Smallholder farming plays a crucial role in sustaining the food security and livelihoods of billions of people. Rapid social-ecological changes, including population growth, climate change and the incursion of external actors, are affecting smallholder farmers. In this thesis, I evaluate the changing social-ecological system of smallholder farming, and how interventions can support farmers to respond, using a case study in Papua New Guinea (PNG).
I focused my research on swidden cultivation (a type of smallholder farming). In PNG, the vast majority of the population depends on swidden agriculture, but current social-ecological changes are posing risks to farmers’ well-being and environmental sustainability. Land tenure is relatively secure in PNG, making it worthwhile for swidden farmers to invest in solutions that allow them to respond to these changes. PNG is thus a unique and highly relevant site to study swidden agriculture in a changing world.
I used an interdisciplinary research approach to address the aims of my thesis. I started by investigating which factors may limit crops yields in swidden fields. Insect pests and seedeaters often negatively affect crops. I quantified foliar herbivory and seed disturbance (ecosystem disservices) and pest predation (an ecosystem service) in swidden fields along an elevational gradient. I found that the level of pest-related ecosystem disservices was relatively low compared to global levels, with foliar herbivory averaging 0.99%, disturbance of large seeds averaging 3.9% and disturbance of small seeds averaging 68%. The level of the ecosystem service, on the other hand, was relatively high with pest predation averaging 6.4%. Rapid and ongoing social-ecological changes, including increasing land shortages and climate change, may change these favourable patterns. Current farming practices, including establishing gardens close to forests, burning fields at the start of the cropping season and planting a variety of crops, are likely to be enhancing pest-related ecosystem services and reducing disservices. These practices may therefore form the basis for designing future interventions for optimising biotic pest control in swidden agricultural systems.
Another major limiting factor in many agricultural systems is soil quality. I investigated whether locally available fertilisers could enhance soil quality and crop yields. I established ten experimental fields on the land of swidden farmers. Three locally available fertilisers, including compost consisting of decaying banana peels, chicken manure and NPK fertiliser, were applied to different plots within each field, and soil quality and sweet potato yields were tracked over a year. In my study site, fertilisers that increased the level of available nitrogen and reduced soil moisture enhanced crop yields. For example, chicken manure increased yields by 16% and NPK fertiliser by 47%. So improving soil quality through applying fertilisers may be one way in which farmers could navigate increasing land shortages as a result of growing populations.
When identifying agricultural practices that may allow swidden farmers to respond to social-ecological changes, it is crucial to understand which interventions are welcomed by farmers. I evaluated which soil management practices farmers adopted and how information on them disseminated through the village's social network by conducting interviews at the beginning and end of the research project. I found that practices that bore resemblance to existing practices, such as applying compost, were more likely to be adopted than practices that required additional information and materials, such as applying chicken manure and NPK fertiliser. I also showed that people created meaning from the research in unexpected ways; farmers started to mulch, and to plant the specific variety of sweet potato that was used in the experimental fields, even though I did not aim to test the effect of mulching or promote any crop variety. The project also had another unintentional effect in that it changed the community’s social network, with local research assistants becoming more sought-after for advice, and knowledge about the research project not flowing far from initial recipients. This shows that projects can have impacts beyond their original objectives. Enhancing our understanding of intended and unintended outcomes can improve our understanding of what interventions are useful to farmers, and how they might affect the social-ecological system of a swidden farming village.
Finally, there is a need to better understand what farmers themselves see as opportunities and challenges for their future. This is important because of the intrinsic importance of public participation, and because it can help produce more appropriate and sustainable adaptation plans. In collaboration with local farmers in PNG, I conducted a participatory photography project in which we explored local perspectives on resource management, drivers of change and adaptive strategies. Farmers highlighted that the main challenges they face included crop diseases of their cash crops, land shortages and lack of training. Farmers saw collaboration and education as key to their future as it would allow them to better manage their land and diversify their livelihoods. So there is a need to improve the wider context in which swidden farmers work, beyond increasing and intensifying yields. Research and planning processes that aim to support swidden farmers to respond to social-ecological changes should incorporate farmers’ priorities.
Overall, my work shows how social-ecological changes are influencing farmers in PNG, and what interventions can help people navigate these changes. The results provide evidence for how swidden farming can continue to be a viable and sustainable way of living, now and in the future
