SUPPLEMENTARY MATERIAL
Figure S1
A Eddy covariance forest site measurements of GPP (squares), TER (triangles) and NEP
(circles) from July to September in 2002 (open symbols) and in 2003 (filled symbols). B.
Same quantities simulated by the biosphere model used to upscale productivity changes
over the European continent (see text). C. Measurements of July to September air
temperature (red) and annual precipitation changes at each site between 2003 and 2002.
The 13 forest sites plotted from south to north are El Saler (SA), San Rossore (SR),
Pianosa (PI), Castelporzianno (CP), Rocca (RO), Puéchabon (PU), Bray (BX), Hesse
(HE), Vielsam (VI), Tharandt (TH), Hainich (HA), Soroe (SO) and Hyytiälä (HY).
Figure S2
A. Average crop harvest converted to crop NPP for wheat (stars) and maize (circles) for
selected countries in year 2002 (open symbols) and 2003 (filled symbols). B. Comparison
between observed (black for wheat) and modeled (green) changes in crop NPP during
2003 vs. 1998-2002. The model results are averaged over all-crop covered grid-points
within each country. C. Country averaged July to September air temperature and annual
precipitation changes between 2003 and 1998-2002 over cropland areas (ES = Spain ; IT
= Italy ; FR = France ; D = Germany ; PL = Poland ; CZ = Czech Republic ; RO =
Romania ; UR = Ukraine)
Figure S3
A. Observed versus modeled difference of mean daily gross primary production (2003
minus 2002) for each site and month (monthly averages of half-hourly observations and
model output). Only months are compared where more than 80% of half-hourly eddy
covariance data was available or gap-filled with highest confidence. B. Histogram of
observed versus modeled difference of mean daily gross primary production, GPP, (2003
minus 2002) for all sites and months. Only months are compared where more than 80%
of half-hourly eddy covariance data was available or gap-filled with highest confidence.
In nearly 50% of the months the variation from 2002 to 2003 is predicted within ±0.5 gC
m-2 day-1, in 88% within ±1.5 gC m-2 day-1
Figure S4
From top to bottom. Regression of observed and modeled NEE, GPP and TER
differences in 2003 vs. 2002 at the eddy-covariance sites (red triangles) as a function of
observed air July to September temperature differences (left) and of April to October
rainfall differences (right). On the same scale is shown the regression of simulated NEE,
GPP and TER changes in 2003 vs. 2002 for all the model grid points over Europe,
defined here as the area bounded by 10°W and 37°E in longitude and by 36°N and 69°N
in latitude. The eddy covariance observations and the model simulations over Europe
illustrate the fact that there is a larger correlation of flux changes with rainfall than with
temperature changes. The largest correlation is found for GPP.
Figure S5
Tree circumference measurements performed at Hesse for the period 1999-2003 on 11
beech trees from the co dominant and dominant crown classes (both classes represent ca.
75% of the whole standing biomass). Electronic dendrometer bands with 0.01 mm
resolution installed at 1.6 m height on the stems were used. Growth reduction during
2003, as compared to the wet year 2002, reached on average 27%. This growth reduction
is explained by the drought onset date as trees fulfilled most of their normal annual
biomass increment at this date. The large GPP decrease in summer probably reduced the
amount of carbohydrate reserves in trees and therefore would have important
consequences on the 2004 growth and leaf area index.