commercial moss harvest in northwestern oregon: biomass and accumulation of epiphytes

Commercial moss harvest in northwestern Oregon: biomass andaccumulation of epiphytes

JeriLynn E. Peck *, Bruce McCuneDepartment of Botany and Plant Pathology, Cordley 2082, Oregon State University, Corvallis, OR 97331-2902, USA

Received 1 February 1997; received in revised form 10 February 1998; accepted 11 February 1998

Abstract

As concern over the sustainability of commercial moss harvest in the Paci®c Northwest has grown, so too has the need to developmethods for estimating the rate of harvest, the biomass inventory, and the rate of accumulation of commercially harvestable epi-phytes. We estimated biomass and net moss accumulation in 10 sites in both the historically heavily moss-harvested Coast Range

and the historically relatively unharvested Cascade Range of northwestern Oregon. Harvestable epiphyte biomass in the lowercanopy (<2m above ground) ranged from c. 120 to 1470 kg haÿ1 in the Coast Range, and 25 to 1068 kg haÿ1 dry weight in theCascade Range. The greater biomass at the Coast Range sites resulted from a higher density of suitable substrates, with epiphytemass per unit area of substrate roughly equal in the two sets of sites. Epiphyte mass accumulation on vine maple Acer circinatum

was extremely variable within and between sites, especially in the Coast Range. A model describing the factors a�ecting epiphytemat accumulation is described. We recommend active management to conserve epiphytic bryophytes through promoting hardwoodtree and shrub substrates, restricting moss harvest to the lower canopy, controlling the rate of harvest, and instigating rotation

periods. # 1998 Elsevier Science Ltd. All rights reserved.

Keywords: Bryophytes; Commercial moss harvest; Biomass; Paci®c Northwest; Non-timber product

1. Introduction

Commercial moss harvest is a trade about whichfew data exist. Anecdotal reports indicate a history ofharvesting in Mexico, Great Britain, and southeastUSA, but no detailed accounts exist outside of thenorthwest corner of Oregon in the Paci®c Northwestof North America (e.g. Peck, 1997a). Ecologists in thisregion have only recently begun to explore the eco-system roles of epiphytes, yet epiphytic bryophytes areincreasingly being removed from the western forests ofthe Paci®c Northwest to feed a global multi-milliondollar ¯oral industry (Schlosser et al., 1992). Poorrecords make estimates of past harvests impossible, butcommercial `moss' harvesters in northwestern Oregonindicate that harvesting has greatly increased since 1990(moss harvesters, Tillamook, OR, personal communica-tion, 1996). A conservative estimate for northwest Ore-gon is >226 800 kg yearÿ1 (500 000 lb yearÿ1; 10±30%water content; unpublished data). Althoughmost moss isharvested from publicly owned land, some agencies do

not issue formal permits, and those that do are awarethat most moss is harvested illegally (F. Duran, SiuslawNational Forest, personal communication, 1996).

Concern over the impact of commercial moss har-vesting is particularly acute now that data exist todocument the removal of a number of species associatedwith old-growth forests (Peck, 1997a) that may be listedfor greater protection in the future (ROD, 1994). Thereis also concern over the impact on the ecological role ofepiphytic bryophytes and the likelihood that commu-nities may require decades to recover (Peck, 1996). Inresponse to these concerns, some agencies have begun totighten regulations on moss harvesting. One NationalForest district in northwestern Oregon (56 660 ha) hasset a ceiling of 49 896 kg yearÿ1 (110 000 lb yearÿ1),which has been the average legal harvest for the past10 years, but is generally considered to be less than halfthe actual annual harvest from this district (USDAForest Service, 1995).

Public lands managers realize that moss harvestingwill continue whether or not it is legal as long as thedemand exists for fresh green moss. The immediatee�ect of prohibiting harvest on one National Forest dis-trict was a 20-fold increase in harvest on a neighboring

