The Nature Conservancy (TNC) has a vested interest in helping countries develop science-based Protected area networks and has pledged support through the development of country-driven National Implementation Support Programs (NISPs).

One way to help overcome the technical challenges of the daunting process of evaluating and filling protected area gaps is the development and use of GIS-based user-friendly tools that support the protected area gap process. The development of a Protected Area Gap Decision Support System (DSS) was conceived as part of an ongoing process to help fill the technical void that exists in many countries. Version 1.0 of these tools was completed in September 2006 and works in ArcGIS 9.1. The new version 2.0 was completed in January 2008, renamed to the Protected Area Tools (PAT) and is now compatible with ArcGIS 10. This version includes many new features requested from our users.

It is hoped that PAT will continue to evolve and provide utility for evaluating land purchase/acquisition for achieving maximum return on investment in terms of overall contribution to a country's conservation goals. In addition to questions that may be asked about the best remaining core habitat or covering a comprehensive representation of biodiversity, the ultimate question conservation planners want answered is "Where do I get the best ecological return for my conservation dollar?" This question has driven the design of a systematic, logical, and repeatable toolkit that helps planners evaluate activities or events that may be threatening habitat health, identify a comprehensive representation of biodiversity for protection, and configure an optimal portfolio solution for meeting habitat conservation goals. PAT consists of three conservation modules which operate within Environmental Systems Research Institute's (ESRI) ArcGIS Geographic Information System (GIS) software:


The majority of the work that goes into a protected area gap assessment involves the spatial delineation and critical evaluation of habitats/species, protected areas, and risks to focal habitats. The Protected Area Tools are ready to be used only after users have obtained the highest quality data available, conducted an ecological inventory and assessment of these data layers through expert review, and carefully considered all model scenario settings. Three modules presented in this tutorial will guide users through the process of

    • Developing a customized Environmental Risk Surface (ERS) based on mapped risk elements (i.e. socio-economic activities) that have been identified through expert review as having negative impacts on the health of targeted habitats, species or ecological systems;
    • Calculating a landscape?s Relative Biodiversity Index (RBI), which measures relative rareness or uniqueness, measured in terms of biodiversity feature abundance in comparison to the overall study area. Individual scores for each biodiversity occurrence can be used as a stand alone assessment for each planning unit or subsets of units (e.g. hexagons, watersheds);
    • Creating input files and viewing model results for Marxan, powerful software which provides users an easy way to manipulate input parameters and test/review various conservation scenarios in order to achieve an optimal configuration of protected areas that meet user defined conservation goals.