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

Joseph C. Blankinship, Emma P. McCorkle, Matthew W. Meadows, Stephen C. Hart

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


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 < 0.05) of altered snowmelt timing on fluxes of CO2 or N2O, or soil microbial abundances. Soil CH4 fluxes, however, did respond to snowmelt timing, with 18% lower rates of CH4 uptake in the earlier snowmelt treatment, but only after a dry winter. Cumulative CO2 emission and CH4 uptake were 43% and 88% greater, respectively, after the dry winter. We conclude that soil GHG fluxes can be surprisingly resistant to hydrological changes associated with earlier snowmelt, likely because of persistent moisture and microbial activities in deeper mineral soils. As a result, a drier California in the future may cause seasonally snow-covered soils in the Sierra Nevada to emit more GHGs, not less.

Original languageEnglish (US)
Pages (from-to)5933-5947
Number of pages15
JournalGlobal change biology
Issue number12
StatePublished - Dec 2018


  • Southern Sierra Critical Zone Observatory
  • methane oxidation
  • nitrous oxide
  • snow manipulation
  • soil respiration

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • General Environmental Science


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