I believe nature is abundant, and too often we overlook the forest for the trees.
Farmers for centuries have cleared land of trees to grow crops and livestock.To play off Aldo Leopold's “Thinking Like A Mountain,'' If land with fewer trees meant that you could grow more crops, or graze more livestock, then having no trees must be a farmer’s paradise. But no one asked the forest.
As a lifelong gardener and farmer, a lover of trees, and a trained forester, I’ve taken a keen interest in trying to understand how trees can fit into agriculture. We all know the benefits of trees; the shade they provide on a hot summer day, blocking cold north winds in January, stabilizing water and nutrient cycles, providing food and lumber, and increasing wildlife habitat, to name a few. Intentionally incorporating trees and shrubs into planned agricultural systems, called agroforestry, can provide many benefits.
The First Agroforesters
Indigenous peoples were the first agroforesters. In tropical regions they practiced a sustainable form of agriculture called “slash and burn,” or “shift” agriculture. In these wet tropical environments, plant regrowth is extremely fast. Native people would cut and burn a section of the forest, and as the vegetation regrew they would thin and release species that provided food and fiber for their needs. After a period of time, the forest would take back over and the people would move to a new site and repeat the process. For millennia this dramatic disturbance and long rest and recovery period was sustainable, but is now under threat due to population increases and loss of rainforest to other forms of agriculture and development.
In North America, indigenous people also used fire as a tool to keep land in an early succession stage. These frequently disturbed sites had fewer trees and were more diverse, providing fruits and nuts that they could harvest. Areas around waterways were burned to promote early succession tree species that beavers could feed on.
The beaver was valued for its engineering skills, which slow water cycles and diversify habitat in waterways, and the beaver was also a valuable source of food and clothing for the first Americans. Frequent fires kept forests in check and promoted grass and other forage that sustained large numbers of grazing and browsing animals which were hunted for food. This system built the Midwest's most fertile and abundant ecosystems.
The Mean Fire Return Interval (MFRI) is an important metric in grassland and forest management that provides insights into the historical fire regimes of these ecosystems. By maintaining or restoring fire patterns within their historical ranges, land managers can help ensure the resilience, health, and sustainability of these environments while mitigating the risks associated with uncontrolled wildfires.
From: MN Prescribed Fire Council, Minnesota Fire Needs Assessment
<10 years >100 years
Consequences of Drought and Development
After experiencing drought for at least some of the growing season in 2021, 2022, and 2023 the government is now issuing natural disaster declarations for areas around Minnesota due to flooding from extreme rain events. Disasters like these are exacerbated by the historical loss of wetlands and other native habitats which held water on the land and slowed it down.
Continued development without good stormwater controls accelerates runoff, increasing stream flow velocities downstream and increasing streambank erosion and flooding. And degraded agricultural soils have less ability to infiltrate/absorb water and decreased water holding capacity, unable to hold water on the landscape. One stressor after another, creating an accelerating negative feedback loop which further degrades our soil and water resources.
A growing body of research shows that agriculture without trees or other perennial plant cover does little to stop or reverse these negative cycles. While practices that help farmers align with the soil health principles can go a long way in reducing the negative impacts of row crop farming, the vast majority of row crop acres still exceed tolerable soil loss rates, and water leaving those lands most often doesn’t meet clean water standards.
Benefits of Agroforestry
Agroforestry, on the other hand, offers a multitude of benefits. The agroforestry practices of Riparian buffers and alley cropping provide deep roots year round that can intercept surface and groundwater, cleansing it of sediment, excess nutrients, and harmful chemicals. Silvopasture systems, the integration of trees, livestock and forage, provide shade to livestock during extreme heat and protect them from harsh winter winds.
When designed to provide a harvestable yield, agroforestry systems can create alternative revenue streams for farmers and ranchers. Hybrid hazelnuts and elderberries are two tree crops that have potential to turn a profit, but currants, serviceberries, and other edible crops are being researched. Value-added products like high quality saw timber, decorative florals, mushrooms, and woody biomass can be designed into agroforestry systems and are other possible products farmers could market.
Early forest succession habitats, such as oak savannas, and pine barrens are some of the most productive and diverse ecosystems. In the transition zone from prairie to forest, these communities contained species from both major ecosystems, maximizing diversity and habitat for wildlife. Kept in this stage of evolution with fire and animal disturbance, these systems create an accelerated positive feedback loop, increasing productivity and abundance.
Agroforestry systems work to mimic these natural habitats, to increase overall productivity and ecological function of the land. However, these systems are more complicated to manage and often there isn’t easy to access markets for the products that come from them. When competing against well-established commodity crops, they are a hard sell to farmers. While significant work has been done to develop economically viable agroforestry systems, much more still needs to be done.
For further reading, check out these blog posts: highlights from a 2018 agroforestry conference, how agroforestry contributes to soil health, and the recent exciting news on hybrid hazelnuts.
Happy Dancing Turtle is working to advance agroforestry through educational programming, grant writing, and consulting with landowners. Check out our website for more information and resources, or contact us if you have specific questions or requests.
Comments