MOSSES & LIVERWORTS
Dr. K.J. Adams
Epping Forest is without doubt the most important refuge of moss and liverwort species now left in
Essex. 225 of the 357 taxa ever recorded for the county having been reported at some time from the
statutory Forest area. Unfortunately however, due to the ravages of atmospheric pollution and adverse
changes in management, some 3 7 mosses and 11 liverworts are now believed to be extinct, and several
more are on the verge of extinction. On the other hand, a number of alien species have been added to
the list in recent years, and several of them are clearly here to stay. The full list of taxa recorded from
1800 to the end of 1991 is presented in Table 1. The earliest records are those of Edward Forster whose
herbarium (undated c. 1800) is lodged at the Natural History Museum, London (BM).
Bryologically the most interesting parts of the Forest are the areas of ancient woodland, the acid
beechwoods of the hill tops overlying the Bagshot sands and Pebbly Clay Drift, and the hornbeam
areas of the lower slopes over the Claygates.
The most obvious of the Forest bryophytes are probably the cushion and carpet forming mosses
that clothe the floor of the beechwoods on the highest parts of the Epping Ridge. The whitish-grey to
blue-green cushion mosses Leucobryum glaucum and L. juniperoideum cover many acres of the Forest
floor. The former primarily on the valley slopes, the latter on tree stumps, roots and the drier hill tops.
Rarely found fruiting in Britain, both species never-the-less regularly produce thousands of capsules
in the early spring, in two of the more sheltered of our Forest valleys. Those of L. juniperoideum being
exact replicas, just half the size, of L. glaucum.
In the Lower Wake Valley just above Bellringer's Hollow, a relict colony of the leafy liverwort,
Barbilophozia attenuata, grows in amongst the Leucobryum shoots, only one of just two sites now
left in eastern England. In between the Leucobryum cushions several carpet forming mosses stabilise
the thin fragile soil of the beechwoods. Campylopus paradoxus forms sheets of dark-green over soil
and tree roots, while its close relative from South America. Campylopus introflexus, first noted on the
Forest in 1961, now competes with it in many areas, and is fast becoming the dominant ground cover.
Patches of Dicranum scoparium also occur on some of the valley sides, and in one or two places small
relict tufts of Dicranum majus, now a rarity in eastern England. The largest patch of the latter having
been removed by JCB when the Green Ride was cleared in 1988.
Tragically, the fragile moss cushions and carpets are now seriously endangered, due to the increase
in horse riding on the Forest in recent years. Detached and fragmented by galloping horses in the dry
summer months, they are washed downslope by the autumn rains, leaving the thin friable soil unstable
and open to erosion.
On the lower banks close to stream sides, a few scattered but persistent patches of Plagiothecium
undulatum still occur, and on the steepest stream and gravel working banks in the beechwoods, a
liverwort community comprising: Diplophyllum albicans. Cephalozia bicuspidata, Gymnocolea
inflata. Calypogeia fissa, Cephaloziella divaricata and C. hampeana, occurs; with occasional patches
of Lophozia ventricosa and Calypogeia muellerana, on the more acid soils over the Bagshot Sands.
A third Calypogeia. C. arguta, is abundant on freshly exposed clay banks of the minor streams cut
into the Claygates, usually in association with Fissidens bryoides; and in some years the rare
Dicranella rufescens is to be found fruiting abundantly, just above the waterline, in the same habitat.
On the bare clay banks where the soil has been washed away, thin pioneer wefts of Isopterygium
elegans occur, reproducing vegetatively from tiny clusters of twig-like axillary gemmae. With the
closure of the canopy after the cessation of lopping, there must have been a considerable increase in
bare-ground as a substrate, and /. elegans is probably more abundant on the Forest now than it has
ever been. Once these soil-less patches are stabilised carpets of Hypnum jutlandicum form a more
durable protective cover. Where layers of deeper humus occur extensive patches of Polytrichum
formosum (dry woodland) and Polytrichum commune (wet acid peat) occur. Following clearance of
the scrub east of Wake Valley Pond some years ago, several acres of P. commune colonised the thin
layer of wet peat under developing birch scrub, kept moist by the perched water-table over the Pebbly
Clay Drift.
Few epiphytic bryophytes are to be found in Epping Forest today, due to the devastating and highly
specific toxicity of sulphur dioxide, brought downwind from the London conurbations dunng the
worst of the coal burning era from around 1850 to about 1980. Highly sensitive species such as
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