Summary 1.We introduce a novel method that analyses environmental filtering of plant species in a geographic and phylogenetic context. By connecting species traits with phylogeny, traits with environment, and environment with geography, this comprehensive approach partitions the ecological and evolutionary processes that influence community assembly. 2. Our analysis extends RLQ ordination, which connects site attributes in matrix R (here environmental variables and spatial positions) with species attributes in matrix Q (here biological traits and phylogenetic positions), through the composition of sites in terms of species presences or abundances (matrix L). This methodology, which explores and identifies environmental filters that organize communities, was developed to answer four questions: which combinations of trait states are filtered by the environment, which lineages are affected by these filters, which environmental variables contribute to the assemblage of local communities and where do these filters act? 3. At La Mafragh in north-eastern Algeria, our approach shows that plant species traits were distributed according to environmental filters associated with a salinity gradient. Traits associated with the salinity gradient were convergent among Juncaceae, Cyperaceae and Amaranthaceae. The observed phylogenetic and trait patterns were related to how species survived the xeric season. Juncaceae and Cyperaceae, being perennials and anemogamous, tolerate the xeric hot season by restricting their range to the humid centre of the study area (where conditions are close to a subtropical climate). Several Amaranthaceae species co-occur with the Juncaceae and Cyperaceae in two areas with the highest salinity. Most dicots were observed at higher elevations (up to 7 m a.s.l.), had hairy structures that can retain water and reflect solar radiation and were mostly annual or biennial, completing their life cycle before the onset of the xeric season. 4. Synthesis. Our methodology describes environmental filters in terms of identified combinations of traits and environmental factors. It allows spatial and phylogenetic signals to be determined by identifying convergent and conserved patterns in the evolution of traits and spatial scales that structured the environment. Our statistical framework is generic and can be readily extended to a wide range of exciting issues, such as host-parasite, plant-pollinator and predatorprey interactions.

Le concept de point chaud de biodiversité, au niveau mondial et régional, a permis d'améliorer les stratégies de conservation. La nécessité d'évaluation précise des enjeux se heurte à des lacunes dans la connaissance de certains points chauds régionaux méditerranéens. L'objectif de ce travail est d'analyser la diversité de la flore rare et endémique dans le Nord de l'Algérie. À partir des données disponibles dans la bibliographie, les secteurs les plus remarquables pour l'endémisme sont la côte oranaise, suivie par la Petite Kabylie et la Grande Kabylie. En ce qui concerne les espèces rares, la Numidie littorale arrive en tête, suivie par la Mitidja d'Alger. Cet ensemble « Kabylies-Numidie-Kroumirie » forme un point chaud régional méconnu, constitué de forêts, de montagnes et d'écosystèmes littoraux, menacés par l'anthropisation. Face à ces menaces croissantes, il est urgent d'appuyer les politiques nationales et internationales de conservation et de coopérer à une meilleure connaissance floristique de l'ensemble des territoires concernés.

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Abstract:A study was undertaken in 2010 to identify Important Plant Areas (Key Biodiversity Areas for Plants) in the south and east Mediterranean region, in order to prioritise the best sites for plant conservation action. It follows a first work of identification of Important Plant Areas (IPAs) initiated for Algeria and relates exclusively to the flora of northern Algeria. These IPAs were delineated in northern Algeria for those sites harbouring a number of "IPA selection species" (threatened species and locally endemic or restricted range). Recent taxonomic revisions estimate the number of national endemics for the north of Algeria (excluding the Sahara) to be over 300 taxa. In the present study, data were extracted from the global list of 22 IPAs identified for the north of Algeria. The species considered are i) threatened species as defined by the 1997 IUCN global red list of plants, ii) locally endemic species, iii) nationally threatened species. Trigger species, identified by combining the criteria of endemism and rarity, are mainly Algerian national endemics but also include some AlgerianMoroccan and Algerian-Tunisian endemics. One hundred and fifty two (152) trigger species were identified and these species, which have high ecological value, can be used to characterize the particular floristic interest of a site and can therefore be a useful tool for conservation purposes. Important gaps in knowledge have been highlighted, in particular those relating to taxonomy and the lack of up-to-date field data. It is therefore essential to undertake in situ research in order to better understand the distribution and status of these species. A flexible approach to identifying and recognising priority sites for plants using surrogate criteria, supplemented by expert opinion, alongside existing globally standardised criteria, is therefore essential if the most important sites for plant diversity are to receive the conservation attention they deserve.

Northwest Africa is a major hotspot of plant biodiversity, but very little is known about the Quaternary range dynamics of plant species in this region. Here we investigate the range-wide population structure and phylogeography of Atlas cedar (Cedrus atlantica), an emblematic forest tree endemic to Morocco and Algeria. We genotyped 261 individuals from 11 populations using AFLP markers. Data were analyzed using both conventional F(ST)-based techniques and Bayesian clustering. Overall population differentiation was high (F(ST) = 0.25). Two major groups of populations were identified, one distributed through the Rif and Middle Atlas mountains in Morocco and the other through the Algerian Tell Atlas and Aurès mountains as well as the Middle Atlas. Combined molecular and fossil data indicate that C. atlantica survived the Last Glacial Maximum in at least three disjunct refugia along the coast of the Mediterranean Sea, whereas the Middle Atlas, today the core of the species range, has been colonized relatively recently (<10000 yr BP). The colonization history of individual populations has left clear imprints in their present-day diversity, which may vary greatly even between nearby stands. Our study illustrates how integrating different data sources and analytical approaches can help elucidate complex range dynamics that would otherwise remain undeciphered.