Detecting the fingerprint of drought across Europe’s forests: do carbon isotope ratios and stem growth rates tell similar stories?

Forest Ecosystems

Table 1 Overview of the FunDivEUROPE plot network

	Finland	Poland	Germany	Romania	Italy	Spain
Forest type^a	Boreal	Hemiboreal	Beech	Mountainous beech	Thermophilous deciduous	Mediterranean mixed
Coordinates	63 °N, 30 °E	53 °N, 24 °E	51 °N, 11 °E	47 °N, 26 °E	43 °N, 11 °E	41 °N, 2 °W
Number of plots	28	43	38	28	36	36
Elevation range (m.a.s.l.)	80–200	135–185	500–600	600–1000	260–525	960–1400
Mean annual temperature (°C)	2.1	6.9	6.8	6.8	13.0	10.2
Mean annual precipitation (mm)	700	625	775	800	850	500
Non-drought year	2004	2010	2002	2001	2002	2002
Drought year	2006	2002	2003	2003	2003	2001
Water stress index of the drought year (unitless)	1.5	44.6	74.2	50.6	50.1	46.4
Water stress index between May – Oct of the drought year	1.5	40.3	59.2	35.4	49.7	44.8
Number of days with REW^b < 0.4 during the drought year	13	92	157	171	88	109
Mean basal area (m² ha⁻¹)	22.8	37.8	35.7	51.3	27.2	22.0
Species pool	Betula pendula	Betula pendula	Acer pseudoplatanus	Acer pseudoplatanus	Quercus ilex	Quercus ilex ^c
	Picea abies	Carpinus betulus	Fagus sylvatica	Fagus sylvatica	Castanea sativa	Quercus faginea
	Pinus sylvestris	Quercus robur	Fraxinus excelsior	Abies alba	Ostrya carpinifolia	Pinus nigra
		Picea abies	Quercus petraea	Picea abies	Quercus cerris	Pinus sylvestris
		Pinus sylvestris	Picea abies		Quercus petraea

^aCategories of the European Environment Agency (EEA 2007)
^bRelative extractable water in the soil, calculated across the entire calendar year
^c Quercus ilex was not targeted for isotope analysis in Spain due to difficulties in distinguishing between earlywood and latewood