© 2003 Heron Publishing—Victoria, Canada
Interactive effects of temperature and precipitation on soil respiration in a temperate maritime pine forest
J. Curiel Yuste (1, 2), I. A. Janssens (1), A. Carrara (1), L. Meiresonne (3) and R. Ceulemans (1)
1. University of Antwerpen, Department of Biology, Research Group of Plant and Vegetation Ecology, Universiteitsplein 1, B-2610
Wilrijk, Belgium / 2. Author to whom correspondence should be addressed (jorge.curielyuste@ua.ac.be) / 3. Institute for Forestry and Game Management (IBW), Ministry of the Flemish Community, Gaverstraat 4, B-9500 Geraardsbergen,
Belgium / Received June 11, 2002; accepted May 17, 2003; published online November 17, 2003
Summary
Soil respiration (SR) was monitored periodically throughout 2001 in a Scots pine (Pinus sylvestris L.) stand located in the Belgian Campine region. As expected for a temperate maritime forest, temperature was the dominant
control over SR during most of the year. However, during late spring and summer, when soil water content (SWC) was limiting,
SR was insensitive to temperature (Q10 = 1.24). We observed that during prolonged rain-free periods, when SWC was less than 15% (v/v), SR decreased dramatically
(up to 50%) and SWC took over control of SR. During such drought periods, however, rain events sometimes stimulated SR and
restored temperature control over SR, even though SWC in the mineral soil was low. We hypothesize that restoration of temperature
control occurred only when rain events adequately rewetted the uppermost soil layers, where most of the respiratory activity
occurred. To quantify the rewetting capacity of rain events, an index (Iw) was designed that incorporated rainfall intensity, time elapsed since the last rain event, and atmospheric vapor pressure
deficit (a proxy for evaporative water losses). To simulate SR fluxes, a model was developed that included the effects of
soil temperature and, under drought and non-rewetting conditions (Iw and SWC < threshold), an SWC response function. The model explained 95% of the temporal variability in SR observed during
summer, whereas the temperature function alone explained only 73% of this variability. Our results revealed that, in addition
to temperature and SWC, rain plays a role in determining the total amount of carbon released from soils, even in a maritime
climate.
Keywords:
drought stress, Q10, Scots pine, soil temperature, soil water content.
