engleski

The influence of land abandonment on farmland bird communities : a case study in the alluvial lowlands of Continental Croatia

The abandonment of less productive agricultural land on the one hand and intensification and concentration of parcels on the other are the main characteristics of the Common Agricultural Policy (CAP) that Croatia is going to enforce when entering the EU. Due to demographic changes and the economic transition in Croatia as a consequence of war activities in 1990es, abandonment of substantial parts of the agricultural lands occurred. We investigated two habitat types in a protected area (50, 650 ha) in the continental part of the country: arable land and pastures. Both habitat types were formed and maintained by the agricultural activities and suffered from partial abandonment of production and maintenance. Data on bird communities were obtained during the breeding season in 2010, by a standard point count method designed in the way to avoid autocorrelation in data. Data was collected at 63 point-count stations and a total of 1447 individuals from 70 species were recorded during the study. Habitat characteristics were gathered through geographic information system (GIS) on the basis of CORINE Land cover for the country from several layers like database of habitat types and derivates of digital elevation model. We found that bird community structure was primarily associated with presence/abandonment of agricultural land use (traditional low intensity management, i.e. grazing and crops, vs. abandonment of these types of management) and habitat type, and that structure of bird communities of the same habitat type differs due to different management intensity. Land abandonment mostly influenced specialist bird species tied to pastures with significantly higher abundance in grazed pastures than in abandoned ones. However, the conservation value (detected according SPEC value of the species) of pastures still was not significantly different due to suitability of overgrown pastures on extremely wet year as 2010 for Acrocephalus species. Changes in bird community structure in arable lands had different pattern from those in pastures showing more rapid changes in structures of the pastoral communities after abandonment that is the. Finally, we emphasise on the urgent need for a national wide monitoring program for farmland birds in the whole country.

landscape structure; invasion; management; biodiversity; depopulation

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