BIOLOGICAL

CONSERVATION

Biological Conservation 86 (1998) 299±305

0006-3207/98/$19.00 # 1998 Elsevier Science Ltd. All rights reserved

PII: S0006-3207(98)00033-0

* Corresponding author. e-mail: [email protected]

district and an unknown increase in illegal harvest(F. Duran, Siuslaw National Forest, personal commu-nication, 1996). The goal of conservation e�orts, there-fore, is to propose management practices that willprotect the epiphytic bryophyte community whileserving the multiple-use mandate of US National For-ests. To manage commercial moss harvest for sustain-ability, we must know the rate of harvest, the rate ofaccumulation, and the biomass inventory of availableharvestable moss. The rate of illegal harvest is ambig-uous at best (Peck, 1990), requiring detailed economicand anthropological studies beyond the scope of thecurrent paper. Managers are, however, able to controlthe rate of legal harvest by setting harvest limits. Someestimates of accumulation rates based on post-harvestrecovery (e.g. Peck, 1997c) are available, but requiremany more years of data collection to provide reliableestimates of growth trends. The objectives of this paper,therefore, were to report estimates of the available bio-mass of harvestable epiphytes, describe a retrospectivemethod for estimating accumulation of harvestablemoss, consider some of the factors in¯uencing thisaccumulation, and demonstrate how managers can usethis information to manage commercial moss harvestsustainably.

2. Methods

2.1. Sites

We focused on two areas in the northwestern cornerof Oregon, as commercial moss harvesters indicate thisas the region of primary harvest activity in the state: (1)the Coast Range, which historically and currently pro-duces the vast majority of commercial moss; and (2) theCascade Range, which is closer to the population cen-ters of the Willamette Valley, but has only recentlyproduced commercial moss. Although there were nosigns of recent disturbance at any of the sites, we suspectthat the Coast Range sites may have been partially har-vested for moss c. 15 years ago.

In the Coast Range, 10 sites were sampled within theHebo District of the Siuslaw National Forest, Oregon(45�20±45�130N, 123�50±123�550W). These sites werechosen speci®cally to represent suitable sites for com-mercial moss harvest and typically supported mixedconifer±hardwood stands of c. 100 years (natural post-®re regeneration) between 120 and 410m in elevation.The basal area of conifers, estimated using a wedgeprism (basal area factor=2.3m2 haÿ1=10 ft2 acreÿ1) at®ve points, was between 2.5 and 46.5m2 haÿ1 (Peck,1997a).

In the Cascade Range, nine sites were sampled onBureau of Land Management land and one on the San-tiam State Forest (44�300±45�200N, 122�120±122�350W).

These sites were chosen to span a broad range of standages, including unmanaged old growth and plantationsecond growth and included mixed conifer±hardwoodstands of c. 50±290 years between 75 and 780m in ele-vation. The basal area of conifers was between 12.5 and40m2 haÿ1 (Peck, 1997a).

2.2. Moss mat sampling

Epiphyte abundance has typically been evaluatedusing percent cover (e.g. Ho�man and Kazmierski,1969; Pike et al., 1977) rather than destructive biomasssampling (Russell, 1988). Exceptions include Wolf(1993), who directly sampled epiphyte biomass on tro-pical trees, McCune (1993) and Nadkarni (1984), whosampled biomass of canopy epiphytes from temperatetrees, and the current study, which mimics commercialepiphyte harvest. Most studies concerned with theaccumulation of epiphytic bryophytes have only focusedon the growth component, reporting increases over timein length or cushion area (Tallis, 1959; Pitkin, 1975),cover (Vance and Kirkland, 1997), or CO2 assimilation(Green and Sneglar, 1982; Aro et al., 1984). Our esti-mates of harvestable moss accumulation are netestimates for 1m long contiguous segments of epi-phytes, dominated by live, green brophytes, whichincorporate processes such as growth, mortality, her-bivory, litterfall and stochastic disturbance events.

The objective of the moss mat sampling was toapproximate the methods used by commercial mossharvesters in this area. These include partial removal ofcontiguous epiphyte mats in the lower canopy that aredominated by fresh, green bryophytes that are easy toremove, but often include a variety of epiphytic taxathat are taken incidentally (Peck, 1997a). Only `har-vestable quantities' of moss were sampled, de®ned asquantities of non-adherent species (i.e. no tiny appres-sed liverworts, e.g. Radula, ®rmly attached species, e.g.Dendroalsia, or individual tufts, e.g. Ulota) that a har-vester would consider worth removing. Generally, matsof at least 100 cm3 were considered harvestable quan-tities. Harvestable `moss' mats were typically composedof the mosses Isothecium myosuroides and Neckera dou-glasii, with varying amounts of the mosses Antitrichiacurtipendula, Eurhynchium oreganum, and Rhytidiadel-phus loreus and the liverworts Frullania and Porella,with a dozen other bryophytes, half a dozen lichens(especially Parmelia sulcata and Lobaria oregana), and acouple of vascular plants (Montia sibirica and Poly-podium glycyrrhiza) (Peck, 1997a). Nomenclature fol-lows Anderson et al. (1990) for mosses, Stotler andCrandall-Stotler (1977) for liverworts, and Hitchcockand Cronquist (1973) for vascular plants.

