Abstract
The study area is dominated by Juniperus sp and Pistacia sp, the two species, the study aimed to investigate the effect of chemical defences on the density of insect herbivores, and the results showed that the two species differed very much in their levels of phenols. Pistacia had the highest concentrations (overall 2308 ± 43 ppm, n = 45), with Juniperus quite a bit lower (1516 ± 43, n = 45). Overall levels of phenols were highest in plants from the middle and lowest in those from the bottom elevation level. This effect of the level was significant, showing that the two species showed the same pattern with elevation. There were substantial differences among plots within levels. This has affected the numerical density of the insects, where it was observed that their density on the tested Juniperus sp shrubs was more than the intensity on the tested Pistacia sp shrubs.
Publisher
Omar Al-Mukhtar University
Reference19 articles.
1. Bryant, J. P., Heitkonig, I., Kuropat, P., & Owen-Smith, N. (1991). Effects of severe defoliation on the long-term resistance to insect attack and on leaf chemistry in six woody species of the southern African savanna. The American Naturalist, 137(1), 50-63.
2. Bryant, J. P., Reichardt, P. B., & Clausen, T. (1992). Chemically mediated interactions between woody plants and browsing mammals. Rangeland Ecology & Management/Journal of Range Management Archives, 45(1), 18-24.
3. Coley, P. D., Bryant, J. P., & Chapin, F. S. (1985). Resource availability and plant antiherbivore defense. Science, 230(4728), 895-899.
4. Dallman, P. R. (1998). Plant life in the world's Mediterranean climates: California, Chile, South Africa, Australia, and the Mediterranean basin: Univ of California Press.
5. Dement, W. A., & Mooney, H. A. (1974). Seasonal variation in the production of tannins and cyanogenic glucosides in the chaparral shrub, Heteromeles arbutifolia. Oecologia, 15(1), 65-76.