Journal of Plant Nutrition and Soil Science, February 2018, Vol.181(1), pp.31-35
Quantifying and understanding fluxes of methane (CH) and carbon dioxide (CO) in natural soil–plant–atmosphere systems are crucial to predict global climate change. Wetland herbaceous species or tree species at waterlogged sites are known to emit large amounts of CH. Upland forest soils are regarded as CH sinks and tree species like upland beech are not known to significantly emit CH. Yet, data are scarce and this assumption needs to be tested. We combined measurements of soil–atmosphere and stem–atmosphere fluxes of CO and CH and soil gas profiles to assess the contribution of the different ecosystem compartments at two upland beech forest sites in Central Europe in a case study. Soil was a net CH sink at both sites, though emissions were detected consistently from beech stems at one site. Although stem emissions from beech stems were high compared to known fluxes from other upland tree species, they were substantially lower compared to the strong CH sink of the soil. Yet, we observed extraordinarily large CH emissions from one beech tree that was 140% of the CH sink of the soil. The soil gas profile at this tree indicated CH production at a soil depth 〉 0.3 m, despite the net uptake of CH consistently observed at the soil surface. Field soil assessment showed strong redoximorphic color patterns in the adjacent soil and supports this evaluation. We hypothesize that there is a transport link between the soil and stem the root system representing a preferential transport mechanism for CH despite the fact that beech roots usually do not bear aerenchyma. The high mobility of gases requires a holistic view on the soil–plant–atmosphere system. Therefore, we recommend including field soil assessment and soil gas profiles measurements when investigating soil–atmosphere and stem–atmosphere fluxes to better understand the sources of gases and their transport mechanisms.
Ch 4 ; Soil Gas Profile ; Gas Flux ; Stem Gas Flux ; Co 2 ; Methanogenesis