Spatial Patterns of Soil Surface C Flux in Experimental Canopy Gaps
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To explore within-gap spatial patterns of soil surface CO2 flux, we measured instantaneous soil surface CO2 flux, soil surface temperature, and soil moisture in north–south transects across canopy gaps and in adjacent contiguous forest from April to November 2010 in a second-growth northern hardwood forest in Wisconsin, USA. Throughout the growing season, soil surface CO2 flux was higher in the northern 1/3 and northern edge of gaps compared to the central and southern portions. These patterns were driven primarily by within-gap variation in soil temperature, which was itself driven by within-gap patterns of insolation. Most locations in the northern 1/3 and northern edge of gaps had significantly higher modeled total growing season C flux (mean 725 g C m−2) compared to the contiguous forest (mean 706 g C m−2), whereas C flux in the central and southern portions of gaps (mean 555 g C m−2) was significantly lower than both the contiguous forest and the northern portions of gaps.
KeywordsCanopy gap C flux Gap microclimate Respiration Soil temperature Soil flux Northern hardwood forest
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