Moss Harvest Research

Harvest Schedule

Most nontimber forest products are poorly managed, not necessarily by intent, but because their relatively low value has not been sufficient to drive the research necessary to quantify the components of even the most basic harvest schedule.  In this regard, PNW commercial moss is unusual because we have more data on this resource than almost any other NTFP.

We chose to adopt an approach used for decades in the timber industry and develop a volume control model by which we determine what harvest levels will permit even-flow moss production given assumptions about inventory, increment, mortality, and poaching.

The first step was to determine the biomass inventory of harvestable moss on the Hebo Ranger District, which we did by conducting an inventory by simulating commercial harvest in 21 stratified random plots.  We stratified the sampling to stay out of the protected riparian areas (right) and to avoid forests (below) with little potential for moss production--dark stem-exclusion stage coniferous and equally dark young hardwood stands (Peck 2005a).

Although it seems obvious in the field where you have and have not harvested, after-the-fact it can seem as if there is virtually no difference even after the removal of several sacks of moss in a given 1/8 ha plot.  Can you tell the before (left) and after (right) difference?

We had to lay our moss out to dry for several days to get it down to the 10-20% moisture content (dry to the touch) required for sale.

We then took advantage of the over 180 other plots on the district for which we had estimated the number of standard harvestable moss mats (12"x6"x2") over the past decade to evaluate the estimate from the limited inventory. 

The number of moss mats was estimated for each inventory plot before harvest to allow a calibration, which was then applied to the other 180+ plots and found to fall within the confidence interval for the field inventory estimates. 

This was done at both the stand level, and the individual mat level, where it was noted that not all mats are equal--mats of Antitrichia are particularly fat, while those of Neckera and Eurhynchium can be quite thin.

We then took the results from the 10-year regrowth study as biomass increment, estimated mortality from the 8-year harvest impacts study (the % of shrubs that perished over the course of the study), and asked harvesters and buyers to estimate the poaching rate.  Based on these parameters, it appears that the current harvest level is nonsustainable (Peck et al. 2007).  Combined with previous management recommendations, we may finally be able to develop a defensible management strategy for harvestable moss (Peck 2005d, Peck 2006a, Peck & Christy 2006).