Within each site, a 200m (seven sites) or 300m (13sites) transect was established, 50m from the nearestroad. Every 50m along each transect a sampling point

300 J.E. Peck, B. McCune/Biological Conservation 86 (1998) 299±305

was established, such that there were ®ve samplingpoints on the 200m transects and seven on the 300mtransects. At each sampling point, four quadrants wereestablished, using the transect line and a line perpendi-cular to it as boundaries (Cottam et al., 1953). Withineach quadrant we sampled harvestable quantities ofmoss below a 2m vertical height cut-o� on the stems ofshrubs such as vine maple Acer circinatum and huckle-berry Vaccinium parvifolium, and on the trunks ofhardwood trees such as red alder Alnus rubra and big-leaf maple Acer macrophyllum. Because most sampleswere taken from shrubs, we refer to all hosts hereafteras `stems'. Although the upper canopies of conifer treesoften support harvestable quantities of epiphytes, wedid not sample conifers, because harvestable quantitiesof moss are rare on conifer boles and live conifer bran-ches are rare below 2m.

For each selected stem, the distance to the transectpoint and the total length of the stem up to the 2mheight cut-o� were recorded (Fig. 1). Many shrub stemsgrow at an angle and, thus, never reach this verticalheight. All harvestable epiphytes (the `moss mat') werethen removed from a 1m length of stem (the `micro-plot') randomly selected between the ground and the2m height cut-o�, and the stem diameter measuredfrom the center of the microplot. An increment core orcross-section was taken from the center of the microploton all vine maples to determine stem age. Most stemswere permanently tagged to enable future regrowthmeasurements (e.g. Peck, 1997c). In the laboratory, themoss mats were sorted by species, their abundance esti-mated visually as a percentage of the total volume ofmaterial in a given mat (after McCune, 1990), then ovendried (60�C for 24 h) and weighed. All epiphytes weregrouped together for biomass estimates, to bestapproximate the harvest techniques of commercial mossharvesters. The biomass of individual species, their

relative abundances, their relationship to site character-istics (Peck, 1997a) and their relationship to the hostspecies (Peck, 1997b) are presented elsewhere.

2.3. Calculations

The density of harvestable stems at each site per unitarea was estimated using the point-centered quartermethod. If the mean value of the distances to the fournearest stems d1±d4 is �m, then 1/�2 gives an estimateof the density of stems per m2. Thus, the density ofstems per ha is given by 10 000/�2. Although the point-centered quarter method is known to underestimatedensity in aggregated populations, this bias is con-sidered marginal unless stems grow in tight clusters(Persson, 1971), a condition we did not observe at thesesites. The point-centered quarter method was chosen asa fast and e�cient means of selecting samples to esti-mate harvestable epiphyte biomass given the time con-straint of 1 day per stand, which was desirable to makethe method practical for use by public land managerswith limited budgets. In our sites, the densities of vinemaple, which was the host for 60% of our samples,averaged 3053 stems haÿ1 in the Cascade Range and3940 stems haÿ1 in the Coast Range. This falls withinthe range of values for previous estimates of 104±4144 stems haÿ1 for vine maple alone (O'Dea et al.,1995).

The total biomass of harvestable epiphytes per sitewas estimated from the 20 or 28 samples and thesedensity calculations. To describe the accumulation ofthe moss mats, we plotted the mass of each microplotsample against the age of the stem from which it washarvested.

3. Results

3.1. Biomass estimates

Moss mat biomass was highly variable among allsites, ranging from 24 to 1068 kg haÿ1 in the CascadeRange, with an average of 358 [standard error (SE) 99],and from 119 to 1469 kg haÿ1 in the Coast Range, withan average of 550 (SE 130) (Table 1). This variabilitycan be considered a function of variability in (1) sitequality for growing harvestable moss and (2) theamount of suitable substrate among sites. Thus, the matmass was positively correlated with host surface area(Pearson correlation coe�cient r=0.74), such that siteswith more large surface area hosts had higher averagemat masses.

