Papers by Dalila Kherchouche
BOIS & FORETS DES TROPIQUES
Pour mieux comprendre l'impact des facteurs climatiques et l'influence de la diversité de... more Pour mieux comprendre l'impact des facteurs climatiques et l'influence de la diversité des habitats sur le dépérissement des cédraies des Aurès, une approche dendrochronologique basée sur la relation cerne-climat a été adoptée et appliquée à six stations, réparties sur deux cédraies méridionales, du Belezma et du Chélia (Atlas saharien), distantes de 60 km et impactées par différentes perturbations climatiques. Pour les deux sites étudiés, un sondage de 120 arbres a été réalisé, permettant d’extraire au total 240 carottes. Une chronologie maîtresse a été établie pour chaque station et une série moyenne de données a été élaborée pour chaque site. Les chronologies obtenues ont été standardisées afin d’atténuer les effets et les tendances non liées à la variation climatique. Puis, les chronologies résiduelles ont été utilisées pour appréhender la relation cerne-climat. Les résultats obtenus montrent une hétérogénéité de la réponse du cèdre de l’Atlas au sein des deux massifs. L...
Dendrochronologia
Abstract Forty-one fire-scarred samples from two new Cedrus atlantica sites in the Ouled-Yaâgoub ... more Abstract Forty-one fire-scarred samples from two new Cedrus atlantica sites in the Ouled-Yaâgoub Forest were collected and combined with the two previous sites from the Chelia Forest reported in Slimani et al. (2014) to develop a regional analysis of fire history in the Aures Mountains, northern Algeria. Prior to 1850, cedar forests were characterized by high frequency, low-intensity surface fire regimes. Fire frequency declined after 1850 after the elimination of the Barbary lion and the enforcement of the first laws governing land and forest use in Algeria. Most of the fire events in both forests occurred in the summer season, the latter part of the growing season, or in the dormant season. We compared past fires occurrences and an October-June precipitation reconstruction. On a regional scale, precipitation was significantly reduced in the months prior to the fire occurrence. In addition, precipitation during the first year preceding the fire years was significantly above average. This study provides a baseline for planning and justifying improved ecosystem management programs.
BOIS & FORETS DES TROPIQUES
L’objectif de ce travail est d’élaborer des tarifs de cubage d’arbres individuels de pin d’Alep, ... more L’objectif de ce travail est d’élaborer des tarifs de cubage d’arbres individuels de pin d’Alep, Pinus halepensis Mill., de la pinède des Ouled-Yaâgoub en Algérie. Neuf fonctions linéaires et non linéaires ont été ajustées systématiquement sur des données collectées à partir de 340 arbres, représentatifs des différentes classes de diamètre et de hauteur, choisis parmi les arbres abattus dans le cadre des coupes d’exploitation finales dans les chantiers installés dans la zone étudiée. L’approche adoptée pour l’estimation des paramètres des différentes fonctions testées est basée sur la régression, linéaire et non linéaire, selon la technique des moindres carrés ordinaires pondérés. Des analyses numériques et graphiques basées essentiellement sur la distribution des résidus et la précision des tarifs obtenus ont été employées pour comparer les différentes fonctions étudiées. Deux fonctions ont été retenues pour le cubage d’arbres individuels dans la pinède du massif des Ouled-Yaâgoub ...
Science et Changements Planetaires - Secheresse
ABSTRACT
Journal of Arid Environments, 2016
Abstract Drought is one of the main natural factors in declining tree-ring growth and the product... more Abstract Drought is one of the main natural factors in declining tree-ring growth and the production of agricultural crops in Algeria. This paper addresses the variability of growing conditions for wheat in Algeria with climatic data and a tree-ring reconstruction of January–June precipitation from ten Pinus halepensis tree-ring chronologies. A regression-based reconstruction equation explains up to 74% of the variance of precipitation in the 1970–2011 calibration period and cross validates well. Classification of dry years by the 30% percentile of observed precipitation (131 mm) yields a maximum length of drought of five years (1877–1881) and increasing frequency of dry years in the late 20th and early 21st centuries. A correlation-based sensitivity analysis shows a similar pattern of dependence of tree-growth and wheat production on monthly and seasonal precipitation, but contrasting patterns of dependence on temperature. The patterns are interpreted by reference to phenology, growth phases, and – for wheat – agricultural practices.
