R data script: From acacia to eucalypt: productivity and fertility implications of plantations species shift in Indonesia

The plantation forestry sector in Indonesia has seen a change in species from Acacia mangium to Eucalyptus pellita. This change, forced by diseases spreads, has affected more than 90% of the plantation area in Indonesia and it is unprecedented in its scale in the history of plantation forestry (Nambiar et al., 2018). It is also a change of tree species with very different eco-physiological patterns: Acacias – in contrast to eucalypts - are leguminous trees and therefore self-sufficient in nitrogen supply and capable of building significant stocks of nitrogen and carbon in the soil, two main determinants of plantation productivity. The large-scale species shift therefore raises questions about the sustainability of the pulp and paper sector in Indonesia in the coming decades as well as the role of past land use and site quality in Indonesia’s forest restoration pledge. The proposed contribution therefore aims at analyzing the sustainability in terms of productivity of the Indonesian plantation forestry sector under the new eucalypts regime. To that end, we will deploy the BioGeoChemistry Management Model (BGCMAN; Pietsch, 2014) which is capable of representing the carbon, water and nitrogen cycles in great detail. Expected results will include a reconstruction of the rise and fall of A. mangium and shift to E. pellita as well as forecasts of plantation productivity and soil fertility over the next decades; it will notably answer the question for how long soil N-stock accumulated by acacias will be able to feed eucalypts.