The stewardship of rangelands is increasingly undermined by degradation entailing declining productivity and the collapse of the social-ecological rangeland or agro-pastoral systems. One recent key factor of land degradation is the spread of alien invasive plant species. Future-making strategies differ greatly between the different agents, comprising policies to sedentarise former nomads and channel herd movements to migration corridors, but also community or household strategies such as land clearing by fire or risk reduction by shifting herd composition and a shift to agro-pastoralism. Such changes combined with enhanced mobility of agents expand the permeability of subsystems for the transfer of organisms. The seasonal availability and quality of pasture are increasingly restricted by the expansion of crop agriculture and the establishment of wildlife conservancies. Rainfall variability drives seasonal and inter-annual variability in the availability and quality of forage. In addition, the undesired spread of the exotic invasive plants Parthenium hysterophorus, Opuntia spp. and Prosopis juliflora is negatively affecting (agro-)pastoral livelihoods in the Kenyan Rift Valley. Plant invasion thus impacts current and future land uses, accelerating social-ecological transitions in future crop- and rangelands.
Research Areas: Kenya
Keywords: Plant Nutrition; Agricultural Economics and Sociology
Which attributes and management practices favor enhanced invasion?
How does invasion affect the productivity of crop- and rangelands (forage availability and quality, crop yields)?
Which economic constraints, risks and opportunities affect aspirations and future-related behaviour (economic mobility)?
Which feedback processes and patterns of transformation emerge and how do poverty traps constitute barriers for future-making capacities (future rangelands)?
a) Invasive spread: Prosopis has been established in the area since the 1980s. It is mostly found in the seasonally inundated plains, where 65% of households report being infested. Grazed pastures had much higher infestations than frequently cropped farmlands, and semi-nomadic pastoralists and agro-pastoralist households were more impacted by Prosopis infestation than cropland farmers.
Parthenium was reported by most pastoralists and many crop farmers to be an emergent problem in the area. It invades mainly moist places, along irrigation and drainage channels, and as ruderal plant along roadsides (water runoff from tarmac roads create moist niche environments). Parthenium is likely to expand north of Marigat supporting progressing infrastructure development and system shift from (agro-)pastoralism towards sedentary crop cultivation.
b) Environmental attributes: Results indicate that high stand densities or recent spread dynamics of Parthenium and Prosopis are closely linked with high soil moisture or with larger quantities of available water in the environment. Thus, seasonal dynamics of soil moisture are related to dynamics in seed germination, growth, and stand densities of the invasive plants. The relation between species vigor and recent spread dynamics appears further to be associated with soil fertility attributes such as relatively high soil C and N contents, with low C:N ratios in the soil organic matter, and, to a lesser extent, with plant available P.
c) Impact on households and livelihoods: An economic survey collected attributes of 530 households and aspirations of farmers and (agro-)pastoralists in the face of these invasive species and the related livelihood threats. Households generally aspire beyond their current status regarding income, assets, livestock, and social status. However, ecological shocks such as massive invasion dynamics of Prosopis and the emerging spread of Parthenium have negative effects on aspirations. Education, access to agricultural extension services, and households’ wealth status are additional determinants of aspiration formation. Cooperative membership contributes positively to the formation of income and asset aspirations.
d) Response strategies and land-use patterns: Coping with risks and uncertainties entails changes in livelihood strategies and shifts in production systems. Preliminary observations indicate that practices of future-making appear to be dominated by shifts from pastoral land use towards agro-pastoralism or even intensive crop farming. The extent of livelihood shifts further appears to depend on resource endowments and on physical, social, and educational infrastructure with better-off actors acting as pacemakers.
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Tabe-Ojong M, Ihli H, Alvarez M, Becker M, Heckelei T 2021 ‘Control strategies against Parthenium hysterophorus L. on smallholder farms in Kenya‘ (Forthcoming).
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Outlook for phase II funding
From the findings of the first phase of the CRC, we recognize that the combined diversity of environmental conditions, uncertainties, and agents result in diverse future-making strategies. Species invasion impacts rangeland users more negatively than crop farmers and differentially affects farmers’ abilities to respond to unexpected disasters (locust invasion) or to more gradual change processes (land degradation). Recent changes entailed system shifts with the emergence of new forms of sedentary crop farming but also with the creation of new niches for invasion that are likely to expand their spread.
In the second phase of the CRC, we will focus on assessing and predicting future invasive spread dynamics and related effects on soil attribute changes (soil science). In addition, we analyse determinants and consequences of “infrastructuring” and of emerging agricultural land uses and management strategies (agronomy). We expand our analysis towards understanding how changes in invasive species affect households’ aspirations and future-oriented investments through panel analysis and behavioral experiments (agricultural economics). Finally, as invasion-related livelihood strategies develop in the interplay between infrastructure development, resource base quality changes, and individual households’ strategic decisions, we will jointly assess system shifts and the emergence of new patterns of land use in Baringo and beyond.