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The Lungwort Lichens
By Terry Taylor
Lungworts are large lichens with a surface covered by ridges and bowlshaped
depressions. They grow on trees and are only numerous in
areas with clean air. Along the coast in sites with old trees they can be
quite numerous and branches fallen from the canopy look as if they are
covered with strange pitted leaves. As their large thalli are only loosely
attached to the branches, windstorms can bring them down quite regularly.
In such locations these lichens are more than curiosities. They are
the fertilizer factories of the forest.
The substance Lungworts give to the soil is nitrogen. Nitrogen is often
the limiting nutrient in land ecosystems. It is an essential component in
the proteins of all organisms, and is the element that makes up most of
the air we breathe. However, nitrogen molecules are very stable, and
almost inert. It takes a great deal of energy to pry them apart so that they
can be combined with other elements and used by living organisms. The
only life forms that have developed the biochemistry to do this are a few
groups of bacteria. All the larger organisms owe their existence to these
bacteria. The reason why we grow legumes to enrich soil is due to the
fact that legume roots contain nitrogen fixing bacteria that extract nitrogen
from the atmosphere. When their plant hosts die these nitrogenous
compounds are released into the soil.
Lichens differ from most of the other organisms with which we are
familiar as they are actually two or three separate organisms so closely
intermeshed that they form a composite life form that functions as a single
organism. Most lichens are a cooperative venture by two kingdoms - a
fungus and a plant. The plant is usually a green alga that produces sugars
to feed the fungus. The Lungworts are composed of three kingdoms -
fungi, plants, and bacteria. The bacteria are blue-green bacteria, one of
the groups that fixes nitrogen. Nitrogen-fixation is the process of splitting
nitrogen molecules apart and combining the two atoms within each
molecule with hydrogen, to make fertilizer. This fixed nitrogen builds the
proteins of the lichen while the lichen is alive, but some of the nitrogen
leaches out of it, and the rest of it goes into the soil once the lichen falls
from the tree.
The common Lungwort (L. pulmonaria) most often grows in the canopies
of old Broadleaf Maple trees. It is most common on the maples of
the east coast of Vancouver Island. If you are walking in such a site after
a winter storm you may be fortunate enough to find great piles of their
leaf-like thalli covering the forest floor. A disaster for the fallen Lungwort,
but a banquet for the plants growing here.
Nechako White Sturgeon Conservation Centre
Photo: R.Taylor
Lobaria pulmonaria
Another Lungwort is the Oregon Lungwort
(L. oregana). Its preferred habitat is the canopies
of old-growth Douglas firs. It is very similar
to the previous species, but has a slightly
different colour, and the edge of the lichen is
minutely frilly. In its coniferous forest habitat
its fertilizer contributions are probably even
more important than those of the previously
described Lungwort. Coniferous forest soils are
more acidic and nutrient-poor than those of
deciduous forest stands. Veteran Douglas firs
can live for a thousand years, and in some old
forests such as in the Elaho Valley the ground is
covered with Oregon Lungwort fragments. The
lichens in such areas have been raining down
onto the ground for century after century, and
are probably the main nitrogen reservoir for
these old trees and their associated ecosystem.
By June Wood
The Nechako White Sturgeon Conservation Centre,
owned and operated by the Freshwater Fisheries
Society of BC, has, after many years of hard work
and collaboration led by the Nechako White Sturgeon
Recovery Initiative (NWSRI), finally become
a reality. The first brood program will be carried
out late this spring and it is anticipated that up
to 12,000 juveniles will be released each year.
Whether the first juveniles will be released this fall
or held over until the spring of 2015, when they
stand a better chance of survival, is still in question.
While the hatchery is a great achievement for the
NWSRI, and absolutely necessary to prevent the
Nechako white sturgeon from slipping into extinction,
it is recognized that the facility is not a permanent
solution for this ancient fish’s recovery — but it
Photo: J. Wood
will buy time for the continued research and moni-
Nechako White Sturgeon Conservation Centre
toring that will hopefully lead to a self-sustaining population. One prong of the NWSRI, a hatchery, has been achieved but the
second prong, the health of the Nechako River, is still waiting.
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BCnature Spring 2014