In the course of globalization, more and more plant and animal species settle outside their natural area of origin and dispersal. Some of them put native species under pressure within their natural habitats and thus endanger regional or local biodiversity. In this case, they are considered to be invasive. Existing legislation has regulated the handling of invasive species in the Federal Nature Conservation Act.

Particularly along rivers, some invasive species can spread rapidly and over long stretches. In case of construction or restoration measures being carried out, there is a big danger of spreading seeds or root parts of invasive species even more.

The LIFE project is testing concepts for dealing with invasive plant species in watercourses along the Perf and Kerkerbach catchment areas. After recording (mapping) the invasive plants, prioritized occurrences of selected species, such as the giant hogweed, goldenrod and asian knotweed, were combated over several years and the success of the measures documented by means of accompanying monitoring. Monitoring control sheets were used to record the time and effort required for each individual measure for each occurrence to be combated.  Another project approach was the investigation of measures to prevent entrainment during construction work on the watercourse.

In the period from 2016 to 2022, a total of 115 occurrences of various invasive plant species were combated and monitored. The experience gained and the data collected over this period have provided important insights into the effort, costs and prospects of success in combating invasive plants. 64 % of all controlled populations had been eradicated by the last monitoring, with only small residual populations remaining in a further 10 %. In 25 % of the occurrences, the measures were less successful.

Further data evaluations are currently being carried out with the aim of formulating species-specific recommendations for action with cost estimates. These results, as well as all other empirical values, e.g. on public relations work, the involvement of local authorities and other stakeholders or experiences/problems with contracted companies, are being summarized and processed.

The aim is to produce a guideline on reducing the long-distance spread of invasive species in watercourse systems. This should be transferable to other regions as a general recommendation for action and be available to nature conservation authorities, local authorities, planning offices and all interested parties. The completion is planned for the end of 2024.