2:10 PM
 A shady business: Effects of pine afforestation on litter decomposition along a precipitation gradient in Patagonia, Argentina
Patricia I. Araujo, University of Buenos Aires, IFEVA-CONICET; Amy T. Austin, University of Buenos Aires, IFEVA-CONICET
2:50 PM
 Forest carbon cycling: Insights gained from radiocarbon measurements
Claire Phillips, Lawrence Livermore National Laboratory
3:10 PM
3:40 PM
 Regional modelling of forest carbon dynamics for national reporting
C. Boisvenue, Canadian Forest Service; Werner Kurz, Canadian Forest Service; Graham Stinson, Pacific Forestry Centre, Canadian Forest Service; Carolyn Smyth, Canadian Forest Service; Juha Metsaranta, Natural Resources Canada; Eric Neilson, Canadian Forest Service
4:00 PM
 Climate change and landscape legacy effects on forest carbon dynamics and wildfires in the Lake Tahoe Basin
Louise Loudermilk, USDA Forest Service; Robert M. Scheller, Portland State University; Peter Weisberg, University of Nevada-Reno; Jian Yang, University of Nevada-Reno; Alison E. Stanton, Research Botanist; Carl Skinner, US. Forest Service, Pacific SW Research Station; Tom Dilts, University of Nevada-Reno
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