Nature conservation areas no haven for butterflies

March 17, 2016, Technical University Munich
“The observations carried out over a period of 200 years confirm the general trend of a decline in habitat specialist species despite the fact that these species are the target of nature conservation measures,” explains Dr. Jan Christian Habel. Credit: TUM/ J. Habel

What do the brimstone, meadow brown and small heath butterfly species have in common? All of them are rather habitat specialists, with no specific ecological demands, they tend to have modest requirements when it comes to habitats and larval host plants. They are also more resistant to nitrogen pollution than sensitive habitat specialists, which are going extinct - even in nature conservation areas.

A collaborative research study carried out by the Technical University Munich (TUM) and Bavarian State Collection of Zoology (ZSM) confirms the loss of past decades and the modest effectiveness of nature and species conservation.

The study is based on one of the longest observation series ever carried out. Species lists and butterfly collections from 1840 until today were evaluated. All of the data were provided by lepidopterologists, i.e. butterfly researchers, from areas around the city of Regensburg in Bavaria. The southern slopes along the Danube there mainly consist of rare oligotrophic grasslands and, accordingly, oligotrophic biotopes for butterflies and other insects. Around 45 hectares of land there have been designated as a conservation area since 1992.

The institutes involved in the study included beside TUM and ZSM also the Senckenberg German Entomological Institute, and Nicolaus Copernicus University Torun, Poland. The results of the collaborative study were published in the American journal Conservation Biology.

Habitat specialists most vulnerable

"The observations carried out over a period of 200 years confirm the general trend of a decline in habitat specialist species despite the fact that these species are the target of nature conservation measures," explains Dr. Jan Christian Habel from TUM's Terrestrial Ecology Research Group. For example whereas 117 butterfly species and diurnal moths were recorded between 1840 and 1849, only 71 species were recorded between 2010 and 2013.

Moreover, the composition of the butterfly species also changed. While the region was populated by a diverse butterfly community during the past, it is now dominated by a few habitat generalists. Many habitat specialists, which require certain larval host plants and habitat structures to survive, have disappeared.

Overfertilization ousts larval host plants

According to the study, high emissions of reactive nitrogen is one of the reasons of this species decline. Reactive nitrogen is generated, for example, by the combustion of the fossil fuels wood and peat, industrial incineration processes, the cultivation of legumes, and the increasingly intensive agriculture of recent decades. Nitrogen alters the nutrient composition of plants by the airborne route and overfertilizes the very sensitive type of vegetation found in this region.

But the flora and fauna there are adapted to a low-nutrient environment. The high nitrogen supply promotes the growth of plants like the dandelion, thistles, and sorrel, which oust the typical flora and, hence also, larval host plants. "These changes in the environment have a very serious impact on the habitat specialists," says the biogeographer from TUM.

Nature conservation areas largely ineffective

"Most conservation areas are very small and isolated and sparsely distributed in the landscape," says Habel - "Moreover, atmospheric nitrogen does not respect the boundaries of the protected areas."

According to the study, despite climate warming, thermophilic species, which like warm and dry conditions, are also in decline. This may seem surprising to non-experts." The vegetation is growing faster due to the nitrogen inputs. This creates more shade close to the ground, which is too much shade for heat-loving butterflies," explains Habel. Because the observations used for the study were recorded using very different methods by the scientists involved, they could only be used as records of the presence and disappearance of the recorded species. It was not possible to calculate species abundances and population densities and development in relation to abundance.

"The question that emerges here is whether the established network of fauna-flora habitat will enable us to achieve effective in the long term," adds Dr. Habel. "The answer is clearly no."

Explore further: Butterflies illustrate the effects of environmental change

More information: Jan Christian Habel, Andreas Segerer , Werner Ulrich, Olena Torchyk, Wolfgang W. Weisser und Thomas Schmitt: Butterfly community shifts over 2 centuries, Conservation Biology 2016. DOI: 10.1111/cobi.12656

Related Stories

Butterflies illustrate the effects of environmental change

July 24, 2014

Changes in butterfly fauna are yielding surprising insights into our changing environment. The effects of nitrogen from fertilizer or precipitation on the food plants and microclimate of caterpillars have a significant impact ...

How to save Europe's most threatened butterflies

March 28, 2012

New guidelines on how to save some of Europe's most threatened butterfly species have been published by a team of scientists co-ordinated by Butterfly Conservation Europe. The report covers 29 threatened species listed on ...

Recommended for you

Can people learn to embrace risk?

March 18, 2019

Studies have shown women are more risk-averse than men, more likely to opt for the smaller sure thing than gamble on an all-or-nothing proposition, a trait experts say could help to explain the persistent wage gap between ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.