Agroforestry – A Sink for Carbon

Trees and shrubs contribute to balancing the global carbon cycle, and there is no better place than the Canadian Prairies to plant trees for the purpose of reducing carbon emissions in the atmosphere.

Agricultural activities occur on approximately 61 million hectares in Canada. Agroforestry is an intensive land management system that optimizes the benefits created when trees and shrubs are combined with crop and livestock production. These practices can be used to address such environmental issues as water and tillage erosion, soil salinity, desertification, pollution of air and water, loss of wildlife habitat and climate change.

In agroforestry, combinations of trees, crop and livestock are intentionally designed and managed as a whole unit. The biological and physical interaction between the crop and livestock components are manipulated to enhance the agricultural production of the land base. They are structurally and functionally combined into a single integrated management unit (see planning brochures).

Potential benefits from properly designed and managed agroforestry practices include:

• Increased crop production
• Improved economic gain and efficiency
• Improved soil quality
• Improved water quality
• Increased biodiversity of landscapes
• Reduction of greenhouse gases
• Sequestration of atmospheric carbon

As part of an ecologically based land management system, agroforestry can contribute significantly to generating the ecosystem diversity and processes important to long-term sustainability and profitability.

Properly planned shelterbelts decrease energy use. They reduce the speed of cold winds around farmsteads, control blowing snow, protect livestock, buildings and gardens, and trap snow to replenish dugouts.

Shelterbelts also provide diversification opportunities, such as fruit and maple syrup production, as well as other benefits such as habitat for wildlife and reduced greenhouse gas emissions.

There are multiple combinations of practices available under the broad term of agroforestry, but almost all will fall into one of five general categories.

Alley cropping combines trees, planted in single or grouped rows, with agricultural or horticultural crops cultivated in wide alleys between tree rows. By alleycropping, producers can increase or diversify farm incomes, reduce soil erosion and nutrient loading and protect watersheds.

Riparian Buffers consist of trees or shrubs planted between cultivated crop land and streams, lakes, ponds, wetlands or drainage ditches. Riparian buffers are managed to reduce runoff and non-point sources of pollution from agricultural land. They have the ability to stabilize stream banks, protect flood plains, trap sediment, filter and store excess nutrients and degrade pesticides. Trees grow rapidly, storing carbon in riparian zones due to favourable moisture and nutrient conditions. When suitable trees and shrubs grow in these moist environments, they also filter out excess nutrients, pesticides, animal waste, and sediments produced by adjacent agricultural or urban activities.

Shelterbelts that are properly planned provide many benefits to farm families. They decrease energy use, reduce wind, control blowing snow, protect livestock, buildings and gardens, and trap snow to replenish dugouts. Shelterbelts also provide diversification opportunities (fruit production and maple syrup production), habitat for wildlife, reduce greenhouse gas emissions and sequester atmospheric carbon.

Short Rotation Woody Crops (SRWC) are fast-growing woody crops, such as hybrid poplar trees, which can be used for fuel and fibre. Low prices for traditional crops have increased farmers' interest in production of fast-growing woody crops. SRWC systems provide a way of increasing on-farm income, while also treating agricultural, livestock, community and industrial wastes. The rapid growth of SRWC results in high rates of nutrient uptake and large amounts of carbon storage over rotation lengths as short as 15 years.

Silvopastures combine trees with forage and livestock production. Timber/grazing systems managed on the same area of land can increase net carbon storage. When both tree and grass components are properly managed, an increase in net carbon storage can be achieved.