Tropical landscapes in transition? : Widespread land-use change and measures to maintain forests, carbon stocks and biodiversity in North and East Kalimantan, Indonesia

The production of commodities such as palm oil and pulpwood is leading to large-scale land use change in the rural tropics to fulfil the demands of the increasing world population and overall living standard. On the one hand, such land use changes provide income to companies, smallholders and government actors. On the other hand, these can lead to land use conflicts and declines in forest cover, biodiversity, carbon stocks, and local food production. In this dissertation, firstly, we quantified and visualised land use change processes and trajectories that contributed to forest loss in the West Kutai and Mahakam Ulu districts between 1990 and 2009. These districts are part of a landscape that is under high land development pressure in East Kalimantan, Indonesian Borneo. Over the time period analysed, about one third of the study area changed and forest cover declined substantially with almost 10 %. The main contributors to forest loss included smallholder rubber, pulpwood plantations, mixed cropland and oil palm, the latter with a rapidly increasing land area. Secondly, we projected and visualised the impacts of four contrasting land use change scenarios with varying levels of land development and restrictions of land zoning on forest cover in these districts between 2009 and 2030. We found that with unlimited development of the aforementioned commodities, forest cover declines substantially stronger (~0.4-1.6 Mha, ~17-60%) than with limited development (~ 0.1 Mha, ~4%). Thirdly, we estimated the impacts of the four scenarios on plant biodiversity and carbon. We found that between 1990 and 2030, mean species richness declined much stronger (-22% to -52%) than AGB (-19% to -37%). Under all scenarios, the lowlands showed the highest risk of land use change. Fourth, we analysed whether and how the production of palm oil can be reconciled with the production of pulpwood, rice and rubber, while mitigating unwanted land use changes. We analysed the technical potential of four measures to mitigate unwanted land use change between 2008 and 2020 in North and East Kalimantan. We found that the expansion on under-utilised land is the most important measure (45-62% of total potential), followed by improvements in yields (32-46%), chain efficiencies and chain integration. Finally, we discussed the findings of the previous chapters in the context of the Forest Transition Theory. We estimate that our study region is only at the start of the forest transition curve, possibly in stage 2, given the high forest cover and high deforestation rates. We estimate that a stabilising forest cover in the study region is possible, but only with an integrated perspective on mitigating unwanted land use change that includes significant efforts in i) establishing a limit-to-growth on land development for the production of palm oil, rubber, pulpwood and coal; ii) responsible land use planning and zoning, by using underutilised lands and accounting for land tenure; iii) developing or strengthening incentives to maintain forests, such as Reducing Emissions from Deforestation and forest Degradation+; iv) implementing additional measures, such as yield improvements; v) supporting these measures by capacity building and enabling policies