10 research outputs found
Monitoring Forest Recovery Following Wildfire and Harvest in Boreal Forests Using Satellite Imagery
In eastern Canada, spruces (Picea spp.) and pines (Pinus spp.) are among the main commercial species being logged for their lumber or wood fiber. Annually, about 175 million seedlings are planted in areas totaling ~100,000 ha. Appropriate microsite selection is essential during reforestation operations, given that it can improve the chances of survival and initial growth of the seedlings. In fir (Abies spp.) and spruce forests of eastern Canada, the optimal characteristics of establishment microsites have yet to be identified; these would be determined by different physical and climatic variables operating at several scales. Our study determined the influence of climatic (regional-scale), edaphic (stand-scale), local (microsite-scale) and planting conditions on the establishment substrate and initial growth of black spruce (Picea mariana Britton, Sterns and Poggenb.) and jack pine (Pinus banksiana Lamb.). Substrate characterization and growth monitoring (three growing seasons) for the two species were conducted on 29 planted cutblocks that were distributed over an east-west climatic gradient (precipitation and temperature) in the balsam fir and black spruce-feather moss forests of Quebec (Canada). Linear mixed models and multivariate analyses (PCAs) determined the effects of climatic, edaphic and micro-environmental variables and their interactions on the establishment substrate and seedling initial growth. The predictive models explained, respectively, 61% and 75% of the growth variability of black spruce and jack pine. Successful establishment of black spruce and jack pine depended upon regional conditions of precipitations and temperature, as well as on their interactions with stand-scale edaphic variables (surface deposit, drainage and slope) and local variables (micro-environmental) at the microsite-scale (establishment substrate types and substrate temperature). Mineral, organo-mineral and organic establishment substrates exerted mixed effects on seedling growth according to regional precipitation and temperature conditions, as well as their interactions with edaphic and local variables at the stand and microsite-scales, respectively
Monitoring Forest Recovery Following Wildfire and Harvest in Boreal Forests Using Satellite Imagery
In the managed boreal forest, harvesting has become a disturbance as important as fire. To assess whether forest recovery following both types of disturbance is similar, we compared post-disturbance revegetation rates of forests in 22 fire events and 14 harvested agglomerations (harvested areas over 5â10 years in the same vicinity) in the western boreal forest of Quebec. Pre-disturbance conditions were first compared in terms of vegetation cover types and surficial deposit types using an ordination technique. Post-disturbance changes over 30 years in land cover types were characterized by vectors of succession in an ordination. Four post-disturbance stages were identified from the 48 land thematic classes in the Landsat images: âS0â stand initiation phase; âS1â early regeneration phase; âS2â stem exclusion phase; and âS3â the coniferous forest. Analyses suggest that fire occurs in both productive and unproductive forests, which is not the case for harvesting. Revegetation rates (i.e., rapidity with which forest cover is re-established) appeared to be more advanced in harvested agglomerations when compared with entire fire events. However, when considering only the productive forest fraction of each fire, the revegetation rates are comparable between the fire events and the harvested agglomerations. The S0 is practically absent from harvested agglomerations, which is not the case in the fire events. The difference in revegetation rates between the two disturbance types could therefore be attributed mostly to the fact that fire also occurs in unproductive forest, a factor that has to be taken into account in such comparisons
