Environmental measures can support agriculture biodiversity and wild bee populations. However, new research has revealed that the effectiveness of such strategies depends on various factors.
The research team found that when assessing the effectiveness of measures such as organic or conventional farming, biodiversity benefits should be evaluated differently. The results show that it could be misleading to make across the board comparisons of different conservation efforts.
For the investigation, ten agricultural landscapes were studied. The landscapes contained three winter wheat fields, one organic field, one conventional field with flower strips, and one conventional field without flower strips. The abundance of wild bees was recorded for two years at each site.
After comparing the data, the experts concluded that conventional fields with strips of flowers might attract many more bees than organic fields. However, this does not capture the full story.
“When we looked more closely, this did not give us a complete picture because it did not take into account that flower strips only cover about five percent of conventional fields which has significantly fewer bees overall than the organic farmland,” explained Professor Teja Tscharntke, Department of Agroecology at Göttingen University.
“In short, organic farming, which typically has more wild plants than conventional fields, is actually more successful than conventional fields with flower strips in promoting bees,” added Dr. Péter Batáry of the Centre for Organic Research.
Fields of grain in organic farming yield only half the harvest of conventional farming. When the loss in wheat yield is taken into account, a ten-hectare area of organic farmland should be compared to five hectares of conventional farmland plus five hectares of flower strips. This would lead to 3.5 times more bees but the same yield. Therefore, organic farming would not be the best way to support wild bees.
This research demonstrates the importance of using different benchmarks and criteria when evaluating agri-environmental measures.
“It is only when we take into account the area along with the yield together with the type of farming that we can achieve a balanced understanding of the ecological and economic effectiveness of environmental measures,” said the study authors.
The research was conducted by agroecologists from the University of Göttingen, Germany and the Centre for Ecological Research in Vácrátót, Hungary.