Carbon balance in a cronosequence (Q. cerris L.) in central Italy

Manca G.(1) , Tedeschi V.(2) , Tirone G.(1) , Borghetti M.(2) , Valentini R.(1)

Abstract

This work shows the firsts results on carbon balance study in two stands of different age (P11 11 years old and P07 two years old), into a Q. cerris cronosequence near Viterbo - Italy. This cronosequence is a coppice having an extension of 1350 ha and it's subdivided in 15 stands of various age, 0 - 18 years old. To calculate the carbon balance we use the eddy - covariance method; it's a micrometeorological method offering a mean to monitor directly the CO2, water vapor and heat exchange between forest and atmosphere. In this technique the CO2 concentration and wind speed are sampled at high frequency (10 Hz) over a period of 30 minutes, above the forest canopy. (Aubinet et al., 2000). The measurements in P11 started at the end of March 2000, immediately after the cutting and they are still going, while the study of P07 is begun at the end of September 2000. The two years old stand has showed interannual variability of carbon fluxes highlighted by the comparison between CO2 exchange in spring 2000 and that in spring 2001. Both the stands have had a clear reduction of carbon uptake during the summer (water stress); the reduction have been bigger in P07 stand, and the stress condition are manifested first in the P11 and next in P07. In the first year after the cutting, the stand P11 is a carbon source, while the data collected in P07 aren't still sufficient to calculate the annual carbon balance.

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