Parsing spatial and temporal variation in stream ecosystem functioning

The decomposition of organic matter is a fundamental ecosystem-level process that governs nutrient cycling, fuels ecosystems, and impacts our global climate. Despite the central importance this for ecosystems across planet, little known about how capacity to decompose matter—that is, their potential—varies time space. Closing gap needed provide baseline information on dynamics tracking anthropogenic impacts, development practical efficient sampling procedures. For nine consecutive years during months July–August, we deployed an identical organic-matter assay in same 26 temperate deciduous-forest streams (234 stream-years total) evaluate interannual among-stream variation matter. Decomposition rates (as k values) ranged widely all (mean = 0.026, SD 0.018, range 0.0020–0.094). Interestingly, variation, expressed per-stream basis, was more than three times greater (expressed per year basis), explaining 75% 22% overall dataset, respectively. Removing effects temperature by adjusting degree days did not substantially impact pattern (stream: 80% year: 17% variation). Surprisingly, despite large differences among streams, explained rates, pointing other factors. When compared from stream sites presented here spanned 27.3% range, highlighting diversity can be found relatively compact geographic area. From perspective using as bioassessment tool, could limit sensitivity decomposition-based assays human although study designs utilized ameliorate problem (e.g., those stratify geology). results dataset are step toward complete understanding ecosystem processes vary