engleski

The impact of invasive species Amorpha fruticosa on the structure of bird communities in agricultural areas in the “Lonjsko polje” Nature Park

Decrease the number of cattle on pastures in the interaction with other environmental disturbances, act as a trigger to accelerate the invasion of certain plant species. One of these, invasive, species is Amorpha fruticosa L.. Field research of how A. fruticosa (ragweed) influence community structure of birds within the Nature Park, were conducted at five levels of ragweed density. The study attempts to answer the question: how the importance of open habitats is changed(grasslands and agricultural areas) for the conservation of birds in areas under this plant species invasion, and to what extent the spread of invasive species impacted bird species of special importance to the protection at the European level (SPEC species). The fieldwork was conducted during 2010 and in 2011 year. We recorded 102 species of birds that use researched habitats as nesting, feeding and/or resting place during migration. The strongest effect of Amorpha is detected on species that uses habitats of interest as nesting grounds such as Alauda arvensis, Motacilla flava, Vanellus vanellus, Saxicola rubetra, Sylvia atricapilla and Sylvia communis where the first three species were most commonly recorded in most open areas (categories 0 and 1) with a slightly difference between very wet and very dry years, as were the 2010 and 2011. Expanding of Amorpha on pastures almost certainly will have a positive impact on the number of species of the genera Locustella/Acrocephalus but a negative effect on species Alauda arvensis, Motacilla flava and Vanellus vanellus. Results of the analysis of overall conservation value of researched habitats revealed its decrease with the increase of Amorpha density. It is necessary to continue research to supplement information on conservation value of habitats on other bird species for which the method counting in point is not the optimal research methods.

invasion; biodiversity; birds; landscape; habitat

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