The Bryophyte flora of the anthills
at Old Hall Marshes
TERRI TARPEY
33 Bristol Road, Colchester, Essex CO1 2YU
Introduction
The Colchester Natural History Society (CNHS) is undertaking a long-term wildlife survey of Old
Hall Marshes nature reserve for the Royal Society for Protection of Birds. Habitats present on the
reserve include coastal grazing marshes in which there are abundant anthills (Yellow Meadow Ant
Lasius flavus). It is estimated that there are over half a million anthills on the reserve. In view of the
number of anthills it was decided to examine a sample and record the bryophytes of each anthill in
the sample. By using a sample it would be possible to also record other disciplines from the same
anthills in the future, which may provide insights into their ecology. The following details the recording
undertaken to date, sets out the species found and makes general observations. Nomenclature follows
that of Blockeel & Long (1998).
Sample Anthills
The first task was to decide on how many anthills to include in the sample and where to site them.
Certain factors needed to be taken into account and these were:
• Anthills occur at various densities and anthills that arc spatially closer could have a more
similar flora than those situated further apart.
• The grazing regime varies from compartment to compartment in order to provide a range of
suitable habitats for nesting birds across the reserve.
• Old Hall Marshes is a peninsula in the Blackwater Estuary and there could be differences in
the flora between those close to the farm as opposed to those at the end of the peninsula.
• Practicality of access both for myself and initially for the tractor to place the marker posts
without squashing the anthills selected.
To get a feel for the size of the problem (it's a case of anthills, anthills, everywhere!) preliminary
counts were made of anthills in seven compartments. This was simply the number of anthills occurring
in a 1 Om2 quadrat; in all 41 quadrats were recorded. The minimum number recorded in any quadrat
was 5 and the maximum 42 with an overall average of 18.66. Map 1 shows the approximate locations
of the quadrats and counts.
From the above it was possible to approximately grade the densities of anthills into three groups:
low density,