Quantifying Human Appropriated Net Primary Productivity (HANPP) in a Ghanaian Cocoa System

Alexandra Morel, Stephen Adu-Bredu, Michael Adu Sasu, Rebecca Ashley Asare, Emily Boyd, Mark Hirons, Yadvinder Malhi, J. Mason, Ken Norris, Elizabeth J.Z. Robinson, Constance L. McDermott

    Research output: Contribution to conferenceAbstractpeer-review


    Ghana is the second largest producer of cocoa (Theobroma cacoa), exporting approximately 18 percent of global volumes. These cocoa farms are predominantly small-scale, ranging in size from 2-4 hectares (ha). Traditionally, the model of cocoa expansion in Ghana relied on clearing new areas of forest and establishing a farm under remnant forest trees. This is increasingly less practical due to few unprotected forest areas remaining and management practices favoring close to full sun cocoa to maximize short-term yields. This study is part of a larger project, ECOLMITS, which is an interdisciplinary, ESPA-funded[1] initiative exploring the ecological limits of ecosystem system services (ESS) for alleviating poverty in small-scale agroforestry systems. The ecological study plots are situated within and around the Kakum National Forest, a well-protected, moist-evergreen forest of the Lower Guinea Forest region. Net primary productivity (NPP) is a measure of the rate at which carbon dioxide (CO2) is incorporated into plant tissues (e.g. canopy, stem and root). For this study, NPP was monitored in situ using methods developed by the Global Environmental Monitoring Network (GEM, http://gem.tropicalforests.ox.ac.uk/). By comparing NPP measured in intact forest and farms, the human appropriated NPP (HANPP) of this system can be estimated. The forest measures provide the "potential" NPP of the region, and then the reduction in NPP for farm plots is calculated for both land-cover change (HANPPLUC) and cocoa harvesting (HANPPHARV). The results presented are of the first year of NPP measurements across the cocoa landscape, including measurements from intact forest, logged forest and cocoa farms across a shade gradient and located at varying distances from the forest edge (e.g. 100 m, 500 m, 1 km and 5 km). These measures will have implications for carbon sequestration potential over the region and long-term sustainability of the Ghanaian cocoa sector.

    Original languageEnglish
    Publication statusPublished - Dec 2015
    EventAmerican Geophysical Union, Fall Meeting 2015 - San Francisco, United States
    Duration: 14 Dec 201518 Dec 2015


    ConferenceAmerican Geophysical Union, Fall Meeting 2015
    Country/TerritoryUnited States
    CitySan Francisco
    Internet address


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