Orchids in the northern part of the Setif province (North-East of Algeria)
Ă la suite de lâĂ©tude prĂ©cĂ©dente sur les orchidĂ©es de la wilaya de SĂ©tif, et de la prospection de diffĂ©rents sites potentiels dans la partie nord de la rĂ©gion, cet inventaire apporte dâautres observations sur les orchidĂ©es dans un secteur qui va de SĂ©tif Ă Kherrata et Ă lâouest de Tababort, reconnu comme zone importante pour les plantes (ZIP). Certaines espĂšces rencontrĂ©es sont observĂ©es pour la premiĂšre fois ; pour dâautres, câest leur frĂ©quence et la taille de leur population qui a Ă©tĂ© rĂ©Ă©valuĂ©e. Notre investigation a permis dâinventorier 31 taxons, dont 1 hybride ; 9 espĂšces et lâhybride ont Ă©tĂ© citĂ©s pour la premiĂšre fois, Ă savoir Anacamptis morio subsp. longicornu (= Orchis longicornu), Androrchis patens subsp. patens (= Orchis patens), Androrchis pauciflora subsp. laeta (= Orchis laeta), Himantoglossum robertianum (= H. longibracteatum), Neotinea tridentata subsp. conica (= Orchis conica, O. tridentata subsp. lactea p.p.), Neottia nidus-avis, Ophrys funerea (= O. fusca auct. p.p), O. omegaifera subsp. hayekii (= O. mirabilis), Orchis italica et Anacamptis fragrans Ăpyramidalis (= ĂAnacamptorchis simorrensis). Cette contribution enrichie met Ă jour les observations pour la zone dâĂ©tude et constitue un apport considĂ©rable pour la cartographie des orchidĂ©es dâAlgĂ©rie
Lâeffet du feu sur la composition des pinĂšdes de Pinus halepensis Mill. dans le nord de la forĂȘt de Bou-Taleb, AlgĂ©rie
The effect of forest fire on the vegetation of the domanial forest of Bou-Taleb (Algeria) was studied in the Pinus halepensis ecosystems by the method of tables. These communities which were burned at different dates and other ones unburned (older) are located in north part of the forest. The comparative method showed a post-burn progressive recovery of vegetation without a great modification in their floristic composition. This post-fire recovery is realised by three groups of species : the first group, met in the young stages after fire, is dominated by therophytes ; the second which characterizes the adult stages is represented essentially by perennials species (chamaephytes and phanaerophytes), and the last one represented by the species indifferent to fire is met at all the stages. A comparison between the different states using Sörensen coefficient shows a great difference between state II (4 years) and state IV (over 33 years) with 38.29%, so it reaches 59.37% between the states III and IV. However this similarity is more important when we exclude taxa which are present only one time (f > 1) ; in this case, it can reach the 73% between the states III and IV. This shows the role of exogenous species in post-burn recovery of Pinus ecosystems.Lâeffet du feu sur la composition des pinĂšdes Ă
Pinus halepensis Mill. du versant nord de la forĂȘt domaniale de Bou-Taleb (AlgĂ©rie) a Ă©tĂ© Ă©tudiĂ© par la mĂ©thode des tableaux. Des relevĂ©s floristiques ont Ă©tĂ© rĂ©alisĂ©s selon la mĂ©thode sigmatiste dans des pinĂšdes brĂ»lĂ©es par des feux sauvages Ă diffĂ©rentes dates. Dâautres relevĂ©s rĂ©alisĂ©s dans des peuplements non brĂ»lĂ©s ont Ă©tĂ© pris pour tĂ©moin. La mĂ©thode comparative a montrĂ© une reconstitution progressive des pinĂšdes sans variation dans leur composition floristique. Ce sont les mĂȘmes espĂšces qui existaient avant le feu qui rĂ©apparaissent aprĂšs. Cette reconstitution se rĂ©alise par trois groupes dâespĂšces. Le premier groupe se rencontre Ă lâĂ©tat juvĂ©nile, il est dominĂ© par les thĂ©rophytes ; le deuxiĂšme caractĂ©rise les Ă©tats adultes, il est reprĂ©sentĂ© essentiellement par les chamĂ©phytes et