Prevalence and causes of monkey debarking across age cohorts of cuppressus lusitanica in the mt Kenya ecosystem

Abstract

Game debarking has been a major hindrance to high quality timber production. Debarked parts not only provide entry points to the destructive Oemeda gaani but also adversely affect the tree growth. Though fruits and leaves of Moraceae family form the most preferred diet for monkeys, other families act as fallback resource when the top diet is scarce. In a study carried out in the Mt Kenya ecosystem, it is likely that C. lusitanica is one the fallback resource. These monkeys were found to prefer the barks of this species. Prevalence of debarking and its associated effects pose a threat to major plantations i n the Mt Kenya ecosystem. Surveys were undertaken in 2008 at Mt Kenya Ecosystem to evaluate the prevalence and cause of monkey debarking across the age cohorts of C. lusitanica . The study, that was confined between 1998 - 2100, 9968000 - 9996000 and 0287000 - 02 98000 (altitude, longitude and latitude respectively), covered Nanyuki, Naromoru, Gathiuru and Kabaru forest ecosystems. Three age cohorts, 5 - 10, 11 - 20, and >20years were selected and presence/absence of debarking, height of debarking and part of the tree trunk debarked were assessed. Total enumeration/sampling was done on 0.04ha and 0.02ha for age cohorts 11 - 20, >20 and 5 - 10 years respectively. Laboratory analysis of the tree barks was also done to determine nutritive composition. Though debarking prevalen ce was present in all sites, Nanyuki forest was the most statistically significant site (P<0.05). Test of homogeneity of variance showed that among the three age cohorts tested for debarking, >20 years was the most statistically significant age class (P<0. 05). Duncan Multiple Range Test also showed that the most preferred part of the trunk was the upper portion compared to the lower, middle and top. The debarked parts of the stem showed a strong positive Pearson correlation (n = 4, r s = 0.876, p = 0.05) wit h the height of debarking. Though study sites correlated positively with presence/absence of debarking and part of the trunk debarked, they had weak correlation (0.129 and 0.101 respectively). Lack of the most preferred Moraceae family in the Mt Kenya ecos ystem was found to cause a shift in the diet base for the monkeys. Based on the findings of this study, it is likely that C. lusitanica is one among the fallback resource for the monkeys. Mass exodus of not only monkeys but also majority of the wild animal s in the Mt Kenya ecosystem in the early 2000(s) from the higher to lower regions of the mountain has also contributed to this. C. lusitanica form 80% of exotic plantations in the sampled area while all the exotic species form around 95%. The indigenous sp ecies forms at least 5% and are mainly restricted to water catchment areas. This low percentage of indigenous species coupled with mass exodus of wild game to the lower regions has exerted pressure on the monkey diet base. There is need to plant Moraceae f amily and other fallback resource around C. lusitanica plantations to act as buffer zones. Restriction of movement of wild animals into the plantations like the case of the Abardere ecosystem is required. There is need to carry out further survey to establ ish the causes of mass exodus of wild animals from the higher to the lower regions of the mountain. Also, it is worth to carry out a socio - economic survey to determine the economic and social losses that accrue from monkey debarking and other game damage.