Two sides of the silvopasture coin

Young trees in silvopastures must be protected from grazing livestock and wildlife to minimize damage.

Silvopasturing is the integrated production of trees, forages, and livestock that has been practiced in some corners of the world for many decades. However, in the mixed hardwood forests of the eastern U.S., silvopasturing has struggled to take hold.

Early foresters and conservationists recognized that farm woodlands were being treated as sacrifice paddocks and thus irreparably damaged and degraded from excessive livestock access. Therefore, the mantra “keep livestock out of the woods” discouraged the adoption of this agroforestry practice that has huge potential in the naturally forested Northeast.

Farm viability, heat stress, and a growing list of noxious plants that want to overrun the landscape are just a few of the modern challenges for grazing farms that warrant a rethinking of livestock in the woods. With a much better understanding of rotational grazing principles and tools to manage the impacts in more positive ways, the past concerns about grazing in and around trees can be largely eliminated.

Cornell University Cooperative Extension’s work with silvopasturing inadvertently started in the early 2000s with the Goats in the Woods project that evaluated the effectiveness and feasibility of using livestock to control problematic plants in forest understories. That project gave rise to educational efforts on silvopasturing in both farm plantations and naturally occurring woodlands, as well as the opportunity to add multipurpose trees into open pastures.

Although there were some useful earlier experiences to draw from in places like Missouri and the mid-Atlantic, the learning curve of silvopasturing in the humid and high-value hardwood forests of the Northeast was unique.

In New York alone, there are an estimated 2 million acres of degraded farm woodlands and invasive shrublands with potential for silvopasturing. There are another 2 million acres of pastureland that could be enhanced through the profitable incorporation of trees.

Even after filtering down those acres to suitable land that is accessible and operable by skilled and capable graziers, there is potential to implement environmentally-friendly livestock production in our own backyards. The following is a synopsis of experiences and challenges of establishing silvopasture.

Adding trees into pastures

For the trees into pastures pathway of silvopasture creation, one of the more important barriers is the cost of successfully establishing trees in a sod environment that is full of both domestic and wild herbivores.

Electric fencing is the tool of choice for protecting young, vulnerable trees from livestock, but additional protection may be needed to prevent deer, rodents, and rabbits from browsing and girdling the investment. Additional threats include pest outbreaks, drought stress, and smothering weeds and vines, to name a few. All of these are manageable with proper planning, preparation, and ongoing maintenance.

The initial high costs of establishing trees can be offset by the advantages of choosing trees that suit multiple objectives and are planted in functional designs. The book “The Grazier’s Guide to Trees” available at treesforgraziers.com is a good starting point for thinking through key considerations. If producers are new to tree planting, they should start small and seek out experienced people who can help reduce costly mistakes and wasted efforts.

From personal planting efforts of a quarter-million trees in the past 35 years on our family farms in New York and Argentina, here is some advice to anyone starting out:

• Don’t bite off more than you can chew. It’s a lot of work to plant trees, and even more work to keep them alive early on. Don’t underbudget.
• Hedge your bets against serious future pest issues with more species diversity, and match trees to their site requirements to promote long-term vigor and resilience.
• Don’t cut corners. Doing so will cost more in the end and possibly lead to a complete failure of the planting.

Adding pasture into trees

By contrast, adding pasture into trees utilizes existing trees, but the same caveats apply to forage selection and establishment. Successful forage establishment in existing woodlands is a three-step process.

• Reduce tree and understory shrub density. This will reallocate sunlight to the ground surface where it can be utilized by forage plants. In forestry, this is known as thinning, and it can be accomplished commercially through a timber sale if there is adequate volume and value or precommercially where there is a net cost to accomplish the necessary thinning treatment. The services of a professional forester can be invaluable for planning and implementing tree thinning.
• Pay attention to forage germination requirements and conditions. Soil scarification, seed-to-soil contact, adequate temperature and moisture, and sufficient soil pH are all critical factors that influence the germination and survival of young forage plants. Many farm woodlands have abundant soil seed banks of forage species that can thrive in the light shade of silvopastures, but supplemental and timely broadcast seeding can accelerate desirable stand development after initial thinnings.
• Use skilled grazing and other management tools where possible. Doing so will shift the understory composition in a positive direction. Clipping and spraying may not be options with trees in the way, so the use of intensive rotational grazing and adjusting grazing density to promote the growth of the desirable species while pressuring the undesirable ones will gradually influence forage quality, composition, and productivity.

For technical details on manipulating forest density to create silvopasture within existing wooded areas, search for the “Cornell Guide to Silvopasture in the Northeast,” which is available under the publications page of forestconnect.info.

Research is ongoing

More work is needed to develop shade tolerant varieties of cool-season forages, but a number of cool-season forages have already been observed to produce well in silvopastures where cooler, wetter conditions encourage prolonged growth periods to compensate for slightly reduced photosynthesis.

Orchardgrass, tall fescue, and reed canarygrass have some of the best documented shade tolerance, though most cool-season forages remain productive under well-thinned silvopasture canopies. Well-thinned is approximately 50% crown closure, which is also the point at which growth and competition is optimized amongst trees.

Additional work is also needed to document the economics of silvopasturing. Studies in New York, Oregon, South Carolina, Louisiana, and Missouri have all shown significant economic benefits for silvopasturing over just timber production or grazing open pastures. Silvopastures have also been widely recognized to provide superior carbon capture and storage benefits, and emerging markets are developing for producers to market carbon from new tree establishment in silvopastures.

This article appeared in the February 2024 issue of Hay & Forage Grower on pages 8-9.

Not a subscriber? Click to get the print magazine.