PARENT SESSION
Oral Session 13: Rare, Threatened, and Endangered Species I: Management I.
Presiding: H Balbach
Monday, August 2, 8:00 AM to 11:30 AM, Meeting Room D 135.

Estimating abundances and testing habitat associations for over 300 Survey and Manage species within the Northwest Forest Plan (western Washington, western Oregon, and northern California).

Rittenhouse, Bruce^*,1, Turley, Marianne², ¹ National Park Service, Fort Collins, Colorado, USA² Bureau of Land Management, Portland, Oregon, USA

ABSTRACT- A random grid survey was conducted on 24 million acres within the Northwest Forest Plan (NWFP) to: 1) estimate abundances for over 300 Survey and Manage species, and 2) test their association with late-successional forests, using binary data (detection/non-detection) per sample unit. Specific sample units per taxa, e.g. 1/2-acre for botanical species (lichens, bryophytes, vascular plants), one hectare for mollusks, and 100 m² and 1,000 m² for fungi were sampled at randomly selected Current Vegetation Survey/Forest Inventory Assessment plots. Plots were selected using a spatially-balanced, stratified design to ensure distribution of the sample across the NWFP and within subpopulations of interest: land use allocation (Matrix vs. Reserve) and habitat (late-successional forest vs. non-late-successional forest). A total of 750 plots were sampled for botanical species, 660 for fungi, and 450 for mollusks. Taxa-specific sampling protocols were implemented at each plot. Abundances, estimated by proportion and numbers, represented a species occurrence per sample unit area in the NWFP. Chi-square and exact tests were used to test the association of species detection with habitat. Detections were made for 187 species and ranged from one to 181. Examples of abundance estimate results include: 1) Buxbaumia viridis expected to occur on 1.74 ± 0.95 percent of the NWFP or 750,000 ± 409,000 1/2-acres; and 2) Lobaria oregana expected to occur on 9.99 ± 2.43 percent of the NWFP or 4,312,000 ± 1,050,000 1.2-acres. Most detected species had very low abundance estimates. Species with positive, statistically significant associations with late-successional forests included Ptilidium californicum and Chaenotheca furfuracea. Most species had too few detections for association tests or showed no statistically significant association with habitat. Information collected from this survey is critical in making management decisions for federal land management agencies and state heritage programs.

Key words: stratified random sample, Northwest Forest Plan, rare species