Patricia S. Muir

Growth of Usnea longissima Across a Variety of Habitats in the Oregon Coast Range

Abstract The sensitive lichen Usnea longissima Ach. has a limited, patchy distribution across forested landscapes in the U.S. Pacific Northwest. To gain insight into whether the current distribution within the Oregon Coast Range has resulted from a lack of suitable habitat or from dispersal limitations, we measured growth of U. longissima transplants placed in four habitats. Transplant study site locations and habitats were determined through an accompanying study that identified significant U. longissima habitat characteristics, based on the present distribution of the species, and used predictive modeling to identify areas of apparently suitable habitat within the study area. Transplants were placed in 12 sites, comprised of three replicates of the four habitats. Ninety transplants were placed in each habitat (n = 360). Growth was measured as changes in biomass and length after one year. Transplants grew in all habitats, particularly in sites where habitat was predicted to be least suitable for U. longissima. Although transplants in those sites had mean biomass increases that were 2.7 to 4.6 times greater than those of transplants placed in the other three habitats, their overall rate of attrition was 1.5 to 1.8 times higher than transplants in the other three habitats. Increases in length were also greatest in sites where habitat was predicted to be least suitable. The fact that the transplants grew well in all habitats and actually thrived in sites where habitat was predicted to be least suitable indicates that dispersal limitations may play a more significant role than the availability of suitable habitat in determining the distribution of U. longissima in the Oregon Coast Range. These findings underscore the importance of green tree retention during timber harvests. Trees containing U. longissima should be retained so that they may inoculate the regenerating stand with U. longissima fragments. It is also recommended that stands harboring significant populations of U. longissima (typically old stands) be preserved as source locations of this dispersal-limited species.

Responses of Chaparral and Oak Woodland Plant Communities to Fuel-Reduction Thinning in Southwestern Oregon

Abstract Fire suppression has led to large fuel accumulations in many regions of the United States. In response to concerns about associated wildfire hazards, land managers in the western United States are carrying out extensive fuel-reduction thinning programs. Although reductions in cover by woody vegetation seem likely to cause changes in herbaceous communities, few published studies have reported on consequences of such treatments for native or exotic plant species. We compared vegetation and abiotic characteristics between paired thinned and unthinned chaparral and oak woodland communities of southwestern Oregon 4–7 yr posttreatment and contrasted impacts of manual vs. mechanical treatments. Herbaceous cover increased on thinned sites, but species richness did not change. Herbaceous communities at thinned sites had an early postdisturbance type of composition dominated by native annual forbs and exotic annual grasses; cover by annuals was nearly twice as high on treated as on untreated sites. Absolute and proportional cover of native annual forbs increased more than any other trait group, whereas exotic annual forbs and native perennial forbs declined. Exotic annual grass cover (absolute and proportional) increased, whereas cover by native perennial grasses did not. Shrub reestablishment was sparse after thinning, probably because of a lack of fire-stimulated germination. Manual and mechanical treatment impacts on abiotic site conditions differed, but differences in vegetation impacts were not statistically significant. Fuel-reduction thinning may have some unintended negative impacts, including expansion of exotic grasses, reductions in native perennial species cover, persistent domination by annuals, and increased surface fuels. Coupled with sparse tree or shrub regeneration, these alterations suggest that ecological-state changes may occur in treated communities. Such changes might be mitigated by retaining more woody cover than is currently retained, seeding with native perennials after treatment, or other practices; further research is needed to inform management in these ecosystems.

Environmental Factors Influencing the Distribution of the Lichens Lobaria oregana and L. pulmonaria

Lobaria oregana (Tuck.) Miill. Arg. and L. pulmonaria (L.) Hoffm. are parapatric in western North America. However, L. pulmonaria is more widely distributed than L. oregana; in western Oregon, L. pulmonaria occurs in the Willamette Valley and forests of the Cascades and Coast Ranges, while L. oregana is largely restricted to the mountain forests. To determine whether distribution patterns are related to differential environmental tolerances, we examined responses to heat and desiccation and growth responses of transplanted thalli. Heat tolerances were tested by exposing thalli (air-dry or moist) to temperatures ranging from 24-400C (30C intervals) and 25- 600C (5 0C intervals)for 1 hr. Sensitivity was assessed by measuring electrical conductivity ofdeionized water in which thalli were immersed, which reflects membrane damage. Heat tolerances of the two species did not differ. Lobaria pulmonariafrom the Willamette Valley was apparently less desiccation tolerant than L. oregana from upper canopies in the Cascade Mountains. Intraspecific differences in desiccation tolerance depended on the environment from which thalli were collected and were as great as interspeciic differences. Thus, differences in distribution between the two species do not appear to be due simply to differential heat or desiccation tolerances. Lobaria oregana from upper canopies in the Cascades grew more slowly than L. pulmonaria from lower tree trunks in the Willamette Valley when both were transplanted to the Willamette Valley for 18 weeks. However, survival of the two species did not differ 9 weeks after transplanting to the Willamette Valley.

