The annual "International Seminar of Ecology - 2021" was held online on 29-30th September and provided a platform for students, early-stage and experienced scientists to present their research in the fields of:

• Biodiversity and conservation biology
• The biotic and abiotic impact on the living nature, ecological risk and bioremediation
• Landscape ecology, ecosystem research and services
• Ecological agriculture and
• Ecological education.

A total of seven plenary lectures, 28 oral and 31 posters presentations were presented by scientists working in Bulgaria, Egypt, Portugal, Russia, Germany, the Czech Republic, Lithuania, Romania, Slovenia, Spain and the U.S.A. Manuscripts of the materials, presented at the Seminar and recommended by the reviewers will be published in this special issue of BioRisk.

The "International Seminar of Ecology - 2021" was organized by the Union of Scientists of Bulgaria, Section "Biology" and by the Institute of Biodiversity and Ecosystem Research of the Bulgarian Academy of Science, with the financial support of Ltd Pensoft and BULGAP Ltd.