Forest-floor respiration, N 2 O fluxes, and CH 4 fluxes in a subalpine spruce forest: drivers and annual budgets

作者：Luana Krebs, Susanne Burri, Iris Feigenwinter, Mana Gharun, Philip Meier, Nina Buchmann · 发表于：Biogeosciences · 年份：2024 · DOI：10.5194/bg-21-2005-2024 · 被引用次数：9 · 研究领域：Atmospheric and Environmental Gas Dynamics、Fire effects on ecosystems、Cryospheric studies and observations

Forest ecosystems play an important role in the global carbon (C) budget by sequestering a large fraction of anthropogenic carbon dioxide (CO 2 ) emissions and by acting as important methane (CH 4 ) sinks. The forest-floor greenhouse gas (GHG; CO 2 , CH 4 , and nitrous oxide (N 2 O)) flux, i.e., from soil and understory vegetation, is one of the major components to consider when determining the C or GHG budget of forests. Although winter fluxes are essential to determine the annual C budget, only very few studies have examined long-term, year-round forest-floor GHG fluxes. Thus, we aimed to (i) quantify seasonal and annual variations of forest-floor GHG fluxes; (ii) evaluate their drivers, including the effects of snow cover, timing, and amount of snowmelt; and (iii) calculate annual budgets of forest-floor GHG fluxes for a subalpine spruce forest in Switzerland. We measured GHG fluxes year-round during 4 years with four automatic large chambers at the ICOS Class 1 Ecosystem station Davos (CH-Dav). We applied random forest models to investigate environmental drivers and to gap-fill the flux time series. The forest floor emitted 2336 g CO 2 m −2 yr −1 (average over 4 years). Annual and seasonal forest-floor respiration responded most strongly to soil temperature and snow depth. No response of forest-floor respiration to leaf area index or photosynthetic photon flux density was observed, suggesting a strong direct control of soil environmental factors and a weak, or even lackin...