HR: 15:10h
AN: GC33B-07    [Abstracts]
TI: Effects of Climate and Fire on Thermal Habitats Within Mountain Stream Networks: An Example With a Native Charr Species
AU: * Isaak, D
EM: disaak@fs.fed.us
AF: US Forest Service - Research, 322 E. Front St., Suite 401, Boise, ID 83702, United States
AU: Luce, C
EM: cluce@fs.fed.us
AF: US Forest Service - Research, 322 E. Front St., Suite 401, Boise, ID 83702, United States
AU: Rieman, B
EM: brieman@fs.fed.us
AF: US Forest Service - Research, 322 E. Front St., Suite 401, Boise, ID 83702, United States
AU: Nagel, D
EM: dnagel@fs.fed.us
AF: US Forest Service - Research, 322 E. Front St., Suite 401, Boise, ID 83702, United States
AU: Peterson, E
EM: disaak@fs.fed.us
AF: CSIRO, 120 Meiers Road, Indooroopilly, QLD 4068, Australia
AB: Climatic trends associated with warming air temperatures, changing hydrology, and increasing fire activity will affect thermal regimes in mountain streams. Because most aquatic species are ectotherms, disruptions of these ecosystems will be significant as the distributions of thermal habitats change. Although local stream temperature models have frequently been developed, network-scale models necessary for conservation are generally lacking. Using a new class of spatial statistical model that accommodates network topology and multiple types of spatial autocorrelation based on instream and Euclidean distance, we modeled the effects of geomorphology, climate, and fire on stream temperatures across a 6th-order network in central Idaho. Satellite imagery of riparian vegetation pre- and postfire was used to quantify the amount of solar radiation reaching the stream and consequent effects on temperature. Climate covariates were derived from weather and flow gauging stations and relevant geomorphic features were derived from digital elevation models. The spatial models yielded more accurate parameter estimates than traditional regression models and offered improved predictive ability for the temperature metrics examined (e.g., R² ~ 0.60 vs. 0.85). Upon completion, the spatial models were used to assess changes in the distribution of thermally suitable habitats for bull charr (Salvelinus confluentus) over a 15 year period with extensive fire activity. Habitat losses were spatially variable, as were the relative effects of the covariates. In general, the greatest habitat loss was attributable to the effects of fire and recent trends of increasing air temperatures and decreasing flows played lesser roles. Our results suggest that impairment and loss of aquatic habitats due to climate change can be caused by direct or indirect effects and may occur as gradual trends or during episodic disturbances. If future efforts to conserve aquatic species are to succeed, models that incorporate the spatial complexity of landscape responses to ongoing climate trends are needed.
UR: http://www.fs.fed.us/rm/boise
DE: 0483 Riparian systems (0744, 1856)
DE: 0496 Water quality
DE: 1630 Impacts of global change (1225)
DE: 1637 Regional climate change
DE: 1813 Eco-hydrology
SC: Global Environmental Change [GC]
MN: 2007 Fall Meeting