Journal of Arid Environments, 2014
ABSTRACT The first fire history of the Cedrus atlantica forest of Chélia in northern Algeria is r... more ABSTRACT The first fire history of the Cedrus atlantica forest of Chélia in northern Algeria is reconstructed from samples of 14 and 12 dead fire-scarred trees from lower and upper elevation stands respectively. Superposed epoch analysis is applied to summarize mean climate conditions before, during, and after sets of fire years in both stands. Prior to 1850, C. atlantica forests in both sites were characterized by high frequency and low intensity fire regimes. The sharp decline in the fire frequency after the mid-nineteenth century coincided with the promulgation of the first laws governing land and forest use in Algeria. Most fire events occurred in the summer, during the latter part of the growing season. No significant relationships were found between an October–June precipitation reconstruction and fire events. This could be due to anthropogenic and topographic factors. The findings of this study provide baseline knowledge on the ecological role of fire in the C. atlantica forest. This information is vital to support ongoing ecosystem management efforts in the region.
Forests
Annual river discharge is a critical variable for water resources planning and management. Tree r... more Annual river discharge is a critical variable for water resources planning and management. Tree rings are widely used to reconstruct annual discharge, but errors can be large when tree growth fails to respond commensurately to hydrologically important seasonal components of climate. This paper contrasts direct and indirect reconstruction as statistical approaches to discharge reconstruction for the Chemora River, in semi-arid northeastern Algeria, and explores indirect reconstruction as a diagnostic tool in reconstruction error analysis. We define direct reconstruction as predictions from regression of annual discharge on tree ring data, and indirect reconstruction as predictions from a four-stage process: (1) regression of precipitation on tree rings, (2) application of the regression model to get reconstructed precipitation for grid cells over the basin, (3) routing of reconstructed precipitation through a climatological water balance (WB) model, and (4) summing model runoff over ...
Croissance et ecologie du pin d'Alep (Pinus halepensis Mill.) dans le massif des Beni-Imloul (Aur... more Croissance et ecologie du pin d'Alep (Pinus halepensis Mill.) dans le massif des Beni-Imloul (Aur es, Alg erie) Pour citer cet article : Kherchouche D, Bentouati A, Kaabeche M, 2011. Croissance et ecologie du pin d'Alep (Pinus halepensis Mill.) dans le massif des Beni-Imloul (Aur es, Alg erie). S echeresse 22 : 43-8.
The Algerian Green Barrier, mainly composed of native and artificial Aleppo pine 35 forests, spre... more The Algerian Green Barrier, mainly composed of native and artificial Aleppo pine 35 forests, spreads along the presaharian steppes and is threatened by anthropogenic and 36 natural disturbances, including climate change. We hypothesized that the 37 ecophysiological functioning of this conifer has been substantially modified in reaction 38 to recent warming and drought much beyond the expected effect of CO2 fertilization.
La s echeresse et le d ep erissement du c edre de l'Atlas (Cedrus atlantica Manetti) dans le mass... more La s echeresse et le d ep erissement du c edre de l'Atlas (Cedrus atlantica Manetti) dans le massif du Belezma (Alg erie) Pour citer cet article : Kherchouche D, Kalla M, Gutierrez E, Briki A, Hamchi A, 2013. La s echeresse et le d ep erissement du c edre de l'Atlas (Cedrus atlantica Manetti) dans le massif du Belezma (Alg erie). S echeresse 24 : 129-37.
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Papers by Dalila Kherchouche