Cattle Overwintering Areas in Middle-European Conditions - Important “Point” Sources Of Nitrous Oxide Emissions

Nitrous oxide (N2O) emissions in grazed grasslands are strongly influenced by animal excreta (Fowler et al., 1997). In addition, soil compaction caused by animal traffic significantly influences soil physical conditions and thus directly or indirectly impacts on the microbial processes producing N2O. In the Czech Republic pastures are mostly located in hilly and mountain areas. During the growing season, cattle are typically grazing, while during the winter the animals are concentrated near the animal house on a relatively small plot called an overwintering area . The objective of this study was to estimate the fluxes of N2O from a typical overwintering area, where the combined effects of soil compaction and deposition of urine and dung occur

Reviews and syntheses: Carbon use efficiency from organisms to ecosystems – definitions, theories, and empirical evidence

The cycling of carbon (C) between the Earth surface and the atmosphere is controlled by biological and abiotic processes that regulate C storage in biogeochemical compartments and release to the atmosphere. This partitioning is quantified using various forms of C-use efficiency (CUE) – the ratio of C remaining in a system to C entering that system. Biological CUE is the fraction of C taken up allocated to biosynthesis. In soils and sediments, C storage depends also on abiotic processes, so the term C-storage efficiency (CSE) can be used. Here we first review and reconcile CUE and CSE definitions proposed for autotrophic and heterotrophic organisms and communities, food webs, whole ecosystems and watersheds, and soils and sediments using a common mathematical framework. Second, we identify general CUE patterns; for example, the actual CUE increases with improving growth conditions, and apparent CUE decreases with increasing turnover. We then synthesize &gt;&thinsp;5000&thinsp;CUE estimates showing that CUE decreases with increasing biological and ecological organization – from unicellular to multicellular organisms and from individuals to ecosystems. We conclude that CUE is an emergent property of coupled biological–abiotic systems, and it should be regarded as a flexible and scale-dependent index of the capacity of a given system to effectively retain C.</p

Soil CO2 efflux in three wet meadow ecosystems with different C and N status

Data on soil respiration of three wet meadow ecosystems in the Czech Republic are presented. There were three study sites: two sites with peaty soil, one of them aneutrophic (nitrogen rich) and second of them oligotrophic. Third site was mesotrophic with mineral soil. Soil respiration was measured in situ as CO2 efflux using a Licor 6400 equipped with a soil chamber during the vegetation seasons, since June until October 2006. Soil respiration rates were significantly affected by soil temperature, although they differed among the sites, just as nutrient availability differed on each site. Despite of seasonal variation, the nutrient rich site on organic soil consistently yielded the highest respiration rates, and nutrient poor site yielded the lowest respiration rates. The highest CO2 emissions rates in situ were measured in June, when the soil temperature was 19°C. The rates reached up to 10.31 μmol CO2 m-2 s-1 at eutrophic site, at peaty oligotrophic site 7.03 μmol CO2 m-2 s-1 , and 8.38 μmol CO2 m-2 at mineral mesotrophic site, respectively. When we used a temperature dependency exponential model to avoid the effect of different soil temperature, the pattern observed in the field was even clearer. The peaty eutrophic soil was more sensitive to temperature then the mineral and peaty oligotrophic soil and C mineralization was more enhanced there

Soil microbial biomass, activity and community composition along altitudinal gradients in the High Arctic (Billefjorden, Svalbard)

The unique and fragile High Arctic ecosystems are vulnerable to global climate warming. The elucidation of factors driving microbial distribution and activity in arctic soils is essential for a comprehensive understanding of ecosystem functioning and its response to environmental change. The goals of this study were to investigate microbial biomass and activity, microbial community structure (MCS), and their environmental controls in soils along three elevational transects in the coastal mountains of Billefjorden, central Svalbard. Soils from four different altitudes (25, 275, 525 and 765 m above sea level) were analyzed for a suite of characteristics including temperature regimes, organic matter content, base cation availability, moisture, pH, potential respiration, and microbial biomass and community structure using phospholipid fatty acids (PLFAs). We observed significant spatial heterogeneity of edaphic properties among transects, resulting in transect-specific effects of altitude on most soil parameters. We did not observe any clear elevation pattern in microbial biomass, and microbial activity revealed contrasting elevational patterns between transects. We found relatively large horizontal variability in MCS (i.e., between sites of corresponding elevation in different transects), mainly due to differences in the composition of bacterial PLFAs, but also a systematic altitudinal shift in MCS related to different habitat preferences of fungi and bacteria, which resulted in high fungi-to-bacteria ratios at the most elevated sites. The biological soil crusts on these most elevated, unvegetated sites can host microbial assemblages of a size and activity comparable to those of the arctic tundra ecosystem. The key environmental factors determining horizontal and vertical changes in soil microbial properties were soil pH, organic carbon content, soil moisture and Mg2+ availability