old pollards. Particularly interesting are rot-holes. When a branch is removed from a tree, either
naturally or by pollarding, living tissue is exposed and this allows the entry of fungi which begin to
break down the wood. Once this happens beetles are able to exploit the decaying wood and between
the fungi and beetles a sizeable cavity may form - the rot-hole. Depending on the orientation of the
original aperture, the hole admits rainwater to a greater or lesser extent and leaves may also accumulate
in the hole. Thus a whole range of rot-holes with different water contents can occur: some very wet,
others just moist, others mainly dry. The degree of wetness can vary over the seasons. Some shallow
rot-holes dry out in summer and yet are constantly wet in winter. Ultimately the inner trunk of the
pollard can rot, leaving a huge cavity often filled with leaf litter accumulated over many decades.
These, if protected from the sun, retain their moisture throughout the year, only the upper layers drying.
Sometimes a callus forms where a branch has been removed and this can further restrict the entrance
to the rot-hole and hence moisture loss. The varying degree of moisture has implications for the species
of invertebrate found in the rot-hole. In Epping Forest, the wettest harbour the larvae of species such
as the rare mosquito Orthopodomyia pulchripalpis, the Ceratopogonid Dasyhelea dufouri and the
little black Chironomid Metriocnemus martinii. The beetle Prionocyphon serricornis, one of Britain's
rarer beetles, has also been found in wet rot-holes. From the cavity of a single Beech pollard at Hill
Wood I reared the lovely yellow and black Cranefly Ctenophora pectinicornis and two rare
Dolichopodid flies Systenus leucurus and S. scholtzi. The latter two species are known from very few
sites in Britain and are always associated with mature trees. The larvae of these species may be active
predators of the larvae of other fly species in the decaying rot-hole material.
Unlike many hedgerow pollards which are in a very open situation and hence subject to very rapid
drying out, the Forest pollard trees today are in a very shaded environment which reduces the tendency
to dry out. This cannot always have been the case. In the 19th century the very open aspect of the
areas of pollard trees in the Forest must have meant a considerable tendency to dry out in hot summers.
Dry rot-holes tend not to be so productive of flies but will attract woodlice, centipedes, millipedes,
spiders and some beetles. A great range of invertebrates makes use of old decaying trees. The list of
Flies and Beetles associated with dead wood in ancient woodland in Britain is about 850 species. The
list includes species which depend on others associated with the habitat, for example the beetle
Batrisodes buqueti found in tree stump nests of the ant Lasius brunneus, the ant itself being virtually
confined to old wood-pastures (Harding and Rose, 1986; Stubbs and Chandler, 1978).
Holes in trees are also important for birds. The Redstart, now reduced to a few pairs in Epping
Forest, was once a common and regular nester in old pollards. The remaining pairs often show
faithfulness to a particular tree nesting site in successive years. The Redstart may be the classic bird
of wood-pasture. It favours large, mature trees in open habitats.
Pollard trees are of outstanding historical interest and wildlife significance in the Forest - a living
link with our ancient past and worthy of the highest conservation priority (Table 1). There are still
many pollards left in the Forest, but year by year their numbers dwindle: many have been felled; others
were victims of recent hurricane force winds (Plate 22). Greater effort should be put into saving these
great, gnarled, wrinkled veterans so that generations as yet unborn can delight in their mysterious
rugged beauty.
Table 1. A list of the rarest insects associated with large, old trees found in Epping Forest. The larvae
of most of these species are found in rot-holes, decaying wood and sap runs.
Diptera Coleoptera
Brachypalpus laphriformis Ampedus cinnabarinus
Ctenophora flaveolata nigerrimus
pectinicornis Batrisodes buqueti
Ferdinandea ruficornis venustus
Mallota cimbiciformis Bibloporus minutus
Myolepta luteola Enicmus rugosus
Orthopodomyia pulchripalpis Euryusa optabilis
Pocota personata Malthodes crassicornis
Solva maculata Megapenthes lugens
marginata Notolaemus unifasciatus
Systenus leucurus Prionocyphon serricornis
pallipes Ptenidium gressneri
scholtzi Rhizophagus oblongicollis
Xylota abiens Silvanus bidentatus
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