les nanophanĂ©rophytes ; le dernier correspond Ă des espĂšces indiffĂ©rentes au passage du feu et qui se rencontrent Ă tous les stades (+ 76 %). Une comparaison entre les diffĂ©rents Ă©tats en utilisant le coefficient de similitude de Sörensen montre une grande variation entre lâĂ©tat II (4 ans) et lâĂ©tat IV (33 ans â tĂ©moin), avec un coefficient de 38,29%, il atteint son maximum aux stades III (7-8 ans aprĂšs feu) et IV (33 ans et tĂ©moin) avec un coefficient de 59,37%. Cependant cette similitude floristique est beaucoup plus importante si on considĂšre uniquement les espĂšces dont la frĂ©quence est Ă©gale ou supĂ©rieure Ă 2. Elle atteint une valeur maximale de 73,78% entre les Ă©tats III et IV. Cette diffĂ©rence entre les Ă©tats est due beaucoup plus aux nouvelles espĂšces Ă©trangĂšres aux pinĂšdes qui ont profitĂ© de lâespace laissĂ© libre par le passage du feu.Madoui Amar, GĂ©hu Jean-Marie, Alatou Djamel. Lâeffet du feu sur la composition des pinĂšdes de Pinus halepensis Mill. dans le nord de la forĂȘt de Bou-Taleb, AlgĂ©rie. In: Ecologia mediterranea, tome 32,2006. pp. 5-13
Wildfire effects on Pinus halepensis Mill. plantations in a semi-arid region of north-eastern Algeria. A case study of Zenadia forest, SĂ©tif
Fire is considered as the most important factor responsible for the diminution of Algerian forested area. Every year, thousands of hectares of vegetation burn affecting different species. The natural Aleppo pine forests have been the most affected, but recently, fire tends to affect also the planted forests. The effect of fire on Aleppo pine natural stands is well documented ; however, there is a lack of knowledge on planted ones. The objectives of this paper were to assess the fire effects on Pinus halepensis plantations in northern Algeria in terms of floristic diversity and pine regeneration. Floristic diversity surveys were performed three years after fire in burned and unburned plots, using the Braun-Blanquet method. Additionally, the number and height of P. halepensis seedlings were assessed and continued to be monitored in the best regenerated area four, six, eight, and ten years after fire occurrence. The floristic surveys performed showed large differences between the unburned and the burned plots, both in terms of vegetation structure and plant diversity. Three years after fire, the burned plots were dominated by an herbaceous layer and had a much higher floristic richness when compared with the unburned plots. Pine regeneration was absent in the unburned area, while in the burned area it reached up to nearly three seedlings per m2 after three years. Seedling density decreased over time while maximum height increased up to two meters ten years after fire. Our results suggest that prescribed burning, associated to selective logging, could be an interesting management tool to explore in these artificial stands. This could create forest gaps that would permit the natural regeneration of Aleppo pine and others species, favouring multi-strata forest and biodiversity.Le feu est considĂ©rĂ© comme le plus important facteur responsable de la rĂ©gression des forĂȘts algĂ©riennes. Chaque annĂ©e, des milliers dâhectares de vĂ©gĂ©tation brĂ»lent en affectant diffĂ©rentes essences. Les peuplements naturels de pins dâAlep sont les plus touchĂ©s, mais rĂ©cemment, le feu a tendance Ă affecter Ă©galement les forĂȘts plantĂ©es. Lâeffet du feu sur les peuplements naturels de pin dâAlep est bien documentĂ© ; toutefois, il y a un manque de connaissances au sujet des peuplements plantĂ©s. Lâobjectif de cet article est dâĂ©valuer les effets du feu sur les plantations de Pinus halepensis
