HYDROCHEMISTRY OF FORESTED CATCHMENTS¹

“The song of a river ordinarily means the tune that waters play on rock, root, and rapid. …This song of the waters is audible to every ear, but there is other music in these hills, by no means audible to all. To hear even a few notes of it you must first live here for a long time, and you must know the speech of hills and rivers. Then on a still night, when the campfire is low and the Pleiades have climbed over rimrocks, sit quietly and listen for a wolf to howl, and think hard of everything you have seen and tried to understand. Then you may hear it—a vast pulsing harmony—its score inscribed on a thousand hills, its notes the lives and deaths of plants and animals, its rhythms spanning the seconds and the centuries.” Aldo Leopold, Song of the Gavilan [Reprinted in part from (Leopold (1940), by permission of The Wildlife Society.]

The pathways that water may take through a catchment and its reactions with organisms and soils are myriad and ever varying. A promising means to unraveling the mystery of watershed hydrochemistry is the study of “small” catchments, yet the hydrochemical function of even the smallest of catchments involves an amazingly intricate web of flowpaths and biogeochemical processes. Monitoring of catchments and comparison of their inputs to their outputs yields clues to their workings. Manipulation of catchments offers some means of “controlled” experimentation as to their nature. Modeling of catchment hydrochemical response attempts to put it all together. Every forested catchment is individual in its structure and hydrochemical response, yet a select, carefully studied few often are drafted to serve as representatives in assessments of responses to environmental influences or perturbations (e.g. acid rain). Many factors must be considered in such extrapolations. Studies of forested catchments often are driven by environmental concerns and thus fluctuate accordingly as to their location and intensity. Despite such fluctuations, the future of the field is clear and bright. Much has been learned as a result of recent studies, not only of what to think about catchment function but, more importantly, how to think about it.