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About The nugget. (Sisters, Or.) 1994-current | View Entire Issue (Nov. 29, 2017)
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