Using Transplants to Measure Accumulation Rates of Epiphytic Bryophytes In Forests of Western Oregon

Abstract We sought a simple and effective transplant method that could be used to measure biomass accumulation rates of epiphytic bryophytes. Trials were carried out in the Pseudotsuga menziesii-dominated forests of western Oregon. We tested multiple transplant methods over a 13-month period while comparing accumulation rates of Antitrichia curtipendula (Hedw.) Brid. and Isothecium myosuroides Brid. among an old-growth stand, a young stand, and a recent clearcut. In our study area, Antitrichia is considered to be an old-growth associate while Isothecium is a more ubiquitous species. Methods tested included containment in net bags, containment in hairnets, and directly tying mats to substrates. Three sizes of transplants were tested with both natural and inert artificial substrates. Transplants of approximately five g enclosed in plastic net bags and tied to either natural or artificial substrates worked well for our purposes. Only minor differences were found in mean accumulation rates between the old growth and young stand, though variation in accumulation rates was higher in the old growth. Neither species appeared capable of surviving in the clearcut. Antitrichia accumulated biomass 60% faster in the canopy than in the understory on average. Antitrichia also accumulated at a faster rate than Isothecium, with mean 13-month biomass increases of 11.8 and 3.7% respectively for 5 g transplants in the understory. Our results suggest that Antitrichias association with old growth may be due more to dispersal or establishment limitations than to a decreased ability to grow in young stands.

Quantity and value of commercial moss harvest from forests of the Pacific Northwest and Appalachian regions of the U.S

Abstract The work reported here addresses two primary questions: (1) How much “moss” (a mixture of mosses and liverworts) is harvested commercially from forests in the Pacific Northwest (PNW) and Appalachian regions of the U.S.? (2) What is the commercial value of this nontimber forest product? Methods included surveying land managers, botanists and moss dealers, querying U.S. government databases, and interviewing people involved in the moss trade. Approximately 35% of land manager respondents issued permits for moss harvest in the last five years. These reported that permits were issued for an average of 4,009 (Appalachian) and 96,433 (PNW) air-dry kg/yr of moss over the years 1997–2002, with a maximum reported permitted harvest of 166,793 air-dry kg across both regions in the year 2000. Official U.S. Forest Service sources listed the maximum yearly reported harvest for these regions as 115,661 air-dry kg in 2000 (PNW = 71,534 kg and Appalachians = 44,127 kg) and official Bureau of Land Management sources for OR and WA listed the maximum permitted harvest as 54,978 air-dry kg in 2001. Yearly revenues from sales of commercial moss harvest permits were reported to be ≤ US

Harvestable Epiphytic Bryophytes and their Accumulation in Central Western Oregon

19,650. In contrast, estimates of total harvests based on export data and assumptions about those data suggest that the mean yearly harvest for the years 1998–2003 was between 4.6 and 18.4 million air-dry kg (yearly minimum and maximum estimated at 0.9 and 37.4 million air-dry kg, respectively). Moss sales (domestic plus exports) are estimated to total between US

Does Kochia prostrata Spread From Seeded Sites? An Evaluation From Southwestern Idaho, USA

˜6 million and 165 million per year. The wide ranges in these estimates illustrate how little is known about the moss harvest trade. In combination with lack of information about the size of the moss inventory, reaccumulation rates, and species and ecosystem functions potentially affected by harvest, results indicate that policy makers and land managers lack critical information on which to base harvest regulations.

