HR: 1340h
AN: H13D-1541    [Abstracts]
TI: Quantifying Radiative Inputs to Headwater Streams in Recently Harvested Forests
AU: * Klos, P Z
EM: zion.klos@coloradocollege.edu
AF: Water Resources REU, Department of Forest Resources University of Idaho PO Box 441133, Moscow, ID 83844-1133, United States
AU: Link, T
EM: tlink@uidaho.edu
AF: Water Resources REU, Department of Forest Resources University of Idaho PO Box 441133, Moscow, ID 83844-1133, United States
AB: Removal of streamside forest canopy during timber harvest can lead to large increases in the amount of shortwave (solar) radiation reaching the stream surface. Shortwave radiation increases may be partially offset by longwave (thermal) radiation decreases due to the decrease of the vegetation canopy. Rapid recovery of herbaceous streamside vegetation in recently harvested areas may act to negate the increased shortwave radiative inputs caused by tree canopy reduction. A quantifiable difference in the radiative inputs affecting streams was found by measurement of incoming shortwave and longwave radiation. Arrays of 10 shortwave and 2 longwave radiation sensors were installed in first-order stream systems for 24-hour periods of high radiation loading to quantify the contribution of incoming solar and thermal radiation in headwater systems. Sensors were installed in unimpacted forested reaches, a partial cut reach (~50% canopy removal), densely vegetated and sparsely vegetated 5 year-old clearcut reaches, and a simulated freshly cut (absent of any streamside vegetation). Results indicate that thermal radiation is the dominant source of radiation in all treatment reaches. All-wave incoming radiation was reduced by 36 to 39% in the undisturbed reaches, compared to open areas. The partial cut area and heavily vegetated 5-year old clearcut were very similar to intact forested reaches, with 37% and 38% all-wave reduction relative to open areas. The sparsely vegetated 5-year old clearcut exhibited a 16% reduction in all-wave radiation, and the simulated fresh clearcut exhibited a 9% reduction, relative to open areas, due to shading by overhanging banks. Results from this study indicate that recently clearcut headwater streams are able to recover to pre-harvest shading characteristics if adequate regrowth of herbaceous vegetation occurs.
DE: 1813 Eco-hydrology
DE: 1814 Energy budgets
DE: 1834 Human impacts
DE: 1874 Ungaged basins
DE: 1895 Instruments and techniques: monitoring
SC: Hydrology [H]
MN: 2007 Fall Meeting