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Importance of Mosses, Lichens,
and Liverworts to ONP
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Lichens, and Liverworts" index page
Coastal areas from Alaska to northern
California, including Olympic National Park (ONP), are home to unique
forests often referred to as "temperate rainforests". High annual
precipitation and mild winter temperatures in these areas result
in immense trees and a lush non-vascular flora. The aesthetic experience
of visitors to ONP is strongly influenced by the communities of
mosses, lichens and liverworts that drape its tree branches and
carpet the ground. These organisms, also called 'non-vascular cryptogams'
in reference to their simple structure and small size, contribute
significantly to the unique character of the park.
South Fork Hoh trail through second growth Sitka spruce forest hung
with Isothecium myosoides
Non-vascular cryptogams have important ecological
roles in addition to comprising a significant portion of forest
biomass. They influence availability of water by intercepting rainfall
and fog, reduce the effects of torrential rain, prolong water input
after precipitation has stopped, and maintain high humidity which
aids growth of other forest vegetation. They provide shelter and
nesting materials for animals and birds, and winter forage for deer
and small mammals. Non-vascular cryptogams also have a role in nutrient
cycling. Most of their nutrients come from the atmosphere and are
subsequently added to the rest of the system either through leaching
by rainwater or during decomposition after falling from trees as
litter. In some systems the nutrient contribution from non-vascular
plant litterfall is comparable to that from all vascular plant litter.
A significant source of nitrogen in Olympic forest is litterfall
of the nitrogen fixing lichen Lobaria oregana.
Lobaria oregana |
Sphagnum is known to retain several times
its own weight in water. |
Lichens, mosses and liverworts also have great potential
as indicators for long-term ecological monitoring. They have no
protective cuticle so they cannot regulate gain and loss of water.
Daily drying and wetting cycles concentrate chemicals and pollutants
dissolved in rain, fog, or dust in their tissues. These may include
sulfur, nitrogen, metals, radioactivity, and pesticides. Hence,
tissues of these organisms have been sampled for decades as indicators
of air pollution. If pollution is high enough, the lichens and mosses
themselves may disappear. Measurements showing changes in abundance
then become important assessment tools for pollution damage. Similarly,
some ground dwelling cryptogams are good indicators of soil conditions
because they indiscriminately absorb chemicals dissolved in the
soil solution.
Alectoria sarmentosa, known to be sensitive to air pollution.
Consequently, ONP is concerned about the conservation
of mosses, lichens and liverworts for many reasons. They are obviously
an important aesthetic and functional part of park ecosystems, they
are susceptible to changes in air quality, precipitation chemistry
and climate, and some species are extremely rare. They are also
of management concern because they are illegally harvested from
the park in increasing amounts for sale to the floral industry.
Moss illegally stripped from standing trees
Pickers typically use large bags to remove
moss. Here, confiscated bags are being weighed. |
To get some idea of the size of impacts,
moss bags were weighed and the approximate surface area per
pound of moss was calculated. |
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and Liverworts" index page
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