Fogwater Chemistry in a Wood-Burning Community, Western Oregon

Abstract Methods for characterizing the composition, biomass, and accumulation rates of harvestable epiphytic bryophytes in the understory of temperate forests have recently been developed, but have yet to be implemented in a much wider geographical area and adapted to provide estimates at the individual mat level. In response to regulatory need, we modified and implemented these methods in 27 50+ yr-old upland and riparian forest stands below 915 m to: a) characterize the composition of harvestable epiphytic bryophytes in central western Oregon, b) evaluate the compositional changes immediately following harvest, and c) retrospectively estimate minimum simple accumulation rates for harvestable bryophyte mats. Twenty-two bryophyte species, two lichens, and one vascular plant were found in a total of 433 sampled mats, dominated by Isothecium myosuroides, Neckera douglasii, Antitrichia curtipendula, Frullania tamarisci subsp. nisquallensis, and Porella navicularis. Harvest brought on significant shifts in the relative abundance of species primarily through the disproportionate removal of these species, which are commonly found in harvestable bryophyte mats throughout western Oregon. The minimum simple accumulation rate for bryophyte mats from 13 of these stands, calculated as the oven-dried mat mass per unit surface area divided by the stem age, was 22.4 (std 15.5) g/m2/yr and is approximately comparable to that previously observed in the Coast and Cascade Ranges of northwestern Oregon. This accumulation rate translates into a commercial harvest rotation period of at least 21 (std. 12) yr. This long rotation time, coupled with the scarcity of sites supporting harvestable mats, leads to our recommendation that commercial bryophyte harvest be prohibited in the study region.

Vegetation Change from the Euro-American Settlement Era to the Present in Relation to Environment and Disturbance in Southwest Oregon

Abstract Purposeful introductions of exotic species for rehabilitation efforts following wildfire are common on rangelands in the western United States, though ecological impacts of exotic species in novel environments are often poorly understood. One such introduced species, Kochia prostrata (L.) Schrad (forage kochia) has been seeded on over 200 000 ha throughout the Intermountain West to provide fuel breaks and forage, and to compete with invasive plants. Despite its potential benefits, K. prostrata has been reported to spread from some seeded areas, and no studies have addressed its potential interactions with native species. A systematic investigation is needed to increase understanding of the extent to which K. prostrata spreads from seeded areas, the environmental conditions under which it spreads, and its interactions with the associated plant communities. We sampled 28 K. prostrata postfire rehabilitation and greenstrip seedings in southwestern Idaho, which ranged from 3 to 24 yr since seeding. We analyzed cover of K. prostrata and the associated plant community in adjacent seeded and unseeded areas, and quantified extent of spread from seeded areas. Abundance of K. prostrata was negatively associated with that of most plant functional groups, including native species, but was positively associated with abundance of exotic annual forbs. Kochia prostrata spread to unseeded areas on 89% of sampled sites; distances of the farthest individual from the seeding boundary were greater than those previously reported, ranging from 0 to 710 m, with a mean distance of 208 m. Further, although the area covered by K. prostrata increased with time since seeding, we found no evidence that plant community composition affected spread of K. prostrata. Results contribute to current understanding of potential ecological implications of seeding K. prostrata and will enhance the ability of land managers to make scientifically based management decisions about its use.

Conservation Management of the Mixed Species Nontimber Forest Product of “moss”—Are they Harvesting What we think they’re Harvesting?

Fogwater chemistry in Corvallis, Oregon, a wood-burning community (pop. approximately 43,000) was compared with the chemistry of fogwater collected in more remote and in more highly industrialized areas. The fogwater was not acidic (median pH = 5.7) and was usually dominated by SO4=, NO3-, and NH4+ whose concentrations were generally lower than in fogwater in other urban areas but higher than in remote areas. Concentrations of formic and acetic acids (medians = 61 and 52 microN, respectively) were comparable to those in fogwater in Los Angeles, California and were typically much higher than concentrations in fogwater from more remote areas. Formate and acetate concentrations were often comparable to those of SO4= and NO3-. Formaldehyde concentrations (range = 0.4-3.0 mg L-1) were comparable to those in fogwater in some urban areas of southern California, yet lower than concentrations in highly industrialized areas of southern California. Because concentrations of organic compounds in Corvallis fogwater were often comparable to those in larger urban areas, sources in addition to motor vehicles must be important in Corvallis. Additional sources may be natural and anthropogenic, the latter including residential wood burning and wood products industries.