The relationships between farmland birds, land use and landscape structure in Northern Europe
Date
2013-11-11
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Abstract
Põllulindude ja põllumajanduse seosed on tänini väga aktuaalsed, kuna suleliste arv on Euroopas dramaatiliselt vähenenud. Näiteks on viimase 30 aastaga Euroopas välja surnud 300 miljonit põllulindu. Teema tähtsusest tingituna käsitles doktoritöö lindude seoseid põllumajandusmaastiku elementide ja põllukultuuridega. Pikaaegsed tehtud uuringud aastatest 2002–2011 hõlmasid nii Eestit, teisi Balti riike, Soomet kui ka Venemaad. Tulemused näitasid, et põllumajandusmaastiku struktuur omab väga olulist tähtsust linnurohkuse seisukohalt: mida rikkalikum on maastikumuster (põllukultuuride rohkus ja maastikuelementide rikkus), seda rohkem on seal ka linde.
Doktoritöös keskenduti maastikuelementidest peamiselt kuivenduskraavidele ja nende servadele, sest need on olulised pesitsus- ja varjekohad ning toitumispaigad. Kahe tavalise põllulinnu, põldlõokese ja sookiuru arvukus kasvas märgatavalt kuivenduskraavidega põldudel. Drenaažkuivendusega põldudel oli nende liikide arvukus seevastu stabiilne. Seega osutuvad inimloodud maastikuelemendid põllumajandusmaastikus olulisteks elupaikadeks ning neid elemente ei tohiks kindlasti maastikest drenaakuivenduse käigus eemaldada. Selle uurimistöö tulemused näitavad selgelt, et drenaažkuivendust tuleks kombineerida kraavkuivendusega.
Põllukultuuride analüüs viitas omakorda, et kõige kõrgemad lindude liigirikkuse ja rohkuse näitajad leiti kasutusest väljajäänud (söötis) põldudel, karjamaadel ja mitmeliigilistel rohumaadel. Oluliselt madalamad liigirikkuse ja mitmekesisuse näitajad ilmnesid juurvilja- ning teraviljapõldudel. Huvitavaks tulemuseks oli see, et nii liigirikkus, isendite rohkus kui ka mitmete liikide arvukuse muutus sõltus nii põllutüübist (karjamaa, söötis maa, teraviljapõld) kui ka pesitsusajast. Seega on põllukultuuride mitmekesisus ääretult oluline, kuna linnud kasutavad pesitsustsükli jooksul erinevate põllukultuuridega põlde.
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.
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.
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Keywords
linnud, arvukus, liigirikkus, põllumaa, birds, abundance, species richness, agricultural land