HR: 1340h
AN: B43D-1588    [Abstracts]
TI: Tree Age, Disturbance History, and Carbon Stocks and Fluxes in Subalpine Rocky Mountain Forests
AU: * Ryan, M G
EM: mgryan@fs.fed.us
AF: USDA Forest Service, Rocky Mountain Research Station, 240 West Prospect RD, Fort Collins, CO 80526, United States
AU: Bradford, J B
EM: jbbradford@fs.fed.us
AF: USDA Forest Service Northern Research Station, 1831 Hwy 169 E, Grand Rapids, MN 55744-3399, United States
AU: Birdsey, R A
EM: rbirdsey@fs.fed.us
AF: USDA Forest Service Northern Research Station, 11 Campus Blvd. Suite 200, Newtown Square, PA 19073, United States
AU: Joyce, L A
EM: ljoyce@fs.fed.us
AF: USDA Forest Service, Rocky Mountain Research Station, 240 West Prospect RD, Fort Collins, CO 80526, United States
AB: Forest carbon stocks and fluxes in vary with forest age, and relationships with forest age are often used to estimate fluxes for regional or national carbon inventories. Two methods are used to estimate forest age: observed tree age or time since a known disturbance. To clarify the relationships between tree age, time since disturbance and forest carbon storage and cycling, we examined stands of known disturbance history in three landscapes of the southern Rocky Mountains. Our objectives were to assess the similarity between carbon stocks and fluxes for these three landscapes that differed in climate and disturbance history, characterize the relationship between observed tree age and time since disturbance and quantify the predictive capability of tree age or time since disturbance on carbon stocks and fluxes. Carbon pools and fluxes were remarkably similar across the three landscapes, despite differences in elevation, climate, species composition, disturbance history, and forest age. Tree age was a poor predictor of time since disturbance. Maximum tree age overestimated age since disturbance for young forests and overestimated it for older forests. Carbon pools and fluxes were related to both tree age and disturbance history, but the relationships differed between these two predictors and were generally less variable for pools than for fluxes. Using tree age in a relationship developed with time since disturbance or vice versa increases errors in estimates of carbon stocks or fluxes. Little change in most carbon stocks and fluxes occurs after a tree age of 60 years, simplifying landscape scale estimates. We conclude that subalpine forests in the Central Rocky Mountains can be treated as a single forest type for the purpose of assessment and modeling of carbon, and that the critical period for change in carbon is < 60-100 years.
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting