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Agroforestry
Agroforestry refers to combinations of trees, crops and livestock that are intentionally designed and managed as a whole production unit. Crop production can be optimized when crops are combined with trees and shrubs.
The benefits include increased crop yields, improved soil and water quality, increased biodiversity, as well as lower greenhouse gas emissions and increased carbon sequestration. (1)
In addition, alternate crop uses related to trees and shrubs, including bio-energy, fruits, nuts, horticulture nursery stock, wood fibre and livestock shelter, could diversify farms and enhance their profitability.
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Shelterbelts
Shelterbelts consist of one or more rows of trees strategically planted on the farm. They are an effective tool for fighting climate change because they remove carbon dioxide from the atmosphere and can moderate the microclimate around the shelterbelt.
Studies at Agri-Food Canada’s Shelterbelt Centre show that the above-ground portion of a mature poplar tree in a shelterbelt stores about 970 kg of carbon dioxide, white spruce about 520 kg and green ash trees about 230 kg. There is also carbon stored in the roots—about 50–75 percent of the carbon stored above ground. (2)
Shelterbelts also reduce wind, cut soil erosion and nutrient loss, conserve water, control blowing snow, and may provide diversification opportunities, such as fruit production.
The potential drawbacks are increased shade and competition with crops for water and nutrients. (3)
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Riparian buffers
Riparian buffers consist of trees and/or grasses planted between cultivated crop land and a watercourse. The main benefits of these buffers are to filter surface run-off, which may contain sediments, nutrients and/or pesticides, protect stream banks and shorelines from erosion, and sequester carbon. (4)
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Alley cropping
Alley cropping mixes trees, planted in single or grouped rows, with agricultural crops grown in wide alleys between tree rows. This is not commonly practised in Manitoba, but it has potential for both diversifying farm incomes and increasing on-farm carbon sequestration. It may also reduce soil erosion, decrease nutrient loading and protect watersheds. (5)
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Silvopastures
Silvopastures refers to planted trees, livestock and forage production all combined in one pasture. While this is not currently practised in Manitoba, silvopastures can increase net carbon storage when both trees and forages are properly managed. (6)
Trees perform a further service by providing shade and shelter for livestock during extreme weather. (7)
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Agro woodlots
Fast growing woody crops, such as hybrid poplar trees, provide environmental benefits with high rates of nutrient uptake and large amounts of carbon storage over rotation lengths as short as 15 years. (8)
Biomass from trees can also be used as an alternative fuel (bioenergy). Carbon dioxide emissions from a unit of electricity generated from bioenergy are 10 to 20 times lower than from fossil fuel–based electricity production. (9)
