[Urbanstudy] Urbanisation costs 5 billion years of evolutionary history

Vinay Baindur yanivbin at gmail.com
Thu Apr 27 01:25:55 CDT 2017


Urbanisation costs 5 billion years of evolutionary historyApril 26, 2017
[image: Urbanisation costs 5 billion years of evolutionary history]
Adonis vernalis disappeared from Halle in the 19th century. This species
depends on nitrogen-poor soil. It is currently classified as endangered in
Germany. Credit: André Künzelmann / UFZ

All over the globe, the urbanisation of landscapes is increasing. 60% of
the land surface which is expected to be urban by 2030 is currently not
built on at all. How this will impact on biological diversity will only be
apparent in retrospect. However, for most cities there have been systematic
surveys of biological diversity, although only since the second half of the
20th century. Researchers at the Helmholtz Centre for Environmental
Research (UFZ) and the German Centre for Integrative Biodiversity Research
(iDiv) have now revealed, on the basis of historical data, how plant
diversity in the region of Halle an der Saale has changed in over 300 years
of urbanisation, and have also made predictions about the future.

The researchers drew on lists of species published by botanists since the
17th century as well as data from herbaria. In the 1680s, for example,
physician Christoph Knauth, who was interested in botany, recorded the
plant species that occurred in the area of the modern city of Halle. Rather
than limiting himself to plants of pharmaceutical interest, as was usual in
the 17th century, he produced an almost complete list of species. His work
Enumeratio Plantarum Circa Halam Saxonum Et In Eius Vicinia, Ad Trium Fere
Milliarium Spatium, Sponte Provenientium was published in 1687. In the
centuries that followed, during which the city's population increased more
than tenfold, more than 20 botanists recorded the flora of Halle.

Using this comprehensive data, the team led by UFZ geoecologist Dr. Sonja
Knapp were able to demonstrate that the number of plant species in Halle
has risen considerably between the end of the 17th century
<https://phys.org/tags/17th+century/> and the beginning of the 21st – from
711 to 860 species. At the same time, however, the evolutionary diversity
<https://phys.org/tags/diversity/> of plants has declined: native species
<https://phys.org/tags/native+species/> from a wide range of plant families
have died out regionally and been replaced by more closely related species.
These include both common native species and non-native species introduced
from other parts of the world. Overall, 4.7 billion years of evolutionary
history have therefore been lost in the Halle region, so great is the loss
of evolutionary diversity – calculated on the basis of plant pedigrees.
[image: Urbanisation costs 5 billion years of evolutionary history]
Fallopia japonica (Japanese knotweed), like the closely related Fallopia
baldschuanica, has been found in Halle since the end of the 20th century.
An introduced species in Germany, it grows well in warm, nitrogen-rich
locations. Credit: André Künzelmann / UFZ

As well as looking back over the past three centuries, the researchers
looked ahead to the future. The team calculated how the current
evolutionary diversity of Halle's flora would change if, firstly, the
plants found in Halle listed on the Red List of endangered species
disappeared and, secondly, the most common introduced species in Germany
which are not yet found in Halle were to migrate there. "Evolutionary
diversity will very probably continue to fall," says Dr. Marten Winter from
iDiv, who participated in the study.

The evolutionary diversity of plants is considered to be an important
foundation for the stability of ecosystems. It stimulates the diversity of
other organisms and can increase biomass production. How many millions of
years of evolutionary history
<https://phys.org/tags/evolutionary+history/> would
need to be lost to make an ecosystem unstable is however not yet known.
Researchers are therefore appealing for the precautionary protection
of biological
diversity <https://phys.org/tags/biological+diversity/>. As the loss
of evolutionary
diversity <https://phys.org/tags/evolutionary+diversity/> in Halle is
primarily being driven by the loss of native species – including many
species which depend on cool, nutrient-poor environments – Sonja Knapp and
her colleagues are calling for more protection for these species
<https://phys.org/tags/species/> and their habitats.

 *Explore further:* Plant species living in urban backyards are closer
related to each other and live shorter than species in the country sid

*More information:* Sonja Knapp et al. Increasing species richness but
decreasing phylogenetic richness and divergence over a 320-year period of
urbanization, *Journal of Applied Ecology* (2016). DOI:
10.1111/1365-2664.12826 <http://dx.doi.org/10.1111/1365-2664.12826>

Read more at: https://phys.org/news/2017-04-urbanisation-billion-
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