Clear-cutting and land drainage are harmful for stream invertebrate biodiversity

As pointed out earlier in our BIOWATER pages, there is a lack of systematic data on the impacts of forestry on water resources. We are therefore proud to present the work of PhD student Maria Rajakallio (University of Oulu, Finland) and her co-authors: They recently published new data on how forestry and drainage may impact aquatic ecology in a paper titled “Blue consequences of the green bioeconomy: clear‐cutting intensifies the harmful impacts of land drainage on stream invertebrate biodiversity.” (See definition on stream invertebrates at the end of this news item).

Rajakallio and co-authors noted that the growing bioeconomy is increasing the pressure to clear-cut drained peatland forests. They therefore studied effects of peatland drainage and clear-cutting on stream macroinvertebrate communities.

They found that peatland drainage reduced benthic biodiversity in both small and large streams, whereas clear-cutting did the same only in small streams. Small headwater streams were more sensitive to forestry impacts than the larger, downstream sites.

As demonstrated in this study, it is beneficial for the aquatic ecology that the natural vegetation is intact along streams. Photo: Maria Rajakallio.

The authors point out that drained peatland forests in boreal areas are reaching maturity and will soon be harvested. Clear-cutting of these forests incurs multiple environmental hazards, but previous studies have focused on terrestrial ecosystems.

The results of Rajakallio et al. show that the combined impacts of peatland drainage and clear-cutting may extend across ecosystem boundaries and cause significant biodiversity loss in freshwater ecosystems. This information strongly suggests that continuous-cover forestry based on partial harvest will provide the most sustainable approach to peatland forestry.

Rajakallio, M., Jyväsjärvi, J., Muotka, T. and Aroviita, J. (2021), Blue consequences of the green bioeconomy: clear‐cutting intensifies the harmful impacts of land drainage on stream invertebrate biodiversity. Journal of Applied Ecology, 00: 1– 10. https://doi.org/10.1111/1365-2664.13889

Stream invertebrates are small animals such as insects, mites, crayfish, and worms. They are important as food for fish, reptiles, amphibians, and birds, and they help clean the stream waters of dead or decaying bacteria, plants, and animals. Invertebrates are used as indicators of stream water quality since they are affected by physical, chemical and/or biological conditions in the stream, and are therefore much used in monitoring related to the EU Water Framework Directive. As oposed to grab water samples, they can show the cumulative effect of different pressures over time.

Example of an invertebrate: A caddisfly larva, belonging to Hydropsychidae family. Photo: Maria Rajakallio.    

Feature photo: Maria Rajakallio.