Draft species management guide for Arabis hastatula Greene

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Abstract:

Hells Canyon rockcress (Arabis hastatula Greene), is a newly rediscovered species, which is found on isolated cliff faces in a portion of Hells Canyon, in Wallowa County of northeastern Oregon. It is currently known only from the Hat Point Ridge system, located between the Imnaha and Snake River Canyons, with all locations on east facing cliffs between 6000 and 7000 feet in elevation, on lands managed by the Wallowa-Whitman National Forest. Arabis hastatula is a species which was largely unknown until this year. In 1910, E.L. Greene (Greene 1990) described a small, purple flowered rock cress discovered from rocky outcrops, mountain ridges of eastern Oregon, as Arabis hastatula. The type specimen had immature fruits only, and so when the genus was revisited by the current expert, Reed Rollins, he was unsure that it was a distinct species, because of the poor fruits of the existing specimens. As a result, the species was excluded from the Flora of the Pacific Northwest, and other regional floras, and disappeared from view. In 1993, Reed Rollins published his revision of The Cruciferae of Continental North America. In this, he included Arabis hastatula, with a comment that he had found an additional specimen, collected by J.T. Howell in 1952 between Hat Point Ranger Station and Saddle Creek View Point, in Hells Canyon of Oregon. This new specimen had mature fruit, and confirmed this was indeed a distinct species. Dr. Kenton Chambers (an Emeritus Professor at Oregon State University) and Larry Morse (the Nature Conservancy's Chief Botanist) independently noticed this new taxon, and brought it to the attention of the Oregon Natural Heritage Program in December of 1995. As a result of this information, efforts to relocate this taxon and to determine its status were included in a challenge cost share project between the Oregon Natural Heritage Program and the Wallowa Whitman National Forest in the summer of 1996. The fieldwork resulted in the rediscovery of Howell's site, and the discovery of an additional nine occurrences, all on cliffs and bluffs at the top of a 20 mile, 6000-7000 foot ridge system at the highest point in the Oregon portion of Hells Canyon. The canyon is over a mile deep at this point, and the plant only grows in a narrow band at the very top of the cliffs, which may help to explain why it was not seen for so long. All of the occurrences of Arabis hastatula were quite small, the largest having only about 50 plants - with a total of less than 1000 individuals in the world. However, they are located on fairly steep cliffs and bluffs, (barely) within the Hells Canyon Wilderness Area, which means they are not currently very threatened. The primary objective of this Management Guide is to outline a plan for managing Arabis hastatula on the Wallowa-Whitman National Forest, which will allow for the species' survival through time, and will reduce the need for its placement on the USFWS's list of endangered and threatened species. This guide is divided into two major sections. The first provides the most recent information on the range, distribution, population biology, and habitat requirements of Arabis hastatula. The second identifies management practices consistent with the species' needs, including the identification of essential monitoring needs.

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Reference Code: U97KAG01IDUS

Full Citation: Kagan, J. 1997. Draft species management guide for Arabis hastatula Greene.Oregon Natural Heritage Data Base, unpublished report prepared for Wallowa-Whitman National Forest. 8 pp. plus appendices.

Location: PLANT EF: ARABIS HASTATULA