No abstract

A definition of the «edge effect», considered as a case of synergism at the ecosystem level, is given. A quantitative method to study edge effects is proposed, with fitted sam¬ple designs. This «triple census technique» was tested during the pilot-study of a woodland-open field mosaic in Burgundy, whose results are summarized. A better knowledge of edge effect values on bird abundance and species richness is important when studying patchy habitats.