To many people, forests are primarily reserved for timber and firewood harvesting. In Farming the Woods (Chelsea Green, 2014), authors Ken Mudge and Steve Gabriel invite a remarkably different perspective: that a healthy forest can be maintained while growing a wide range of food, medicinal, and other non-timber products. In the following excerpt, Mudge and Gabriel touch on a number of food crops that can be grown using forest farming techniques and highlight a particular crop that has the potential to make a comeback as a mainstream commodity, the pawpaw.
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Food from the Forest
At the Cornell campus in Ithaca, New York, there is a woodlot called the MacDaniels Nut Grove, where students and the public come to learn about forest farming. In the fall of 2006, a memorable culinary occasion was held there called the forest feast, in which an array of edible nontimber forest products (NTFPs) were prepared and served. The main course was roast goat. This wasn’t just any goat. This goat had been raised at Cornell’s Arnot Forest as part of a research project called “Goats in the Woods,” to see if goats could be used as part of a forest management plan.
The MacDaniels Nut Grove has an abundance of hickory and black walnut trees, with a few white oak trees and some Chinese chestnuts, which played a role in the feast. Nyla, who had recently spent her summer internship shepherding the goats in the woods, was smashing hickory nuts, shells and all, in a large wooden mortar and pestle. These were thrown into a pot of boiling water to separate the rich oil, called pawcohiccora (hickory milk), from the nut meat/shell mash. After everyone at the forest feast got a taste of the hickory milk, the rest was used to fry acorn ash cakes. First, the acorns were leached several times in water to remove the bitter tannins, then ground into a flour to make the ash cakes (“pancakes”) that were cooked on a hot stone. Several other students were cooking a stir-fry of pickled ramps (wild leek), forest-cultivated shiitake mushrooms, and wild lion’s mane mushrooms, as well as wildcrafted black trumpets and porcini. Jim made a fragrant porridge from the inner bark of slippery elm. Forest fruits were in abundance. Abdoul came up with “Cornus mas sauce,” made from the fruit of Cornelian cherry dogwood. Just a little tart, it went well with the goat.
There was a soup made from nettle and lambsquarter, and applesauce made from wild crab apples. Beverages included tea made from hemlock and pine, and dandelion wine (from Isaac’s lawn). For dessert there were brownies made with hickory nuts and walnuts collected from the site. Marguerite made a pawpaw mousse, and Sefra contributed a wild berry torte made from blackberries, raspberries, elderberries, and blueberries!
Although this description of the forest feast may seem like the introduction to a forest cookbook (not a bad idea), the real point is to emphasize the considerable diversity of edible forest products that were sourced from local temperate deciduous forests. Some of the nontimber forest products were deliberately grown (forest farmed) at the MacDaniels Nut Grove, some were wildcrafted or foraged, and others, such as the goat, were from a nearby research forest site.
Just as the feast at the MacDaniels Nut Grove combined cultivated with wild NTFPs, any managed forest farm may produce both. Forest farming involves deliberate management of cultivated nontimber forest products, including bed preparation, planting, mulching, weeding, and so on, whereas wildcrafting does not involve such cultivation in the strict sense. Much of contemporary wildcrafting is focused on “gourmet” foods, such as wild mushrooms and ramps, and medicinals, such as ginseng, that are intended for sale to consumers. In addition to gathering wild foods, there are many that can successfully cultivate a smaller but significant cast of characters that offer amazing flavors, nutrition, and unique niche crops with commercial potential.
Getting a Yield: Light and the Forest
Besides mushrooms, when we consider the majority of food crops in the forest farm, most are trees and woody shrubs that produce fruit and nuts. Anyone looking into the potential of these will notice that many plant profiles claim the plants will “tolerate” shade, but rarely do you see a mention of such crops thriving in shade. This is simply because production of fruits and nuts, from a biological perspective, is energy intensive. So while many plants will accumulate trunk wood, grow, and photosynthesize in surprisingly low light conditions, most need access to direct sunlight to produce a decent yield.
Literature often emphasizes the need for sunlight in fruiting plants, yet there are examples of high-yielding currants (Ribes), blackberries, pawpaws, and other fruits within the forest. As cultivars are bred and released, emphasis has not been on selection for any shade tolerance; in fact, in many cases, plants are selected for performance in open sun. This is another justification for forest farmers to plant seedling stock in a variety of locations, so that selection can be done to maximize efficiency in more forested settings.
That said, there are multiple directions in which to take the concept of “light regime”; that is, the amount of available light and how it will affect both plant growth and fruiting. The good news is that healthy forests need to have a range of light regimes, and as forest farmers it is our job to help cycle them through the various stages.
Defining Light Regimes
Defining the difference in light regimes will assist in understanding their relationship to crop production. In the most basic sense classifications are made on the basis of the percentage of canopy cover; that is, the percentage of shade cast onto the forest floor.
It’s important to remember that not all closed canopies are created equal. Even if dealing with an 80 to 100 percent canopy cover, both the type of tree and the height of the canopy can have implications for light coming through to lower layers of the forest. For example, at the MacDaniels Nut Grove, the area called Walnut Island is named for a small zone with a seasonal creek that is dominated by several 80-year-old eastern black walnuts as the overstory. These trees range from 50 to 80 feet in height and cast shade over the site while still allowing for a significant amount of secondary light to penetrate. This amount of light has proven to be acceptable for many species, including pawpaw and elderberry, while fruit production on the raspberries planted there has been inadequate from a cropping standpoint. This contrasts significantly with the forest at Wellspring Forest Farm, which is a 100 percent canopy of sugar maple. This type produces a very dense shade in which none of the above crops would fare well. Of course, the conditions are perfect for mushroom cultivation.
