Forest Landscape Restoration (FLR) is seen as central to achieving global ecosystem restoration ambitions and to reverse ecological impacts of land degradation and enhance human wellbeing (Mansourian & Vallauri, 2014). FLR is meant to restore multi-functional landscapes for multiple benefits to different stakeholders. In theory, this ambition aligns well with the Bonn challenge and other targets that are used as a roadmap for global restoration progress, within and beyond the UN Decade on Ecosystem Restoration.
Tree centred nature-based solutions may include the management of crop production landscapes for multi-functionality and resilience to environmental shocks (Rockström et al., 2017), for example through agro-ecology or agroforestry. Millions of people in tropical rural landscapes rely on agroforestry farming and recognise the values of trees and native tree species (Nyong et al., 2020). Trees on and around farms regulate ecosystem processes relevant for crops, including water regulation and prevention of soil erosion (Hurni et al., 2015), microclimate buffering, and maintenance of populations of pollinator and natural pest control species. Yet, trees can also act as a source for human–wildlife conflicts including crop damage through wildlife acting as pests (König et al., 2020). Trees may negatively impact yields, yet evidence is limited for humid areas and overall inconclusive with yield changes due to competition with trees depending on tree species, tree maturity and crop type (Ndoli et al., 2017)
Using FLR to improve outcomes for ecological and human wellbeing in landscapes used for agriculture is a challenge that requires careful consideration of trade-offs and synergies that emerge when the natural and social components of the system interact. And practitioners agree that the choice of trees for planting on and around farms has to be considered carefully. Importantly, there is limited understanding of the ecological network impacts of tree restoration and how these may play out to affect services and disservices provided by wildlife to wellbeing or local communities. In other words: If we restore trees in the landscape, does this alter movements of wildlife at higher trophic levels, and if so, does it alter the distribution of risks in crop damage or of potential for pollination and natural pest control.
In this PhD, the candidate will focus on the interconnections between birds, crops and habitats (configuration, management and quality) in forest-agricultural systems in East Africa. They will study the role of birds in shaping crop yield outcomes through their impacts on crops (acting as pests), insect and other pests (acting as natural pest controls), focussing on key food and cash crops grown by rural communities for food and livelihood securities. The candidate will implement fieldwork in a case study landscape in Tanzania to acquire in depth, mechanistic understanding on: (i) habitat dependencies of birds in relationship to trees and farms (configuration of trees and crops, quality and type of trees and crops) using observational data and spatially explicit modelling, and (ii) interactions with crops using experiments.
The key objectives include:
• Objective 1: Analyse tree cover dependency, interactions with different crop types and distribution of focal bird species in forest-agricultural landscapes in East Africa.
• Objective 2: Model the movements of focal bird species through the forest-agricultural landscape in the north of the Kilombero Valley (Agrisys Tanzania case study landscape) as function of landscape configuration, crop type and tree species
• Objective 3: Analyse trade-offs and synergies resulting from forest conservation and tree restoration with regards to carbon stocks in trees, bird biodiversity, and bird regulated services and disservices to crops.
• Objective 4: Work with local communities to understand perceptions of ‘good’ versus ‘bad’ bird species and how tree restoration may need to be implemented and managed to avoid negative outcomes for human wellbeing.