The effects of temporary ballast roadways on heathland vegetation.
A series of trials was established to assess the effects of temporary roadways on heathland vegetation. These temporary roadways were set up on both dry (dominated by Calluna vulgaris) and wet (a higher proportion of Erica tetralix and some Molinia caerulea) heath in Dorset, S. England. The roadways were in place for periods of 2, 4 and 12 weeks in the spring, summer and autumn of 1986. The mean height, percentage cover and species composition of the vegetation were recorded before treatment and at the end of each growing season (1986-88). The mortality of rootstocks and the establishment of seedlings were assessed in Oct. 1987. Plots disturbed early in the growing season regenerated more rapidly than those disturbed later in the year, and this trend was continued in subsequent years. No species was lost or severely reduced as a result of the treatments and changes in the abundance of some species were similar to those changes produced by standard heathland vegetation management. Ten invasive species were recorded on the plots following treatment; none established in large enough numbers to change the original vegetation type.