Abstract
Juniperus procera is an important tree species in Ethiopia. Increasing demand for fuelwood and construction material has also created markets for J. procera products. The impact of cypress aphid, Cinara cupressi, on J. procera is becoming catastrophic in the country. However, the level of cypress aphid damage on J. procera has never been studied in Entoto Mountain forest and Gullele Botanical Garden (GBG) in Ethiopia. The objective of this study was to assess the cypress aphid densities and extent of damage caused by the cypress aphid on solely and mixed planted J. procera in Entoto Mountain forest and GBG in Addis Ababa, Ethiopia, by evaluating aphid adult and nymph densities and damage to J. procera trees. Eight plots of 50 m ∗ 50 m planted with pure J. procera and mixed J. procerawere selected at each site. Five 5 m ∗ 5 m subplots were formed. To assess aphid density hthree tree twigs per whorl were sampled from each tree in the subplots randomly. The collected samples were examined in the laboratory for the presence of nymph and adult cypress aphid. Tree damage was assessed by visually observing the percentage of infestation in the tree crown and was scored on a 1–5 scale. The results showed significant differences in aphid densities between the sites. The highest aphid count was observed at Entoto Mountain. Besides, the solely planted J. procera trees had higher cypress aphid numbers than the mixed plantation. The mean percentage of aphid-infested trees in Entoto and GBG was 53.6 and 46.4, respectively. Tree mortality was extremely low in both sites and planting systems. The level of aphid damage was also significantly different between the planting systems, where mixed plantations had a lower aphid infestation level. Tree damage was directly correlated with the density of aphids collected. In conclusion, cypress aphid was apparent in both sites, and most of the trees were infested by this pest. However, the extent of damage varied with the planting system. Therefore, it is recommended to consider a mixed plantation of trees as one of cypress aphid management tools in J. procera.
Highlights
People rely on forests as sources of livelihood, and they obtain varieties of valuable products such as timber, fuelwood, fiber, and nonwood forest products
It is an economically valuable tree used for building fences/houses and manufacturing pencil, and the oil extracted from wood can be used for soap and International Journal of Forestry Research perfume production [9]. e cypress aphid, Cinara cupressi (Buckton), is a notorious pest of Cupressaceae forests and is among the 100 most devastating invasive pest species in the world [10]
Cypress aphid density per twig, the damage level of incidence caused by the aphid, percentage of trees infested by the aphid, and tree mortality between the study sites and planting system were analyzed by using Student’s t-test when the normality assumptions were fulfilled; otherwise, the nonparametric Wilcoxon test was used. e percentage of tree infestation and mortality was arcsine transformed before analysis
Summary
People rely on forests as sources of livelihood, and they obtain varieties of valuable products such as timber, fuelwood, fiber, and nonwood forest products. J. procera, commonly known as African pencil cedar, is one of the two indigenous conifers found in Ethiopia [9] It is an economically valuable tree used for building fences/houses and manufacturing pencil, and the oil extracted from wood can be used for soap and International Journal of Forestry Research perfume production [9]. Cypress aphid is an exotic species in Ethiopia, and since its first report in 2003 caused more than $10 million worth of damages to J. procera and Cupressus lusitanica plantations across the country [10]. Erefore, the present study assessed the density and extent of damage by the cypress aphid on J. procera in Entoto Mountain forest and Gullele Botanical Garden (GBG), Ethiopia, under varying planting conditions: mixed and sole planting Us, investigating the role of tree diversity in minimizing damage caused by C. cupressi on J. procera may provide necessary information to work on the management of C. cupressi. erefore, the present study assessed the density and extent of damage by the cypress aphid on J. procera in Entoto Mountain forest and Gullele Botanical Garden (GBG), Ethiopia, under varying planting conditions: mixed and sole planting
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