Effects of soil rewetting and thawing on soil gas fluxes: a review of current literature and suggestions for future research

[摘要] The rewetting of dry soils and the thawing of frozen soils are short-term,transitional phenomena in terms of hydrology and the thermodynamics of soilsystems. The impact of these short-term phenomena on larger scale ecosystemfluxes is increasingly recognized, and a growing number of studies show thatthese events affect fluxes of soil gases such as carbon dioxide (CO₂),methane (CH₄), nitrous oxide (N₂O), ammonia (NH₃) and nitricoxide (NO). Global climate models predict that future climatic change islikely to alter the frequency and intensity of drying-rewetting events andthawing of frozen soils. These future scenarios highlight the importance ofunderstanding how rewetting and thawing will influence dynamics of thesesoil gases. This study summarizes findings using a new database containing338 studies conducted from 1956 to 2011, and highlights open researchquestions. The database revealed conflicting results following rewetting andthawing in various terrestrial ecosystems and among soil gases, ranging fromlarge increases in fluxes to non-significant changes. Studies reportinglower gas fluxes before rewetting tended to find higher post-rewettingfluxes for CO₂, N₂O and NO; in addition, increases in N₂Oflux following thawing were greater in warmer climate regions. We discusspossible mechanisms and controls that regulate flux responses, and recommendthat a high temporal resolution of flux measurements is critical to capturerapid changes in gas fluxes after these soil perturbations. Finally, wepropose that future studies should investigate the interactions betweenbiological (i.e., microbial community and gas production) and physical(i.e., porosity, diffusivity, dissolution) changes in soil gas fluxes, applytechniques to capture rapid changes (i.e., automated measurements), andexplore synergistic experimental and modelling approaches.

[学科分类] 地球化学与岩石