Average mat mass is our most direct indicator of sitequality, with the `best' site having 81 gmÿ1 and the`worst' site, still with harvestable quantities of moss,having only 19 gmÿ1 on average. Sites in both the

Fig. 1. Harvestable moss mat sampling schematic. Microplots (1m

long) were randomly centered between 0.5m above the ground and

0.5m below the 2m height cut-o�.

J.E. Peck, B. McCune/Biological Conservation 86 (1998) 299±305 301

Cascade and Coast Ranges averaged 44 gmÿ1 (SE 6.3and 5, respectively). Stem density, however, was higherin the Coast Range sites (Table 1). The variability in sitequality and substrate availability results in variability inthe stand-level biomass estimates; Fig. 2 models theharvestable moss biomass (kg haÿ1 oven-dry weight) asa function of average biomass per stem and stem den-sity. The position of sites on the mat biomass axisdepends on site quality and the relative in¯uence ofcommercial moss harvest and mat development. A sitethat is harvested for moss would shift down the bio-mass axis, but if allowed to accumulate moss, it would

gradually move up the axis. The position of sites on thestem density axis depends on host availability. Man-agement to reduce shrub density would decrease mossbiomass and shift a site to the left, while management toincrease shrub density would shift a site to the right.

3.2. Mat mass accumulation estimates

Harvested vine maple stems ranged from 4 to 83 yearsin age in the Cascade Range, and from 7 to 76 years inthe Coast Range. Moss mats on these stems rangedfrom 1 to 222 gmÿ1 in the Cascade Range, and from 1to 191 gmÿ1 in the Coast Range. Averaging over theperiod from 10 to 60 years of stem age (Fig. 3), the meanaccumulation rate was, therefore, 1.4 (standard devia-tion (SD) 1.3) gmÿ1 yearÿ1 for the Cascades, and 1.6

Table 1

Mean values for mat mass, stem length, stem density, and stand-level oven-dry biomass estimates of harvestable epiphytes in the Cascade (letters) and

Coast (numbers) Ranges, northwestern Oregon. Values in parentheses are standard errors

Site Mat mass

(gmÿ1)Stem length

(m stemÿ1)Stem density

(stems haÿ1)Biomass

(kg haÿ1)Site Mat mass

(gmÿ1)Stem length

(m stemÿ1)Stem density

(stems haÿ1)Biomass

(kg haÿ1)

Ca 19 2.6 6090 (870) 288 (40) 1 38 2.6 3140 (290) 329 (30)

Da 37 3.6 2920 (425) 1068 (200) 2 30 3.1 4620 (480) 339 (35)

Ea 29 2.9 3220 (325) 612 (113) 5 41 2.2 2710 (95) 210 (10)

Ga 81 2.3 1010 (65) 195 (22) 8 50 2.5 2790 (250) 597 (87)

L 64 2.2 340 (20) 37 (2) 9 78 2.7 4440 (415) 712 (50)

Oa 55 3.5 5030 (465) 379 (29) 10 40 3.0 7300 (565) 1469 (194)

Pa 51 2.3 4130 (435) 519 (44) 11 38 2.7 1260 (60) 119 (6)

Q 22 2.4 610 (20) 24 (1) 13 65 2.7 3040 (260) 558 (54)

Sa 54 2.6 1710 (75) 211 (16) 14 23 2.9 3210 (115) 227 (21)

T 27 2.8 4630 (275) 501 (56) 15 38 3.4 7450 (380) 947 (53)

Mean 44 (6.3) 2.8 (0.2) 3050 (633) 385 (99) Mean 44 (5) 2.8 (0.1) 4000 (635) 550 (130)

a Sites with 20, rather than 28, samples per site.

Fig. 2. Harvestable moss biomass (kg haÿ1) as a function of moss mat

mass per stem (kg stemÿ1) and stem density (stems haÿ1). Triangles areCascade Range sites; dots are Coast Range sites. Sites low on both

axes are of generally lower site quality than sites high on both axes.

