Diversity of bark beetles (Curculionidae: Scolytinae) and their attack strategy in a natural forest of semi-arid region (Djelfa- Algeria)

Abstract

The Aleppo pine woods in the Algerian Saharan Atlas semi-arid zone are one of the remaining woodlands and constitute the last combat desertification. The Senalba Chergui pine forests of the Djelfa region are among the last relics that fight desertification. The forests have declined recently due to climatic, anthropogenic, and biotic factors such as wood-boring insects. Their socio-economic importance necessitates reducing biotic hazards resulting from bark beetle outbreaks to reduce the vulnerability of stands exposed to these disturbances. Based on dendrometric parameters (trunk diameter, bark thickness and tree height) and variations in environmental factors (altitude and slope), six decayed trees were selected on the north and south slopes at different altitudes. Each tree was cut into 4 trunks measuring 1 meter according to the height of the tree, i.e. a total of 24 samples (trunks). The PCA analysis revealed that hillside and tree morphology are determining factors in the selection of bark beetles. In contrast, altitude did not show a significant effect on bark beetle behaviour, while tree height itself had a negative effect on attack density and vice versa.

The Aleppo pine woods in the Algerian Saharan Atlas semi-arid zone are one of the remaining woodlands and constitute the last combat desertification. The Senalba Chergui pine forests of the Djelfa region are among the last relics that fight desertification. The forests have declined recently due to climatic, anthropogenic, and biotic factors such as wood-boring insects. Their socio-economic importance necessitates reducing biotic hazards resulting from bark beetle outbreaks to reduce the vulnerability of stands exposed to these disturbances. Based on dendrometric parameters (trunk diameter, bark thickness and tree height) and variations in environmental factors (altitude and slope), six decayed trees were selected on the north and south slopes at different altitudes. Each tree was cut into 4 trunks measuring 1 meter according to the height of the tree, i.e. a total of 24 samples (trunks). The PCA analysis revealed that hillside and tree morphology are determining factors in the selection of bark beetles. In contrast, altitude did not show a significant effect on bark beetle behaviour, while tree height itself had a negative effect on attack density and vice versa.

The Aleppo pine woods in the Algerian Saharan Atlas semi-arid zone are one of the remaining woodlands and constitute the last combat desertification. The Senalba Chergui pine forests of the Djelfa region are among the last relics that fight desertification. The forests have declined recently due to climatic, anthropogenic, and biotic factors such as wood-boring insects. Their socio-economic importance necessitates reducing biotic hazards resulting from bark beetle outbreaks to reduce the vulnerability of stands exposed to these disturbances. Based on dendrometric parameters (trunk diameter, bark thickness and tree height) and variations in environmental factors (altitude and slope), six decayed trees were selected on the north and south slopes at different altitudes. Each tree was cut into 4 trunks measuring 1 meter according to the height of the tree, i.e. a total of 24 samples (trunks). The PCA analysis revealed that hillside and tree morphology are determining factors in the selection of bark beetles. In contrast, altitude did not show a significant effect on bark beetle behaviour, while tree height itself had a negative effect on attack density and vice versa.