The present study shows farm types are associated with the agroecological gradient, and by extension to associated wetland types and to existing wetland cluster groups. The agroecological gradient in terms of agro-climatic conditions has a strong influence on agricultural production activities determining the production systems hence the corresponding farm types. The distribution of the production systems in the study environment are mainly determined by agroecological factors like the agro-climate and rainfall patterns that partly drive land uses. Crop and mixed crop non-dairy-based production systems are associated with “mixed sub-humid and semi-arid” areas, whereas livestock-based system concentrate in semi-arid zones. The mixed crop-dairy system tend to dominate the wetter parts of the study sites that are located in humid midland and highland areas. The results on the environmental association of both mixed and livestock systems are consistent with findings in eastern Africa by Staal et al. (2001) and Cecchi et al. (2010). Moreover, the integration of livestock by more than 70% of the households at the study sites supports its importance to income strategies of smallholder rural communities in the region (Sandford and Ashley, 2008). The association of livestock-based systems with the driest environment reflects the aridity, erratic rainfall, and frequent drought in the area, all factors that together make rain-fed agriculture a risky enterprise in these areas (Chilonda et al., 2010). Thus, such an association determines the suitability of the environment for large scale ranching or nomadic pastoralism, which is considered as the most important and sustainable livelihood system in semi-arid to arid areas in Africa (Reid et al., 2008).
The environmental association of either the farm type or the production system is further linked, either directly or indirectly, to population density and its subsequent land scarcity, market opportunity, the relative value of non-wetland related livelihood strategies with respect to wetland-agriculture, and the access to wetlands. Most factors constitute wetland use modifiers that have been observed elsewhere (e.g. Erenstein et al., 2006; Wood and van Halsema, 2008) and are reflected in wetland cluster groups. Crop-based production systems dominate the dry environments with low population density whereby concentrate in floodplains, supporting the use their large areas for crop production (Schuijt, 2002). Factors resulted from population modifier of wetland use, such as, land shortages and immigration are seen to accelerate wetland conversion (Oucho and Gould, 1993; Sakané et al., 2011), shaping the specific relation between farm types and wetland cluster groups. The
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agroecological gradient is reflected in wetland types whereby the rainfall patterns partly influences the occurrence of floodplain and inland valley in different landscapes (Windmeijer and Andriesse, 1993; Dixon, 2002). Wetland uses, in terms of diversity and use intensity that partly determine a household’s production system, vary with wetland type, the prevailing hydrological regime, and the physical accessibility (Rebelo et al., 2010;
Sakané et al., 2011).
Moreover, the production objectives of migrant farmers in conjunction with market access are likely to increase the wetland conversion for food and production of high-value crops. This supports the capacity of large semi-arid floodplain to use diversification as suggested by (Rebelo et al., 2010) but implies the increase in land use intensity of related wetland land units like those of cluster group 2 in our study. Consequently, possible transitions between wetland cluster groups through the corresponding farm types can be expected in the future. The study suggest that such modifiers in combination with free access rights to land in the wetland will exacerbate the pressure on wetland production resources in semi-arid environments. Land use changes are being observed in such areas where floodplains are traditionally considered as back-falls grazing by the local pastoralist communities (Thenya, 2001). Moreover, migrant modifier is likely to influence the socio-cultural nature of local communities, implying changes in household’s production system where livestock herders integrate crop production in the foreseeable future. This may result in transition between farm types like those of the agro-pastoralists within the same production system. Consequently, transitions are likely to occur at different levels of aggregation with respect to the scale of interest.
A key lesson is the importance of farmers’ characteristics and the relative importance of wetland-related livelihood strategies in the relation between farm types and wetland cluster groups rather than the commonly known land use modifiers. Noteworthy is that this was observed in the wetter parts of the study sites where factors on favourable agroecological conditions, good market opportunity, and agricultural population density are met for dairy farming and crop integration (van de Steeg et al., 2010). Moreover, the population growth-induced land scarcity did result in land fragmentation, whereby the ratio of wetland field to farm size had its lowest value. Furthermore, associated wetlands to these environments were all narrow inland valleys that support either a more or a moderate intensity use of wetlands. Factor on land use
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intensity did discriminate wetland land units; hence wetland cluster groups (Sakané et al., 2011). The analyses show that the scarcity of family labour, aging of household head, and cash generating power of non-wetland related strategies reduces the market orientation and thus reduces land use intensity and inland valley development. This leads to a more subsistence oriented farming in partially drained valleys practiced by households in complement to the prevailing intensive zero-grazing livestock systems.
Nevertheless, in absence of non-wetland related income strategies, combined factors on the growing food demands by urban centres (Lynch, 1999) and the potential of income generation of wetlands (Olindo, 1992) are expected to increase market orientation of wetland related production activities. This may result in increasing land use intensity of narrow valleys through several seasons of market-oriented high-value crops production. Such land use intensification contributes to livelihood diversification, hence to the food security of the young and middle age families in expansion.
In conclusion, the twelve farm types identified in the smallholder wetland-agriculture system in eastern Africa differed in endowment and access to key production (livestock, land, and labour), financial resources, access to market, and the potential to diversify. This typology of farm(er)s distinguished households that differed in wetland field: farm size ratio, hence in their dependence on wetland area for cropping land. All these factors have influence on wetland agricultural use, whereas some specific factors determine changes in land use. Moreover, the derived farm types were linked to the wetland environment (through wetland cluster groups), relating the land user to the prevailing land use factors (use type and use intensity) and biophysical characteristics of the wetland. Such associations revealed the interactions between decision-making units and their environment, which can be used to analyse and explore changes and dynamics in land use.