Late this summer I finally got a chance to scout for one of my favorite herbs or forbs – ginseng. American ginseng is highly sought after for its medicinal attributes. It’s also special since it’s one of the longer-lived perennial herbs in the forest, living for decades to 100 years.

Forbs are any non-woody flowering broadleaf plant that isn’t grass, sedge, or rush. Ginseng likes to hide, but chances of seeing it are increased if certain indicator plants are found. Many of these indicator plants are also forbs like Dutchman’s breeches, wild ginger, blue cohosh, doll’s eye, leeks, jewelweed, squirrel corn, etc. But these plants got me thinking. What makes them grow in some areas and not in others?

Aspect seems to matter – north or east-facing slopes seem to hold more moisture which perhaps these plants need. Elevation too. Somewhere between 1,500 and 2,500 as a guess. But I also wonder if aspect and elevation are a cause or effect of deer browse. For instance, north-facing slopes and higher elevations normally carry fewer deer; Deer sign or their bedding areas seem to be more on warmer south-facing slopes. Perhaps it’s both! But there is something else too. Something that I’ve undervalued or overlooked its importance for too long.

Diversity! It’s so hot right now. Well, it’s been hot or really a popular notion for a long time in natural resources management. Species diversity, structural diversity, size diversity; the more the better. In school, diversity was pounded into us. And some of it still seems like a good thing. But I’ve been thinking about where diversity has led us astray. Something I’ve been telling members of CFA or forest landowners for years when it came to wildlife management – Canopy stratum or vertical diversity. Sounds complicated but not so.

This can be summarized into three layers or “stratums” in the forest – overstory, midstory, and forest floor. Vertical diversity was commonly treated as a general benefit to wildlife; Having all three stratums in the forest is seen as beneficial to many types of wildlife, like birds who may nest or feed at differing canopy levels, to deer seeking bedding areas or browse from plants, to small mammals seeking cover from predators. In other words, my training or knowledge was against the “park-like” look in the forest where one could see longer distances through the forest beneath a mature overstory. Foresters were trained to encourage woody growth in all three layers – overstory, midstory, understory (forest floor) for meeting both wildlife goals, and the provision of seedlings or regeneration for future trees. Makes sense, right?

Midstory Smothering

My ginseng foray got me questioning this notion of “vertical diversity” though. I started to think about all the forests I’ve been to where the shy plant and its comrades have been found. The forest is mostly pleasant to walk through, or rather there aren’t pesky beech whips whipping my face or dense black birch either. There is some sugar maple regeneration, but it normally is confined by hungry deer to the forest floor or beneath two feet. In other words, it seldom reaches the midstory. Instead, this forest has that “park-like” look consisting of a mature overstory of sugar maple, and some basswood that I was trained to abhor. More importantly is that what it lacks is the middle canopy stratum – or a midstory, with the occasional sapling here and there.

I’m starting to believe that I’ve overrated the midstory. I’m not going to say it’s not sometimes used by wildlife, but rather that this midstory is played out; We have plenty of it. Many stands are commonly packed with a midstory of ironwood, red maple, black birch, white pine, or American beech depending on where you are in the Catskills. The midstory consists of trees from about 3 inches in diameter to about 10 inches or trees that are saplings to poles.

According to University of Tennessee’s Craig Harper, taking out the midstory is one way to increase sunlight just enough to set the stage for oak seedlings. While that may be true for oak, I believe it to be true for growing other crucially needed plants like forbs. According to Dr. Harper, forbs are highly underrated for the importance in feeding the white-tailed deer.

A forest lacking forbs or herbs has significantly less food. A lot of this is caused by a dense midstory. Opening the canopy in the overstory can also help other plants grow too, which is something that has been covered in this column before. However, the midstory should be dealt with first. Why is it so important that deer are well-fed? Deer, being a keystone consumer of plants, will over-browse or severely impact vegetation from 5 feet down if not provided with quality habitat. In other words, satisfy their bellies first, so forest midstories and below don’t become empty for other wildlife.

To remove the midstory, one of three methods is typically used. The first includes herbicides that normally include “hack and squirt,” cut stump, or basal bark spray. The other is to mechanically cut them using a chainsaw. This can be achieved by either felling or girdling; Girdling includes severing the connection of the cambium – the thin layer just inside the bark – between roots and shoot or canopy. The last method isn’t really used in the northeast but hopefully will someday – fire. A ground fire can knock out certain tree species with thin bark, especially in the smaller diameter classes. The “park-like” forest settlers noted when they first arrived to these forests were probably artificially created by indigenous people trying to enhance sightlines, wildlife habitat, pest reduction, etc. In any case, the next time you’re in the woods, pay attention to the three canopy stratums and how they interact.