Project B01, Invasive Futures

Project Summary

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

Key Questions

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)?


B01 employs a diverse set of methodological approaches to tackle the questions at hand. These include the analysis of digital elevation models, monitoring of wells, remote sensing moisture assessments, and field surveys. In order to analyse the impact of the perception of ecological shocks on the intention to engage in future-making activities related to land use, B01 plans to include behavioural-economics experiments. The randomized field experiment involves an information treatment (possibly video-based) on invasive species and possibilities of mitigation relevant for households in similar situations. Actors are interviewed both immediately after screening and after one year to examine the persistence of any changes in aspirations and related behaviour from this experiment targeting the locus of control. As a result of this experience, subjects may re-evaluate their perceptions of their own lives and opportunities. The field experiments will assess implications of potential future invasions at the household level and as a possible driver for further system shifts.

Key Findings from Phase I

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.


Peer Reviewed
Alvarez, M., Heller, G., Malombe, I., Matheka, KW, Choge, S. & Becker, M. 2019. ‘Classification of Prosopis juliflora invasion in the Lake Baringo basin and environmental correlations’. African Journal of Ecology vol. 57(3), pp. 296-303. DOI

Alvarez, M., Curran, M. & Malombe, I. 2021. SWEA-Dataveg: A vegetation database for sub-Saharan Africa. Vegetation Classification and Survey. DOI

Agha, SB., Alvarez, M., Becker, M., Fèvre, EM., Junglen, S., Borgemeister C 2021. ‘Invasive alien plants in Africa and the potential emergence of mosquito-borne arboviral diseases—A review and research outlook‘. Viruses vol.13, pp. 32. DOI

Tabe-Ojong, M.P. 2022. 'Ecological shocks and non-cognitive skills: Evidence from Kenya', Ecological Economics, vol. 194, no. 107330 DOI

Tabe-Ojong, M.P., Hauser, M., Mausch, K. 2022. 'Does Agricultural Commercialisation Increase Asset and Livestock Accumulation on Smallholder Farms in Ethiopia?', The Journal of Development Studies. href="" target="_blank" rel="noopener">DOI

Tabe-Ojong, M.P., Alvarez, M., Ihli, H., Becker, M., & Heckelei, T. 2021. ‘Action on Invasive Species: Control Strategies of Parthenium hysterophorus L. on Smallholder Farms in Kenya’, Environmental Management. href="">DOI

Tabe-Ojong, M.P., Gebrekidan, B.H., Nshakira-Rukundo, E., Börner, J., & Heckelei, T. 2022. 'COVID-19 in rural Africa: Food access disruptions, food insecurity and coping strategies in Kenya, Namibia, and Tanzania', Agricultural Economics, pp. 1– 20. DOI. href="" target="_blank" rel="noopener">Full Text

Tabe-Ojong, M.P., Heckelei, T. & Baylis, K. 2021. ‘Aspiration formation and ecological shocks in Rural Kenya. The European Journal of Development Research. (Online First Articles).Link

Tabe-Ojong, M.P., Mausch, K., Woldeyohanes, T., Heckelei, T. 2021. 'Three hurdles towards commercialization: Integrating subsistence chickpea producers in the market economy'. European Review of Agricultural Economics. DOI

Tabe-Ojong, M.P. & Nshakira-Rukundo, E. 2021. ‘Religiosity and parental educational aspirations for children in Kenya,’ World Development Perspectives, Volume 23, 100349. href="">DOI

Conferences & Working Papers

Conference contributions / Working papers / Papers under review

Alvarez, M., Kiboi, S., Becker, M. & Malombe, I. 2019. ‘Modelling potential dispersal of Prosopis juliflora in East Africa: Scaling and assembling correlations‘. Presentation at EMAPi, Prague.

Sainepo, B., Alvarez, M. & Becker, M. 2021. ‘Impact of Parthenium hysterophorus invasion on plant species composition and soil properties in grassland communities in the Njemps flats, Kenya’. Paper to be presented at the Joint International Grassland Congress/International Rangeland Congress 2021 virtual conference, August 2021.

Sainepo, B., Tabe-Ojong, M.P., Kiboi, S., Malombe, I., Becker, M., Heckelei, T. & Alvarez, M. 2019. Parthenium hysterophorus in East Africa: a numerical review’. Presentation at EMAPi, Prague, Czech Republic

Tabe-Ojong, M.P., Heckelei,T & Baylis, K. 2020. ‘Aspiration formation and ecological shocks: An exploratory analysis in rural Kenya‘. Paper presented at the Annual Meeting of the American Applied Economics Association (AAEA), Kansas City, July 26-28.

Tabe-Ojong, M.P., Heckelei, T. & Baylis, K. 2020. ‘Collective action and smallholder rural households: Implications for income and asset aspirations‘ Paper presented at the Annual Meeting of the American Applied Economics Association (AAEA) in Kansas City, July 26-28

Tabe-Ojong, M.P., Heckelei, T., Baylis, K. & Rasch, S. ‘How does collective action affect the aspirations of smallholder households?’ (working paper) Access Link

Tabe-Ojong, M.P., Rasch, S. ‘Income aspirations and livestock savings: Evidence of aspiration failure in Kenya’ (working paper) Access Link

Tabe-Ojong, M.P., Ihli, H., Alvarez, M., Becker, M., Heckelei, T. 2021. ‘Action on invasive species: control strategies of Parthenium hysterophorus L. on smallholder farms in Kenya’ (under review) Access Link

Tabe-Ojong, M.P. et al Coping with locusts and COVID-19 in rural Africa: An analysis of household-level coping strategies to food insecurity (under review) Access Link

Partner Institutions

University of California
Santa Barbara