Restoration of riparian habitats on sugarcane plantations for bird diversity, bird – regulated ecosystem services and climate change mitigation and adaptation in rural tropical landscapes, Tanzania
The growth of the agricultural sector in the rural tropics, is seen as crucial to improve food security and reduce poverty of millions of rural households (1-2). In Sub-Saharan Africa, agricultural growth corridors have seen rapid, coordinated investments in transport infrastructure, e.g. the Tanzania Agricultural Growth Corridor SAGCOT linking Malawi, Zambia, Democratic Republic of Congo, and Tanzania (3). How to implement this growth without risking large scale negative ecological and social impacts remains contested (6). The agricultural growth poses a pervasive threat to natural capital (here: forests, water, soil) and ecosystem restoration that aims to reverse biodiversity loss (4) and enhance climate change mitigation and adaptation of local communities (5). Riparian zones, i.e. natural non-converted habitat, actively restored natural habitat, or unmanaged areas, are an important conservation tool used to maintain biodiversity and ecosystem functions in tropical agricultural landscapes (7). Riparian zones benefit hydrology, water quality, biodiversity. However, large uncertainties remain on their effects on habitat connectivity for wildlife, crop pollination and pest control and carbon storage and emissions reduction and how their functions are mediated by width and quality (composition, structure) of the restored riparian habitat (8). Scientific evidence used to inform policies on riparian zones is dominated by ecological values at the expense of ecological disvalues (e.g. impacts on abundance of pests and crop yields), cultural values and socio-economic needs. The evidence base is particularly poor for agricultural landscapes in Sub-Saharan Africa.
With this research, we now want to urgently close the knowledge gaps. The focus of this PhD project is on the Kilombero Valley in Tanzania as a case study, from which upscaling to wider regions may be possible. The aim is to work with our partner, Illovo Sugar, to integrate across ecological and socio-economic evidence to inform the restoration and management of riparian zones on land used for sugarcane production, including small-holder and industry farmed land. The industry plantation fully supports our work with access to plantation land and facilities.
The three main objectives are: (O1) to identify variables that allow stakeholders, in particular industry, to determine what to restore in riparian zones (vegetation composition, water health) to maximise benefits to carbon storage, water quality and bird diversity/pest control functions. (O2) to evaluate where to restore to maximise benefits whilst minimising trade-offs against disservices such as less land and increased pest pressure (zonation, matching based on biophysical and socio-economic parameters) and (O3) establish best practice guiding how to restore (practicalities, co-design).
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