Seeing beyond the smoke: smallholder farming in Papua New Guinea in a changing world

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 ...