engleski

First results of Soil Respiration Measurements in a Pedunculate Oak Stand of the Pokupsko Basin

Deviations in amounts and patterns of precipitation caused by climate change will, to a certain extent, affect all ecosystems and Pedunculate oak (Quercus robur L.) forest are one of them. Negative aspects of climate changes particularity reflect in older Pedunculate oak stands with reduced mast or increase in tree dieback. Sufficient water supply, but also nutrient availability is of vital importance for stand growth. Dynamics of processes in soil, particularly decomposition of litter and other organic matter, is therefore very important. Soil water content and temperature are key environmental variables that affect processes in soil such as root respiration and rate of decomposition of organic material. Dynamics of those processes can be explored by research of soil respiration (SR), or more precisely, measurement of CO2 efflux from soil into the atmosphere. Aim of our research is to present the preliminary quantitative estimates of soil respiration for the period May – August of 2008. In our measurements of soil respiration we used a closed dynamic system with two chambers described by Delle Vedove et al. (2007). SR was performed in two modes: quasi-continuous (every 4 hours) on a fixed plot near the existing CO2 flux station (Marjanović et al. 2008) and periodically (2 times per month) on four different plots within the footprint of the station. Station within which the SR system was installed was established within the framework of an international project Carbon-Pro located within a lowland forest complex, in a 35-years old Pedunculate oak stand with significant share of other tree species (Black alder, Field ash, Hornbeam etc). Results indicate that SR strongly depends on soil temperature and soil water content (SWC). Observed daily CO2 efflux from soil ranges from 10 kgC ha-1 d-1, when SWC is high and soil temperature lower, up to 60 kgC ha-1 d-1, when the soil temperature is high and soil sufficiently dry. Further research is necessary to understand SR dynamics during the whole vegetation period and to better estimate spatial variability of SR.

soil respiration; soil carbon; soil water content; soil temperature; Pendunculate oak

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