Low Hanging Fruit: Why Zone 5 Agroforestry in the Northeast is Hard

(Disclaimer: this post is somewhat technical and does not explain all of its terms.  Proceed at your own risk.)

As I mentioned earlier, I spent my birthday a little over a week ago pruning wild apple trees with friends on the ridge behind my house.  They ran the spectrum from vigorous to nearly dead.  We removed dead, damaged, and misdirected wood, thinned competing stems, felled some shading trees, and scattered seed of native bunchgrasses in the understory.  A tending the wild birthday!

In general, though, I think that “wild” or “zone 5” agroforestry of this kind is, at this moment in eco-social history, difficult to pull off effectively in the Northeast.  And I’ll try to explain why I think this is.  Even in a region like the Northeast with a relatively homogenous climate, the diversity of landscapes is vast.  But the diversity of landscape types, if you zoom far enough out to a broad pattern scale, is very finite.  And certain landscape types – particularly, certain structural landscape types – are well-suited for agroforestry products.  A list of these in the Northeast might include:

• Mature hardwood forest with rich, moist soils
• Nut mast producing forest with open midcanopy and understory
• Savannas and open woodlands
• Patchy, open early- and mid- succession mosaic
• Shrub-dominated early succession

You could certainly make a case for other environment types being included in this survey, and/or for any of these to be split into multiple types.  But let’s use this as a starting point.  Here’s the rub: these landscape types are rare, and in many places near-nonexistent, in the Northeast!

Part of this is climate related.  High, year-round moisture means that the “horizon habitat” for nearly all environments is closed-canopy forest, and a majority of the landscape types listed above are somewhere between open prairie and full canopy closure.  So those landscape types require disturbance cycles in order to be present in the landscape in any significant acreage.  And now, here’s the part that’s land use related: those disturbance cycles that would create and maintain those intermediate-succession landscape types are themselves rare to nonexistent, or they’re in specific circumstances unsuited to food production (like powerline mowing).

That’s kind of a brain-burn nerdy point, but I think it goes a long way to explaining why it’s easy to think of agroforestry examples from elsewhere in the world but hard to describe good, larger-scale examples in the contemporary Northeast.  Our climate requires disturbance to have midsuccession environments, and our historical and current land use mean that we have very little of the kind of disturbance we’d need.  And most exciting agroforestry happens in something resembling an open, midsuccession environment.  It’s actually pretty simple!

What I think this means for insatiable people like me is, we need to choose low-hanging fruit and pick landscapes that are structurally suited to agroforestry to begin with.  Basically, we have to look for those landscape types above or something close to them, not start with dense 80-120 year mixed-canopy forest and expect it to work well.  There’s just way too much wood out there to remove and not enough mast producers to make clearing worthwhile.  Better to plant medicine in the understory of older forest, thin and clear out existing acorn or nut woodlands, and direct succession in the relatively-easy-to-modify pre-canopy-closure stage* of old fields and abandoned lots.  That’s the low-hanging fruit that’s out there, and that’s my two cents on where we should be focusing our zone 5 agroforestry design attention for now.

*Another one here is abandoned orchards.  Lots of work to restore, and sometimes heavy metal contaminated, but if you’re up for an enterprise-level (or very slow) project it’s probably worth more net-energy-wise than letting it succeed to forest.