Ecology and Development Series No. 10, 2003 - ZEF

Conservation of the wild Coffea arabica populations in situ(Malckzewski 1999). Linear scale transformation is the most frequently used method oftransforming input data into criterion maps of a common numeric range.In this study, all the criteria map layers were transformed by a linear scaletransformation method to index values ranging between 0 and 1 (Jiang and Eastman 2000).The two most often used linear transformation methods are maximum score and range scoreprocedures (Malckzewski 1999). The range score procedure of transformation is given by theformula:'xijxx jx jxmin−ij= Equation 6.1max min−jThis formula was used to transform the coffee and diversity index criteria attributevalues to criterion scores, where X´ij is the standardized score for the i th object (alternative)and the j th attribute, X ij is the raw score, X max j is the maximum score for the j th attribute, andX min j is the minimum score for the j th attribute. The elevation criterion attribute values weretransformed by the formula:'xijxx jx jxmin−ij= 1−Equation 6.2max min−jin order to give more weight to sites at lower altitude. Hence, a point at lowest elevationreceives the highest criterion score, 1, and a point at highest elevation receives 0.ConstraintsThe constraint map is a qualitative criterion and defines the social suitability of the reserve. Itdetermines the areas that are used by the local people, which can then be excluded from theprotected reserve zones. If, for example, a forest area is used by the local people as a semiforestor plantation coffee production system, it is no longer available for a reserve core zoneand has to be excluded. The index of the constraint criterion map layer is Boolean (Jiang andEastman 2000); i.e., the values are either 1 for suitable or 0 for unsuitable areas. Theconstraint map is based on a map demarcating the undisturbed forest from the forestsmanaged for coffee production and agriculture, provided by Yayu District Department ofAgriculture (unpublished map) and the topographic map of the area obtained from the105