Mow shrubland to reduce impacts of pollutants
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 2
Background information and definitions
Pollutants such as nitrogen can accumulate in the soils and vegetation of shrublands. Mowing or cutting of vegetation may help to reduce nitrogen pools and aid recovery of plant species supressed by pollution.
Supporting evidence from individual studies
A controlled study in 1998-2000 in a heathland site in Surrey, UK (Barker et al. 2004) found that mowing to reduce the concentration of pollutants did not alter the cover or shoot length of heather Calluna vulgaris relative to areas where prescribed burning was undertaken. After two years, heather cover did not differ significantly between mowed areas (77–88% cover) and areas where prescribed burning was undertaken (83%). Additionally, heather shoot length did not differ significantly between mowed areas (14–16 cm) and areas where prescribed burning was undertaken (14 cm). In 1998 eight 16 m2 plots were mowed and four plots were burned. Vegetation cover and shoot length were estimated every year in 1998-2000.Study and other actions tested
A randomized, replicated, controlled study in 1998-2000 in a lowland heathland site Surrey, UK (Power et al. 2001) found that mowing to reduce the impact of nitrogen deposition did not alter the shoot length of common heather Calluna vulgaris or the number of purple moor grass Deschampsia flexuosa seedlings when compared to prescribed burning. In areas that were mowed common heather shoot length did not differ significantly (13-15 cm) from shoot length in areas where prescribed burning was used (13 cm). The number of purple moor grass seedlings did not differ significantly between areas that were mowed and areas that where prescribed burning was used (mowed: 1-1.5 seedlings/plot; burned: 1.6 seedlings/plot). In January 1998 four 4 x 4 m plot were established. Nitrogen was added to each plot as a mist of ammonium sulfate to simulate nitrogen deposition. Each plot was divided into four subplots, two of which were mowed, one of which was burned using prescribed burning methods, and one of which was burned to simulate a wildfire. Shoot length and cover were measured in 25 points in each subplot in October 1998-2000. Seedlings establishment was recorded in September 1999.Study and other actions tested