8
Wednesday, November 29, 2017 The Nugget Newspaper, Sisters, Oregon
Floods are necessary for maintaining river ecosystems
By Steve Lundeberg
Correspondent
CORVALLIS — Flooding
rivers can wreak havoc on
homes and roads but are
necessary for healthy eco-
systems, research at Oregon
State University suggests.
The study shows that alter-
ations to rivers’ natural flow
patterns — because of dams,
diversions and changes in
precipitation — cause dam-
age to riparian plant commu-
nities and river ecosystems in
general.
Even minor shifts in tem-
poral flow patterns harm
networks of competing veg-
etation, said the study’s cor-
responding author, Jonathan
Tonkin of the OSU College
of Science.
The most severe effects,
he said, occur when cyclical
flooding is removed from the
equation.
“We think of floods as
being these damaging forces
because of what they can do
to human infrastructure,”
said Tonkin, a postdoctoral
scholar in integrative biology.
“But flooding has benefits
across the board, for both
organisms and habitats in and
around rivers.”
Findings were published
in Nature Ecology and
Evolution.
Researchers used models
to explore how a variety of
possible flow scenarios could
affect the diversity and integ-
rity of riparian forests along
major rivers and looked at
five tree and shrub guilds
common to rivers worldwide.
The guilds were groupings of
species with similar responses
to water availability and river
flow disturbance.
The scientists used
detailed species biology and
83 years of flow data from
Colorado’s Yampa River, an
undammed, 250-mile water-
way, to build a computer
model to predict future flows
and to quantify the effects
of flow changes on riparian
plant communities.
Results showed that even
modest alterations in the his-
torical patterns of flood and
drought can have negative
effects on ecological net-
works, in this case, competing
plant guilds, and that network
— connectance — decreased
as flow regime alteration
increased; connectance is a
measure of just how linked
species in a network are to
one another.
Study results also indicate
that river flow homogeniza-
tion, a result of damming,
may be just as detrimen-
tal as drought to riparian
communities.
“Connectance plays a
fundamental role in main-
taining biodiversity,” Tonkin
said. “Evidence suggests that
highly connected communi-
ties are better able to deal
with species losses in food
webs and are more resistant
to invasion by non-native
species. The simplification
of these networks, including
because of drought conditions
that are predicted to increase
widely over the next century,
may predispose networks to
collapse.”
Thus, preserving or restor-
ing key components of natu-
ral flow regimes, which
enhance connectance, should
be a priority for river manag-
ers, he said.
“River-dependent com-
munities have evolved over
millennia and have been tai-
lored by natural selection to
the volume and seasonal vari-
ability of the flows,” he said.
“Maintenance of flooding is
fundamentally important for
ecosystem health. Flooding is
a vital driver of the ecology
of rivers.”
One of the effects of
reduced flooding is a change
regarding which riparian
guild plays the keystone
role; keystone refers to hav-
ing the single largest effect
on the ecological network in
terms of influences on other
species.
“Removing floods, in par-
ticular, led to a loss of key-
stone status of hydroriparian
pioneer trees, which are spe-
cies like cottonwoods, alders,
PHOTO BY JIM CORNELIUS
Whychus Creek runs high and fast through Sisters. Restoration work is allowing for natural and healthy flooding
patterns.
and river red gum,” Tonkin
said. “Loss of keystone guilds
leads to changes in funda-
mentally important ecosys-
tem services.”
Those include habitat
provision for wildlife, flood
mitigation and bank stability,
microclimatic regulation, and
nutrient cycling.
“Because different guilds
have different soil require-
ments and ecological roles, it
is important to predict which
ones will function in a key-
stone role under future flow
regime scenarios,” he said.
Supporting this study
F
LL TODAY
E IN OR CA
OR YOUR
E
C
N
A
R
U
S
FREE I N ISON!
COMPAR
COM
541-588-6245
257 S. Pine St., #101 | farmersagent.com/jrybka
AUTO • HOME • LIFE • BUSINESS
were the U.S. Department
of Defense, the U.S. Forest
Service and Dinosaur
National Monument.
Collaborators included
David Lytle of the OSU
College of Science as well
as researchers from the
University of Washington and
the Forest Service.
Dr. Thomas R. Rheuben
General, Cosmetic, Implant
and Family Dentistry
~ Over 22 years Serving Sisters ~
We are preferred providers for Delta Dental PPO and Premier,
MODA, Advantage, Pacifi c Source, Cigna and the V.A.
541-549-0109
|
304 W. Adams Ave.
Now Serving
New Fall Menu
Tasty Thursday: November 30
Whychus Cellar, 5-7 p.m.
Live Music Sat., Dec. 2
7-9 p.m. No cover!
Open T
O
Tuesday-Saturday
d S t d 12
12-8
8 pm
391 W. Cascade Ave. | 541-549-2675
corkcellarswinebistro.com
|
Sisters