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Inverkan på fåglar och fältvilt av putsning av ekologiska trädor och vallar

{Project} Inverkan på fåglar och fältvilt av putsning av ekologiska trädor och vallar. [Skylarks on set-aside land, a field investigation of nesting in Central Sweden and its relation to vegetation and topping strategy.] Runs 2003 - 2005. Project Leader(s): Kvarnbäck, Olle, The Rural Economy and Agricultural Societies .

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Projektet syftar till att genom fältstudier och fältförsök undersöka hur putsning av ekologiska trädor och vallar påverkar fågel- och viltbestånden. Målet är att hitta den tidpunkt, och putsningsteknik, som gör minst skada på faunan, men ändå ger ett gott resultat ur odlingssynpunkt. Resultatet ska användas för rådgivning och rekommendationer för trädesskötsel och naturvård/viltvård. Odlingslandskapets fågelfauna är stadd i kraftig minskning, inte minst många arter knutna till åkermark minskar. En viktig orsak befaras vara det moderna jordbrukets tidiga vallskörd samt putsning av trädor. I en pågående utredning av trädesreglerna förespråkar Naturvårdsverket ett förbud mot putsning av trädor före 1 juli. Detta kan eventuellt förbättra situationen för fåglar och fältvilt, men kommer i stark konflikt med eko-odlingens behov av att putsa gröngödslingsträdor för att hantera ogräs och få optimal gröngödslingseffekt.
Vi undersöker:
* Hur mycket fåglar och vilt som finns på ekologiska trädor?
* Hur trädan sköts i ekologisk odling. När putsas den, varför putsas den och på vilken höjd över marken?
* Vad händer med fåglar och vilt på trädor som putsas? Vid vilken tidpunkt är det "ofarligt" att putsa?
Målet är att:
* Hitta en optimal tidpunkt och teknik som gör minst skada på fåglar och vilt.
* Undersöka möjligheten att utveckla en prognosmetod som gör det enkelt för lantbrukaren att veta när det är lämpligt att putsa.

Summary translation

Discussions regarding environmental legislation for set-aside land have been underway for a long time in Sweden, but in conjunction with the introduction of statutory conditions for agricultural subsidies, an interpretation of the EU Bird Directive [EU Bird Directive (79/409/EEC)] is required. Statutory conditions mean that operational and maintenance requirements for the entire agricultural operations of a farm unit are coupled to payment of agricultural subsidies. One of the operational requirements is based on the Bird Directive, which specifies that it is forbidden to deliberately disturb birds, particularly during the periods of breeding and rearing. In addition, the deliberate destruction of, or damage to, their nests and eggs, is forbidden.
The area of set-aside land will presumably increase with the new application of CAP (Common Agricultural Policy). Set-aside encompasses a multitude of biotopes ranging from stubble set-aside to flowering clover-based green manure crops. Set-aside can thus fulfill a range of different functions for birds, insects and other animals.
The Swedish Environmental Protection Agency has proposed an interpretation of the Bird Directive such that a topping and tillage ban applies before 1 July on set-aside land and other land where the intention is to not remove the mown plant material. An investigation of how the population density and breeding success of skylarks Alauda arvensis is related to the vegetation present on set-aside land and the way in which the farmer manages the set-aside, was carried out in central Sweden in 2005. Spring cereals were also included in this study. The set-aside types investigated were stubble set-aside, long-term set-aside and organically grown set-aside/green manure leys. The green manure leys were also studied in 2004.
Skylarks comprised approx. 90% of the nesting birds on the set-aside. Other species claiming territory on open set-aside included meadow pipit, yellow wagtail and quail, while whinchats and grey partridge were present in boundary zones.
The territory density of skylarks on set-aside land was generally high to very high, approx. 0.8 breeding pairs/ha, but variation between fields was great. The position of the field in the landscape proved to be of greater significance for lark density than the type of vegetation growing/planted on the field. This means that set-aside surrounded by forest is completely devoid of nesting skylarks, while a cornfield can have a high density of skylark territories if it is located in open countryside without much forest or dense habitations.
The larks investigated had low breeding success and produced on average only 0.67 clutches of fully-fledged young (15 days old) per territory. According to our calculations, this is not sufficient to replace losses during winter. The low productivity is probably an important factor in the decline in skylarks, but more intensive studies are required to confirm this assumption. One reason for low breeding rate was that the vegetation on several of the fields with spring cereals and long-term set-aside became too dense in June to suit skylark behavior. Several of the green manure set-asides became also too dense but were topped in June, which reduced the density and in particular the height of the vegetation. However, stubble set-aside remained sparsely vegetated throughout the entire season and remained attractive to skylarks. On stubble set-aside, the main problem for the larks was early ploughing-in of the set-aside at the end of June or beginning of July. Another threat to skylarks on set-aside is repeated topping and soil tillage during their nesting season, which occurs within the period 1 May – 1 August in the area investigated in Mälardalen, Central Sweden. In an earlier experiment with artificial nests, topping destroyed half of the nests, while in addition predation increased after topping. The topping is a way to control weeds or stimulate the clover to fixate nitrogen. The early topping is important in organic farming especially in green manure set-asides, since organic farming is reliant on ‘growing its own’ nitrogen through green manure crops.
These investigations indicate that in order to increase the reproductive output of skylarks, they have to be offered a choice of fields in an open landscape with sparse and/or patchy vegetation, where the birds are able to seek and find food. It is also important to provide long continuous periods during the nesting season when the field and the vegetation are not topped or tilled.
Stubble set-aside = Arable field with stubble remaining from the previous year’s crop, often cereal. No undersown crop.
Long-term set-aside = Arable field under set-aside for several years and with established grass and herbage vegetation that has either been undersown or has established naturally.
Spring cereal = Arable field with spring-sown cereal. We endeavoured to carry out our inventory primarily in barley fields, but one wheat field was included in the investigation.
Eco set-aside/green manure = Organically grown green manure ley. The green manure ley is like a stubble set-aside but is undersown with a grass mix with a high proportion of clover. It is regarded as set-aside because it is not harvested but simply topped.

EPrint Type:Project description
Location:The Rural Economy and Agricultural Societies
HS Landsbygdskonsult AB
P.O. Box 412   
SE-751 06 Uppsala
Keywords:breeding success, vegetation density, Alauda arvensis
Subjects: Environmental aspects > Biodiversity and ecosystem services
Research affiliation: Sweden > The Rural Economy and Agricultural Societies
Research funders: Sweden > Swedish Board of Agriculture SJV
Start Date:1 January 2003
End Date:31 December 2005
Deposited By: Fredriksson, Pelle
ID Code:7723
Deposited On:20 Feb 2008
Last Modified:20 Aug 2009 14:31

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