Use Natural Forest Patterns - Gaps, Clearings, and Edges
Another way to take advantage of a natural forest pattern (disturbance) is to utilize (or create) spaces in and around the forest that get some extra sunlight throughout the course of the day and season. In wild forests this happens all the time: A tree falls in the forest and creates an opening where more sun-loving species can thrive. In addition, utilization of forest edges (including old hedgerows) can be seen as a form of forest farming that also offers some flexibility in terms of light access.
Forest Farming Plant Selection Criteria
There are a number of plants to choose from in temperate agroforestry. Here are some criteria to keep in mind:
• Evidence exists (literature or grower or other expert advice) of successful cultivation in a forest niche
• Natural habitat of the plant is in the forest
• Potential exists for both domestic and commercial applications
• Demonstrated cultivation techniques exist, even if underdeveloped
• There are health and nutritional benefits for humans
Growing Pawpaws on the Forest Farm
While light may be the limiting factor in getting good yields, there are nonetheless several species that have evolved to benefit from the shade and shelter that the forest offers. Pawpaw is a good example of a forest fruit prime for commercial production and possibly a comeback as a mainstream commodity.
A ripe pawpaw looks like it’s borderline rotten. The fruit is really soft, the skin often dark and bruised. And it’s best to get the fruit right off the tree this way, though you can pick somewhat unripe pawpaws and store them for three weeks at about 35°F (2°C); a refrigerator is closer to 41°F (5°C). The poor shelf life of pawpaw has led to its demise as a mainstream commodity. Yet with the renewed interest in local, nutrient-dense foods, and consumer willingness to take time to process and preserve foods with a limited season, the pawpaw may just make a comeback.
The pawpaw boasts these unique qualities that cannot be matched by other forest fruits:
• It has the largest fruit of any fruit tree that can be grown in the cool temperate climate. Large fruits may exceed 1 pound in size.
• The fruit is a relative of the custard apple and both looks and tastes very “tropical”—hints of vanilla, mango, banana, and avocado are common descriptors.
• It’s both shade tolerant and, unlike many species, it can grow in association with black walnut; (i.e. it’s juglone tolerant)
• The pawpaw is high in vitamin C, magnesium, iron, copper, and manganese. It’s a good source of potassium and several essential amino acids and also contains significant amounts of riboflavin, niacin, calcium, phosphorus, and zinc.
• Studies from Purdue and other institutions have indicated the presence of cancer-fighting compounds in the fruit.
Ready for the kicker? It is deer resistant! It’s even goat resistant. Grower Chris Chmiel of Integration Acres in southeastern Ohio grazes goats with his pawpaws, with no negative consequences, save the occasional small tree that gets trampled. Its deterrent effect on browsing herbivores, both wild and domestic, is attributed to toxins in the leaves.
From a forest farming perspective, the pawpaw is interesting, as it is found naturally as an understory tree, sometimes in very dense shade. The pawpaw thrives in floodplains where the soils are moist and rich in organic matter. While hardy to zone 4, in areas of the East north of Ohio, it is recommended that the trees be planted in warmer microclimates for good production. While many producers grow pawpaws in orchard-style plantings in full sun, the tree will fruit well in part shade and in forests with a full canopy, provided the overstory species are tall enough to allow for secondary light. Several pawpaws are thriving in the black walnut forest that is part of the MacDaniels Nut Grove at Cornell.
Basic Planting Requirements for Pawpaws
• It likes loamy, well-drained soil.
• A pH between 5.5 and 7 is ideal.
• When young (years one through three), seedlings need to be protected from direct sunlight.
• At least two seedlings or different varieties or other genetically different trees (e.g., two different cultivars) are necessary for cross-pollination (the trees are self-incompatible).
• If there are fewer than fifty trees in a planting, hand pollination is likely necessary.
Hand Pollinate Your Pawpaws. It’s Easier Than You Think!
Hand pollination may at first glance appear as a deterrent to growing pawpaws, yet all that is really required is to take a paintbrush out to the trees for one to two weeks in late spring (the last few weeks of May in New York) and transfer pollen from the mature flowers where pollen is loose. The key point is that this loose pollen must be transferred to the stamen of flowers in which the pollen mass is still solid. Of course, these trees must be genetically different (seedlings or different cultivars). Knowing both when pollen is ready to transfer and when the receiving flower is ready to accept is critical.
Pawpaw trees left unmanaged can grow to a height of 30 feet, so it is recommend that the trees be topped when they begin to grow beyond harvest and pollination height, usually at eight to ten years.
Propagation of the pawpaw is achievable from seed, which can be collected from fresh fruits. Seeds must be stratified (cold, moist pretreatment to overcome dormancy), either by letting them overwinter in the ground or by stratification in a refrigerator.. However, like most trees that are cross-pollinated, pawpaw seedlings are not genetically uniform, and the outcome will be some degree of variability among different trees and between generations. For this reason many species are deliberately propagated with clones that have been selected for superior characteristics that will come true to type. In the case of the pawpaw some clones (cultivars) have been selected for early ripening, for use in more northerly locations. To maintain this early ripening characteristic from generation to generation, a cultivar must be grafted (or budded).
The bottom line is that almost anyone who tastes a pawpaw is hooked. It’s a truly wonderful culinary experience—while pawpaw can be used in a number of recipes, the best method of eating is simply to slice the fruit and eat it right out of the peel with a spoon. It’s a fruit perfect for the backyard grower, as two to four trees would provide all the fruit a family could eat. The time is also coming for its reemergence as a commercial crop. Farmers looking for something different, especially if they are willing to process the pulp of fruit they can’t sell fresh (easiest as frozen pulp) have a niche market just begging for attention.
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