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Livestock is both threatened by and contributing to climate change. The contribution of livestock to climate change and greenhouse gas (GHG) emission greatly vary under different management regimes. A number of mitigation options comprise livestock management, although there are a lot of uncertainties as to which management regime to use for a given pedoclimatic and farming system. Therefore, we 1) tested if an extensive cattle livestock farm is a net sink or a net source for GHG (carbon–dioxide, CO 2 ; methane, CH 4 ; nitrous oxide N 2 O) in Central–Eastern Europe, 2) compared the annual GHG balances between the grazed and mowed treatments of the farm 3) and investigated the role of climate variability in shaping these balances. Net ecosystem exchange of CO 2 ( NEE ) was measured with eddy covariance technique in both the grazed and mowed treatments. Estimations of lateral C fluxes were based on management data. Other GHG fluxes (CH 4 , N 2 O) were determined by chamber gas flux measurements technique (in case of soil) and IPCC guidelines (in case of manure decomposition and animal fermentation). Net greenhouse gas balance ( NGHG ) for the grazed treatment was 228 ± 283 g CO 2 equivalent m −2 year −1 (net sink) and −475 ± 144 g CO 2 equiv. m −2 year −1 (net source) for the mowed treatment. Net source activity at the mowed treatment was due to its higher herbage use intensity compared to the grazed treatment. At the farm scale the system was estimated to be a net sink for NGHG in a year with wet (135 g CO 2 equiv. m −2 year −1 ), while a net source in years with dry soil moisture conditions (−267 ± 214 g CO 2 equiv. m −2 year −1 ). We conclude that under a temperate continental climate extended extensive grazing could serve as a potential mitigation of GHG in contrast to mowing. Our study highlights the fact that livestock farming could create a net sink for GHG under proper management regimes. [ABSTRACT FROM AUTHOR]

The main objective of the present study was to determine the contributions of autotrophic and heterotrophic components to the total soil CO 2 efflux over three years with high-frequency data acquisition by means of automated measurements. Soil CO 2 efflux was measured continuously by using an automated open system of 10 soil respiration chambers in a sandy grassland in Hungary. Mesh-collar technique was applied to separate the components of the total respiration. Data were collected (1) in root-exclusion (Exr), (2) in root- and mycorrhiza exclusion (Exrm) and (3) in control plots (Exc, roots and mycorrhiza included). We fitted three different models to describe the dependence of total soil CO 2 efflux measured on the Exc (Rs), CO 2 efflux measured on Exr (R TR ) and CO 2 efflux measured on Exrm (R TRM ) on abiotic and biotic drivers. The best fitted model (based on AIC) was later on used in a simulation process. The contribution by rhizospheric respiration (simulated, R rhizo* ) was 36 ± 21%, the contribution by mycorrhizal respiration (simulated, R myc* ) to the total soil respiration was 9 ± 9% while the contribution by heterotrophic respiration (simulated, R het* ) was 55 ± 21% on average. Measured mycorrhizal respiration (R M ) responded to GPP with a time lag of 0–2 days in active period. Drought affected the autotrophic component of soil respiration the most intensively: raise of soil water content resulted in increase of R S by 175% while R TR and R TRM increased by 127% and 93%, respectively. The results highlight the fact that it would be useful to establish and apply separate models for each component. [ABSTRACT FROM AUTHOR]

Abstract: High variability of soil respiration measured at fine spatial scale increases the uncertainty when trying to determine the representative average soil respiration (Rs) flux. A possible way to decrease the uncertainty, while also optimising measurement effort, could be the calculation of required number of Rs measurements (Nopt) together with the optimisation of their spatial arrangement. The goals of this study were to find explanatory variables of the structural parameters of fine-scale Rs spatial pattern and of Nopt for sampling optimisation. We conducted field Rs, soil temperature (Ts) and soil water content (SWC) measurements in a Hungarian sandy pasture over several years along circular transects of 75 evenly spaced (20cm distance) sampling positions. Structural parameters of patterns of Rs and the covariates were determined from variograms. Ranges of spatial autocorrelation varied between 0 and 3.6m for Rs, 0 and 3m for SWC and 0 and 2.9m for Ts. Patch size of Rs depended negatively on transect average SWC. To understand and quantify the spatial dependence of variables, cross-variograms were calculated. Rs proved to be positively spatially correlated to SWC at low water supply, while Ts-Rs and SWC-Ts spatial correlations were mostly negative, both due the direct effect of evaporative cooling on Ts. We found that spatial patchiness became less robust and the correlations generally decreased as soil moisture content was high. We found that explanatory variable of Nopt was also SWC, with negative correlation between them. We conclude that sampling could be optimized on the basis of the easily measurable actual SWC, which determines both the optimal number of Rs measurements and the minimum distances between individual samples in semi-arid ecosystems. [Copyright &y& Elsevier]

• Vegetation composition and diversity did not change for six years after the conversion from grazing to mowing. • Even the detailed fine-scale analyses could not reveal differences. • Carbon uptake differed between grazed vs. mowed sites due to biomass removal intensity. • Returning from mowing to grazing would probably restore C uptake because the vegetation composition remained stable. Grasslands could play an important role in supporting livestock, in carbon sequestration and in biodiversity conservation. Different grassland managements may change the vegetation composition of grasslands, which could alter these ecosystem services. We studied the effects of grazing vs. mowing on the vegetation composition (2012–2016) and on the carbon uptake (2011–2013) of sandy grasslands in Hungary to study if the vegetation composition differs and if it does, whether it affects carbon uptake. To observe differences in vegetation composition between the two types of management regimes we performed fine-scale vegetation survey in adjacent grazed and mowed sites. We compared species compositions and vegetation diversity indices between the management regimes based on permutational ANOVA, mixed effect model and information theory models. We used fine-scale vegetation survey because it has the potential to indicate vegetation changes within six years as changes in species richness and diversity are usually detected after 10–20 years. Carbon uptake was measured in parallel with eddy covariance technique at both sites. In spite of the contrasting management regimes the vegetation composition was stable (no differences observed in the diversity indices), while carbon uptake was significantly greater in the grazed (sink: +1 ± 0.7 t C ha−1 year−1) compared to the mowed site (source: -0.3 ± 0.6 t C ha−1 year−1). The vegetation was heterogeneous (patchy) and had a high species richness at both sites (grazed: 91 species ha−1, mowed: 90 species ha−1) which might have contributed to the stability of the vegetation composition. We concluded that differences in carbon uptake existed between the grazed vs. mowed sites due to biomass removal intensity with no differences in the vegetation composition. [ABSTRACT FROM AUTHOR]