Distribution of Arabica coffee areas (ha) and yields (t ha−1) calculated from the coffee database for 2005 for the ten agro-ecological zones of Rwanda.

aThis area is calculated as the area for each sector in the AEZ; only the sector area in the AEZ is extracted by spatial-analysis tools. The 2005 Rwanda coffee database displays only the number of coffee trees and coffee production per sector. Each sector is an administrative entity divided into cells, which are the lowest administrative units within the Republic of Rwanda.bThis area is extracted from the area with scattered coffee trees in each AEZ and is calculated using the standard tree density of 2500 trees ha−1, i.e. b = a/2500.cThis yield is calculated by averaging the yields for each part of the sector in the AEZ (i.e. sector yield is calculated as the production of each sector divided by the number of trees using the standard spacing of 2× 2 m, or 2500 trees ha−1).dThis yield is calculated using SPSS descriptive statistics; the normality of the data was determined using the Kolmogorov-Smirnov test.Distribution of Arabica coffee areas (ha) and yields (t ha−1) calculated from the coffee database for 2005 for the ten agro-ecological zones of Rwanda.