Abstract. Relationships between plant form, plant function, and environmental factors are analyzed in order to test the efficiency of growth form attributes and phenomorphology for studying vegetation on a regional scale. Examples of sclerophyllous evergreen coppices with Quercus ilex in the mediterranean climate of southern France are examined. The results for three growth form attributes (renewal bud location, leaf consistency, leaf size) and some environmental factors show that these criteria are efficient along a gradient of increasing stress. Concerning phenomorphology, some trends along the main environmental gradient become evident, but these results should be confirmed with descriptions of more species. It is suggested that man's ancient, very strong influence upon these ecosystems could explain some results showing that growth form distribution does not fit the pattern of variation in environmental factors.

BackgroundSmall size eukaryotes play a fundamental role in the functioning of coastal ecosystems, however, the way in which these micro-organisms respond to combined effects of water temperature, UVB radiations (UVBR) and nutrient availability is still poorly investigated.ResultsWe coupled molecular tools (18S rRNA gene sequencing and fingerprinting) with microscope-based identification and counting to experimentally investigate the short-term responses of small eukaryotes (<6 μm; from a coastal Mediterranean lagoon) to a warming treatment (+3°C) and UVB radiation increases (+20%) at two different nutrient levels. Interestingly, the increase in temperature resulted in higher pigmented eukaryotes abundances and in community structure changes clearly illustrated by molecular analyses. For most of the phylogenetic groups, some rearrangements occurred at the OTUs level even when their relative proportion (microscope counting) did not change significantly. Temperature explained almost 20% of the total variance of the small eukaryote community structure (while UVB explained only 8.4%). However, complex cumulative effects were detected. Some antagonistic or non additive effects were detected between temperature and nutrients, especially for Dinophyceae and Cryptophyceae.ConclusionsThis multifactorial experiment highlights the potential impacts, over short time scales, of changing environmental factors on the structure of various functional groups like small primary producers, parasites and saprotrophs which, in response, can modify energy flow in the planktonic food webs.