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The feedbacks between the water and the carbon cycles are of critical importance to global carbon balances. Forests and forest soils in northern latitudes are important carbon pools because of their potential as sinks for atmospheric carbon. However there are significant unknowns related to the effects of hydrologic variability, mountainous terrain, and landscape heterogeneity in controlling soil carbon dioxide (CO2) efflux. Mountainous terrain imposes large spatial heterogeneity in the biophysical controls of soil CO2 production and efflux, including soil temperature, soil water content, vegetation, substrate, and soil physical properties. Further complications are introduced by the superimposed temporal heterogeneity (i.e., the asynchronous response of each variable to changes in environmental conditions). As a result, extrapolating from single- or multiple-point measurements to larger areas requires understanding of the emerging patterns controlled by the underlying spatiotemporal nature of biophysical drivers.