Woodland - Summer 2019 - 20

Seedlings
Continued

MAPPING MICROBIAL SYMBIOSES IN FORESTS
SOURCE: SCIENCE DAILY

In and around the tangled
roots of the forest floor, fungi and
bacteria grow with trees, exchanging
nutrients for carbon in a vast, global
marketplace. A new effort to map the
most abundant of these symbiotic
relationships - involving more than
1.1 million forest sites and 28,000
tree species - has revealed factors
that determine where different types
of symbionts will flourish. The work
could help scientists understand how
symbiotic partnerships structure the
world's forests and how they could
be affected by a warming climate.
Stanford University researchers
worked alongside a team of more
than 200 scientists to generate these
maps, published May 16 in Nature.
From the work, they revealed a
new biological rule, which the team
named Read's Rule after pioneer in
symbiosis research Sir David Read.
In one example of how they could
apply this research, the group used
their map to predict how symbioses
might change by 2070 if carbon
emissions continue unabated. This
scenario resulted in a 10 percent
reduction in the biomass of tree
species that associate with a type
of fungi found primarily in cooler
regions. The researchers cautioned
that such a loss could lead to more

20 WOODLAND * Summer 2019

carbon in the atmosphere because
these fungi tend to increase the
amount of carbon stored in soil.
"There's only so many different
symbiotic types and we're showing
that they obey clear rules," said Brian
Steidinger, a postdoctoral researcher
at Stanford and lead author of the
paper. "Our models predict massive
changes to the symbiotic state of
the world's forests - changes that
could affect the kind of climate your
grandchildren are going to live in."
Three Symbioses
Hidden to most observers, these
inter-kingdom collaborations between
microbes and trees are highly diverse.
The researchers focused on mapping
three of the most common types of
symbioses: arbuscular mycorrhizal
fungi, ectomycorrhizal fungi and
nitrogen-fixing bacteria. Each of these
types encompasses thousands of
species of fungi or bacteria that form
unique partnerships with different tree
species.
Thirty years ago, Read drew
maps by hand of where he thought
different symbiotic fungi might
reside, based on the nutrients they
provide. Ectomycorrhizal fungi feed
trees nitrogen directly from organic
matter - like decaying leaves - so,

he proposed, they would be more
successful in cooler places where
decomposition is slow and leaf litter
is abundant. In contrast, he thought
arbuscular mycorrhizal fungi would
dominate in the tropics where tree
growth is limited by soil phosphorus.
Research by others has added that
nitrogen-fixing bacteria seem to grow
poorly in cool temperatures.
Testing Read's ideas had to wait,
however, because proof required
gathering data from large numbers
of trees in diverse parts of the globe.
That information became available
with the Global Forest Biodiversity
Initiative (GFBI), which surveyed
forests, woodlands and savannas
from every continent (except
Antarctica) and ecosystem on Earth.
The team fed the location of 31
million trees from that database
along with information about what
symbiotic fungi or bacteria most
often associates with those species
into a learning algorithm that
determined how different variables
such as climate, soil chemistry,
vegetation and topography seem
to influence the prevalence of each
symbiosis. From this, they found
that nitrogen-fixing bacteria are
probably limited by temperature
and soil acidity, whereas the two



Woodland - Summer 2019

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

Overstory
Foresets and Families
Forest Interactions
The Family Forest Carbon Program
2019 Regional Outstanding Tree Farmer of the Year Finalists Announced
Tree Farmers Visit Washington to Advocate for Family Forest Interests
Tools and Resources
Woodland - Summer 2019 - Intro
Woodland - Summer 2019 - cover1
Woodland - Summer 2019 - cover2
Woodland - Summer 2019 - 3
Woodland - Summer 2019 - Overstory
Woodland - Summer 2019 - 5
Woodland - Summer 2019 - Foresets and Families
Woodland - Summer 2019 - 7
Woodland - Summer 2019 - Forest Interactions
Woodland - Summer 2019 - 9
Woodland - Summer 2019 - 10
Woodland - Summer 2019 - 11
Woodland - Summer 2019 - 12
Woodland - Summer 2019 - 13
Woodland - Summer 2019 - 14
Woodland - Summer 2019 - 15
Woodland - Summer 2019 - 16
Woodland - Summer 2019 - 17
Woodland - Summer 2019 - 18
Woodland - Summer 2019 - 19
Woodland - Summer 2019 - 20
Woodland - Summer 2019 - 21
Woodland - Summer 2019 - The Family Forest Carbon Program
Woodland - Summer 2019 - 23
Woodland - Summer 2019 - 24
Woodland - Summer 2019 - 25
Woodland - Summer 2019 - 26
Woodland - Summer 2019 - 27
Woodland - Summer 2019 - 2019 Regional Outstanding Tree Farmer of the Year Finalists Announced
Woodland - Summer 2019 - 29
Woodland - Summer 2019 - 30
Woodland - Summer 2019 - 31
Woodland - Summer 2019 - 32
Woodland - Summer 2019 - 33
Woodland - Summer 2019 - Tree Farmers Visit Washington to Advocate for Family Forest Interests
Woodland - Summer 2019 - 35
Woodland - Summer 2019 - 36
Woodland - Summer 2019 - 37
Woodland - Summer 2019 - 38
Woodland - Summer 2019 - 39
Woodland - Summer 2019 - 40
Woodland - Summer 2019 - Tools and Resources
Woodland - Summer 2019 - 42
Woodland - Summer 2019 - cover3
Woodland - Summer 2019 - cover4
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