Fig. 3. Harvestable moss mat net accumulation on Acer circinatum,

Cascade and Coast Ranges, northwestern Oregon. Dots represent

individual 1m long epiphyte mats.


(SD 1.4) gmÿ1 yearÿ1 for the Coast Range. These esti-mates re¯ect a minimum accumulation rate for harvest-able moss on vine maple given the likelihood of human(i.e. commercial moss harvest) or natural disturbanceduring the life of these vine maples.

4. Discussion

4.1. Harvestable moss biomass

The estimated biomass of harvestable moss in thelower canopy at these sites is only a small proportion ofthe total biomass of epiphytes at these sites. Estimatesfrom big-leaf maple alone put biomass of epiphyticbryophytes at >6000 kg haÿ1 in a mature Coast Rangetemperate rain forest (Nadkarni, 1984), while Rhoades(1981) estimated an epiphyte standing crop of4220 kg haÿ1 in a Paci®c Northwest subalpine ®r Abieslasiocarpa forest. Old-growth conifer stands in theCascades are estimated to have >700 kg haÿ1 (McCune,1993) to 900 kg haÿ1 of bryophyte biomass (Pike et al.,1977). Most of the sites chosen speci®cally for harvestablemoss had a greater biomass of epiphytic bryophytes inthe lower canopy than has been found in the entire canopyof conifer stands of comparable age. McCune (1993) esti-mated that a 95-year-old conifer stand in the CascadeRange had c. 165kghaÿ1 of epiphytic bryophytes.

4.2. Harvestable moss accumulation

Studies of bryophyte growth have found highly vari-able rates of growth among sites and among species(e.g. Pitkin, 1975) and have implicated a myriad ofstand characteristics (Hosokawa et al., 1964). In ourarea, site characteristics of importance may include ele-vation, aspect, proximity to standing surface water,exposure to fog, etc. Local characteristics of importanceto bryophyte growth may include canopy cover (relatingto light availability), distance from each sampled stemto the nearest dominant conifer or hardwood tree (lightand/or propagule supply), and density of host shrubs inthe immediate vicinity of the sampled stem (host avail-ability), etc. (e.g. Peck, 1997a). Within-stand dynamics,such as litterfall, also a�ect net mat accumulation. Wesuspect that when mat mass accumulates rapidly onyoung stems it is through the re-establishment of litter-fall from higher in the canopy (Fig. 3). Litterfall fromthe canopy is evident on the forest ¯oor, logs, andshrubs in these stands, and several bryophyte speciescommonly re-establish on the forest ¯oor (Peck et al.,1995) and other substrates. Disturbances, such as treefall, often scrape moss mats from trunks and branches,stripping them bare.

To better understand the mechanisms behind epi-phyte mat accumulation, a number of additional factors

need to be examined. We propose a simple model fornet harvestable epiphyte accumulation (Fig. 4) incor-porating possible inputs, outputs, and processes.Calibrating the model will require experimental eva-luation. The present study provides the initial estimatesof the size of the pool and its dependence on host surfacearea and density. Processes adding to epiphyte biomassinclude the creation of new mats from propagules aswell as recruitment from litterfall, both of which arein¯uenced by climatic and microclimatic featuresand may depend on stand composition and structure,and topography. Outputs include herbivory, litterfall,and in situ decomposition, which will be in¯uencedby similar factors as inputs, and additionally byhuman disturbance.

4.3. Management implications

Protecting the harvestable moss resource is importantif we intend to preserve the ecosystem functions anddiversity of epiphytic bryophytes. This goal can beaccomplished if we begin to manage moss as a com-mercial forest product. This involves creating set-asidesfor the development of `old-growth' moss communities,and allowing moss harvest on a rotation basis in matrixforests that are currently on rotations for timber. Mossharvest should be allowed without restrictions, and evenencouraged, in stands scheduled for timber harvestwithin 5 years, and prohibited in stands set aside as old-growth forest reserves [e.g. Late Successional Reserves(ROD, 1994)].

Fig. 4. Harvestable moss mat net accumulation model. Ellipses

represent sources or sinks, boxes with triangular ends represent pro-

cesses. Lines are material ¯ows.


