Old grassland with lichen-covered granite boulders in Mols Bjerge. Stop of grazing is one of the major problems for our open and bright landscape – heaths, commons, meadows, costal slopes, etc. Photo: Henriette Bjerregaard.

The loss of biodiversity has not stopped in any of the nine Danish ecosystems. This is the conclusion in a new report from The National Environmental Institute (NERI) at Aarhus University, based on the examination of a large variety of species, habitats and processes.

2011.02.10

Biodiversity, i.e. biological variety, is enormous. In Denmark alone we are believed to have more than 30,000 different species. A large group of scientist from NERI and from The Natural History Museum in Aarhus has therefore taken up a tremendous challenge by dividing the Danish landscape into nine ecosystems. Here they have chosen a total of 139 elements of biodiversity: 65 species and groups of species (a total of more than 600 species), 43 habitats and 31 processes.

The result of the efforts of this large group of scientists has now been published in the report (in Danish) ”Danmarks biodiversitet 2010 – status, udvikling og trusler” ("Denmark's biodiversity 2010 – present state, development and threats").

Historic low

The report shows that biodiversity continues to decline in all ecosystems. Out of the 139 elements included in the research, 47 % are declining, 25 % are stable or progressing and for the remaining 28 % the scientists know too little to be able to form an estimate of the development. So more than twice as many elements are declining than elements being stable or progressing.

But why is the situation this serious? Senior scientist and project manager Rasmus Ejrnæs explains:

"We can see that even if the best landscape is protected by laws and regulations, there is no protection against stop of grazing or atmospheric nitrogen deposition. This leads to overgrowing of meadow, grassland and costal habitats, and eventually to the loss of stress-tolerant plants, butterflies, bumblebees and beetles. Another major problem is that our landscape is under pressure. We have seen that the protection of meadows, heaths, mires and grasslands is weak; we can see that the small biotopes in the arable land disappear or are reduced, and we can see that towns and roads keep spreading at the expense of natural habitats."

The report also shows that once species have been lost, they will not automatically return if the habitat is restored. The fact is that - contrary to the white-tailed eagle - many species are dispersal limited so they will only return very slowly. In addition to that, the destruction of habitats has been so comprehensive that a small increase in habitat availability will not be enough to stop the decrease in species. In addition to this delay in recovery time, we also experience a damage delay, i.e. species that disappear in response to historical habitat losses. The scientists demonstrate in the report that several threatened habitats in forests increase whereas the corresponding species continue to decrease.

In the light of the large, historical decrease in species and habitats, the scientists find no ecosystems without continued loss of biodiversity. Rasmus Ejrnæs:

”The characteristic feature is that the occasional progress we have detected is found in areas that had reached a historic low. This is for instance the case of our large lakes which have typically been seriously loaded by nutrients during the previous century and are now slowly recovering. And it is the case in our forests where we have never before found so little dead wood, old deciduous trees, forest glades and wetlands as today."

Summary of the estimate of the development for all 139 examined elements. The elements are divided into species (or species groups), habitats and processes, and into the nine examined ecosystems. The first column corresponds to a decrease in the biodiversity, the middle column corresponds to stability or increase and the last column corresponds to an unknown development.

Action wanted

The report shows that there is a need for evidence-based actions to stop the loss of biodiversity. The comprehensive scientific documentation of the report provides a solid professional basis for future strategies and action plans in the field of biodiversity.

In his preface to the report, Director General Henrik Sandbech writes:

”The Minister for the Environment has announced a national strategy for biodiversity to follow up on the international agreement made in Japan. This UN agreement has given us ten years more; but in the light of the prevailing political agenda for economic growth, we cannot permit ourselves to lean back. Biodiversity will continue its decline if we do not act now. The effort must be applied, evidence-based and long-term. This will not be the case until the day when nature and biodiversity are part of the government basis - on equal terms with other important goals for our welfare society".

About the report

Nature's diversity is on the decline all over the world. Species become extinct at unnaturally great speed because man monopolizes more and more of the natural resources of our planet. The concern for the loss of biodiversity has led to the biodiversity convention of 1992 and to EU's 2010 aim to stop the loss of biodiversity. The target was missed and the world society therefore set up new targets at the UN Biodiversity Conference in Japan, and the year 2020 was set as deadline for a stop to the biodiversity decline.

The so-called 2010 target to stop the loss of biodiversity is one of the most important goals for the Danish environmental policy. In the spring of 2010, NERI decided to start a science-based evaluation of the 2010 goal, and the result of this evaluation is the 148-page report.

The report was presented at the first Danish biodiversity symposium on 20 and 21 January in Aarhus.

The symposium assembled more than 250 Danish scientists, administrators and decision-makers in the field of nature management and biological conservation. The purpose of the symposium was to create a Danish forum where people meet to discuss new knowledge and topical problems related to biodiversity and nature management in Denmark.

Main results:

Forests

• Habitat of the highest number of threatened and vulnerable species.
• Major decline in the number of beetles in dead wood, butterflies in woodland meadows and glades, epiphytic lichens.
• Habitats connected to more natural forests increasing.

Coasts

• Denmark's most important contribution to international biodiversity.
• Seven out of nine species groups are declining.
• Seals flourish, and the nitrogen deposition is falling.

Grasslands, heaths, meadows and bogs

• The area covered by grassland, heath and bog as well as poor and grazed meadows continues to decline.
• Greatest decline of chafers, ground beetles, butterflies and wax capsin grasslands and heaths and for spiders in bogs.
• Increase of heather; the nitrogen loading in bogs and meadows has been stabilized.

Lakes and streams

• The loss of biodiversity in large lakes has been stopped, but continues in other lakes and streams.
• Greatest decline for amphibians in small lakes; decline of pondweed, fish and thick-shelled freshwater mussels in streams.

Sea

• The less known ecosystem.
• Decline for fish, birds and benthic invertebrates.

Arable land, roads and towns

• Cover three quarters of the terrestrial environment.
• Most intensively exploited areas.
• Urban areas provide new habitats for heat-demanding species like lizards.

Basis of knowledge

• Only 40 % of all evaluations are based on empirical data. 60 % are based on expert judgments. For 28 % of all elements the development is unknown.
• The inadequate data available reflects the fact that society still lacks knowledge about the present state and development of the Danish biodiversity.

Contact: Senior Scientist Rasmus Ejrnæs, tel. +45 8920 1515, rej@dmu.dk

Danmarks biodiversitet 2010 – status, udvikling og trusler. Ejrnæs, R. et al. Report from NERI no. 815, 2011 DKK 150,-. | Sammenfatning | Hele rapporten in PDF-format (5,6 MB). The report can be ordered via Aarhus Universitetsforlag.

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