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- Wretenberg, Johan, et al.
(författare)
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Linking agricultural policies to population trends of Swedish farmland birds in different agricultural regions
- 2007
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Ingår i: Journal of Applied Ecology. - : Wiley. - 1365-2664 .- 0021-8901. ; 44:5, s. 933-941
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Tidskriftsartikel (refereegranskat)abstract
- 1. The widespread declines of farmland birds have generally been linked to agricultural intensification. We tested the hypotheses that (i) changes in agricultural policy, through its effects on agricultural intensification and (ii) regional differences in agricultural intensification affect temporal and spatial population trends of farmland birds in Sweden. 2. We analysed regional bird population trends (1976–2003) for seven common farmland bird species: the migratory lapwing Vanellus vanellus, skylark Alauda arvensis, starling Sturnus vulgaris and linnet Carduelis cannabina and the resident tree sparrow Passer montanus, house sparrow P. domesticus and yellowhammer Emberiza citrinella. We identified three periods of agricultural policy in Sweden between 1976 and 2003: the intensification period (i.e. 1976–87; promoting increased production), the set-aside period (1987–95; promoting extensification of farming) and the Common Agricultural Policy (CAP) period (1995–2003; promoting increased production). Population trends were compared between three types of Swedish farmlands: open plains (intensive farming with a marked intensification), mosaic farmlands (i.e. farmland-dominated forest mosaics, less intensive farming, but show moderate intensification) and forest regions (i.e. forest-dominated farmlands with low intensity farming and extensification/abandonment). 3. The four migrants displayed clear significant trend switches between the policy periods, with declines in the ‘intensification period’ and the ‘CAP period’ and less negative or even positive population trends in the ‘set-aside period’. The population trends of the three resident species showed no clear pattern in relation to agricultural policy periods. 4. All species except tree sparrow displayed significantly different population trends between farmland regions. Four species (lapwing, skylark, linnet and house sparrow) declined most in the open plains and the forest regions, whereas two species (starling and yellowhammer) declined most in the mosaic farmlands. 5. Synthesis and applications. Large-scale changes in agriculture policy have a strong potential to change the present poor state of farmland biodiversity as shown by the generally positive population trends in the ‘set-aside period’. It also suggests extensification to be beneficial to farmland birds. However, in regions of low profitability and an already ongoing extensification, a further extensification will lead to loss of both farmland habitat and bird diversity. In such regions mixed farming needs to be retained and hence should be supported.
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| 2. |
- Wretenberg, J, et al.
(författare)
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Population trends of farmland birds in Sweden and England: similar trends but different patterns of agricultural intensification
- 2006
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Ingår i: Journal of Applied Ecology. - : Wiley. - 1365-2664 .- 0021-8901. ; 43:6, s. 1110-1120
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Tidskriftsartikel (refereegranskat)abstract
- Studies, mainly from the UK, show that many farmland birds have declined as a result of recent agricultural intensification. We tested this idea by analysing farmland bird population trends in Sweden, a country displaying less dramatic agricultural changes and less intensive agriculture. Specifically we investigated whether (i) farmland specialists have declined more than generalists, (ii) population declines in Sweden are less marked than in England and (iii) Swedish population trends are associated with changes in the amount of autumn-sown crops, and inputs of pesticides and fertilizers. Data on population trends for 21 farmland bird species collected from the Swedish Breeding Bird Survey 1976-2001 were analysed in relation to agricultural changes in Sweden. Fifteen (71%) farmland bird species declined significantly in number (P < 0.05) over the 26 years. Farmland specialists displayed a significantly stronger average decline (55%) as a group than farmland generalists (7%). For seven species the declines were significantly steeper between 1976 and 1988 than between 1988 and 2001. Farmland bird populations have declined at least as much in Sweden as in England. Several specialist species displayed similar temporal patterns in population change in both countries. The area of autumn-sown crops has remained stable in Sweden, whereas use of pesticides and fertilizers has declined. There are no clear associations between these factors and observed farmland bird population declines. The similarities in bird population trends in Sweden and England, despite large differences in patterns of agricultural change in Sweden and England, may be explained by: (i) common wintering grounds, (ii) similar negative effects of agricultural intensification (England) and intensification/abandonment (Sweden) and (iii) a simultaneous loss of landscape heterogeneity. Synthesis and applications. Farmland birds in Sweden have declined by at least as much as in England, despite clear differences between the two countries in the degree of agricultural intensification over the last 30 years. We suggest that the marked declines in Swedish populations are caused by (i) the dual negative effects of intensification and abandonment of farmland at breeding grounds, and (ii) Swedish populations partly sharing wintering grounds with English populations. We conclude that agri-environmental schemes need to be flexible enough to address the negative effects both of intensification and the abandonment of farming. In addition, our results emphasize that farmland bird conservation is an issue without country borders.
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