SecSel, a new software tool for conservation prioritization that is applicable to ordinal-scale data for multiple biodiversity features

feature i is Ni, the target is achieved when the local units of this feature in the selected sites sat- isfy the top-Ni included criterion. It should be noted that collection of local units of low value is not a substitute for a highly prioritized local unit. Targets may or may not be the same among features. A target can be assigned to each feature independently. Optional input data. In addition to the above-mentioned compulsory input data, SecSel can consider pre-reserved sites, conflicts among features, cost of conservation, and compact- ness of conservation area in the site-selection process. Pre-reserved sites. Sites that should be included in the protected area can be specified as pre-reserved sites. When the current protected area is to be expanded, sites included in the present protected area are specified as pre-reserved sites. SecSel decides which sites should be added to these pre-reserved sites. Conflicts among features. As described above, conflicting features are those that cannot be conserved/used simultaneously in a site. To consider conflicts and avoid incompatibilities, data about conflicting pairs of features should be provided. SecSel decides which feature has higher priority and which has lower priority at each site where there is a conflict among local units of two or more features. Section Resolution of conflicts describes the algorithm of the decision. Site cost data. Secsel can consider the cost of including individual sites in the protected area. For example, the cost can be the amount of money paid to obtain the land and/or to per-

form conservation management in the site. Given cost data for individual sites, SecSel tries to find a set of sites with the lower cost. Like the data of the conservation/utilization values of local units of features, the cost data are on an ordinal scale with no specified degree of resolu- tion. The cost data are used to determine which of the candidate sites of similar conservation efficiency should be selected. Subsection Cost considerations explains the details of the cost consideration process. The cost of a site may depend on which feature is to be conserved/used in the site. SecSel does not handle such multiple cost criteria. If a special cost should be paid for a feature, the evaluation of the local units of the feature may be decided on the basis of the cost of conserva- tion/utilization of the feature within each site. Shared boundary data. The length of the boundary shared by two sites can be used to select the set of sites that is less scattered. Like cost data, the length of the boundary is used to determine which of the candidate sites of similar conservation efficiency should be selected. There is no guarantee that the selected set of sites has the smallest perimeter. Outline of site-selection processes Basic process of site selection. In the first step of the selection process, sites are selected to satisfy the top-1 included criterion for all features. Once that criterion is satisfied, sites are added to fulfill the top-2 included criterion for all features for which the target is 2 or larger.

This process is continued by incrementing the number of top local units to be included. The process is terminated when the targets are fulfilled for all features of interest. For each step of selecting a site to add, a greedy algorithm is employed. For each unselected site, the number of features that would fulfill the top-N included criterion (N being incremen- ted during the selection procedure) is calculated. The site with the maximum number of fea- tures that newly fulfill the top-N included criterion is the site to be added to the sites that have already been selected. If there are ties, one site is selected randomly. Cost considerations. When cost is to be considered, it is used to break ties between sites in the number of features that newly fulfill the top-N included criterion. To place more emphasis on reducing cost in the selection process, candidate sites may include sites that PLOS ONE SecSel, a new software tool for conservation prioritization applicable to ordinal-scale data PLOS ONE | https://doi.org/10.1371/journal.pone.0247737 July 23, 2021 6 / 19