Stream chemistry has been monitored for many years on all of the watersheds at Hubbard Brook Experimental Forest.  Significant changes in the concentration of various base cations in the stream resulted from the harvest of W5, as they did from the harvest and herbiciding of W2 in 1965.  These changes are summarized below.

        1. Abstract
        2. Figure 1:  Potassium output
        3. Figure 2:  Calcium output
        4. Figure 3:  Potassium flux for W2 and W5
        5. Figure 4:  Calcium flux for W2 and W5
 
 
 

1. Abstract

        The whole-tree harvest of W5 resulted in significant and prolonged increases in the concentrations and fluxes of base cations in streamflow (Likens et al. 1994, 1998) (see Figures 1 and 2 below).  Early studies of the responses of W2 (Reiners 1992) to the combination of clear-felling (without any wood product removal) and subsequent suppression of revegetation for three years, provided a basis for comparing base cation balances between these contrasting disturbances.  Streamflow losses of both K and Ca were much larger for W2 than W5 during the first 8 years following disturbance.  For both nutrient cations the combination of lower release from decaying logging residue, and higher uptake by regrowing vegetation in W5 contributed about equally to the lower streamflow losses from W5 than W2 (Figures 3 and 4 below)   The differences in losses between the two watersheds became smaller in years 4-8 than in years 1-3 after disturbance, primarily because vegetation recovery began on W2 in year 4 following 3 years of herbicide suppression.
 
 
 

2. Figure 1    (Figure 21 from Likens et al. 1994. Biogeochemistry 25:61-125.)

 
 
 

3. Figure 2 (Figure 27 from Likens et al. 1998. Biogeochemistry 41:89-173.)

 
 
 

4. Figure 3    (Figure 23 from Likens et al. 1994.  Biogeochemistry 25:61-125.)

 
 
 

5. Figure 4    (Figure 30 from Likens et al. 1998. Biogeochemistry 41:89-173.)

Web page created June 2000
by Thomas Siccama and Ellen Denny