Researchers conducted one of the largest analyses of long-term land-use change to date, comparing modern land use with 6733 historical maps over 1940s-60s Sweden, covering 175 000 km2 , an area larger than England and Wales.
 

Open land cover such as grasslands decreased in the majority of landscapes in southern Sweden (yellow to red pixels) while they were more likely to increase more agricultural regions (blue pixels).
 

“The most striking trend is that landscapes have become more homogeneous, with a lower variation in the types of habitat found within an individual landscape”, says Alistair Auffret, researcher at the Swedish University of Agricultural Sciences, one of the researchers behind the study.

Pasture at Labro Ängar, Nyköping. Photo: Alistair Auffret.


More than two thirds (67%) of all of the landscapes that made up the study region homogenised in this way, driven by an 11% increase in forest cover. These increases in forest were largely at the expense of historically open land including species rich ancient grasslands, with 94% of the historically most open landscapes becoming less varied.

In order to link the landscape change that has occurred at the regional scale to its effects on biodiversity at the local scale, the researchers used a governmental database of grassland plant species in more than 46 000 pastures and meadows. The number of these specialist species found in each grassland was strongly coupled to the size and quality of the grassland.

Pasqueflower is a specialist grassland wildflower that is threatened by widespread grazing abandonment. Photo: Jan Plue.


“Because we can see from the historical maps that a lot of grassland has been lost or degraded, we can be quite confident that many populations of these wildflowers have disappeared too”, adds Alistair Auffret.

However, the number of species is not only related to the grassland itself, but also on the surrounding landscape. Here the team found that in many cases the landscape of the 1940s-60s explained the number of grassland species better than today’s landscape. This slow reaction time means that some wildflowers that are still present today may be condemned to disappear in the future, but at the same time that there may still be time to prevent these losses, given appropriate conservation management.

“It is very important that we protect and continue to manage the species-rich grassland that we have left”, says Emelie Waldén from Stockholm University, another of the study’s authors. “Following that, we also believe that a lot of grassland that has been abandoned to become forest can and should be restored. In that way, we can both increase the total cover of grassland and help to reverse the homogenisation of land use that we have seen at the landscape scale”.

The study is published in the open-access scientific journal Nature Communications.

Links

Artikeln i Nature Communications: https://doi.org/10.1038/s41467-018-05991-y

Framtagning av historiska kartorna: https://doi.org/10.1111/2041-210X.12788

Historisk kartdata: https://doi.org/10.17045/sthlmuni.4649854 (GIS-program krävs för att öppna filerna, till exempel QGIS http://www.qgis.org)

Contact

Alistair Auffret, Sveriges lantbruksuniversitet alistair.auffret@slu.se 0767158975

Jan Plue, Stockholm University jan.plue@natgeo.su.se 0721602423

Emelie Waldén, Stockholm University emelie.walden@natgeo.su.se