67
Tabic 4b Changes to the structure of the plant community in the
Molinia-dominated Northern Grid as a result of grazing.
Heather
Other heathland plants have benefited from the Purple Moor-grass decline too. Bare ground for
seedling establishment, created by the trampling of the cattle, has been one of the most
important factors. Prime amongsl the plants to benefit has been Heather. In the northern plot iis
frequency has risen significantly from 10% to 37% of quadrats (Table 4a above). This simple
statistic, however, does not reveal the full transformation. Following grazing, the situation has
changed from one of a scatter of old Heather plants amongst a dense cover of grass to one of a
predominance of thousands of Heather seedlings and young plants.
In the Bracken-dominated southern plot, however, the situation is different. From the quadrat
statistics there has been no significant increase in Heather. In 1994, 1 quadrat contained Heather
and in 1998 there were two records (Table 3a above). Bracken cover (see below) seems to have
had an influence on this but again the quadrats do not give a complete picture. As with the
northern plot, the southern one contains far more Heather seedlings and more bare ground for
their spread.
Bracken
As intimated above, Bracken has not responded in the same way as Purple Moor-grass. In fact,
although young fronds were eaten by the cattle early in each year and, initially at least, the
trampling does seem to have affected the height of the stands, it has responded by producing a
greater density of shoots. For example, in the southern plot the number of shoots rose from 15
per m in 1994 to 22 in 1995 before falling back to 18 in 1998 (Table 3b above). The samples
are without controls and too few from which to draw ready conclusions and Bracken may be
weakened in the long-term. However, experience elsewhere suggests that Bracken will have to
be reduced in vigour by mechanical or by chemicals or by a combination of both treatments (see
Discussion below).
Other heathland plants
Although the Bracken-dominated southern plot has less Heather, other heathland specialist
plants traditionally typical of the Forest have increased in this plot as in the other. Scarce sedges
like Green-ribbed Sedge and Common Black Sedge (Carex nigra) from not being recorded at all
in the quadrats, although known from the site, have increased significantly and are now present
Essex Naturalist (New Series) 16 (1999)