Butterfly populations in many countries are declining at alarming rates. In June it was revealed that grassland butterfly numbers in the UK have halved in the past 20 years and 2012 was declared the worst year on record for butterfly populations, when poor conditions led to observed declines in 52 of the 56 monitored species of butterfly.

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Many of the monitored populations of butterfly are closely associated with the agricultural landscape, and changes in farming practices and land use are therefore thought to have had serious consequences for butterfly health. A research team from Sweden and Germany have reviewed effects of land management on butterfly diversity using historical and current surveys during the last 100 years and released their findings this week.

The focus of their review was on butterfly population trends and extinction rates in southern Swedish agricultural landscapes. In some areas, half of the butterfly fauna has been lost over the past 60-100 years. As a valuable insect pollinator, the decline of the butterfly could have ramifications for farmers.

Marked changes in land use in Northern Europe, such as loss of hay meadows, has impacted severely on butterfly species, as the creatures now lack many of their key habitats. In the UK, the loss of species-rich meadowland has had the same effect.

In Sweden, grazed, mixed open woodlands have been transformed into dense forests and domestic grazers have been relocated from woodlands to arable fields and semi-natural grasslands, the researchers said. Hay and silage harvests now start much earlier in the season, which has reduced the time available for butterflies' larval development.

Alongside these changes, intensified land use has also markedly reduced the availability of nectar in the landscape. Adding to these problems, current agricultural subsidy systems favour intensive grazing on the remaining semi-natural grasslands, which has compounded the impacts of land use change on butterfly diversity, by drastically limiting the species of plants growing on grasslands.

Despite their worrying findings, the researchers revealed that relatively minor adjustments to land management could drastically counteract the declines. They recommended that, in order to mitigate risks of further species loss and to work towards recovery of threatened butterfly populations, farmers could receive incentives to graze later, introduce rotational grazing with parts of semi-natural grasslands grazed only in late summer in some years, and carefully choose their grazers.