Precipitation-dependent flowering of Globularia alypum and Erica multiflora in Mediterranean shrubland under experimental drought and warming, and its inter-annual variability.
OBJECTIVE
Relationships between autumn flowering, precipitation and temperature of plant species of Mediterranean coastal shrublands have been described, but not analysed experimentally. These relationships were analysed for two species of co-occurring, dominant, autumn-flowering shrubs, Globularia alypum and Erica multiflora, over 4 years and in experimentally generated drought and warming conditions. The aim was to improve predictions about the responses and adaptations of flowering of Mediterranean vegetation to climate change.


METHODS
Beginning of anthesis and date of maximum flowering intensity ('peak date') were monitored over 4 years (2001-2004) on a garrigue land type in the noth-east of the Iberian Peninsula. Two experimental treatments were applied, increased temperature (+0.73 degrees C) and reduced soil moisture (-17%) relative to untreated plots.


RESULTS
Flowering of Globularia alypum and Erica multiflora differed greatly between years depending on the precipitation of the previous months and the date of the last substantial rainfall (>10 mm). Globularia alypum flowered once or twice (unimodal or bimodal) as the result of differences in the distribution and magnitude of precipitation in late-spring and summer (when floral buds develop). The drought treatment delayed and decreased flowering of Globularia alypum in 2001 and delayed flowering in 2002. Warming extended the period between the beginning of flowering and the end of the second peak for autumn flowering in 2001 and also increased peak intensity in 2002. Flowering of Erica multiflora was unaffected by either treatment.


CONCLUSIONS
Autumn flowering of Globularia alypum and Erica multiflora is more dependent on water availability than on temperature. Considerable inter-annual plasticity in the beginning of anthesis and peak date and on unimodal or bimodal flowering constitutes a 'safe strategy' for both species in relation to varying precipitation and temperature. However, severe changes in precipitation in spring and summer may severely affect flowering of Globularia alypum but not Erica multiflora, thus affecting development/structure of the ecosystem if such conditions persist.
Unitat d'Ecofisiologia i Canvi Global CREAF-CEAB-CSIC (Centre for Ecological Research and Forestry Applications), Universitat Autònoma de Barcelona, Edifici C, 08193 Bellaterra, Spain. patricia@creaf.uab.es
Patricia
P
Prieto
Josep
J
Peñuelas
Romà
R
Ogaya
Marc
M
Estiarte
D000704:Analysis of Variance; D004190:Disasters; D029791:Ericaceae / Q000254:growth & development*; D035264:Flowers / Q000254:growth & development*; D018521:Plant Physiological Phenomena; D011891:Rain; D028083:Scrophulariaceae / Q000254:growth & development*; D012621:Seasons; D013030:Spain; D013696:Temperature; D014867:Water
D014867:Water