Ecological focus areas need a minimal ecological quality to be effective.
Ecological focus areas (EFAs) can be useful options in agri-environment schemes to support farmland birds and farmland biodiversity in general. But to reach this aim, it is important that a minimal ecological quality is achieved and EFAs and/or semi-natural habitats are present on about 15% of the landscape.
The European-wide decline in the populations and diversity of farmland birds has not been stopped despite dedicated conservation efforts such as agri-environment schemes (AES). The main reason for the lack of success is considered to be low ecological quality and insufficient area of the Ecological Focus Areas (EFA), one option of AESs in many countries. Understanding the effects of different management strategies on the ecological quality of EFAs is therefore important. Recently, we published an article in IBIS which highlights the relationship between breeding bird density, species richness and the age of wildflower areas, a widely used type of EFA in Switzerland (Zollinger et al. 2013). But the age and size are only two of several factors influencing biodiversity on EFAs. A team of conservation scientists at the Swiss Ornithological Institute is searching for answers to the question how farmland birds and biodiversity in general could be supported. Findings from the non-EU-member state Switzerland could be interesting for the EU too, where a debate on ‘greening- or ‘green-washing- of EU Common Agricultural Policy Reform is running (Ieronymidou 2013)
In Switzerland, since 15 years, EFAs are mandatory for farmers to get any subsidies (cross compliance). The mean proportion of EFAs on the utilised agricultural area in the Swiss lowland is 9.5%. Nevertheless, no substantial improvement of population sizes of typical farmland species is seen on a national scale. Meanwhile we know that it is not the presence of EFAs that crucial for biodiversity but the proportion of EFAs possessing a minimal ecological quality.
Ecological quality is often described by the presence of certain indicator species. In Switzerland, EFA-meadows (which are not fertilised and not cut before a certain date in the year) are said to possess quality, if at least six plant species out of an extensive (specific?) list are present. In some cases, species richness alone is not a good indicator for desired quality. E.g. for birds, the accessibility of food is an important factor. Many farmland bird species forage on the ground. For these species, low or sparse vegetation plays a key role (Schaub et al. 2010). Studies showed that Common Redstart cannot exploit food in dense sward. Territories occupied by Redstarts contained a significantly higher proportion of surfaces with sparse vegetation than unoccupied control sites (Martinez et al. 2010). The same is true for species like Hoopoe, Wryneck, Woodlark and others (Schaub et al. 2008). Wild flower areas and herbaceous strips, both options in Swiss agri-environmental scheme, are not mown every year and support up to 8 times more small mammals than ordinary fields and grassland (Aschwanden et al. 2005). But Kestrels and Long-eared Owls are not capable of catching mammals in old wildflower areas or herbaceous strips, probably because of tall vegetation. However, both species preferred to hunt on freshly mown grassland and meadows bordering a wildflower area or herbaceous strip. Voles from these strips probably invaded the adjacent freshly mown grassland and became an easy prey for kestrels and owls (Aschwanden et al. 2005). The vegetation of wildflower areas is very heterogeneous – dense vegetation stands next to small patches of bare ground. This heterogeneity might be the reason for high bird densities in wildflower areas (Zollinger et al. 2013). The proportion of dense vegetation and bare ground is changing over time due to succession of vegetation. Therefore, it is not astonishing that wildflower areas show an optimal age which is about 4-6 years, depending on bird species.
Obviously, a single ecological focus area is not enough to support farmland bird populations. The question is how much EFA is necessary to reach the target. Based on statistical models, we conclude that about 14% of high-value habitat (focus areas with high ecological quality and/or semi-natural habitat) is necessary in Swiss arable regions to increase populations of typical bird species to considerable densities (Meichtry-Stier et al. subm.). In several case studies we have managed to improve landscapes with high-quality EFAs. In these cases bird populations have increased (Birrer et al. 2007, Meichtry-Stier et al. subm.).
The next question is how to get such high proportions of EFA in the landscape. The key is in the hands of the farmers who play a decisive role in the realisation of EFAs. We have repeatedly shown that farmers who got a whole-farm advisory service providing solutions for ecological and economic aspects, increase their biodiversity performance. In one project all 24 involved farmers agreed to increase the proportion of high-quality EFAs on their farms. On average, high-quality EFAs increased from 3.3% to 8.7% in three years. Together with the already existing semi-natural habitats the target of 14 % was achieved (Chevillat et al. 2012).
