title: Riparian vegetation as an indicator of riparian condition: Detecting departures from historic condition across the North American West.
abstract: Floodplain riparian ecosystems support unique vegetation communities and high biodiversity relative to terrestrial landscapes. Accordingly, estimating riparian ecosystem health across landscapes is critical for sustainable river management. However, methods that identify local riparian vegetation condition, an effective proxy for riparian health, have not been applied across broad, regional extents. Here we present an index to assess reach-scale (500 m segment) riparian vegetation condition across entire drainage networks within large, physiographically-diverse regions. We estimated riparian vegetation condition for 53,250 km of perennial streams and rivers, 25,685 km in Utah, and 27,565 km in twelve watersheds of the interior Columbia River Basin (CRB), USA. We used nationally available, existing land cover classification derived from 30 m Landsat imagery (LANDFIRE EVT) and a modeled estimate of pre-European settlement land cover (LANDFIRE BpS). The index characterizes riparian vegetation condition as the ratio of existing native riparian vegetation cover to pre-European settlement riparian vegetation cover at a given reach. Roughly 62% of Utah and 48% of CRB watersheds showed significant (>33%) to large (>66%) departure from historic condition. Riparian vegetation change was predominantly caused by human land-use impacts (development and agriculture), or vegetation change (native riparian to invasive or upland vegetation types) that likely resulted from flow and disturbance regime alteration. Through comparisons to ground-based classification results, we estimate the existing vegetation component of the index to be 85% accurate. Our assessments yielded riparian condition maps that will help resource managers better prioritize sites and treatments for reach-scale conservation and restoration activities.
authors.affiliation: Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT 84322-5210, USA. Electronic address: wally.macfarlane@usu.edu.
authors.forename: William W
authors.initials: WW
authors.lastname: Macfarlane
authors.affiliation: Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT 84322-5210, USA. Electronic address: jtgilbert89@gmail.com.
authors.forename: Jordan T
authors.initials: JT
authors.lastname: Gilbert
authors.affiliation: Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT 84322-5210, USA. Electronic address: martaljensen@gmail.com.
authors.forename: Martha L
authors.initials: ML
authors.lastname: Jensen
authors.affiliation: Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT 84322-5210, USA. Electronic address: joshuadgilby@gmail.com.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Gilbert
authors.affiliation: Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT 84322-5210, USA. Electronic address: nate@natehough-snee.org.
authors.forename: Nate
authors.initials: N
authors.lastname: Hough-Snee
authors.affiliation: Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT 84322-5210, USA; Eco Logical Research, Inc., Providence, UT 84332, USA. Electronic address: peter.a.mchugh@gmail.com.
authors.forename: Peter A
authors.initials: PA
authors.lastname: McHugh
authors.affiliation: Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT 84322-5210, USA; Anabranch Solutions, LLC, Nibley, UT 84327, USA. Electronic address: joe.wheaton@usu.edu.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Wheaton
authors.affiliation: Department of Watershed Sciences, Utah State University, 5210 Old Main Hill, Logan, UT 84322-5210, USA; Eco Logical Research, Inc., Providence, UT 84332, USA; Anabranch Solutions, LLC, Nibley, UT 84327, USA. Electronic address: bennett.ecological@gmail.com.
authors.forename: Stephen N
authors.initials: SN
authors.lastname: Bennett
mesh_terms: D000383:Agriculture; D044822:Biodiversity; D017753:Ecosystem; D006801:Humans; D045483:Rivers; D014481:United States; D014589:Utah
keywords: Columbia River Basin; Condition assessment; Floodplain assessment; Landscape planning; Riparian restoration; Utah