Woodland - Spring 2019 - 11

Old-growth forests, especially
those in North America, are
perceived to be rich in biodiversity,
in addition to capturing aesthetic
and spiritual values. These forests
are usually defined by the age of
the trees, with conservation and
management practices developed
accordingly. McMullin and Wiersma
said this is an over-simplification,
as it overlooks the importance of
biodiversity in those habitats.
"Forests with old trees in them are
certainly awesome and important,"
said Wiersma. "However, forests
change through time and something
that is an older forest now may not
always be a forest."
The approach of the researchers
lets them look at the presence of
forests in the context of the broader
landscape.
"If we think of the landscape as
a patchwork quilt of different types
of forests of different ages, some
of those patches of forest will stick
around for a long time, while others
might wink in and out over different
time frames. Our approach lets
us identify which patch has been
a forest for the longest period of
time, even if it's not the one with the
oldest trees."
McMullin and Wiersma argue
that old trees are only a proxy
for biodiversity in old-forest
ecosystems and that biodiversity
should be measured directly - with
lichens as the ideal candidates.
"The advantage of lichens as
indicators for this biodiversity is that
they don't go anywhere, you can
study them anytime of the year, and
they 'eat the air' which makes them

one of the most sensitive organisms
in the forest," explained McMullin.
Many old-growth forests have
high sustained moisture and a high
number of microhabitats suitable
for certain species, which can't
disperse easily. Having these forests
in the landscape provides a refuge
for the seeds and spores that helps
with the continued preservation of
this biodiversity.
In their paper, McMullin and
Wiersma propose that suites of
lichens associated with known oldgrowth areas can be used to develop
"an index of ecological continuity" for
forests of interest. This scorecard of
lichen species could then be used as
a tool by conservation biologists and
forest mangers - the more species
that are old-growth dependent, then
the higher the forest's conservation
value.
The scientists note that lichens are
already being used to assess oldgrowth value and forest continuity
in parts of Europe, less so in North
America. As examples, they cite the
studies of British botanist Dr. Francis
Rose, who developed an index of
about 30 lichens associated with
Britain's Royal Forests or medieval
parklands, which have been relatively
untouched going back hundreds or
even thousands of years.
McMullin has also built on the
work of Dr. Steven Selva at the
University of Maine. Selva has
documented that species of stubble
lichens (the calicioids), which
tend to be found predominantly
in old-growth areas, can be good
indicators of continuously forested
lands in Acadian forests.

So, what next? McMullin and
Wiersma propose they can build
on this knowledge to develop lists
of appropriate lichen suites for
forest types such as Carolinian,
Boreal or Great Lakes-St.
Lawrence. The next steps could
include training those responsible
for assessing the forests, offering
access to the expertise of
trained lichenologists, and taking
advantage of new technologies
such as DNA barcoding.
Lichens 101
There are an estimated 2,500
species of lichens in Canada.
Lichens are found on every
continent and can grow in frigid
polar regions, harsh deserts, as
well as your backyard! A lichen is
part fungus and part green alga
or a cyanobacterium (sometimes
both). Some lichens fix nitrogen for
the soil and lichens play important
roles in ecosystems: they are
among the first colonizers of
bare rock and prevent erosion by
stabilizing soil, they provide food
for animals, habitats for insects,
and they can serve as monitors
for air-pollution. The Canadian
Museum of Nature houses the
National Herbarium of Canada,
which includes about 150,000
specimens of lichens. A
JOURNAL REFERENCE:
1

R. Troy McMullin, Yolanda F Wiersma.
Out with OLD growth, in with
ecological continNEWity: new
perspectives on forest conservation.
Frontiers in Ecology and the Environment,
2019; DOI: 10.1002/fee.2016

Spring 2019 * WOODLAND 11



Woodland - Spring 2019

Table of Contents for the Digital Edition of Woodland - Spring 2019

Overstory
Forest Interactions Seedlings
Forests and Families
Brittany Vanderwall: Saying Yes to Opportunity
‘chipping In’ to Reduce Wildfire Risk in California
Strength in Numbers: Tree Farmers and Advocacy Leaders Rally to Recover Post-Disaster
Tools and Resources
Growing Forest Conservation, Together: The 2019 National Leadership Conference
Woodland - Spring 2019 - Intro
Woodland - Spring 2019 - cover1
Woodland - Spring 2019 - cover2
Woodland - Spring 2019 - 3
Woodland - Spring 2019 - Overstory
Woodland - Spring 2019 - 5
Woodland - Spring 2019 - Forest Interactions Seedlings
Woodland - Spring 2019 - 7
Woodland - Spring 2019 - 8
Woodland - Spring 2019 - 9
Woodland - Spring 2019 - 10
Woodland - Spring 2019 - 11
Woodland - Spring 2019 - 12
Woodland - Spring 2019 - 13
Woodland - Spring 2019 - 14
Woodland - Spring 2019 - Forests and Families
Woodland - Spring 2019 - 16
Woodland - Spring 2019 - 17
Woodland - Spring 2019 - Brittany Vanderwall: Saying Yes to Opportunity
Woodland - Spring 2019 - 19
Woodland - Spring 2019 - 20
Woodland - Spring 2019 - 21
Woodland - Spring 2019 - 22
Woodland - Spring 2019 - 23
Woodland - Spring 2019 - ‘chipping In’ to Reduce Wildfire Risk in California
Woodland - Spring 2019 - 25
Woodland - Spring 2019 - 26
Woodland - Spring 2019 - 27
Woodland - Spring 2019 - 28
Woodland - Spring 2019 - 29
Woodland - Spring 2019 - Strength in Numbers: Tree Farmers and Advocacy Leaders Rally to Recover Post-Disaster
Woodland - Spring 2019 - 31
Woodland - Spring 2019 - 32
Woodland - Spring 2019 - 33
Woodland - Spring 2019 - 34
Woodland - Spring 2019 - 35
Woodland - Spring 2019 - Tools and Resources
Woodland - Spring 2019 - 37
Woodland - Spring 2019 - Growing Forest Conservation, Together: The 2019 National Leadership Conference
Woodland - Spring 2019 - cover3
Woodland - Spring 2019 - cover4
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