Linking Pastoralists to a Heterogeneous Landscape

Abstract

Experience gained inlooking at land-use change issues over recent decades has shown that human land-use strategies impact and are simultaneously impacted by ecological patterns and processes. In this chapter, we provide an example of a methodology to quantify the linkages between people and environment in a communal resource landscape and detect the impacts of landscape patterns on human land use. Pastoral production strategies in semiarid regions were predicated historically on opportunistic and extensive livestock movements in search of grazing and water across heterogeneous landscapes. However, macroscale political-economic factors that drive land subdivision and economic sedentarization compromise the ability of herders to maintain large-scale and opportunistic grazing patterns by fragmenting the landscape. We used remote sensing, GIS, GPS, and household socioeconomic surveys to: (1) identify a methodology to quantify the ecological heterogeneity of pastoral landscapes in Kajiado District, Kenya, (2) identify the daily spatial scale of pastoral resource use, and (3) illustrate the degree of seasonal variability inherent in this example of a semiarid pastoral system. We defined landscape heterogeneity using NDVI images for wet and dry periods of the year, a 1-km resolution digital elevation model, and a soils layer. We merged heterogeneity layers for wet/dry NDVI, elevation, and soils to form six combinations of heterogeneity indices, then used Monte Carlo assessments to quantify the degree of selection pastoralists made for landscape heterogeneity. Daily pathways did not reveal selection within seasons. Daily path lengths were related to the degree of subdivision and economic sedentarization of households. Integrating annual grazing pathways into these analyses will be a key to better depicting pastoralists’ relationships with landscape heterogeneity.

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