Supervisors: prof Ülo Mander, Dr. Irina Herzon (Helsingi Ülikool)
Opponent: prof Piotr Tryjanowski (Poznani Maaülikool, Poola)
Modern agriculture has had a tremendously negative influence on farmland biodiversity in Europe during the 20th century. For instance, 300 million farmland birds in Europe have been lost since 1980. This thesis examines the relationships between farmland birds and landscape structure and land use in Northern Europe. Long-term monitoring work from the years 2002-2011 included Estonia, the other Baltic countries, Finland and Russia. Results indicated that farmland landscape structure (landscape elements and land use) plays a very important role in farmland bird abundance. For instance, landscape structure is directly correlated with bird diversity. This thesis mostly concentrated on agricultural ditches and their edges as important habitats for nesting, hiding and feeding. The trends in the numbers of two common farmland bird species, Skylark and Meadow Pipit, were significantly positive on open drainage fields, while trends on subsurface drainage fields were stable. Thus man-made landscape elements such as ditches are important habitats on farmland and should be protected against subsurface drainage. Unfortunately, subsurface drainage is a real issue in Estonia, as it is in neighbouring countries. Land use analysis indicated that the highest values for bird species richness and abundance were on abandoned grasslands, on abandoned cereal fields, on pastures and on multispecies grasslands. Significantly lower values of bird species richness and abundance were found on root vegetables and arable fields. Interestingly, we found that overall species richness, abundance and species-specific abundance depends on field type (pasture, abandoned land, arable land) and also breeding season. Thus mixed land use is highly important, because birds change their utilisation of different field types during the breeding season.