Description
Windbreaks comprise one or more rows of trees and shrubs of different heights placed perpendicular to the prevailing wind direction. Their purpose is to reduce the force of the wind close to the ground, and thus its mechanical action on crops, pasture and livestock. They are used to curb wind erosion and to help regulate climate conditions on farms. Windbreaks may also be used as living fences that demarcate the boundaries of a property or zones within it. In addition to their main purpose, they provide benefits such as climate regulation and landscape improvement.
Location
Windbreaks are recommendable in the Andean Altiplano as well as regions whose topography is characterized by steep slopes and frequent, intense winds. They are of particular interest in locations with low precipitation and more intense winds during the winter or dry environments, where it is necessary to conserve moisture and regulate climate conditions.
Threats and Impacts Addressed
Windbreaks are used mainly to diminish the impact of strong winds that may damage crops and cause soil erosion. They also reduce the effect on crops of drought, extreme heat and even frost, due to the microclimate that trees foster.
Implementation Steps
- Position the barrier such that it will be perpendicular to the predominant winds.
- Plant the rows of trees and shrubs taking into account the three heights of trees and shrubs that normally compose a windbreak barrier: high, medium, low. The row with the tallest trees should have trees with flexible wood.
- Space the trees out such that, once they are fully grown, the tree density in the barrier will be compact (occupying between 50% and 60% of available space) and turbulent currents due to wind infiltration will be prevented.
- Fertilize, water and perform the required maintenance until the rows have taken hold. Trees about two years old should be planted to maximize the survival rate and accelerate the formation of the barrier.
Inputs and costs
The cost of implementing a 400 m windbreak barrier with trees of three different heights, with a 3 m planting density for the row with the tallest trees, is given below. The main costs relate to the purchase of plants and labour for planting. One day of training is included, as well as five days of annual upkeep.
| Windbreak barrier 400 m long with three different heights | US$ |
|---|---|
| Labour | 330 |
| Materials | 1380 |
| Training | 60 |
| Total | 1770 |
Economic and Ecosystemic Benefits
Strong winds may cause 70% to 100% of a crop to be lost or damaged, especially in the case of bananas, sugar cane, vegetables and fruit trees. Windbreaks may reduce wind speed by 60% to 80% (SAGARPA, 2012). Other benefits include the generation of a favourable microclimate for plant development and the reduction of wind erosion. For example, Altieri and Nicholls (2000) report 0.38 cm soil loss in a crop protected by a Gliricidia sepium and Paspalum conjugatum barrier, compared with 4.20 cm for an unprotected crop. These barriers also help regulate soil and air temperatures, reduce evapotranspiration and improve the distribution of soil moisture and the provision of such marketable products as fruits, seeds, timber and firewood. The trees increase the economic value of a property and improve the aesthetics of the landscape. They also favour biodiversity and reduce the pressure on the forests (Ojeda and others, 2003).
Limiting Factors
Some trees and shrubs may not be apt for the particular conditions of the location in question. Hence, it is important to select windbreak species according to site characteristics (soil, slope, climate, endemism) and the desired service (height, density, width of the crown, branches, rate of growth, longevity, resistance to drought, aesthetic value and value for wildlife).
Lessons Learned
In areas with long dry seasons, irrigation may be necessary to ensure that the barrier takes hold. Windbreak barriers are an important element of sustainable production methods like agroecology and permaculture, because, in addition to their main function, they allow for more efficient water management, enhance biodiversity, increase the organic-matter content of the soil and even help control pests.
Additional Considerations
A single species should be planted in a given row to avoid growth variations. In windbreaks with multiple rows, a different species can be used in each row to minimize the risk of tree loss due to disease, increase the life of the curtain and improve growth. “Woodland shelter” barriers protect livestock from the wind and provide shade.
Units to Monitor Project Progress
- Length of windbreaks planted (m)
- Area under windbreak protection (ha)
Unites to Monitor Measure's impact
- Decrease in losses or damages (t/ha, US$)
- Additional windbreak products (number, t)
References
- Altieri, M.A. and C. Nicholls (2000). Agroecología: Teoría y práctica para una agricultura sustentable. Mexico City: UNEP.
- Ojeda P.A., M. Restrepo, Z. Villada and C. Gallego (2003). Sistemas silvopastoriles, una opción para el manejo sustentable de la Ganadería. Santiago de Cali, Valle del Cauca, Colombia: Fundación para la Investigación y Desarrollo Agrícola (FIDAR).
- Ospina, A. (2003). Cercas vivas. Cali. Valle del Cauca. Colombia: Fundación Ecovivero.
- SAGARPA (Mexico) (2012). "Cortinas Rompevientos" in Fichas Técnicas sobre Actividades del Componente de Conservación y Uso Sustentable de Suelo y Agua (Conservación y Uso Sustentable de Suelo y Agua, COUSSA).
- Venegas, P. (n.d.). Establecimiento de Barreras Rompevientos. Costa Rica: Ministerio de Agricultura y Ganadería, Dirección Regional Pacífico Central.