Controlling invasive species: An experimental approach using bracken (Pteridium aquilinum (L.) Kuhn.

Invasive species are a major problem for conservation worldwide. Pteridium aquilinum is a native species that poses serious problems in Britain and elsewhere. However, there is a lack of knowledge about its long-term control and subsequent vegetation restoration. Here, we present selected results from a long-term experiment (1993-2021) testing the effects of three P. aquilinum-control treatments in factorial combination with sheep grazing/no grazing at a site in the Peak District of England. The P. aquilinum treatments were (i) untreated, (ii) cutting once-yearly, (iii) sprayed with asulam in 1993. The asulam spray treatment was re-applied in 2005 followed by annual spot-spraying until 2012, after which all treatments were stopped and recovery allowed. In 2013, after 20 years of treatments, good control of P. aquilinum and the restoration of an acid-grass/grass-heath community was achieved. After the treatments were stopped the grazed treatments remained as an acid-grass/grass-heath community but when ungrazed there the cutting treatments in particular regressed towards the untreated state dominated by P. aquilinum and woodland species. Importantly, these results emphasize the need for many years of intensive management and long-term experiments with a well-planned, statistically-valid experimental design. [ABSTRACT FROM AUTHOR]