often acts as a facilitator, creating small "islands"
of protection for more fragile plants. These are all
a threat to the native flora and fauna of shingle,
with, for instance, the Walmer area being the
most important site in southeast England for the
nationally scarce sea pea (Lathyrus japonicus).
How did the holm oaks get to Walmer? We are
fortunate in Kent to have air photography for the
whole county covering the period from the 1940s
to the present. The initial invasion of the beach
seems to be some 600 metres (1,968 feet) to the
south of Walmer Castle, originally built as one of a
number of coastal defences for Henry VIII (Photo
3). The castle grounds contain some magnificent
mature trees, and this is the putative source, with
the original specimens planted within the grounds
in the 1860s (Photo 4). An area of scrub behind the
esplanade appears to have been the route by which
the oaks may have reached the beach (Photo 5).
Several holm oaks are well established in this area,
probably dispersed by birds and other animals from
the castle grounds. The conundrum is how the oaks
crossed the esplanade to reach the beach. There
would be very little incentive for a bird or squirrel
to carry acorns across open shingle toward the sea.
One intriguing thought is that the dispersal mech-
anism might be play! Children notoriously collect,
kick, and throw nuts including acorns and conkers
(the large seed of the horse chestnut, Aesculus
hippocastanum). Once trees had been established
in this manner, bird dispersal could recommence.
One very large holm oak, just to the landward
side of the esplanade and next to the first houses
at Kingsdown, appears to be at the epicentre
of the dispersal to the beach. Air photography
shows this oak to be well established in the 1940s,
and the invasion of the beach then commences
in both directions, north and south, until there
are now nearly eighty well-developed holms
on the shingle. The oaks' crowns are dense and
evergreen, and they reach the ground around
most of their perimeter, supressing any vege-
tation beneath, while dead leaves form a >>
34 CityTREES
Photo 3: Walmer Castle with dark crowns of holm oaks on
the beach with their "halo" of bare shingle. Google Earth
