In recent years, species distribution models have been used to gain a better understanding of past and future range dynamics of species. Here we focuse on a keystone species of the North African forest ecosystem (Cedrus atlantica) by calculating a consensus model of the species current geographic potential distribution in North Africa, based on a weighted average method aiming to decrease uncertainty. The consensus model is obtained using seven species distribution model algorithms taking into account twenty-four environmental variables. The model is then applied to several past and future time slices. Past projections refer to the Middle-Holocene and the Last Glacial Maximum, whereas those of future are related to expect conditions around 2050 and 2070.We found that the current potential distribution of Cedrus atlantica is larger than its actual geographical distribution. For some explanatory variables the analysis revealed their importance for the species current distribution. Among all obtained models, that for the Middle-Holocene showed the maximum expansion of the species potential distribution. The Last Glacial Maximum model provided new putative glacial refugia of Cedrus atlantica, not shown by other mechanistic models and palaeorecord localities. Future projections revealed a significant and fast contraction with shifting in altitude of the species range, showing more fragmented areas and even species disappearance in many North African localities.These findings can help to restore cedar forests and conserve them by ex-situ strategies according to the future defined refugia in North Africa. Attention should be paid to the resolution of related output maps, the current biotic interactions and those that may arise under climate change.
Contribution des Légumineuses à la régénération après feu des forêts de Quercus suber et Pinus halepensis du Nord-Est Algérien. -Le rôle des Légumineuses dans la régénération après feu a été largement étudié sur la rive nord de la Méditerranée, mais aucune donnée n'est disponible concernant la rive sud. Le but de cet article est d'analyser la dynamique des Légumineuses dans une subéraie et une pinède à Pin d'Alep du Nord-Est Algérien durant les premiers mois après un feu de faible intensité. Les aspects de la démographie des germinations des Légumineuses, leur contribution à la biomasse totale et la richesse spécifique sont considérés. Les deux communautés ne présentent pas de différences majeures. Toutes deux montrent des modèles démographiques similaires : les germinations de Légumineuses commencent à émerger très tôt (novembre) après le feu (octobre) et continuent à s'établir abondamment avec un premier pic en décembre et un deuxième en mars, avec un ralentissement significatif en janvier et février. La germination diminue à partir d'avril pour atteindre son minimum en mai et complètement s'arrêter en début juin. Ce modèle en deux pics plutôt qu'un seul, comme déjà rapporté, serait vraisemblablement dû au froid exceptionnel durant janvier et février 2005 (neige jusqu'au niveau de la mer) d'où un ralentissement de la germination et son décalage à mars. Huit mois après l'incendie (vers la fin juin, période où la végétation herbacée commence à sécher), la biomasse aérienne des Légumineuses affiche un maximum de 37,8 ± 1,83 g/m 2 dans la subéraie et 26,7 ± 1,63 g/m 2 dans la pinède. Sept mois après le feu, relativement aux autres familles de plantes, les Légumineuses sont floristiquement bien représentées avec 19,8 ± 1,11 % des espèces dans la subéraie et 24,3 ± 2,05 % dans la pinède, valeurs nettement supérieures à celles rapportées pour d'autres écosystèmes de type méditerranéen (3,8 -13,3 %), probablement en raison de la localisation géographique (basse latitude) de notre aire d'étude et la pression de surpâturage qui favorise l'installation des Légumineuses.SUMMARy. -The role of legumes in post-fire forest regeneration has been extensively studied in the northern Mediterranean basin but no published data are available concerning the southern part of the area. The aim of the present paper is to analyse the dynamics of the leguminous species in a Q. suber and a P. halepensis forests in Northeastern Algeria during the first months after a wildfire of low intensity. The aspects of seedling demography of legumes, their contribution to total biomass and species richness were considered. No major differences were detected between the two communities. They presented similar demographic patterns: legume seedlings began to emerge very early (November) after the fire (October) and continued to increase massively with a peak in December and another in March, and a significant slowdown in January and February; in April, they resumed to gradually decrease again to reach their minimum in May and completely stop in early June...
Pinus nigra (black pine) is a Mediterranean taxonomic complex (including different subspecies), with a discontinuous distribution. The southernmost part of its range is in North Africa, in Morocco and Algeria, where it is present as P. nigra subsp. mauretanica. Currently, an extremely limited number of trees of this subspecies still persist within its natural range, giving this taxon an outstanding ecological importance. These residual stands are threatened by many biotic and abiotic factors, putting at risk the survival of this subspecies in its natural habitat. This paper reports for the first time the presence of Eulachnus tuberculostemmatus (Hemiptera: Aphididae: Lachninae) in Algeria, and its infestation on P. nigra subsp. mauretanica. This insect was detected in three sites of the Djurdjura National Park in May 2012 and identified in February 2016. The aphid seems to be responsible for needle discoloration and premature senescence, symptoms observed since spring 2008 on the infested pines. These clusters of P. nigra subsp. mauretanica trees are protected by park regulations, and given their conservation status further investigations into this pest species, and other biotic and abiotic factors that may threaten this important tree, are required.
