Effects of land cover, abiotic and biotic soil properties on in situ methane flux of montane and subalpine soils

Wien

2014

S. 8

Artikel aus einer ZeitschriftUnselbständiges Werk

200189765

The ongoing debate on climate change led to a proliferation of studies concerning methane (CH4) flux rates of soils as well as the microbial key players involved in the consumption (methanotrophic bacteria) and production (methanogenic archaea) of this greenhouse gas. Nevertheless, in spite of the global concern of this topic major ecosystems such as alpine regions have been poorly studied so far. Therefore, we examined CH4 flux rates of 16 forest and 14 grassland soils which were sampled on calcareous or siliceous parent material at approximately 500, 1000, 1500, and 2000 m above sea level in order to reflect the regional topography of North Tyrol. Field measurements were conducted by using manually operated closed static chambers. Gas samples were collected in pre-evacuated tubes and analyzed by gas chromatography in the laboratory. To reveal possible connections and functional similarities with CH4 flux, soil physicochemical factors, microbial biomass, and soil microbial activities were determined. Our results implied that 23 of the soils had the capacity to consume CH4, whereas net CH4 emission occurred at five grassland sites. Land cover type not only influenced the physicochemical and microbiological properties, but beyond that significantly affected the CH4 flux rates of the soils. Forest soils tended to act as sinks while grasslands showed a significantly reduced capacity to remove CH4. With respect to H4 flux rates, soils formed on calcareous rocks did not differ from those formed on siliceous rocks although general microbial activities and abundance were higher in calcareous soil s. We could also detect a distinct effect of the altitude on CH4 flux. Soils located at 500 to 1500 m a.s.l. strongly removed CH4. By contrast, soils at 2000 m a.s.l. tended to be sources of CH4. Multiple regression analysis pointed to positive influences of pH, organic matter, NH4+-N, and Cmic on CH4 flux.