For the rest of our forest lands, active management isappropriate. It is clear from this study that the supply ofappropriate substrates, i.e. hardwood trees and shrubs,must be maintained to facilitate growth of harvestableepiphytes. This goal is contrary to the traditionalemphasis of forest management in the Paci®c Northwestof suppressing hardwoods and shrubs in favor of con-ifers. Given the potential importance of litterfall inaccumulating epiphyte biomass, it may also be impor-tant to restrict moss harvest to the lower 2±3m of theforest to preserve the supply of litterfall from higher inthe canopy.

We propose that if moss harvest is regulated liketimber harvest, on a rotation basis, that the resourceand its ecosystem function can be sustained. Knowingthe biomass of available harvestable epiphytes, and therate of net mat accumulation, managers can determinethe maximum rate of harvest possible to ensure sus-tainability. Managers on the Hebo District of the Sius-law National Forest will be able to apply our estimateof biomass from the Coast Range sites to evaluate thesustainability of their permit system based on severalscenarios. These managers regulate moss harvest byselling harvest permits for a ®xed fee per pound of wetmoss, with no correction for water content at the time ofharvest. Most moss is harvested and sold at a moisturecontent of c. 30% of the oven-dry weight (N. Vance,Paci®c Northwest Research Station USDA, Corvallis,OR, personal communication, 1995). Our inventoryestimates for the Coast Range averaged 550 kg haÿ1

(638 lb acreÿ1) oven-dry weight of moss at 30% moist-ure content. Recent work on the impact of commercialharvest on community composition, diversity, andspecies abundance suggest that commercial mossharvest should not exceed a maximum level of86 kg haÿ1 (100 lb acreÿ1) on the Hebo District (Peck,1996).

Given the 86 kg haÿ1 rate, and the biomass inventoryestimate of 550 kg haÿ1 provided by the current study,moss harvest on the Hebo District would be sustainableon a 5-year rotation if the mat accumulation rate was3.5% or higher (calculated using a compound interestformula to estimate growth). An estimate of a net mataccumulation rate for the Coast Range can be derivedfrom Fig. 3 by averaging over the period from 10 to60 years of stem age and using the compound interestformula to solve for the rate. Although very rough, thisestimate (1.9%yearÿ1) is similar to those based on3 years of growth data (0.6±1.6%yearÿ1) (Peck, 1997c).These lower rates would indicate a 10- or 15-year rota-tion, which would require growth rates of roughly1.7%yearÿ1 and 1.1%yearÿ1, repectively. Sustainablemanagement of epiphytes subject to commercial mossharvest is, thus, achievable through the establishment ofepiphyte reserves and the instigation of rotation periodsfor active moss harvest.

Acknowledgements

The authors wish to thank R. Babcock, F. Duran, K.Grenier, C. Hibler, M. Peck, N. Peck, P. Peck, and J.Knurowski for assistance with site selection and for helpin the ®eld. S. Bloomer, B. Davis, P.-A. Esseen, A.Moldenke, P. Muir, E. Zenner, and an anonymousreviewer provided valuable comments on the manu-script. Funding was provided by cost-share agreementsbetween Oregon State University and the Salem Districtof the Bureau of Land Management, Salem, OR, andthe Siuslaw National Forest, Corvallis, OR.

References

Anderson, L., Crum, H., Buck, W., 1990. List of the mosses of North

America north of Mexico. Bryologist 93, 448±499.

Aro, E., Gerbaud, A., Andre, M., 1984. CO2 and O2 exchange in two

mosses, Hypnum cupressiforme and Dicranum scoparium. Plant

Physiology 76, 431±435.

Cottam, G., Curtis, J., Hale, B., 1953. Some sampling characteristics of a

population of randomly distributed individuals. Ecology 34, 741±757.

Green, T., Sneglar, W., 1982. A comparison of photosynthesis in two

thalloid liverworts. Oecologia 54, 275±280.

Hitchcock, C., Cronquist, R., 1973. Flora of the Paci®c Northwest.

University of Washington Press, Seattle, WA.

Ho�man, G., Kazmierski, R., 1969. An ecologic study of epiphytic

bryophytes and lichens on Pseudotsuga menziesii on the Olympic

Peninsula, Washington. I. A description of the vegetation. Bryolo-

gist 72, 1±19.

Hosokawa, T., Odani, N., Tagawa, N., 1964. Causality of the dis-

tribution of corticolous species in forests with special reference to

the physio-ecological approach. Bryologist 67, 396±411.

