Looking after Green Shield-moss (Buxbaumia viridis) and ... - Plantlife

BACK FROM THE BRINK MANAGEMENT SERIES
Buxbaumia viridis capsules may be grazed probably by slugs, birds or rodents. © Stewart Taylor
The problems
The loss of woodland cover over the
centuries and, more recently, the intense
management of woodland areas has led to a
significant loss of habitat for these bryophyte
species. The removal or ‘tidying up’ of fallen
trees has been a particular problem so that
the volume of dead wood, in even the least
managed of our woodlands, is far below that
in natural woodland. In stands that have had
little recent management, the volume of fallen
dead wood may be in excess of 60m 3 per
hectare, which is comparable with old-growth
woodland in Europe and America. However, in
woodland managed for timber, volumes of
dead wood can be less than 20m 3 per hectare.
The problem for these bryopyhtes is not just
one of simple loss of habitat but also lack of
continuity of habitat at any one site when the
absolute volume of dead wood is so small.
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The species
Green Shield-moss (Buxbaumia viridis) is
different to virtually all other mosses in that it
has tiny leaves which are invisible in the field;
this means that it can only be spotted when it
has its distinctive fruiting-body. With most
other mosses it is the green leaves (the
gametophyte) that you see frequently with
small fruiting bodies (the sporophytes).
Buxbaumia viridis has a relatively large capsule
raised on a stalk so that the whole structure is
about 2cm tall. The capsule is green in the
winter, turning a brownish-straw colour in
summer when the millions of spores are shed.
Confusion is only possible with the related
Brown shield-moss (Buxbaumia aphylla), which
can also occur on dead wood. It is probable
that the vegetative parts of the plant persist
on logs but only produce fruiting bodies when
the conditions are favourable. As it rots away,