PARENT SESSION
Poster Session #8: Riparian Ecology.
Monday, August 6, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall
148
Historical vegetation reconstruction to define reference condition.
Barker, Jerry1, McAllister, Lynne1, Bryce, Sandy1, Larsen, David2, 1 2
ABSTRACT- Defining a reference condition for watersheds and riparian corridors is necessary to judge the type and degree of human disturbance to streams and is also useful for restoration and monitoring. Reference condition can be defined by characterizing minimally disturbed or least disturbed sites. Also, historical reconstruction and expert judgement are other ways to define reference condition. We evaluated the usefulness of the General Land Office (GLO) survey notes and plat maps to characterize historical vegetation cover types for defining reference condition for riparian corridors and adjacent forests of the John Day and Deschutes river basins in eastern Oregon. The historical vegetation types of the Cable Creek watershed consisted of prairie, open coniferous forest, and closed coniferous forest. Dominant trees were fir, spruce, alder, and tamarack. Tree densities and basal areas ranged from 32-1520 trees ha-1 and 1.9-136.3 m2 ha-1, respectively. The vegetation data extracted from the GLO notes conformed to information from other sources such as descriptions of potential historical and natural vegetation for eastern Oregon. The GLO survey records were useful for characterizing historical vegetation cover types at broad ecological scales but provided limited information on riparian corridors especially for low order streams.
KEY WORDS: historical, reference condition, watershed, riparian