Planted during and after the dirty 30s to reduce wind and water erosion on the prairies, shelterbelts were for decades a common sight that are becoming less common. A field shelterbelt modifies the microclimate by reduced wind speed and, therefore, reduced soil erosion. Eroded soils are less productive, require higher inputs for crop production and are more prone to further erosion than uneroded soils.Reduced wind erosion is the primary reason farmers have been planting field shelterbelts on the Canadian prairies for more than 90 years. But many of the benefits are at a broader landscape level; while the costs are often related to production impacts and direct private costs (Rempel, 2014). Resulting in many shelterbelts being removed.
A modern inconvenience
Shelterbelts have largely fallen out of favour with farmers as they create challenges for larger equipment with more turning. Micro-climates created from larger snow catch and shade can cause seeding and harvest issues as the ground is too wet to seed or the crop is not mature at the same time of the rest of the field. The argument can be made the risk of wind erosion has been largely addressed by the move to no-till practices.
Changes in farming technology over the last 20 years has increased the cost of maintaining shelterbelts and reduced the benefits. In particular, the benefit from the micro-climate of increased moisture for crop growth, due to snow trapping and reduced moisture loss through evaporation, supporting crop yields is in many cases deemed to small compared to the additional costs.
An unappreciated contribution to ecology
Field shelterbelts are a part of larger conservation management systems that help safeguard the productive quality of our soils. Shelterbelts also generate a variety of social benefits such as enhancing wildlife habitat acting as corridors for birds, small mammals, invertebrates and a reservoir of pest for predators. They provide nesting sites. In addition, the root system goes deeper than annual crops helping maintain the regional groundwater balance, protecting watersheds, cycling oxygen (by taking in carbon dioxide, a greenhouse gas, and releasing oxygen) and providing a varied and attractive landscape.
They also improved safety in winter travel due to reduced snow drifting, lower costs of snow removal from roads, beautification of the prairie landscape, reduced environmental effects of agriculture.
Alberta Agriculture & Forestry notes that they have historically provide shade and shelter for livestock and the opportunity to supplemental farm income from the sale of berries, firewood, pulpwood or lumber. However, they can also possibly harbour pests, disease and weeds.
Production practices have changed on the prairies, and not just for field crops. These is less integrated livestock/grain operations. And even when operations are integrated, like ours, how annual crops are utilized within the livestock operation have changed.
Hedgerows in Europe
The move to remove hedges is not unique to Canada. In Europe the trend has also been noted. Although arable farming is not the only reason for hedgerow removal, it has, in most recent times been the main cause. Arable farmers have less reason to retain and maintain hedgerows and are more likely to see economic reasons for enlarging fields and widening gateways. Historically hedges were used as fencing to control livestock or as boundaries between farms. As consolidation takes place, this becomes redundant as farms are amalgamated or livestock operations abolished.