SLU news

Plenty of bugs in ponds of Southern Sweden

Published: 03 November 2011

In 2010, the Swedish Board of Agriculture inventoried the biodiversity of insects in 20 ponds in the landscapes Skåne and Halland. The survey showed that the ponds contained different types of species, depending on whether they were situated in organic or conventionally farmed land.

A diversity of insects in the ponds on arable land is important for bird life and shows that the environment and the water quality are good.

- We found that the ponds on organically farmed land had more fine-grained sediment than ponds on conventionally farmed land, which instead contained more stones and boulders. This affects the species found in ponds, says Elisabeth Lundqvist on Calluna AB that conducted the survey.

No difference in diversity
Even if the ponds were found to contain different species, there was no difference in the number of species or the total number of individuals of each species. Two of the surveyed ponds had particularly high conservation values. One of them was situated on organically farmed land and the other on conventionally farmed land.

The ponds on organically farmed land had slightly lower pH, while the contents of nutrients were higher in waters at conventionally farmed land, which indicates that these are more affected by fertilization.

The ponds are affected by acidification
In several ponds the species were affected by acidification. During high runoff from agricultural land, for example when snow melts, the ground around the wetlands can not keep up buffering the acidic water.

- If you can reduce the runoff rate of arable land, the problem of acidification of small waters would decrease, says Ann-Marie Dock Gustavsson at the Board of Agriculture.