Spatial distribution model of phragmanthera plant parasite in Rift Valley Ecoregion of Kenya
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Genus Phragmanthera (Loranthaceae) family is in one of the families of mistletoes which are parasitic plants that solely depend on their hosts for nutrients and water once attached. The parasitism leads to wilting and drying up of the infested part and in cases of high infestation mortality of the tree affected. Members of the genus were observed to parasitize tree hosts in the Rift Valley ecoregion through a transect survey. The locations of the parasitic plant were recorded and used for Maximum Entropy (Maxent) modelling to determine environmental conditions making up the niche of the parasite and to develop suitability maps of the parasitic plant within Rift Valley ecoregion. 27 occurrence records representing 102 trees were correlated to the 19 Bioclimatic variables representing temperature and precipitation conditions globally. The species identified in this study is Phragmanthera cornetti (Dewevre) Polhill & Wiens with key host species being Cupressus sempevirens var. pyramidalis, Schinus molle and Jacaranda mimisifolia which are ornamental trees. Maximum Entropy software (Maxent) version 3.4 was used to determine the species suitability of Phragmanthera cornetti identifying Baringo, Nakuru, Uasin Gishu, Transnzoia and Elgeyo Marakwet as hot spots for infestation by the parasitic plant. Environmental variables weighed as most critical to Phragmanthera cornetti distribution in the sampled area were precipitation of coldest quarter, precipitation of driest month, Temperature seasonality, Isothermality and minimum temperature of coldest month. These variables were ranked using their individual contribution to the model (AUC=0.935) computed on MaxEnt correlating the occurrences to Bioclimatic variables. The identified counties within the predicted ranges of Phragmanthera cornetti infestation should begin using more resistant or less susceptible tree species for their tree growing programs. All infested trees and branches should be pruned for short term control of the spreading of Phragmanthera cornetti in the upcoming coldest quarter. Further studies into more effective control measures for the parasitic plants are being investigated for a more integrated approach. This includes use of selective herbicides and management by utilization.
Key words: Species Distribution Modelling, Phragmanthera, Bioclimatic variables, ecological niche
ID: 3623688