Long-term changes in streamwater chemistry following disturbance in the Hubbard Brook Experimental Forest, USA

Biogeochemical change has been the predominant characteristic of the Hubbard Brook Experimental Forest (HBEF), USA, since the inception of the Hubbard Brook Ecosystem Study (HBES) in 1963. Major changes have included: decreases in concentration and flux o f so lin precipitation and stream water (LIKENS et al. 2002) associated with decreases in S02 emissions (BUTLER et al. 200 l, LIKENS et al. 200 l, 2005); and decreases in concentration and flux o f Ca2+ and Mg2+; and increases of pH in precipitation and stream water (LIKENS et al. 1996, 1998). Surprisingly, since 1982 the forest has ceased to accumulate biomass (LIKENS et al. 1994, 1998, SICCAMA et al. 2007). Long-term records have been indispensable for identifying, documenting, and characterizing these important bio-