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Tropentag, September 14 - 16, 2022, Prague

"Can agroecological farming feed the world? Farmers' and academia's views."


Carbon sequestration in aboveground biomass within a diversity gradient of different cocoa agroforestry systems

Johannes Milz1, Hans-Peter Weikhard1, Jonas Steinfeld1, Wiebke Niether2, Ulf Schneidewind3, Laura Armengot4

1Wageningen University and Research, The Netherlands
2Justus-Liebig-University Giessen, Organic Farming with Focus on Sustainable Soil Use, Germany
3Ecotop, Bolivia
4Research Inst. of Organic Agriculture (FiBL), International Cooperation, Switzerland


Abstract


Quantifying biomass and carbon sequestration rates is essential for carbon offsetting programs with cocoa agroforestry systems. However, biomass stocks and (biomass) carbon sequestration rates vary within agroforestry systems and depend on several factors, such as stand age, species density and diversity.
Currently, there are few scientific studies on carbon sequestration rates within a diversity gradient of agroforestry systems, particularly with respect to its effects on carbon sequestration rates. Furthermore, carbon offsetting programs tend to underestimate carbon stocks and sequestration rates in agroforestry systems and only consider some specific carbon pools. To contrast quantifiable /certifiable carbon pools in offsetting programs against actual carbon pools, two independent assessments are conducted.
Hence, the aim of this study is to quantify the long-term carbon sequestration and storage in aboveground biomass within a diversity gradient of different agroforestry systems The study will be conducted in the long-term trial (SysCom - FiBL) and will compare 3 different 13-year-old cocoa agroforestry systems with four repetitions each, allocated to a randomised complete block design. Inventory data from 2011 and 2015 along with current data from 2022 will be used to create a biomass growth function.
Aboveground biomass of timber and fruit trees, cacao trees (Theobroma Cacao L.), palms, and bananas (Musa) is calculated using allometric equations. Herbaceous biomass, litter and deadwood are determined destructively. The farming systems under investigation are comprised by systems under organic (AFS ORG) and conventional (AFS CONV) management as well as a highly diversified successional agroforestry system (SAFS) without external input use. In all systems, cacao tree density is 625 ha-1(4×4m), timber and fruit trees 78 ha-1 (16×8m), leguminous trees 156 ha-1 (8×8 m) and palm trees at much lower spacings. Furthermore, Coffea arabica L. were planted in all systems. The density of banana plants was 625 stems ha-1 (4×4m).
Note: Since this is an ongoing investigation first results will be available in August 2022.


Keywords: Agroforestry, cacao, carbon sequestration


Contact Address: Johannes Milz, Wageningen University and Research, Plevierenweide 38, 6708BW Wageningen, The Netherlands, e-mail: johannes.milz@wur.nl


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