Our all-day field trip to the H.J. Andrews was a great success. A contingent of 9 Hydrophiles enjoyed a mostly sunny (if at times a bit chilly) day learning about some of the many long-term hydrologic monitoring activities, long-term experiments, and current research in hydrology and stream ecology at this internationally known long-term ecological research (LTER) facility. We toured a gaging station in the "control" watershed for a long-term paired small watershed experiment testing the effects of clear-cutting and road construction on basin hydrology and sediment yield, at which streamflow, water quality, and sediment yield are monitored. We also toured one of 4 main weather stations in the forest at which an impressive array of meteorological parameters (precipitation, snow depth and snow-water equivalent, temperature, relative humidity, wind speed and direction, incoming solar radiation, etc.) are monitored at intervals as short as 15 minutes and relayed to the Andrews headquarters via radio telemetry. (Precipitation and temperature data are available on a near-real-time basis on the Andrews website.)
Those who had never visited old-growth Douglas-fir forest were very impressed by the huge trees and abundant in-stream woody debris at Mack Creek, famous among stream ecologists as one of the key field sites where the "River Continuum Concept" was originated and site of intensive, long-term research into the effects of coarse woody debris (CWD) on stream channel morphology and CWD dynamics within fluvial systems. More recently, it was chosen for an LTER inter-site study of nitrogen dynamics in riparian ecosystems using N15 (a stable isotope present only in minute quantities in nature) as a tracer. We also learned about research into the role of forest canopy shading, alluvial vs. bedrock stream channels, and other factors influencing the spatial pattern and diurnal fluctuations of stream temperature.
At our last stop, we visited a 1 km^2 watershed that was clear-cut without roads using an experimental cable logging method in the 1960s as part of a paired-watershed experiment and now is one site in a study of the extent, significance, and controls on hyporheic flow (exchange flows between the stream and the subsurface). Large cut logs remaining from the logging operation have created as step-pool morphology that enhances hyporheic flow and also stabilizes the channel by trapping sediment. Some of these structures are beginning to break down as the logs decay, releasing the alluvial sediment accumulated behind them. Since conifer regrowth at the site has been very slow and input of large logs through tree mortality is probably at least a century away, the channel may lose much of its CWD and alluvial sediment over the coming decades, evolving toward a bedrock channel with no hyporheic zone.
I would be remiss if I did not acknowledge publicly those who contributed to making this trip a success. Thanks to Craig Creel and John Moreau of the USFS for acting as our tour guides at the watershed monitoring and meteorology stations. Thanks also to Sherri Johnson (Depts. of Geosciences and Fisheries and Wildlife), and Steve Wondzell (Dept. of Forest Science) for meeting with us at their field sites and sharing with us some of the research that they and others have been involved with at the Andrews. Finally, thanks to Christine May for help with driving, and to all of you who showed up and made this a great trip.
--John Faustini