Bibliothèque Tour du Valat

Se connecter

Mot de passe oublié ?
Pas encore inscrit ?

La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Détail

Notice ajoutée !

Notice ajoutée !

Lien vers la notice

Titre :	Effect of environmental factors on natural regeneration of Tetraclinis articulata (Vahl, Master) in Oran region (Algeria)
Auteurs :	Seghir Hadjadj Aoul, Auteur ; Mohamed Chouieb, Auteur ; Roger Loisel, Auteur
Type de document :	Article
Dans :	Ecologia Mediterranea (35(1) 2009)
Article en page(s) :	19-30
Résumé :	In this work, we studied the natural regeneration of Tetraclinis articulata (Vahl, Master) in the Oran region in Algeria. While this species produces large amounts of seeds, it seems to regenerate only by vegetative multiplication (i.e. by tillers) which is a rare phenomenon for gymnosperms. Therefore, its natural regeneration may be characterised by a seedling deficiency. To test this hypothesis and to investigate which obstacles prevent the installation and the development of Tetraclinis seedlings, we studied Tetraclinis regeneration in situ (in the fields). We choose three natural woodlands on the cost and at the back country of Mostaganem.To test this hypothesis and to investigate which obstacles prevent the installation and the development of Tetraclinis seedlings, we studied Tetraclinis regeneration in situ (in the fields). We choose three natural woodlands on the cost and at the back country of Mostaganem.The regional climate is hot and dry in summer (semi arid sensus Emberger) and warm in winter with about 380 mm of precipitation and an average annual temperature of 17.9 degrees C.In each woodland, we set 25 round plots of 100 m(2).In order to sample as many different situations as possible, we varied, for each plot, the combination between the different factors thought to influence seedling establishment.The various factors thought to influence seedling establishment were recorded in each plot and are the following:1: physical characteristics, such as altitude, exposition, slope and topography;2: the structure of the woodland: vegetation structure, number of clusters of adult Tetraclinis shoots, average number of shoots in an adult Tetraclinis cluster, average shoot height and total number of adult Tetraclinis shoots;3: soil characteristics: geology, compaction, litter depth, percent cover of stones and gravels, erosion;4: type of disturbance or artificial impact (pasture, fire, offence, replanting, reforestation);5: number of Tetraclinis seedlings by class of height and spatial position in relation to surrounding vegetation.After coding, we grouped all the observations in a 31 columns-variables and 75 lines-plots chart on which PCA (Principal Component Analysis) and Hierarchical Clustering were run.The results showed that the south, south west and west facing slopes, which are the warmest, are favourable to the installation of Tetraclinis seedlings. On these slopes, which support most adult trees, there are very few seedlings developping without any shelter.The same observations have also been reported for Pinus pinea in Italy by Masseti and Mencuccini (1991), for Quercus suber in Tunisia by Hasnaoui (1991) and for Quercus suber and Quercus pubescens in Sicilia by Di Pasquale and Garfi (1998).Tetraclinis seedlings are mainly found among the low vegetation (Rosmarinus, Cistus, Lavandula), and the maximum number of seedlings appears under the adult Tetraclinis trees themselves.All these observations show that Tetraclinis articulata can regenerate by seedlings, however their establishment seems to be limited by planted Pinus halepensis litter and pasture. In fact, the litter either by its thickness or its nature could stop the normal development of the natural germination.We can conclude that natural regeneration by seedlings is possible but is blocked early by several constraints among which pasture seems to be the most significant one.

FAQ

Infos pratiques

Heures d'ouverture et contact

Lundi , mardi et jeudi de 9h à 12h et de 13h à 17h00 : ouverture au public ...

Liens utiles

A-
A
A+