Yellowstone River Wetland/Riparian Change Detection Pilot Study
Subtitle: prepared by Gregory M. Kudray and Thomas Schemm
By: prepared for: the Custer County Conservation District and the Yellowstone River conservation District Council,
Contributors: Schemm, Thomas; Montana State Library; Montana Natural Resource Information System; Montana Natural Heritage Program
Publisher: Montana Natural Heritage Program
Published: 2006
Place of publication: Helena, MT
Language: eng
Number of pages: 16
Subjects: Riparian ecology; Riparian areas; Wetland conservation
Description: Two reaches of the Yellowstone River riparian  corridor were mapped using the U.S. Fish and  Wildlife Service (USFWS) classification systems  for wetlands and Western riparian types. We used  two series of aerial photography (1950 and 2001) to  map all of this area and also mapped the upstream  reach A16 on two additional series (1976 and  1996). We evaluated but did not map a few photos  from the earliest series available (1937 and 1938)  for their suitability to map wetlands. Our primary  objective was to evaluate the feasibility of mapping  wetlands and tracking wetland change over time on historical aerial photography. Government Land  Office (GLO) notes from the original land survey in  early settlement times were also reviewed to determine if they could be used as a data source.  All photo series were suitable for mapping  wetlands although the 1950 photos for the A16  reach near Columbus had been acquired during a  date of very high water levels resulting in a  probable under mapping of Palustrine wetlands.  The 1950 photos were also of relatively poor  quality compared to all other series and some  vegetation classes could not always be reliably  discriminated. Any future wetland change project  should make sure that the dates of imagery are  comparable.  The riparian corridor is extremely dynamic, as are  the associated wetlands, which are created and  destroyed regularly. Evaluating wetland change  requires a large enough sample or total area  acreage summary to be meaningful.  Created ponds have increased in both reaches but  especially in the more developed reach near  Glendive (D6). Wetland acreage has decreased in  both reaches (-7.6%) with a greater decrease in  D6 (-11%). Natural wetlands have decreased even more due to the acreage of created ponds  added. The less developed A16 reach was mapped  on four dates of aerial photography; wetland totals  varied within about a 10% range. The Riverine  type varied the most, probably due to water levels  and scouring from events within a few years  previous to the photo date.  Large peak flows are important in creating wetland  sites. There may be more wetland change  downstream than upstream since peak flows have diminished more downstream.  The GLO notes can be used to quantify early settlement riparian vegetation and compare it to  current conditions but wetlands are not  distinguished.  We created a crosswalk to the USFWS wetland and riparian systems from Natural Resource  Conservation Service (NRCS) land use and  vegetation cover classification systems used for  mapping on the river. The relationship was typically  complex and the NRCS minimum mapping unit is  too large to identify the small wetlands often  present.
Notes: "July 2006"--Cover.

"Agreement Number : YRCDC011".

Includes bibliographical references (p.16).