Agroforestry Benefit Highlight: Climate Change
/One of the many benefits of agroforestry—the integration of perennial trees and shrubs into agricultural systems—is its potential to mitigate climate change and increase resilience. Here are a few examples of how:
Carbon Sequestration
Plants have the unique ability to take carbon out of the atmosphere, convert it into biomass (leaves, stems, branches, etc.) and store it as an inert form in biomass and soil. Perennial crops are especially important because they increase their biomass every year and grow deeper roots that help soil store more carbon. They also reduce the need for tilling. Any time the soil is tilled, it accelerates decomposition of organic matter and loss of carbon to the atmosphere.
Reducing the need for tilling also helps conserve the expansive network of mycorrhizal fungi which serve as a major global carbon sink. By one estimate, five billion tons of carbon flow from plants to mycorrhizal fungi annually (read more here).
According to the USDA National Agroforestry Center, 110.9 million acres in the United States are eligible for agroforestry, which could sequester at least 156 million metric tons of carbon dioxide equivalent per year, equal to the emissions of over 33.9 million vehicles.
Reducing Greenhouse Gas Emissions
Agroforestry strives to build agricultural systems that are essentially “self-fertilizing,” lessening the need for traditional fertilizers that use large amounts of fossil fuels and add carbon to the atmosphere. Reducing the need for nitrogen-based fertilizers in particular reduces emissions of nitrous oxide—a greenhouse gas 300 times more powerful than carbon dioxide at warming the planet. Because agroforestry reduces the need for tilling, watering, and fertilizing, it also minimizes the use of fossil-fuel powered machinery.
Building Climate Resilience
The Pacific Northwest has already begun to experience some of the effects of climate change, such as increases in intense precipitation events. The addition of tree and shrub cover provided through agroforestry practices can help intercept rainfall, increase infiltration of water into the ground, and reduce the quantity and speed of runoff. All of these reduce flooding, soil erosion, and water pollution.
Agroforestry practices can also help during our summers, which are becoming longer and hotter. The deep roots of trees and shrubs make them much more drought tolerant than annual crops. They also shade the smaller plants below, protecting them from extreme heat. The mulch created from the leaves falling from trees feeds the soil and reduces the need for water.
Lastly, agroforestry practices encourage diverse mixes of plant species, which provides multiple streams of income and helps farmers be more resilient when a crop fails due to extreme weather. Planting diverse species with complimentary needs can also increase resiliency and improve soil health by providing habitat for a wider range of beneficial soil organisms.
Citation:
Bentrup.G; MacFarland, K. (June, 2020). Agroforestry. U.S. Department of Agriculture, Forest Service, Climate Change Resource Center. www.fs.usda.gov/ccrc/topics/agroforestry