McCune, B., 1990. Rapid estimation of abundance of epiphytes on

branches. Bryologist 93, 39±43.

McCune, B., 1993. Gradients in epiphyte biomass in three Pseu-

dotsuga±Tsuga forests of di�erent ages in western Oregon and

Washington. Bryologist 96, 405±411.

Nadkarni, N., 1984. Biomass and mineral capital of epiphytes in an

Acer macrophyllum community of a temperate moist coniferous

forest, Olympic Peninsula, Washington State. Canadian Journal of

Botany 62, 2223±2228.

O'Dea, M., Zasada, J., Tappeiner II, J., 1995. Vine maple clone

growth and reproduction in managed and unmanaged coastal Ore-

gon Douglas-®r forests. Ecological Applications 5, 63±73.

Peck, J., 1990. The Harvest of Moss, an Industrial Perspective.

Department of Sociology and Anthropology, Lin®eld College,

McMinnville, OR.

Peck, J., 1996. Moss Harvest Monitoring Plan. Siuslaw National For-

est, Corvallis, OR.

Peck, J., 1997. Commercial moss harvest in northwestern Oregon:

describing the epiphyte communities. Northwest Science 71, 186±195.

Peck, J., 1997. The association of commercially-harvestable bryophytes

and their host species in Northwestern OR. Bryologist 100, 383±393.

Peck, J., 1997c. Commercial Moss Harvest Post-harvest Recovery.

Siuslaw National Forest, Corvallis, OR.

Peck, J., Acker, S., McKee, W., 1995. Autecology of mosses in con-

iferous forests in the central western Cascades of Oregon. North-

west Science 69, 184±190.

Persson, O., 1971. The robustness of estimating density by distance

measurements. In: Patil, G., Pielou, E., Waters, W. (Eds.), Statistical

Ecology, v. 2. Pennsylvania State University Press, University Park,

PA, pp. 175±190.


Pike, L., Rydell, R., Denison, W., 1977. A 400-year-old Douglas ®r

tree and its epiphytes: biomass, surface area, and their distributions.

Canadian Journal of Forest Research 7, 680±699.

Pitkin, P., 1975. Variability and seasonality of the growth of some

corticolous pleurocarpous mosses. Journal of Bryology 8, 337±356.

Rhoades, F., 1981. Biomass of epiphytic lichens and bryophytes on

Abies lasiocarpa on a Mt. Baker lava ¯ow, Washington. Bryologist

84, 39±47.

ROD, 1994. Record of Decision for Amendments to Forest Service

and Bureau of Land Management Planning Documents and Stan-

dards and Guidelines for Management of Habitat for Late-succes-

sional and Old-growth Forest Related Species within the Range of

the Northern Spotted Owl. US Government Printing O�ce 1994-

589-00001, Washington, DC.

Russell, S., 1988. Measurement of bryophyte growth 1. Biomass (har-

vest) techniques. In: Glime, J. (Ed.), Methods in Bryology. Hattori

Botanical Laboratory, Nichinan, Japan, pp. 249±257.

Schlosser, W., Blatner, K., Zamora, B., 1992. Paci®c Northwest forest

lands potential for ¯oral greenery production. Northwest Science

66, 44±55.

Stotler, R., Crandall-Stotler, B., 1977. A checklist of the liverworts

and hornworts of North America. Bryologist 80, 405±428.

Tallis, J., 1959. Studies in the biology and ecology of Rhacomitrium

lanuginosum Brid. II. Growth, reproduction and physiology. Jour-

nal of Ecology 47, 325±350.

USDA Forest Service, 1995. Special Forest Product Program Envir-

onmental Assessment. Siuslaw National Forest, Corvallis, OR.

Vance, N., Kirkland, M., 1997. Bryophytes associated with Acer

circinatum: recovery and growth following harvest. In: Kaye, T.,

Liston, A., Love, R., Luoma, D., Meinke, R., Wilson, M.

(Eds.), Conservation and Management of Native Plants and

Fungi. Native Plant Society of Oregon, Corvallis, OR, pp. 267±

271.

Wolf, J., 1993. Diversity patterns and biomass of epiphytic bryophytes

and lichens along an altitudinal gradient in the Northern Andes.

Annals of the Missouri Botanical Garden 80, 928±960.