The genus Acer which is largely distributed in the Northern hemisphere is represented in Algeria by four species of which Acer monspessulanum is the most common. These four species and their putative hybrids are coexisting in many parts of their Algerian distribution range but their leaf morphology has not been the subject of quantitative analyses despite the interest of such kind of data in taxon delineation particularly in the case of interspecific hybridization. The present work is the first step towards a quantitative analysis of leaf morphology in Acer species in Algeria. We presently relied on traditional and geometric morphometrics methods in the study of Acer monspessulanum subsp. monspessulanum leaf morphology in two sites of the Djurdjura Mountain with consideration of tree and within-shoot effects. The results showed congruence between the two methods which both highlighted the presence of a marked heteroblasty. Basal leaves are twice as large as apical ones for all measured leaf features. The petiole is longer than the blade in basal leaves and inversely in apical ones. The median leaves have intermediate values. The results revealed also the coexistence of two contrasted leaf morphotypes on distinct trees of both sites.
Cork oak (Quercus suber) as a West Mediterranean species is known for its ecological, economic and social values. Wildfires are one of the most serious problems threatening Quercus suber, endangering its occurrence in its area of distribution. Therefore, knowing the behavior of the species after fire and the factors influencing its responses are particularly important for forest management. In this study we assessed the post fire vegetative recovery in 730 trees affected by wildfires on 2014 in Kiadi cork oak forest, located in the Western side of Akfadou Mountains in Algeria. Few months after the fire, individual tree mortality was very low (7.53%), and nearly, all the trees sampled survived the fire since almost all trees resprouted from canopy and some of them showed basal resprouts. Moreover, those two modes of post fire vegetative recovery were not correlated to each other. The performed redundancy analyzes (RDA) revealed that the cork oak post-fire response was highly correlated with individual characteristics and with the environmental data. The main variables influencing the likelihood of good or poor vegetative recovery were the understory height and cover, soil characteristics, fire severity, tree status (alive/dead trees), tree diameter and tree exploitation. Our results confirmed the fire resistance of cork oak species; which is also the only Algerian tree to resprouts. Hence, this makes the species a good candidate for reforestation programs in fire prone ecosystems.
This paper presents the first data concerning the ground beetles assemblages associated with Pinus nigra mauretanica (Maire & Peyerimhoff, 1927) reserve, Djurdjura southerner, Algeria. Carabids were sampled from two sites which differ in their structural vegetation, site No. 2 being more disturbed and more open than site No. 1. As a result of this survey, 231 carabid beetles belonging to 32 species were collected, of which 53.12 % were common to both sites, while 37.50 % and 9.37 % were restricted to site No. 1 and site No. 2 respectively. Diversity indexes were higher in site No. 1. Statistical analysis showed a significant influence of vegetation type on the specific richness of carabid beetles. Disturbances and structural habitat parameters seem to be the major drivers structuring ground beetles assemblages and influencing species abundance, diversity and richness. Carabid richness and abundance in the studied area are lower in disturbed environments and higher when the forest vegetation cover is developed. Adaptive parameters of species, such as diet and seasonal distribution, showed that 57 % of the species (174 individuals) caught are predatory. Two activity periods of ground beetles were noted, the first one occurred in spring and early summer while the second was mainly autumnal. Our results showed the efficiency of pitfall trapping with 70 % of captured individuals and 38 % of carabid species. Among these taxa recorded in the two sites of Pinus nigra mauretanica reserve, six species have protected status in Algeria, Carabus (Macrothorax) morbillosus, Eurycarabus famini, Laemostenus algerinus, Calosoma inquisitor, Calosoma sycophanta and Sphodrus leucophthalmus, and four were endemic to North Africa, Calathus fuscipes algiricus, Calathus opacus, Carabus (Macrothorax) morbillosus and Bembidion fluviatile unctulum. According to the IUCN categories, four species are in danger of extinction, Sphodrus leucophthalmus, Chlaenius velutinus, Bembidion fluviatile unctulum and Brachinus sclopeta, four are very rare but without current endangerment, Agonum nigrum, Har-palus attenuates, Notiophilus biguttatus and Trechus obtusus, and two were strongly endangered, Calosoma inquisitor and Calosoma sycophanta. Three bioindicator species of forest quality were found, Calathus opacus, Carabus (Macrothorax) morbillosus and Notiophilus biguttatus.Резюме. В настоящей работе представлены первые данные о сообществах жужелиц, приуроченных к заповеднику для Pinus nigra mauretanica (Maire et Peyerimhoff, 1927) (Южаная Джурбжура, Алжир). Пробы жужелиц были отобраны на двух участках, различающихся по растительности, причём участок № 2 более нарушен и открыт, чем участок № 1. В результате этого фаунистического исследования был собран 231 экземпляр жуков-жужелиц, принадлежащих к 32 видам, из которых 53,12 % были общими для обоих участков, а 37,50 % и 9,37 % были ограничены только участками № 1 или № 2 соответственно. Показатели разнообразия выше были на участке № 1. Статистический анализ показал значительное влияние типа раститель...
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