A CONTEMPORARY BRYOPHYTE FLORA OF ESSEX 209
smaller woodlands are clearly doomed, and all but a handful of
the larger ones are to be drained and replanted with conifers. In
the south the drive to reclaim woodland and marsh has not
reached such epidemic proportions but even so woods are being
cleared and pasture converted to arable. Much of Ongar Park
Wood has become arable during the last decade and numerous
smaller woods are disappearing or being nibbled at.
Of the 315 full species mentioned in Pettifer's flora about 50
are no longer extant, although a few may yet be rediscovered.
This gives a false picture of their status, however, as to-day
numerous species are known only from one or two localities.
Cryphaea refound in 1985 could not be found this year.
Orthotrichum lyellii although refound this year is known only
from three trees. Leucodon, Frullania, Radula, the Scapania spp.,
some of the Sphagnum spp., and even Homalia, and Zygodon are
decreasing so rapidly that they appear to be on their way out.
Now that the particulate pollution of the atmosphere has been
more or less curtailed the more insidious sulphur dioxide is sus-
pected to be taking its toll, but the main reasons for the decline
fall into two categories: (1) general drying out of the county as
the water table falls, the natural vegetation and the associated
blanket of humid air are removed, and fields and marshes are
drained. Drainage is now so efficient that within a few hours
heavy rain is causing flooding in the lower reaches of the rivers;
(2) the wholesale removal of trees which will obliterate the
epiphytic species and expose shelter loving ones to the drying
winds. All over the north of the county the effects of these factors
can be seen in areas where clearance has not yet taken place.
Woodlands and hedgerows are left high and dry as surrounding
drainage lowers the water table and wind-scorched perennial
bryophytes can be found deep within quite large woodlands now
bereft of their ground flora. Ditches and ponds in many areas
are now dry for most of the year. An increasing number of land
locked ponds and numerous watercourses are becoming heavily
polluted with effluent from intensive pig farms, and the aquatic
moss Fontinalis is now becoming very scarce. Mature trees are
becoming a rare sight, senescent ones even more so, yet many
epiphytic species will not colonise younger trees. Numerous
'weedy' and 'wayside' bryophytes are on the increase but this does
not, unfortunately, compensate for the loss of variety.
Mapping Scheme
To provide a record of bryophyte distribution, before at least
north Essex becomes one vast windswept arable field, the mapping
is planned for completion by 1972. In 1968 we were joined by
M. O. Hill who has provided numerous lists for many of the 5 km
National Grid squares which serve as the basis of our recording.
The 198 squares (including numerous small part squares) are
expected, when thoroughly worked, to yield an average of not
more than 60 species per square, giving a final target total of