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Using Trees as Forage

By   /  September 14, 2020  /  5 Comments

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Austin Unruh founded Crow & Berry Land Management. He says, “We believe in the power of good practices implemented by thoughtful farmers to revitalize large swaths of land across the world. Our job at Crow & Berry is to research, trial, and learn how best to integrate trees with active pastures for profit and conservation, and advance that through creative education and partnerships.” Click to learn more and to contact Austin.

Spring and fall are wonderful times to be a grass farmer. The weather is pleasant, the livestock are fat and happy, and the forages are lush.

But of course, summer comes right after spring, and the lean, dry times can wipe away the memory of those beautiful lush grasses of spring.

It doesn’t take much observation to note that many summers, trees will stay lush and green long after pastures have gone dry and brown. That’s due to a couple factors, including the deep roots of trees, and the fact that groups of trees will create their own cooler, more humid microclimates that conserve water for much longer.

If you’re running short on forages and have a patch of trees, there’s always the option of felling the nearest grove of oaks or maples for a one-time influx of feed. This is, however, not a great strategy for the long run. A better approach is to start thinking strategically about using woody species in our grazing systems to systematically see us through the summer slump. While none of your neighbors may do so yet, managing trees for fodder has been done for millennia by people around the globe. Here we’ll look at what others have learned, and what we might use in our own context.

Pollarding

If you’ve ever taken a tour through the Netherlands or Belgium, you’ll likely have noted a strange looking tree creature that’s common along canals, in pastures and in front yards. Looking like a severed tree stump with a bad hair day, pollarded willows, poplars, oaks, linden and more are a centuries-old tradition in Europe. Since medieval times these thoughtfully managed trees have allowed farmers to grow fuelwood, construction materials and fodder in the same pastures as sheep and cattle.

Pollarding is the act of cutting a tree back, above browse height, with the intent of promoting new growth. Far from hastening the death of trees, this can in fact stretch out their lifetimes. Willows are known for being fast-growing, short-lived species, but when systematically pollarded, they are kept in a young, actively growing state and are never allowed to reach their peak and deteriorate. Thus, a tree that would usually live for just 30-50 years might grow for well over 100 years.

Regrowth on a pollarded willow.

To establish a pollard tree for fodder, you’ll have to first get it up above browse height and protect the base for the initial years. You can read here about just how to get a tree established in an active pasture. Once the tree has grown past browse height, you’ll cut the top off during the dormant season. Cut it off at 6-7’ to keep the regrowth well above browse height, yet within your reach. After that initial cut is established, a flush of new growth will appear from the cut site the season after, and that’ll be the place you’ll continue to cut from going forward.

The big benefit of using pollards above browse height is that it allows you full control over when your livestock access the fodder, while not needing to fence the livestock off of the trees. The downside is that giving access to that fodder will require your labor to physically cut the branches to make them available. Such a setup can work for certain farms, like where the grazier spends a lot of time in the pasture with the stock but would be too time-consuming for others.

Coppicing

The author in his 10′ tall stand of willows, which had been cut to the ground the previous winter

The alternative to pollarding is what’s called coppice. It’s the same principle of cutting a tree over and over at the same level, but coppicing cuts the tree back to the ground. It’s the difference between a self-serve buffet and you having to bring the food to your livestock’s table. The only work for you is to control access to the browse.

One of the very few examples I’ve seen of this method in use in temperate climates is a trial in the Netherlands. There, willows and alders were planted in rows 80’ apart in an existing dairy pasture. Livestock were thus provided with windbreak and shade, as well as supplemental feed. The report says that leaf fodder intake was low, but that the tree leaves were high in micronutrients that were otherwise lacking in the grasses consumed by the livestock. In the meantime, soil organic matter increased, as did soil biology. The full report can be found here. Sheep and goats would make more full use of the browse, and other tree species (like the more palatable mulberry or poplar) could be chosen to increase fodder intake from cattle, but this serves at least as a valuable snapshot of what is possible.

On Pasture editor Kathy Voth took this picture of cattle chowing down on willows in Montana.

Other than allowing livestock to browse whatever trees and shrubs have grown up in a pasture or hedgerow, using woody plants as browse is uncommon for sure in the United States. It certainly is not something that is being done in any systematic way, yet. (For Greg Judy’s take on using autumn olive, a nitrogen fixing shrub, look here. )

The tropics tell a different story. There, what is called intensive silvopasture has been gaining traction in the past decades as a means of boosting livestock production. There, nitrogen-fixing trees and shrubs are planted at really high densities (several thousand per acre) to serve as a major feed source. Yield increases can be downright impressive, as studies have shown a 2 to 6-fold increase in stocking density, and an increase of meat production per acre by 2 to 10 times. You can find the original review here, and a great summary of intensive silvopasture here.

Whether the results from the tropics could be duplicated in temperate climates is an open question, given the major differences in climate, plant physiology, etc. We know that a well-crafted tree and shrub systems can provide valuable browse during the summer slump, extra nitrogen injected into the soil, shelter from winds during the winter, and shade during the summer. What we don’t know yet is how much benefit we can get from such a system, what species will work best in our climate, and how best to get them established. Be sure I will be researching each of those, and I hope others will experiment as well, sharing their results along the way. We simply won’t know how far we can push regenerative grazing until we try.

