Ancient fruit trees, grape vines, traditional crop and garden cultivars have been inventoried in Pollino National Park by adopting a spatial sampling grid which covers 23 different municipalities (~1500 Km²) and 190 surveyed sites. Each site is a circle with a visible radius of 200 - 250 m. The spatial analysis of the diversity of plant genetic resources has been conducted with pre-fixed landscape units (size: 4 Km × 4 Km). Overall, 49 different woody long cycle (455 ancient cultivars) and 53 short cycle species (102 ancient cultivars) have been scored. Long cycle species exhibit higher cultivar richness than short cycle species. The analysis has recognized that pre-Columbian indigenous cultivars had not been displaced by the American species introduced after the 16^th century. In addition, it is confirmed that small-scale poly-production, under conditions of spatial niche variation, is associated to high species and cultivar richness. The mapped realized niche, for both pre- and post-Columbian genetic resources, includes the actual genetic reserve suitable for in situ conservation of plant agro-biodiversity. Agro-biodiversity models, drivers of genetic erosion, and realistic responses to genetic erosion are outlined.