December 15, 2017
CapitalPress.com
9
Research finds ‘sweet spot’ for plant transpiration
New study may
help farmers
irrigate more
efficiently by
looking at the rate
of transpiration in
plants
By GEORGE PLAVEN
Capital Press
A new study in the journal
Nature Ecology & Evolution
may help farmers irrigate
crops more efficiently, with a
better understanding of how
much water is actually used
beneficially by plants in a giv-
en environment.
Researchers analyzed data
from 45 field stations rep-
resenting different climates
around the world, from jun-
gles to deserts, trying to de-
termine the optimal rainfall
at which plants are most pro-
ductive before water is lost to
evaporation or runoff.
While the study was not
tailored specifically to irri-
gation, lead author Stephen
Good at Oregon State Uni-
versity said the findings do
have a practical link to agri-
culture.
“If you’re irrigating a field,
you want to make sure the
water you’re putting on is ac-
tually being used, and not just
being evaporated off,” Good
said.
The study is based on mea-
suring transpiration, or the
process by which moisture is
carried through plants from
the roots to the leaves, where
it changes to vapor and is
eventually released back into
the atmosphere.
Good, a hydrologist and
assistant professor at OSU,
said transpiration is the part
of the water cycle that is most
linked to the productivity of
plants.
“When you think of water
as a resource, transpiration
is the total amount of water
a plant is able to use,” Good
said.
Despite its importance,
Good said transpiration is
poorly understood. What the
study finds is a general rela-
tionship between transpira-
tion and climate — that essen-
tially there is a “sweet spot”
for rainfall, not too wet and
not too dry.
“You tell me the climate
and aridity in that climate, and
I can tell you how much water
the plant can use in transpira-
tion,” Good summarized.
With that information,
growers could make key
management decisions such
as cropping systems and ir-
rigation rates to maximize
yield while reducing input
costs.
Good said researchers are
now conducting similar stud-
ies on the ground in some of
Eastern Oregon’s more arid
climates, including Hermis-
ton, Milton-Freewater, Dufur,
Maupin and Madras.
Georgianne Moore, co-au-
thor of the study and an asso-
Georgianne Moore, Texas A&M AgriLife
Researchers at Oregon State University, Texas A&M and Ghent University studied plant water use on a global scale across all climates.
ciate professor at Texas A&M
University, said their model-
ing shows how rainfall is split
between plant use, evapora-
tion, runoff and interception,
where water doesn’t actually
make it into the soil.
“We produced a map based
on the model to show what
parts of the world will fall
off the curve and no longer
use their rainfall as efficiently
for beneficial growth,” Moore
said in a statement released
through OSU.
One other wrinkle in the
equation is climate change,
which Moore suggests will
continue to shift away from
intermediate climates and
more toward extremes, with
wet areas getting wetter and
dry areas getting drier.
“There could be big conse-
quences, as it will affect for-
ests, grasslands, savannas and
deserts,” Moore said. “Scien-
tists can now use the model
we have to help make predic-
tions about the future of these
plant communities.”
Changing climates and
transpiration could signifi-
cantly influence agricultural
systems as well, Good said.
“If we move to a drier cli-
mate, or if the climate chang-
es in Oregon, we can expect
a decrease in the transpiration
of plants,” he said.
Eastern Oregon commissioners
weigh in on forest plan in D.C.
By KATY NESBITT
For the Capital Press
ENTERPRISE — Eastern
Oregon county commission-
ers were to make their voices
heard Dec. 12-14 when Pacif-
ic Northwest Regional For-
ester Jim Peña presented the
Blue Mountains Forest Plan
Revision in Washington, D.C.
The Blue Mountains For-
est Plan has been under revi-
sion since 2003 and is a guid-
ing document for the Malheur,
Umatilla and Wallowa-Whit-
man national forests. Susan
Roberts, chairman of the East-
ern Oregon Counties Associa-
tion, said a draft of the plan
released in June had changes
in grazing requirements from
a draft released in January.
“We were concerned that
those changes would have an
economic impact on our local
communities,” Roberts said.
Fearing increased stubble
height along endangered spe-
cies-bearing streams in public
grazing allotments would re-
duce grazing and harm local
economies, Harney County
Commissioner Mark Owens
and other members of the
association asked Rep. Greg
Walden, R-Hood River, to
intervene on their behalf with
the federal agencies.