dans le nord de lâAlgĂ©rie, notamment en termes de diversitĂ© floristique et de rĂ©gĂ©nĂ©ration post- incendie. Des relevĂ©s floristiques ont Ă©tĂ© rĂ©alisĂ©s trois ans aprĂšs le feu dans les parcelles brĂ»lĂ©es et dâautres non brĂ»lĂ©es servant de tĂ©moins en utilisant la mĂ©thode de Braun-Blanquet. Le nombre et la hauteur des plants des pins ont Ă©tĂ© Ă©galement notĂ©s. La collecte de ces derniĂšres donnĂ©es a Ă©tĂ© poursuivie dans la partie mieux rĂ©gĂ©nĂ©rĂ©e Ă quatre, six, huit et dix ans aprĂšs le passage du feu. Les relevĂ©s floristiques ont montrĂ© de grandes diffĂ©rences entre ceux rĂ©alisĂ©s dans le reboisement non brĂ»lĂ© et la zone brĂ»lĂ©e, Ă la fois en termes de structure de la vĂ©gĂ©tation et de la diversitĂ© floristique. Trois ans aprĂšs le feu, les parcelles brĂ»lĂ©es ont Ă©tĂ© dominĂ©es par la strate herbacĂ©e et avaient une richesse floristique beaucoup plus Ă©levĂ©e en comparaison avec le reboisement non brĂ»lĂ©. La rĂ©gĂ©nĂ©ration du pin Ă©tait absente dans la forĂȘt non brĂ»lĂ©e, tandis que dans la zone brĂ»lĂ©e elle a atteint prĂšs de deux plants par m2 trois ans aprĂšs feu. La densitĂ© des semis a diminuĂ© au fil du temps alors que la hauteur maximale a augmentĂ© pour atteindre les deux mĂštres, dix ans aprĂšs le feu. Nos rĂ©sultats suggĂšrent que le brĂ»lage dirigĂ©, associĂ© Ă des coupes sĂ©lectives, pourrait ĂȘtre Ă©galement un outil de gestion intĂ©ressant Ă explorer dans ces peuplements artificiels. Cela pourrait crĂ©er des trouĂ©es forestiĂšres qui permettraient la rĂ©gĂ©nĂ©ration naturelle de pin dâAlep et dâautres espĂšces, favorisant ainsi le dĂ©veloppement dâune forĂȘt multistrates et de la biodiversitĂ©.Madoui Amar, Catry Filipe X., Kaabeche Mohamed. Wildfire effects on Pinus halepensis Mill. plantations in a semi-arid region of north-eastern Algeria. A case study of Zenadia forest, SĂ©tif. In: Ecologia mediterranea, tome 42 n°1, 2016. pp. 79-92
Contribution Ă lâinventaire des OrchidĂ©es de la wilaya de SĂ©tif (N.-E de lâAlgĂ©rie)
International audienceLa wilaya de SeÌtif, reÌputeÌe par sa richesse floristique et pour sa diversiteÌ eÌcologique, heÌberge une biodiversiteÌ floristique remarquable. Cette biodiversiteÌ neÌcessite une bonne investigation sur terrain afin de localiser, dâidentifier et de cartographier les espeÌces rares et menaceÌes de cette reÌgion. Parmi ces espeÌces, les orchideÌes demeurent les plus embleÌmatiques en raison de leur beauteÌ, mais aussi de la fragiliteÌ de leurs habitats et des menaces qui peÌsent sur leur preÌservation. Les auteurs preÌsentent dans cet article les nouvelles stations dâorchideÌes deÌcouvertes dans la wilaya de SeÌtif. Vingt-six (26) espeÌces et sous-espeÌces dâorchideÌes ont eÌteÌ observeÌes, identifieÌes et geÌolocaliseÌes. Parmi ces espeÌces, Orchis purpurea subsp. purpurea, Dactylorhiza maculata subsp. battandieri, Orchis mascula subsp. maghrebiana, Ophrys omegaifera subsp. hayekii et Ophrys marmorata subsp. marmorata ont eÌteÌ observeÌes pour la premieÌre fois dans la reÌgion. Dactylorhiza elata s.l. est bien repreÌsenteÌ, mais seulement dans des zones humides soumises aÌ des deÌgradations humaines reÌcentes ce qui fait craindre pour sa peÌrennisationThe SĂ©tif province is renowned for its floristic and ecological diversity. This biodiversity demands a proper field investigation to locate, identify and map the regionâs rare and threatened species. Of these species, orchids remain the most symbolic, not only because of their beauty, but also because of the fragility of their habitats and the threats to their preservation. In this paper, the authors describe the new orchid sites discovered in the SĂ©tif province. Twenty-six (26) orchid species and subspecies were observed, identified and geolocated. Of these, Orchis purpurea subsp. purpurea, Dactylorhiza maculata subsp. battandieri, Orchis mascula subsp. maghrebiana, Ophrys omegaifera subsp. hayekii and Ophrys marmorata subsp. marmorata were observed for the first time in the region. Dactylorhiza elata s.l. is relatively abundant, but only in wet areas that have suffered recent human deterioration, thus raising fears about its conservation
