Moss Harvest Research

Who, What, and Where

The research reported here addressed the harvest of epiphytic moss in the Pacific Northwest of North America.  More specifically, this industry centers on the western slope of the Coast Mountain Range within a few miles of the Pacific Ocean.

My research sites have been in Oregon, scattered in  BLM and National Forest land in the western slope of the Cascades and a clustering of sites on the Siuslaw National Forest in the Oregon Coast Range.

These Coast Range sites have been on the Hebo Ranger District, which has been the single largest source of commercial moss for decades.  This map shows the district in green against a grey backdrop of BLM, state, and private lands.  Research sites are marked:  the 1994 sites used for the initial characterization of commercial moss and the 10-year regrowth study (orange), biomass inventory sites (red) and harvest impact sites in Stewardship Areas 1 and 2 (yellow).

Why do I study moss harvest on the Hebo Ranger District?  This picture says it all--on a clear, summer day, in rolls the fog from the Pacific just a few miles away and nestles into the valleys and draws.  Well over 2000 cm of rainfall also make it a mossy place.

During the dry summer, tree mosses have access to water through fog that condenses on leaf surfaces, while in winter leaf-fall provides access to light while mild temperatures permit continued growth.  This promotes luxurious moss in the understory of mixed forests, but particularly under hardwoods.

Our first work in 1994 involved cataloguing the harvestable mosses in 1-m microplots randomly placed between 0.5 and 2 m. on hardwood tree and shrub stems in ten different riparian sites on Hebo.

The harvestable mosses within the 1-m microplots were harvested and taken back to the lab to ID and weigh after oven drying.  Hosts were measured and vine-maple stems were permanently tagged so we could return to monitor regrowth.

This initial descriptive work enabled the characterization of which epiphytes (>20 taxa) are actually impacted by harvest (Peck & McCune 1995a,b; Peck 1997a), what tree species (mostly red alder, vine maple) serve as hosts for harvestable epiphytes (Peck 1997b), and a crude estimation of the biomass inventory (hundreds of pounds/acre) and regrowth rate (a little over 1 g/m-stem/yr) of harvestable mosses in mixed forests on Hebo (Peck & McCune 1998).

This work allowed us to identify which taxa are most abundant in what we thought was commercially harvested moss, but it was some years later before we were able to examine moss on the retail end and verify which species are in fact harvested and sold (Peck & Muir 2006).  Fortunately, the lists compared pretty well, although it also confirmed that more moss is being harvested from logs and from the intermountain valley than has been recognized in the past.

The Hebo mixed forests vary in hardwood basal area, but have very consistent and strongly developed shrub and herbacious layers.  Lower and midslope positions are often dominated by vine maple shrubs, but bottomlands are invariably dominated by salmonberry, which can make the forest almost impenetrable for both people and light.  Old-timers report that the bears used to keep the salmonberry at bay, but an active bear eradication program in the last century (to promote tree regeneration after the first and second waves of large scale clearcutting) was very successful and salmonberry now grows unchecked.  The salmonberry can actually be too thick to permit abundant moss growth, so many riparian areas are no longer prime moss habitat.  At the same time, the widespread conversion of hardwood forests to conifer cover-types, combined with the natural succession of early successional hardwoods to conifer forests, has greatly reduced the acreage in moss "production."

The Hebo data were supplemented by sampling in the Cascade Range that estimated regrowth rates (Peck & Muir 2001a) and biomass inventory  (Peck & Muir 2001b), which confirmed predictions that both are lower in these drier forests (Peck & Muir 1998, 1999).