Moss Harvest Research

Harvest Impacts

The mid-1990's saw the birth of the Moss Harvest Monitoring Program on Hebo, which  involved contracting roughly 2200 acre parcels of forest to a commercial moss harvester for periods of 5 years.  Two such areas were successfully created (SA1, SA2), each bounded by roads, rivers, or property boundaries..

The harvester cooperated with the project by agreeing to harvest precise quantities from a series of plot as well as recording how much moss they removed throughout the contract period.  Plots were surveyed before and after harvest at different intensities.  The first stewardship area had research plots in the riparian zone, which is officially off limits to harvesters.  Plots in the second stewardship area were located in upland forest of either conifer or hardwood dominated sites. 

Ten trees or shrubs in each plot were also permanently tagged to facilitate future remeasurement, which was undertaken one, two, and eight years following treatment.  This included primarily vine maple and red alder, but also pacific yew and Douglas-fir, the branches of which are often laden with Isothecium.  Eight years on, 17% of shrub stems had perished underneath a windthrown red alder.  This appears to be the primary form of natural disturbance for these understory moss mats; no natural analogue to the partial mat removal of moss harvest exists.

You have to know where to look to see what was removed in the low-intensity plots.  See if you can determine where the moss is missing in the images below (hint, bare bark is rare out there and reddish brown patches are exposed bits of decomposing wood or epiphytic soil).

Some stems were hardly touched in the low intensity plots.

While others were stripped clean.  Eight years later, some stems had hardly recovered, having been overgrown by ferns or buried by falling trees, while others showed a rich layer of new growth.

This project demonstrated that (1) some moss harvesters want to get involved with management, but most don't (there were very few bids on the lease areas); (2) harvest precisely following current standards and guidelines is probably sustainable, but (3) harvest ignoring those guidelines reduces diversity and moss cover; (4) although the epiphytes of conifer and hardwood forests differ, they do not differ in their response to commercial harvest; (5) restricting access probably does reduce poaching, but the burden of patrol can not be placed on the harvester alone (Peck & Christy 2006; Peck 1996b, 1997d, 1998, 2005b).