Revue internationale d'écologie méditerranéenne International ...
Revue internationale d'écologie méditerranéenne International ...
Revue internationale d'écologie méditerranéenne International ...
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SAMI YOUSSEF, ERROL VELA, ALEX BAUMEL, THIERRY TATONI<br />
Appendix 2.3 – Cluster no 3<br />
Species Frequence Family Biological Seeds Biological Demographic Biogeography<br />
(%) cycle dispersal traits stratigies<br />
Thymus vulgaris subsp. vulgaris 100 Lamiaceae Perennial Zele Ch S Steno-W-Medit.<br />
Galium corrudifolium 94 Rubiaceae Perennial Zepi H S Steno-Medit.<br />
Amelanchier ovalis (s.l.) 82 Rosaceae Perennial Zend P CS Medit.-Mont.<br />
Lactuca perennis 82 Asteraceae Perennial Aleg H CS Euri-W-Medit.<br />
Laserpitium gallicum 76 Apiaceae Perennial Alou H S NW-Medit.-Mont.<br />
Ononis minutissima 76 Fabaceae Perennial AuM Ch S Steno-W-Medit.<br />
Rosmarinus officinalis 76 Lamiaceae Perennial Zele p CSR Steno-Medit.<br />
Brachypodium retusum 71 Poaceae Perennial Zepi Ch CS Steno-W-Medit.<br />
Centranthus ruber 71 Valerianaceae Perennial Alou Ch CR Steno-Medit.<br />
Juniperus phoenicea subsp. phoenicea 71 Pinaceae Perennial Zend P CS Euri-Medit.<br />
Festuca marginata subsp. marginata 65 Poaceae Perennial Zepi H S Endem. W-Alpica<br />
Helichrysum stoechas 65 Asteraceae Perennial Apro Ch S Steno-W-Medit.<br />
Sedum sediforme 65 Crassulaceae Perennial Apro Ch S Steno-Medit.<br />
Teucrium polium subsp. polium 65 Lamiaceae Perennial Zoochory Ch S Steno-Medit.<br />
Sedum ochroleucon 59 Crassulaceae Perennial Hydr Ch S N-Medit.-Mont.<br />
Sesleria caerulea 59 Poaceae Perennial Apro H CS Oroph. C-Europ.<br />
Campanula rotundiflora subsp. macrorhiza 53 Campanulaceae Perennial Apro H S Endem. S-France<br />
Euphorbia characias 47 Euphorbiaceae Perennial Zele p S Steno-Medit.<br />
Catapodium rigidum subsp. rigidum 41 Poaceae Annual Baro Th SR Euri-Medit.<br />
Coronilla juncea 41 Fabaceae Perennial AuM NP CSR Steno-W-Medit.<br />
Reichardia picroides 41 Asteraceae Perennial Aleg H CS Steno-Medit.<br />
Santolina chamaecyparissus 41 Asteraceae Perennial Apro Ch S N-Medit.-Mont.<br />
Staehelina dubia 41 Asteraceae Perennial Aleg Ch S Steno-W-Medit.<br />
Alyssum spinosum 35 Brassicaceae Perennial Baro Th S W-Medit.-Mont.<br />
Anthyllis vulneraria (s.l.) 35 Fabaceae Annual, Perennial Alou Th, H SR Eurasiatic<br />
Arabis collina 35 Brassicaceae Perennial Apro H S Medit.-Mont.<br />
Asperula cynanchica (s.l.) 35 Rubiaceae Perennial Baro H S Euri-Medit.<br />
Asterolinon linum-stellatum 35 Caryophyllaceae Annual Baro Th SR Steno-Medit.<br />
Bupleurum baldense 35 Apiaceae Annual Apro Th SR Euri-Medit.<br />
Helianthemum oelandicum subsp. incanum 35 Cistaceae Perennial Apro Ch SR Oroph. S-Europ.<br />
74<br />
species, decreases as a consequence of trees<br />
colonization, a global pattern of French<br />
Mediterranean landscape change (Debussche<br />
et al. 1999). However, our current knowledge<br />
about the rate and extent of this dynamics in<br />
Basse Provence, as well as dispersal capacities<br />
of G. lobelii, are too scarce to evaluate if<br />
trees colonization represents a real threat for<br />
the persistence of G. lobelii.<br />
In our study, the geological nature of substrate<br />
does not seem to play an important role on the<br />
population size variation of G. lobelii stations<br />
as we observed the three classes of populations<br />
size on each type of substrate (calcareous<br />
or dolomie). However, our field investigations<br />
revealed two geographical trends of<br />
population size variation. First, the surface<br />
occupied by G. lobelii populations regularly<br />
increased with altitude (Figure 3). Above<br />
800 m, near the summits of Sainte-Baume and<br />
Sainte-Victoire mountains, G. lobelii becomes<br />
one of the dominant species. In parallel, when<br />
G. lobelii is found at lower altitude where<br />
populations are smaller, the stations are in<br />
northward exposures promoting the effects of<br />
strong winds (S. Youssef, pers. obs.). Second,<br />
the most isolated populations, found on the<br />
north and south eastern limits, are also the<br />
smallest (Figures 2 and 4). Postulating that<br />
population size is an indicator of individual<br />
fitness and observing that vegetation is different<br />
between central and marginal stations,<br />
we can hypothetize that geographically marginal<br />
populations of G. lobelii, are situated<br />
within non-optimal habitats. These populations<br />
may suffer from non optimal conditions<br />
of individual growth and reproduction in parallel<br />
with genetic stochastic effects that could<br />
reduce individual fitness (Honnay & Jacquemyn<br />
2007). Genetic diversity analysis and<br />
monitoring of reproduction and recruitment<br />
phase are then necessary to check for potential<br />
decrease of individual fitness in marginal<br />
populations of G. lobelii. Cytogenetic studies<br />
in relation to monitoring individual fitness<br />
should also be conducted to investigate the<br />
potential demographic effect of the complex<br />
caryological nature of G. lobelii (Verlaque<br />
1992). At least cost, a regular monitoring of<br />
population size, particularly at the edge of its<br />
distribution, should be a priority for conservation<br />
of this rare species in a context of<br />
global change.<br />
ecologia mediterranea – Vol. 36 (1) – 2010