Quantifying the legacy of snowmelt timing on soil greenhouse gas emissions in a seasonally dry montane forest

The release of water during snowmelt orchestrates a variety of important belowground biogeochemical processes in seasonally snow‐covered ecosystems, including the production and consumption of greenhouse gases (GHGs) by soil microorganisms. Snowmelt timing is advancing rapidly in these ecosystems, but there is still a need to isolate the effects of earlier snowmelt on soil GHG fluxes. For an improved mechanistic understanding of the biogeochemical effects of snowmelt timing during the snow‐free period, we manipulated a high‐elevation forest that typically receives over two meters of snowfall but little summer precipitation to influence legacy effects of snowmelt timing. We altered snowmelt rates for two years using black sand to accelerate snowmelt and white fabric to postpone snowmelt, thus creating a two‐ to three‐week disparity in snowmelt timing. Soil microclimate and fluxes of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) were monitored weekly to monthly during the snow‐free period. Microbial abundances were estimated by potential assays near the end of each snow‐free period. Although earlier snowmelt caused soil drying, we found no statistically significant effects (p