Are ramps being overharvested?

Following simple rules may not apply when it comes to a springtime favorite

NOTE: This week the post digresses from our usual mushroom fare, but don't forget to check out upcoming classes on mushroom cultivation in NY, PA, MA, and VT and info about our summer mushroom CSA.

From Jennifer May for the New York Times: click for article
Anyone who has come across the Ramp, or Wild Leek, allium tricoccum, likely can't help but feel a sense of abundance; the spring ephemerals (plants that make a brief spring appearance before forest canopies have leafed out) often show up in clusters that can range from a few square feet to a solid quarter acre or more of green. 

For years I've looked forward to harvesting this tasty, tangy, and nutritious plants and felt I could easily harvest a hearty share without inflicting any harm on the population. I used as a guideline the common "2/3 rule", which suggests that in harvesting one should gather no more than 1/3 of a population to ensure a stable community persists.

But what is this guideline based on? As I thought more about it, the concept sounded nice and simple but I knew better, for plants and ecosystems are rarely able to be summarized in such a way. Further, I imagined an inherent problem with applying a blanket rule to wild plants when I know that the dispersal patterns, regeneration, and regrowth characteristics are vastly different from plant to plant. Some, like ramps, appear to be very fragile by nature, while others, like Stinging Nettle (urtica dioica) is persistent to the point where many consider it a nuisance species. (not me - I love to consume them as a management tool)

A practice I've been working at for the past year or so is to follow the tracks of hearsay and try to see if I can find research and evidence to support a given claim. The very nature of agroforestry systems is that they operate on longer timescales, demanding careful thought and planning for all activities, whether we are conducting a timber stand improvement, cultivating mushrooms, or wildcrafting edibles.

Recently with the promotion of my fifth year of mushroom classes and the first year of a mushroom CSA, I've committed myself to backing up any claims with documentation. I wanted to be sure there was good documentation behind my post on all the nutrition in shiitake, and also that the claim that shiitake can accumulate Vitamin D when dried in the sun was validated. Backing up ideas with fact is a simple concept, something I hear a lot of talk about in permaculture circles, at my job at Cornell, and as I discuss sustainability in the community. In practice well-researched material seems to often be an afterthought much of the time, so I figured I would look a bit closer at Ramps in this regard.

I must give credit to Professor Ken Mudge, whom I've been fortunate to work with for many years, for pointing me to some good literature on the subject. The only previous mention I'd seen on the issue of overharvesting Ramps was a New York Times article from last April that mostly asked the question without providing any answers. The first, a 2004 study entitled, "Population recovery of wild leek Allium tricoccum following differential harvesting in the southern Appalachians" cites a startling conclusion after trials harvesting at various intensities over a four year period:

"Harvesting wild leek is not sustainable except at very modest levels. Using the results of this study to predict recovery times, by assuming that growth rates and concomitant recovery times are affected in a consistent manner by levels of harvesting, the sustainable harvest level is predicted to be 10% or less, once every 10 years."

Another research project comes from the British Ecological Society, who published a 5 year study in Quebec that studied a dense population of Ramps in detail. The conclusion was less dramatic but still highlighted that even a small harvest percentage could have a big impact:

"In a particularly unproductive season like 1985 -86, even a 5% harvest is deleterious, and in all other years a decline is predicted when a 15% harvest is stimulated."

Many questions remain. It is not only that one harvest, but HOW they harvest that could make a difference (see this interesting blog post). It might be more sustainable if just the green tops are cut and the bulbs left in the ground. It MIGHT be more sustainable if care is taken to harvest the more mature bulbs and leave the young ones. These details we don't know. What we do know is that a harvest over 10% is likely detrimental, but to be safe one should aim for a maximum of 5% each year for a given population.

This becomes trickier when harvesting from populations on public lands where multiple people may come through hunting for the ramps. It demands that we take more time to observe, catalog, and note the changes in populations from year to year. And, when in doubt, we should err on the side of caution. 

To further reduce stress on wild populations, those interested in ramps should consider cultivation. This factsheet from NC State is a useful guide for getting started.

Agroforestry is an exciting agricultural prospect because we can simultaneously become stewards of healthy forests and enjoy harvests both wild and cultivated. Yet, as with any agricultural practice, care and attention needs to be given to ensure that our forest diversity is protected, and that we can ensure our forests can be enjoyed far into the future.