Midsummer spatial variation in methane efflux from stands of littoral vegetation in a boreal meso‐eutrophic lake

Abstract

Summary 1. Spatial variation of methane (CH4) efflux from the littoral zone of a meso‐eutrophic boreal lake was studied with a closed‐chamber technique for three summer days in 22 vegetation stands, consisting of three emergent and three floating‐leaved species. 2. Between‐species differences in CH4 emission were significant. The highest emissions were measured from the emergent Phragmites australis stands (0.5–1.7 mmol m−2 h−1), followed by Schoenoplectus lacustris > Equisetum fluviatile > Nuphar lutea > Sparganium gramineum > Potamogeton natans. Within‐species differences between stands were not significant. 3. In P. australis stands, the stand‐specific mean CH4 emission was significantly correlated with solar radiation, probably indicating the role of effective pressurised ventilation on CH4 fluxes. The proportion of net primary production emitted as CH4 was significantly higher in P. australis stands (7.4%) than in stands of S. lacustris and E. fluviatile (both 0.5%). 4. In N. lutea stands, CH4 efflux was negatively correlated with the mean fetch and positively with the percentage cover of leaves on the water surface. There were no differences in CH4 efflux between intact N. lutea leaves and those grazed by coleopteran Galerucella nymphaeae. In S. graminaeum and P. natans stands, CH4 effluxes were not related to any of the measured environmental variables. 5. For all vegetation stands, the biomass above water level explained about 60% of the observed spatial variation in CH4 emission, indicating the important role of plants as gas conduits and producers of substrates for methanogens in the anoxic sediment.

High methane emissions from a littoral zone on the Qinghai-Tibetan Plateau

“…The littoral zone of lakes has been regarded as hotspots of CH 4 fluxes through several studies (Juutinen et al, 2001;Kankaala et al, 2003;Wang et al, 2006;Hirota et al, 2007). In the present study we also found that CH 4 efflux from the littoral zone of Huahu Lake on the Qinghai-Tibetan Plateau was relatively high among those of boreal and temperate lakes (Juutinen et al, 2001, Kankaala et al, 2003, Wang et al, 2006; summarized in Table 4) and higher than those from alpine wetlands in the same region (Hirota et al, 2004;Chen et al, 2008).…”

“…In the present study we also found that CH 4 efflux from the littoral zone of Huahu Lake on the Qinghai-Tibetan Plateau was relatively high among those of boreal and temperate lakes (Juutinen et al, 2001, Kankaala et al, 2003, Wang et al, 2006; summarized in Table 4) and higher than those from alpine wetlands in the same region (Hirota et al, 2004;Chen et al, 2008). This may be partly attributed to high dissolved organic carbon (DOC) input from nearby peatlands, whose soil is rich in organic carbon on the Qinghai-Tibetan Plateau (Wang et al, 2002).…”

“…Different vegetation covers also resulted in the difference in CH 4 fluxes. Kankaala et al (2003) showed the biomass above water table explained about 60% of the observed spatial variation in CH 4 emission from littoral stands in a boreal lake. The present study also showed that variation in plant biomass and plant height could explain the difference of CH 4 fluxes in the littoral zone of Huahu Lake.…”

Methane Emission from a Tropical Wetland in Ka'au Crater, O'ahu, Hawai'i

“…The emergent macrophyte Schoenoplectus lacustris, for which we have tentative evidence for methane oxidation, has an aerenchymous system and has previously been identified as a conduit of methane from a lake (Kankaala et al 2003). It is a plausible host for a methane-oxidizing microbial community.…”

CO2 and CH4 fluxes across a Nuphar lutea (L.) Sm. stand

“…While a wealth of studies have dealt with CH 4 measurements in helophyte stands (van der Nat, and Middelburg 1998; Brix et al 2001;Kankaala et al 2005;Laanbroek 2010), few data are available for floating-leaved rhizophytes (Dacey, and Klug 1979;Smith, and Lewis 1992;Juutinen et al 2003;Kankaala et al 2003). Moreover, in a very limited number of studies the magnitude and seasonal trends of CO 2 and CH 4 fluxes across the vegetated surface were measured simultaneously (Bolpagni et al 2007).…”