Effects of human-livestock-wildlife interactions on habitat in an eastern Kenya rangeland

Human–livestock–wildlife interactions have increased in Kenyan rangelands in recent years, but few attempts have been made to evaluate their impact on the rangeland habitat. This study identified drivers of increased human–livestock–wildlife interactions in the Meru Conservation Area between 1980 and 2000 and their effects on the vegetation community structure. The drivers were habitat fragmentation, decline in pastoral grazing range, loss of wildlife dispersal areas and increase in livestock population density. Agricultural encroachment increased by over 76% in the western zone adjoining Nyambene ranges and the southern Tharaka area, substantially reducing the pastoral grazing range and wildlife dispersal areas. Livestock population increased by 41%, subjecting areas left for pastoral grazing in the northern dispersal area to prolonged heavy grazing that gave woody plant species a competitive edge over herbaceous life-forms. Consequently, open wooded grassland, which was the dominant vegetation community in 1980, decreased by c. 40% as bushland vegetation increased by 42%. A substantial proportion of agro pastoralists were encountered around Kinna and Rapsu, areas that were predominantly occupied by pastoralists three decades ago, indicating a possible shift in land use in order to spread risks associated with habitat alterations. Resume Les interactions hommes-betail-faune sauvage ont augmente dans les pâturages kenyans ces dernieres annees, mais il y a eu peu de tentatives pour evaluer leur impact sur cet habitat. Cette etude identifie quelles ont ete les raisons sous-jacentes de ces interactions dans l’Aire de Conservation de Meru entre 1980 et 2000, et leurs effets sur la structure de la communaute vegetale. Les raisons etaient la fragmentation de l’habitat, le declin de la surface libre pour le pâturage pastoral, la perte d’aire de dispersion pour la faune sauvage et l’augmentation de la densite de population du betail. L’envahissement agricole a augmente de plus de 76% dans la zone ouest touchant les fermes de Nyambene et l’aire sud de Tharaka, reduisant substantiellement l’etendue du pâturage pastoral et les aires de dispersion de la faune sauvage. La population du betail a augmente de 41%, soumettant les etendues laissees au pâturage pastoral dans la region de dispersion nord a un pâturage intensif prolonge qui a donne aux especes vegetales ligneuses un avantage sur les formes herbeuses. Par consequent, la prairie arboree ouverte, qui etait la communaute vegetale dominante dans les annees 1980 a diminue de pres de 40% alors que la vegetation de broussailles a augmente de 42%. Une proportion substantielle d’agropastoralistes se rencontraient autour de Kinlla et de Rapsu, des zones qui etaient principalement occupees par des pasteurs il y a trois decennies, ce qui indique une evolution possible de l’utilisation des sols afin de disperser les risques lies a l’alteration des habitats.