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About the author

Austin started Crow & Berry in 2017 with the goal of helping landowners do conservation that was also profitable. He started with streamside buffers in southeastern Pennsylvania, and when a client asked how to plant trees in his pastures, Austin started down a rabbit hole that just keeps getting longer and longer. When not planting trees he's probably reading about trees, though he's learned to avoid good tree books right before bed, or he'll lay awake half the night thinking. If not reading about trees, a good afternoon is swimming in the pond and eating wild berries with his growing family.

5 Comments

  1. emily macdonald says:

    The information I am getting from Extension, ATTRA, SARE, and other sources says that , in humid warm climates, you need AT LEAST a 60 day rest period to reduce the number of eggs and larvae to a level that lowers the risk of infection, and a whole year of not grazing with the same animal species to create clean pasture. The grazing period also needs to be less than 4 days because that’s about how long it takes newly deposited eggs to hatch.
    So I agree that moving sheep frequently is essential but not that breaking the parasite cycle is easy. You need a lot of land to create that many paddocks and you have to find a way to keep that grass vegetative while it is resting for 60 days or it will be low quality forage. Usually haying, clipping, or grazing with cattle or horses is suggested but all of those can be difficult, expensive, or impractical depending on circumstances.
    So I think it is worth investigating many tools for parasite management and working to breed sheep for parasite resistance.
    What is inacessible on one farm might be the ideal solution on another!

  2. emily macdonald says:

    Thanks for another interesting article on a fascinating topic.

    Could another possible benefit of grazing (browsing?) sheep on coppice be breaking up the parasite life cycle since the larvae ( of some kinds anyway) are found in the lowest several inches of grass?

    Regarding pollarding: You say the first pruning should be in the dormant season. Why is that, since I’m assuming subsequent prunings would all be during the growing season?

    It seems that species for intensive silvopasture need to be carefully selected so that they grow vigorously but not so agressively that they become a management nightmare. I’m finding that many shrub/tree species listed for nitrogen fixing ability and forage production are also listed as invasive and ecologically detrimental elsewhere.

    • Austin Unruh says:

      Great questions again Emily.

      Yes, I think parasite reduction could be a huge component here. Check out this article on an Australian study looking at acacia planted in pastures: http://sciencewise.anu.edu.au/articles/wattle

      I would have included info from that study in my article, but I literally just came across it. Here’s a quote form the study directly related to parasites:
      “Interestingly, during this trial, two sheep from the pasture paddock became ill due to parasite infestation, while no sheep in the acacia paddock displayed these symptoms. After the trial, 13 sheep from the pasture paddock died from Barber Pole worm. Sheep in the acacia paddock displayed some symptoms of illness, however none were fatally affected. This experience suggests that sheep with access to acacia browse are less susceptible to illness or death due to internal parasites.”

      Good question about pollarding in the dormant season vs in the growing season. The tree is going to prefer being pollarding in the dormant season, when its energy is being stored in roots rather than leaves. That’s when pollarding traditionally happens for basket materials, firewood, etc. However, in order to make the leaves available, we need to cut during the growing season.

      More ideal for the tree would be to have the leaves stripped without the limbs needing cut, so the tree doesn’t have to expend all that energy growing limbs. That’s one more reason I think keeping the browse within reach of the livestock will be the most advantageous way to go.

      You make a very good point about nitrogen fixing species. Most all of these species are strong, vigorous, and want to live! I like that in a tree, and find it much easier to work with trees and shrubs that want to live than ones I have to baby to hold on to life.

      I’m not as interested as many conservationists in drawing stark lines between species that are ‘bad’ and ‘good’. Most all species have their usefulness somewhere. Kentucky bluegrass, corn and autumn olive are all introduced species. We subsidize vast expanses of bluegrass and corn, yet I can say with high confidence that an acre filled with autumnolive, the ‘invasive’, will be ecologically more diverse, sequester more carbon, and filter more water than either of the other two. It’s just that people listing it as invasive don’t appreciate how it could be useful.

      I’d say this: If there’s an opportunistic species that’s not already in your area that you could accidentally spread, don’t introduce it. But if there’s already autumn olive and mimosa and black locust in the area, it might be worth experimenting with them as a resilient, nutritious source of browse.

      • Joe Connelly says:

        I think a more accessible way to break the parasite cycle is to regularly move your flock, and not return to a paddock for at least 21 days. More if you want to maximize pasture yield and quality. Breaking the parasite cycle is not a hard thing to do. That study effectively proved sheep forced to eat larval parasites and manure are more susceptible to parasites than those with access to tall forage.

        Also I agree with Greg about autumn olive. I like browse hight roses too. Sometimes it seems like my sheep prefer roses to clover after a move.

        • Joe Connelly says:

          After thinking about my previous comment I acknowledge that it would be more difficult to put the fencing in to control grazing to break the parasite cycle on a 5000 acre ranch in Montana than on my 50 spread out acres in Massachusetts.

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