Over the last two decades the global number of transboundary protected areas complexes (TBPA) has gradually increased from 59 transborder areas (combined from 70 protected areas) as identified by IUCN in late 1980-es, to 169 (involving 666 individual protected areas) in 2001, and to 188 internationally adjoining protected areas (with at least 818 individual sites) by 2005.

The latest (April 2007) global inventory of transboundary protected areas and other sites, not necessarily ajusent but linked by various transboundary conservation initiatives has been implemented by the UNEP World Conservation Monitoring Centre (UNEP-WCMC). Inventory was based on reviewing the content (digital maps) of the World Database on Protected Areas (WDPA) and identified 227 TBPA complexes incorporating 3,043 individual protected areas or internationally designated sites.

The 2007 TBPA List incorporated both TBPAs that fit entirely into IUCN definition (confirmed international cooperative or sympathetic management through legal or other effective means) and internationally adjoining protected area (IAPA, following the Mittermeier et all., 2005) that may still require development of collaborative efforts or further formalizing of ongoing cooperation.

Considerable increase in the number of PA included into TBPA complexes was related both to much improved and expanded content of the WDPA, to accounting of overlapping sites, e.g. national and international or small in size protected sites (e.g. nature monuments often located within a larger PA) and other assumptions of the methodology applied.

Methodology of 2007 UNEP-WCMC's global inventory of TBPA.

To qualify for inclusion in this TBPA 2007 list the protected area (PA) had to:

• conform to the IUCN definition of a protected area (IUCN, 1994) and be designated either under national legislation or within international or regional conventions or initiatives (e.g. World Heritage Convention, UNESCO Programme on Man and the Biosphere, etc.);
• be included in the World Database on Protected Areas as a georeferenced entity - either polygon outlining PA boundary or point indicating the centroid (latitude/longitude) of the PA. and
  • be adjacent to an international boundary and adjacent to a protected area in a neighboring country (1st-order transboundary neighborhood) or
  • be directly adjacent to (or overlap partially and/or entirely with) 1st-order transboundary sites (these sites constitute 2nd-order component of IAPA complexes) identified above or
  • be contained by 2nd-order sites (these sites are also considered as a 2nd-order component of IAPA complexes)

In addition to sites identified on the basis of these criteria through the GIS analysis, a number of non-adjacent couples or groups of sites are documented in Zbicz (2001) and Mittermeier et al. (2005). Cooperation between countries in managing these sites was evaluated on a case-by-case basis and relevant sites have been included into the list.

Estimation of the total area extent of a particular transboundary complex was made on the basis of the GIS analysis, which avoided double-counting of territories assigned by two or more designations, e.g. by national legislation and under international convention. Therefore the total size of a particular internationally adjoining protected area is often smaller than the sum of territories of individual sites combining transboundary complex. For TBPA/IAPA complexes represented by a single site (or by non-overlapping sites) on each side of the international boundary only the official statistic on PA area was applied. Similarly, for TBPA/IAPA complexes lacking data on site boundaries (i.e. polygon data) official information on PA area was used wherever the GIS-based estimate of a total area for a group of sites exceeded the sum of officially documented area for individual PA's in this group. Relevant calculations and checking were applied separately for every IAPA part belonging to particular country. Total area of TBPA (that includes sites belonging to two or more neighboring countries) was calculated as a sum of relevant national parts of a particular TBPA.

Total Area of TBPA by Region (30.04.2007)