Reclassification of Ghana’s Agro-Ecological Zones

Abstract

Agro-ecological zones (AEZs) are essential for guiding agricultural planning and economic investments. In Ghana, climate change and evolving land use patterns have significantly altered key agro-climatic parameters such as mean annual rainfall (MAR), length of growing period (LGP), and land use and land cover (LULC) characteristics. This study analyzed long-term agro-climatic datasets (1991–2020) and LULC maps (2001, 2010, 2019, and 2021) using standardization, trend analysis, correlation, ANOVA, and Geographic Information System (GIS) tools. Key findings revealed significant reductions in LGP thresholds (P < 0.05) across most zones except the Sudan Savanna AEZ. MAR trends varied, with notable decreases in the Tropical Humid, Deciduous Forest, and Transitional AEZs, while the Coastal Savanna AEZ experienced a slight increase. Intra-zonal variations deviated from old FAO AEZs, as shown by anomalies at stations like Saltpond, Yendi, and Sewhi Bekwai. LULC analysis showed substantial forest (-22%) and agricultural land (-27%) losses, alongside increases in built-up areas (+31%), barren land (+27%), and rangeland (+7%). A GIS-based Multi-Criteria Analytical Hierarchy Process (AHP) reclassified AEZs into six zones (A–F), revealing significant spatial shifts. Notable changes included the southward expansion of the SSAEZ into the Guinea Savanna AEZ, a southwest shift in THAEZ and DFAEZ, and cross-migrations in CSAEZ and GSAEZ boundaries. These findings highlight the challenges posed by AEZ changes to crop suitability, land productivity, and agro-economic investments in Ghana’s agrarian economy. Regular decadal AEZ revisions using GIS and remote sensing are recommended to support sustainable agricultural planning and resource management.