Estimating aboveground net biomass change for tropical and subtropical forests: Refinement of IPCC default rates using forest plot data

Requena Suarez, D and Rozendaal, DMA and De Sy, V and Phillips, OL and Alvarez-Dávila, E and Anderson-Teixeira, K and Araujo-Murakami, A and Arroyo, L and Baker, TR and Bongers, F and Brienen, RJW and Carter, S and Cook-Patton, SC and Feldpausch, TR and Griscom, BW and Harris, N and Hérault, B and Honorio Coronado, EN and Leavitt, SM and Lewis, SL and Marimon, BS and Monteagudo Mendoza, A and Kassi N'dja, J and N'Guessan, AE and Poorter, L and Qie, L and Rutishauser, E and Sist, P and Sonké, B and Sullivan, MJP and Vilanova, E and Wang, MMH and Martius, C and Herold, M (2019) Estimating aboveground net biomass change for tropical and subtropical forests: Refinement of IPCC default rates using forest plot data. Global Change Biology. ISSN 1354-1013

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Abstract

© 2019 The Authors. Global Change Biology Published by John Wiley & Sons Ltd As countries advance in greenhouse gas (GHG) accounting for climate change mitigation, consistent estimates of aboveground net biomass change (∆AGB) are needed. Countries with limited forest monitoring capabilities in the tropics and subtropics rely on IPCC 2006 default ∆AGB rates, which are values per ecological zone, per continent. Similarly, research into forest biomass change at a large scale also makes use of these rates. IPCC 2006 default rates come from a handful of studies, provide no uncertainty indications and do not distinguish between older secondary forests and old-growth forests. As part of the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, we incorporate ∆AGB data available from 2006 onwards, comprising 176 chronosequences in secondary forests and 536 permanent plots in old-growth and managed/logged forests located in 42 countries in Africa, North and South America and Asia. We generated ∆AGB rate estimates for younger secondary forests (≤20 years), older secondary forests (>20 years and up to 100 years) and old-growth forests, and accounted for uncertainties in our estimates. In tropical rainforests, for which data availability was the highest, our ∆AGB rate estimates ranged from 3.4 (Asia) to 7.6 (Africa) Mg ha−1 year−1 in younger secondary forests, from 2.3 (North and South America) to 3.5 (Africa) Mg ha−1 year−1 in older secondary forests, and 0.7 (Asia) to 1.3 (Africa) Mg ha−1 year−1 in old-growth forests. We provide a rigorous and traceable refinement of the IPCC 2006 default rates in tropical and subtropical ecological zones, and identify which areas require more research on ∆AGB. In this respect, this study should be considered as an important step towards quantifying the role of tropical and subtropical forests as carbon sinks with higher accuracy; our new rates can be used for large-scale GHG accounting by governmental bodies, nongovernmental organizations and in scientific research.