Mineral soil and solution responses to experimental N and S enrichment at the Bear Brook Watershed in Maine (BBWM)

Buried mineral soil-bags and natural solutions were studied as indicators o f forest ecosystem response to elevated N and S inputs at the Bear Brook Wa tershed in Maine(BBWM). The BBWM is the site of a paired watershed manipula tion experiment in a northern New England forested ecosystem. The study inc ludes two snail (similar to 10 ha each) catchments dominated by northern ha rdwood forests with red spruce in the upper elevations. Treatments consist of(NH4)(2)SO4 applied to the West Bear watershed six times per year, increa sing N and S deposition 3x and 2x above ambient values, respectively. Burie d mineral soil-bag changes over time reflected both the native soil environ ment and the treatments. Most of the treatment effects on mineral soils wer e evident as higher inorganic S found in the treated watershed soils Adsorb ed SO4 in the buried mineral soil-bags increased by approximately 40% under softwood stands and 50% under hardwood stands over the study period Hardwo od soil solutions responded with significant increases in NO3 and SO4 conce ntrations that resulted in accelerated cation leaching primarily Ca and Al. Few differences that could be attributed to treatments were evident in soi l solutions under softwoods. No treatment effects were evident in throughfa ll and stemflow chemistry.