Monitoring Forest Recovery Following Wildfire and Harvest in Boreal Forests Using Satellite Imagery
In the managed boreal forest, harvesting has become a disturbance as important as fire. To assess whether forest recovery following both types of disturbance is similar, we compared post-disturbance revegetation rates of forests in 22 fire events and 14 harvested agglomerations (harvested areas over 5â10 years in the same vicinity) in the western boreal forest of Quebec. Pre-disturbance conditions were first compared in terms of vegetation cover types and surficial deposit types using an ordination technique. Post-disturbance changes over 30 years in land cover types were characterized by vectors of succession in an ordination. Four post-disturbance stages were identified from the 48 land thematic classes in the Landsat images: âS0â stand initiation phase; âS1â early regeneration phase; âS2â stem exclusion phase; and âS3â the coniferous forest. Analyses suggest that fire occurs in both productive and unproductive forests, which is not the case for harvesting. Revegetation rates (i.e., rapidity with which forest cover is re-established) appeared to be more advanced in harvested agglomerations when compared with entire fire events. However, when considering only the productive forest fraction of each fire, the revegetation rates are comparable between the fire events and the harvested agglomerations. The S0 is practically absent from harvested agglomerations, which is not the case in the fire events. The difference in revegetation rates between the two disturbance types could therefore be attributed mostly to the fact that fire also occurs in unproductive forest, a factor that has to be taken into account in such comparisons
Etude cartographique des orchidées de Kabylie, Numidie, AurÚs (Algérie)
International audienceThis document is a summary of recent data about orchids from north-eastern Algeria. The areas concerned are the Kabylia in the broad sense and the historic Algerian Numidia with its adjacent mountains of Hodna and AurĂšs. They are very diverse territories in terms of geography (from the coast up to + 2000m altitude), bioclimate (from the semi-arid stage to the per-humid stage) and lithology (alluvium, limestone, dolomite, clays, shales, sandstones, granites, etc.).All the data published from 2005 have been synthesised and a lot of unpublished data observed from 2002 has been gathered thanks to around fifteen collaborators. Despite this, many sectors are still untouched for exploration and will need to be investigated in the future.Thus, 55 species have been illustrated and mapped. 8 others are known historically but have not yet been found. Finally, a last one has been reported in the past by mistake. The main synonyms are reminded. The taxonomic choice is following a similar recent work carried out on the Tunisian Orchids, with some rearrangements at the genus levela. A new nomenclatural combination has been created for the needs (Androrchis pauciflora subsp. laeta).A call for contributions is launched to all professional and amateurs Algerian botanists in order to continue the work through the whole Algerian TellCe document est un travail de synthĂšse des donnĂ©es rĂ©centes concernant les OrchidĂ©es du nord-est de lâAlgĂ©rie. Les rĂ©gions concernĂ©es sont la Kabylie au sens large et la Numidie historique algĂ©rienne avec ses montagnes adjacentes du Hodna et de lâAurĂšs. Ce sont des territoires trĂšs divers sur le plan gĂ©ographique (du littoral jusquâĂ + de 2000m dâaltitude), bioclimatique (de lâĂ©tage semi-aride Ă lâĂ©tage per-humide) et lithologique (alluvions, calcaires, dolomies, argiles, schistes, grĂšs, granites, etc.). Toutes les donnĂ©es publiĂ©es Ă partir de 2005 ont Ă©tĂ© synthĂ©tisĂ©es et beaucoup