“We want to make sure
they are addressing economic
conditions as well as ecolog-
ical in the plan’s revision,”
Owens said.
Roberts said the associa-
tion members wanted an op-
portunity to speak to federal
fisheries staff face-to-face
instead of communicating
through the Forest Service.
“The plan had not gone to
formal consultation with the
regulatory agencies and we
wanted to get some things
ironed out before that,” Rob-
erts said.
Justin Discigil, Walden’s
communications director, said
the congressman has worked
with Eastern Oregon counties
throughout the 14 years the
Blue Mountains Plan has been
under revision.
Discigil said Walden,
at the association’s behest,
raised the counties’ concerns
about the Blue Mountains
Plan with the new chief of the
Forest Service, Tony Tooke,
shortly after he was appointed
this fall.
Seeing significant head-
way in meetings with the
federal agencies, Wallowa
County Commissioner Todd
Nash said he asked if Eastern
Oregon could send a repre-
sentative to meet with Forest
Service officials when Peña
presented the plan to Forest
Service leaders in Washing-
ton, D.C.
“When we started to see ef-
fective changes with all of the
agencies in the room I thought
it was of value, as cooperating
agents, for someone from one
of the counties to be in that
presentation,” Nash said.
Peña extended an invita-
tion for one commissioner to
join him in Washington.
“It’s important for our
agency to be transparent about
this process and everything it
entails, so I was happy to ex-
tend this invitation,” Peña said.
“Many of these counties have
signed a memorandum of un-
derstanding to formalize their
role as a cooperating agency
with the Forest Service as part
of this forest plan revision, and
all of them are important part-
ners in this effort.”
Ranchers buoyed by decision to
delay grazing rate formula vote
By SEAN ELLIS
Capital Press
FORT HALL, Idaho —
News that the Idaho Land
Board had delayed a deci-
sion on whether to revise the
grazing rate formula on state
endowment land was viewed
as a positive sign by ranchers
attending Idaho Farm Bureau
Federation’s annual meeting.
IFBF members submitted
the majority of public com-
ments on the issue.
The land board voted 5-0
Dec. 5 to put off a decision
on the grazing formula, which
hasn’t been revised since 1993
and was $9.01 per animal unit
month this year.
An AUM is the amount of
forage needed to feed a cow
and calf for a month. The IDL
manages 1,139 grazing leases
on 1.4 million acres of state
endowment land, representing
a total of 257,370 AUMs.
An Idaho Department of
Lands subcommittee and ad-
visory group has been review-
ing the methodology of the
grazing rate formula.
Four alternative formulas,
in addition to the current one,
are on the table and some cat-
tle ranchers worry the alterna-
tives could result in a signif-
icant increase in the grazing
rate on state land.
The vast majority of pub-
lic comments received by IDL
have recommended keeping
the current grazing rate for-
mula. Most of those com-
ments have been submitted by
farm bureau members.
Cody Chandler, a Weiser
rancher, said cattlemen have
come forward late in the game
to make their voices heard on
the issue “and I appreciate
the fact that the land board
stepped back and they are go-
ing to look at this a little bit
harder.”
During its regular meeting
Dec. 5, the land board met in
executive session to discuss
new information about the
proposed alternatives, Secre-
tary of State Lawerence Den-
ney told Capital Press.
The executive session last-
ed more than an hour.
“There was new informa-
tion that was brought to our
attention and we wanted to
make sure we considered ev-
erything before making a de-
cision,” Denney said.
He said the land board will
likely wait until after the 2018
Idaho Legislature adjourns be-
fore taking up the issue again.
Idaho’s legislative session usu-
ally wraps up about the end of
March or first of April.
“That will give us more
time to collect additional in-
formation,” Denney said.
Russ Hendricks, IFBF’s
director of governmental af-
fairs, said much of the discus-
sion on the issue has centered
on the state grazing rate not
tracking with the private land
grazing rate but that’s not a
fair comparison.
The average grazing rate
on private land in Idaho was
$18 this year.
Private land grazing leas-
es typically include a lot of
services that are not included
with public land leases, such
as fencing, water develop-
ment and maintenance, labor
and predator and noxious
weed control, Hendricks said.
“When you add in all the
additional (services) over and
above the lease rate, the state
rate is already way above the
private lease rate,” he said.
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