Seasonal and daily pattern, temporal and spatial variability of ecosystem CO2-exchange in a temperate Pannonian loess grassland

Szilvia Foti; Janos Balogh; Szilard Czobel; Zoltan Nagy; Sandor Bartha; Zoltan Tuba

doi:10.14720/abs.47.1.16738

Authors

Szilvia Foti Department of Botany and Plant Physiology, Faculty of Agricultural and Environmental Sciences, Szent Istvan University, Hungary
Janos Balogh Departmental Research Group of Hungarian Academy of Sciences, Szent Istvan University, Hungary
Szilard Czobel Department of Botany and Plant Physiology, Faculty of Agricultural and Environmental Sciences, Szent Istvan University, Hungary
Zoltan Nagy Department of Botany and Plant Physiology, Faculty of Agricultural and Environmental Sciences, Szent Istvan University, Hungary
Sandor Bartha Institute of Ecology and Botany, Hungarian Academy of Sciences, Hungary
Zoltan Tuba Departmental Research Group of Hungarian Academy of Sciences, Szent Istvan University, Hungary

DOI:

https://doi.org/10.14720/abs.47.1.16738

Keywords:

carbon-balance, temperate grassland, chamber technique, net ecosystem CO2-exchange, carbon gain

Abstract

In the photosynthetically most active spring, summer and autumn vege tation period the investigated grassland did maintain a relatively strong daytime carbon gain. During winter the grassland displayed a slight daytime carbon loss. These data suggest that the grassland was a weak sink for carbon in the investigated period. CO₂ exchange variability during the day seemed to be independent from that of the daily photosynthetic radiation. Thus other factors like soil respiration, soil moisture content and temperature and their interactions could be responsible for the high daily variabil ity of grassland CO₂-exchange. The considerable temporal (daily and seasonal) vari ability of the grassland CO₂-exchange can be considered as a characteristic feature of the grassland CO₂-exchange. In the investigated loess grassland vegetation the variabil ity of CO₂-exchange showed clear dependence on measuring area, which is obvious in the CV of NEE. We hypothetised that the spatial scale with the lowest variability is the characteristic area of the grassland ecosystem's CO₂-exchange (CO₂-exchange physi ological unit). In general decreased variability indicates a more regulated state.

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