de donnĂ©es inĂ©dites observĂ©es Ă partir de 2002 ont Ă©tĂ© rassemblĂ©es grĂące Ă une quinzaine de collaborateurs. MalgrĂ© cela de nombreux secteurs sont encore vierges de prospection et devront ĂȘtre investiguĂ©s Ă lâavenir.Câest donc 55 espĂšces qui ont Ă©tĂ© illustrĂ©es et cartographiĂ©es. 8 autres sont connues historiquement mais nâont pas encore Ă©tĂ© retrouvĂ©es. Enfin une derniĂšre a Ă©tĂ© signalĂ©e par le passĂ© par erreur. Les principaux synonymes sont rappelĂ©s. Le choix taxonomique sâinspire dâun travail rĂ©cent similaire effectuĂ© sur les OrchidĂ©es de Tunisie, Ă quelques rĂ©arrangement prĂšs au niveau des genres. Une combinaison nomenclaturale nouvelle a Ă©tĂ© crĂ©Ă©e pour lâoccasion (Androrchis pauciflorasubsp. laeta).Un appel Ă contribution est lancĂ© auprĂšs de tous les botanistes professionnels et amateurs algĂ©riens afin de poursuivre le travail Ă lâĂ©chelle de tout le Tell algĂ©rien
Etude cartographique des orchidées de Kabylie, Numidie, AurÚs (Algérie)
International audienceThis document is a summary of recent data about orchids from north-eastern Algeria. The areas concerned are the Kabylia in the broad sense and the historic Algerian Numidia with its adjacent mountains of Hodna and AurĂšs. They are very diverse territories in terms of geography (from the coast up to + 2000m altitude), bioclimate (from the semi-arid stage to the per-humid stage) and lithology (alluvium, limestone, dolomite, clays, shales, sandstones, granites, etc.).All the data published from 2005 have been synthesised and a lot of unpublished data observed from 2002 has been gathered thanks to around fifteen collaborators. Despite this, many sectors are still untouched for exploration and will need to be investigated in the future.Thus, 55 species have been illustrated and mapped. 8 others are known historically but have not yet been found. Finally, a last one has been reported in the past by mistake. The main synonyms are reminded. The taxonomic choice is following a similar recent work carried out on the Tunisian Orchids, with some rearrangements at the genus levela. A new nomenclatural combination has been created for the needs (Androrchis pauciflora subsp. laeta).A call for contributions is launched to all professional and amateurs Algerian botanists in order to continue the work through the whole Algerian TellCe document est un travail de synthĂšse des donnĂ©es rĂ©centes concernant les OrchidĂ©es du nord-est de lâAlgĂ©rie. Les rĂ©gions concernĂ©es sont la Kabylie au sens large et la Numidie historique algĂ©rienne avec ses montagnes adjacentes du Hodna et de lâAurĂšs. Ce sont des territoires trĂšs divers sur le plan gĂ©ographique (du littoral jusquâĂ + de 2000m dâaltitude), bioclimatique (de lâĂ©tage semi-aride Ă lâĂ©tage per-humide) et lithologique (alluvions, calcaires, dolomies, argiles, schistes, grĂšs, granites, etc.). Toutes les donnĂ©es publiĂ©es Ă partir de 2005 ont Ă©tĂ© synthĂ©tisĂ©es et beaucoup de donnĂ©es inĂ©dites observĂ©es Ă partir de 2002 ont Ă©tĂ© rassemblĂ©es grĂące Ă une quinzaine de collaborateurs. MalgrĂ© cela de nombreux secteurs sont encore vierges de prospection et devront ĂȘtre investiguĂ©s Ă lâavenir.Câest donc 55 espĂšces qui ont Ă©tĂ© illustrĂ©es et cartographiĂ©es. 8 autres sont connues historiquement mais nâont pas encore Ă©tĂ© retrouvĂ©es. Enfin une derniĂšre a Ă©tĂ© signalĂ©e par le passĂ© par erreur. Les principaux synonymes sont rappelĂ©s. Le choix taxonomique sâinspire dâun travail rĂ©cent similaire effectuĂ© sur les OrchidĂ©es de Tunisie, Ă quelques rĂ©arrangement prĂšs au niveau des genres. Une combinaison nomenclaturale nouvelle a Ă©tĂ© crĂ©Ă©e pour lâoccasion (Androrchis pauciflorasubsp. laeta).Un appel Ă contribution est lancĂ© auprĂšs de tous les botanistes professionnels et amateurs algĂ©riens afin de poursuivre le travail Ă lâĂ©chelle de tout le Tell algĂ©rien