THE BRYOLOGIST AJOURNAL OF BRYOLOGY AND LICHENOLOGY VOLUME 104 SUMMER 2001 NUMBER 2 The Bryologist 104(2), pp. 181 190 Copyright q 2001 by the American Bryological and Lichenological Society, Inc. Harvestable Epiphytic Bryophytes and their Accumulation in Central Western Oregon JERILYNN E. PECK1 AND PATRICIA S. MUIR Department of Botany & Plant Pathology, Cordley Hall 2082, Oregon State University, Corvallis, OR 97331-2902, U.S.A. Abstract. Methods for characterizing the composition, biomass, and accumulation rates of harvestable epiphytic bryophytes in the understory of temperate forests have recently been devel- oped, 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 modi®ed and implemented these methods in 27 501 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 Isothe- cium myosuroides, Neckera douglasii, Antitrichia curtipendula, Frullania tamarisci subsp. nis- quallensis, and Porella navicularis. Harvest brought on signi®cant 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 accumu- lation 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. In recent years, commercial ``moss'' harvest mits for 49,896 kg (10±30% moisture content; (typically a mixture of bryophytes; Peck 1997a) has 110,000 lbs) of epiphytic moss per year that may become a controversial issue in the Paci®c North- be harvested only outside of riparian areas, in the west. Federal land managers are increasingly faced lower canopy, and from ``every other stem'' in the with writing management guidelines that must bal- forest (USDA 1995). The Eugene District of the ance the demand for the resource, the multiple-use Bureau of Land Management (BLM) in western mandate on U.S. National Forest lands (Wilkinson Oregon also prohibits harvest in riparian areas, as & Anderson 1987), the need to protect species of well as in Late Successional Reserves (LSR). How- concern (ROD 1994), the sustainability of the in- ever, these harvest restrictions are based on almost ventory, and the ecosystem functions of epiphytic no solid information on four critical parameters: 1) bryophytes. For example, the Siuslaw National For- the long-term impacts of harvesting on species est (SNF) in western Oregon currently issues per- composition and the ecosystem functions associat- ed with epiphytic moss, 2) the size of the moss 1 Current address: e-mail: jeri@strengthinperspective. resource (inventory) available for harvest, 3) the com actual amount of moss currently being removed 0007-2745/01/181±190$1.15/0 182 THE BRYOLOGIST [VOL. 104 from the forest, and 4) the rate at which mosses vestable epiphytic bryophyte mats in this area, the reaccumulate following harvesting (Peck & Mc- changes in these communities immediately follow- Cune 1998). Information on these parameters is vi- ing harvest, and our estimates of mat accumulation tally important to guide permitting decisions in the rates based on this modi®ed methodology. future (Liegel 1992). Recent work has begun to ®ll these gaps in our METHODS understanding. Firstly, estimates of the community composition of harvestable bryophytes now exist Of 100 randomly selected sites on the Eugene District for selected areas on the Hebo District, SNF and of the Bureau of Land Management in central western Oregon, only 27 had suf®cient quantities of harvestable the Salem District, BLM (Peck 1997a,b) and for bryophytes to enable sampling. All 100 sites were within various other areas around the state of Oregon the elevation and stand age ranges considered likely to (Vance & Kirkland 1997). Secondly, estimates of support harvestable epiphytic bryophytes in this region: the size of the moss resource are also available for #915 m and $50 yr (see Peck & Muir 2001 for site se- lection and stand characteristic details). Sites were located the Hebo and Salem Districts (Peck & McCune in the rain shadow of the Oregon Coast Mountain Range, 1998). Thirdly, although the illegal harvest is esti- between the eastern foothills of the Coast Range and the mated to remove between two and 30 times the western foothills of the Cascade Range in the Paci®c legal harvest quantity (USDA 1995), harvest permit Northwest of North America (438309±448159 N, 1228309± records provide some information on the rate of 1238509 W). Sites were located between 125 and 744 m in elevation with a basal area of conifers (primarily Pseu- removal of moss from the forest. Finally, some dotsuga menziesii) between zero and 46 m2/ha and were long-term studies of regrowth rates and the impacts in management units of greater than four ha (10 acres). of harvest on species composition are underway on Thirteen sites were in forests less than 150 yr in age (all the Hebo District (Peck 1999), on the Eugene Dis- over 50 yr) and 14 in forests over 150 yr in age. All sites were sampled using one 35 3 35 m plot (1/8 ha 5 1/3 trict, BLM (Peck & Muir 1998), and in western acre), placed so as to be as internally consistent as pos- Washington (N. Nadkarni, pers. comm.; D. Shaw, sible with respect to slope, aspect, and forest composition. pers. comm.). These studies are based on harvest- Sampling occurred during the summers of 1997 and 1998. ing large bryophyte mats from permanently marked Harvestable bryophyte mats were de®ned, following shrub stems and periodically remeasuring reaccu- Peck (1997a), as loose clumps of green epiphytic bryo- phytes of at least 200 cm3 in volume. These harvestable mulation, and will require decades before reliable bryophytes mats were removed from approximately 10 reaccumulation rates can be obtained. However, shrub stems or shrub boles (95% vine-maple, Acer circin- managers are faced with resource utilization issues atum, 5% huckleberry, Vaccinium parvifolium) per plot, right now. which had been randomly selected from among those bearing harvestable bryophyte mats (in most plots this The current project, generated by the recognized was the entire population). From each of these stems a need for inventory, monitoring, and research in single continuous harvestable bryophyte mat (of variable nontimber product programs (USDI 1993), was de- length and volume) was harvested by lifting and peeling signed to characterize the impacted bryophyte com- away from the stem in one motion. All taxa were identi- munities, and estimate rates of mat accumulation, ®ed and their relative abundances estimated, after McCune (1990). The total volume of each mat, as well as the length in sites where harvestable bryophytes occur on the and diameter of the section of stem from which it was Eugene District, BLM in central western Oregon. removed, was also measured. In 13 sites (the ``rate'' sites), Traditional estimates of bryophyte growth, such as an increment core was taken from the center of the har- measuring shoot-tip growth or the length of annual vested section of the stem to provide the retrospective estimation of accumulation rates (see below). Increment growth segments (see discussion in Russell 1988) cores were sanded and annual growth rings counted uti- are inadequate to estimate biomass accumulation in lizing a dissecting microscope. In the other 14 sites (the situ at large spatial scales. A methodology has been ``impact'' sites), all bryophytes remaining on the stem in developed and employed in the Coast Range of the section from which the mat was harvested were also northwestern Oregon that provides stand-level es- recorded and their relative abundances estimated. These stems were not cored and are intended to be remeasured timates through retrospective means (Peck & ®ve years following harvest to facilitate regrowth-based McCune 1998). We chose to employ a modi®ed estimates of accumulation rates (to be remeasured in 2002; version of this procedure in central western Oregon, Peck & Muir 1998). Harvested mats were weighed after where harvestable biomass, and presumably accu- oven drying (24 hr at 60 C). Nomenclature follows An- derson et al. (1990) for mosses, Stotler and Crandall-Sto- mulation rates, are relatively low (Peck & Muir tler (1977) for hepatics, Esslinger and Egan (1995) for 2001). Our goal was to determine the minimum ac- lichens, and Hitchcock and Cronquist (1973) for vascular cumulation rate of individual harvestable bryophyte plants. mats, rather than stand-level estimates, to enable The frequency of occurrence was calculated for each more direct comparisons with the results of prom- species for all sites combined and separately for the im- pact and the rate datasets. The quantitative data in all sub- ising new transplant methods for estimating epi- sequent analyses were relative proportions of each species phytic bryophyte growth rates (e.g., Rosso 2000). out of the total volume of each mat. Comparisons of har- We report here on the species composition of har- vested mat species compositions (``pre'') and post-harvest 2001] PECK & MUIR: HARVESTABLE BRYOPHYTES 183 residual species compositions (``post'') for the impact sites calculated a second set of accumulation values in a way were conducted using the Mantel test, a nonparametric test that approximates theirs as closely as possible.