Within the same project, a tool was developed that is used to score various options promoting biodiversity. An evaluation of this so-called Credit Point System on 133 farms shows that the resulting point score is an adequate and objective proxy for the biodiversity performance of farms (Birrer et al. in prep.). In Switzerland, there is a strong demand for ecological and environmental-friendly produced label products. The Swiss organisation for integrated farming (IP-Suisse) focuses on the promotion of biodiversity and demands a certain ecological performance from all its producers, which is measured with the above-mentioned Credit Point System. Thus, biodiversity is an added value that can be turned into financial benefit for producers by higher prices (Jenny et al. 2013).
References
Aschwanden, J., S. Birrer & L. Jenni 2005. Are ecological compensation areas attractive hunting sites for common kestrels Falco tinnunuculus and long-eared owls Asio otus? Journal für Ornithologie 146: 279-286. DOI: 10.1007/s10336-005-0090-9.
Aschwanden, J., O. Holzgang & L. Jenni.2007. Importance of ecological compensation for small mammals in intensively farmed areas. Wildl. Biol. 13: 150-158. DOI: 10.2981/0909-6396(2007)13[150:IOECAF]2.0.CO;2.
Birrer, S., M. Spiess, F. Herzog, L. Kohli & B. Lugrin.2007. The Swiss agri-environment scheme promotes farmland birds: but only moderately. Journal for Ornithology 148. (Suppl. 2): 295-303. DOI: 10.1007/s10336-007-0237-y.
Birrer, S., P. Mosimann-Kampe, M. Nuber, S. Strebel & N. Zbinden. 2013. ├ûkologischer Ausgleich und Brutvögel- das Beispiel Grosses Moos 1997- 2009. Ornithol. Beob. 110: 475-494. www.vogelwarte.ch/publications-en
Chevillat, V., O. Balmer, S. Birrer, V. Doppler, R. Graf, M. Jenny, L. Pfiffner, C. Rudmann & J. Zellweger-Fischer. 2012. Whole-farm advisory increases quality and quantity of ecological compensation areas. Agrarforschung Schweiz 3: 104-111 (German or French with English summary). www.vogelwarte.ch/publications-en
Graf, R., H. Bolzern-Tönz & L. Pfiffner.2010. Target Species for Agricultural Areas – Development of concept and selection methods using the example of Switzerland. Naturschutz und Landschaftsplanung 42: 5-12. (German with English summary). www.vogelwarte.ch/publications-en
Ieronymidou, C. 2013. EU Common Agricultural Policy Reform. The BOU Blog.
Jenny, M., J. Zellweger-Fischer, O. Balmer, S. Birrer & L. Pfiffner. 2013. The credit point system: an innovative approach to enhance biodiversity on farmland. Aspects of Applied Biology 118: 23-30. www.vogelwarte.ch/publications-en
Martinez, N., L. Jenni, E. Wyss & N. Zbinden.2010. Habitat structure versus food abundance: the importance of sparse vegetation for the common redstart Phoenicurus phoenicurus. J. Ornithol. 151: 297-307. DOI: 10.1007/s10336-009-0455-6.
Schaub, M., N. Martinez, A. Tagmann-Ioset, N. Weisshaupt, M. L. Maurer, T. S. Reichlin, F. Abadi, N. Zbinden, L. Jenni & R. Arlettaz.2010. Patches of bare ground as a staple commodity for declining ground-foraging insectivorous farmland birds. PLoS ONE 5: e13115. DOI: 10.1371/journal.pone.0013115.
Schaub, M., N. Zbinden, N. Martinez, M. Maurer, A. Ioset, R. Spaar, N. Weisshaupt & R. Arlettaz.2008. Vögel brauchen lückige Vegetation zur Nahrungssuche. Faktenblatt. Schweizerische Vogelwarte, Sempach. www.vogelwarte.ch/publications-en
Zollinger, J.-L., S. Birrer, N. Zbinden & F. Korner-Nievergelt. 2013. The optimal age of sown field margins for breeding farmland birds. Ibis 155: 779-791. DOI: 10.1111/ibi.12072.
Photo: Eurasian Skylark © Markus Jenny
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