Valett, H. Virginia Tech, mvalett@vt.edu
Crenshaw, C. Virginia Tech, ccrensha@vt.edu
Wagner, P. F.. Virgina Tech, pwagner@vt.edu

 
SURFACE - HYPORHEIC INTERACTIONS AND NUTRIENT RETENTION IN HEADWATER STREAMS: OLD GROWTH VS SECOND-GROWTH FORESTS
 
Land-use practices such as clear cutting may have strong impacts on lotic ecosystem functioning. This has been well demonstrated for headwater streams in the Appalachian Mountains (USA) where felled trees were dragged down stream beds as a logging practice. While benthic communities may recover in a matter of years, other aspects of the ecosystem may remain altered for many decades. In this study, we compared the structure and function of headwater streams in an old growth forest (n=3) with those (n=3) in an adjacent forested catchment of 75 yr second growth. Chlorophyll concentrations were low (mean = 33.0 and 33.1 mg/m2) and did not differ between groups, reflecting the substantial canopy present for all streams. Standing stock of woody debris, however, was significantly lower (P < 0.001) in second-growth streams. We used solute injections to assess how impacts from logging (i.e removal of woody debris and associated geomorphic change) may impact stream hydrology and retention of nutrients. Results suggest that surface-hyporheic exchange and biological retention of phosphate-phosphorus may still be altered even after 75 years of successional recovery.
 
Day: Wednesday, Feb. 3
Time: 09:00 - 09:15am
Location: Sweeney Center
 
Code: CS59WE0900S