An agroforestry practice

This presentation was developed by the USDA National Agroforestry Center

Presentation Objectives  Define windbreaks  Describe the benefits and types  Recognize basic design considerations Windbreaks 2

What is Agroforestry?

…the

intentional

combining of agriculture and working trees to create sustainable farming systems.

Riparian buffer Forest farming

Windbreaks

Silvopasture Windbreaks Alley cropping

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What is a windbreak?

 Plantings of single or multiple rows of vegetation (trees, shrubs, grass) that are established for one or more environmental and economic purposes.

Windbreaks 4

What are the benefits?

 Reduce soil erosion      Protect plants Enhance plant growth Manage snow Provide shelter Reduce energy needs   Improve wildlife habitat Enhance aesthetics  Moderate noise  Screen views  Reduce airborne chemical drift  Improve irrigation efficiency  Increase carbon storage  Mitigate odors Windbreaks 5

How does a windbreak work?

Modify: • Air flow • Sound waves • Odor plumes • Microclimate dynamics Trap/filter air borne: • Sediment • Snow • Nutrients • Pesticides • Pathogens • VOCs Windbreaks 6

What are the effects?

Windbreaks:  lower wind velocity causing air-borne material to be deposited  physically trap air-borne material  adsorb some of the chemicals attached to air-borne material  alter the microclimate on the downwind side of the windbreak Windbreaks 7

How can air flow patterns be modified?

Modification of the wind depends upon six key windbreak features:  Height  Density  Orientation  Length  Width  Continuity 8 Windbreaks

Why is height important?

 H = Effective height of the windbreak  The height determines the distance of the downwind sheltered (protection) zone

H 10H to 15H 10H to 15H

Windbreaks 9

Why is density important?

 Dense: maximum wind reduction but short wind shadow  Moderately dense: less wind reduction but longer wind shadow Windbreaks 10

Why is orientation important?

Location or layout:  Directly influences area protected  Effects vary with critical weather periods and wind directions Windbreaks

Wind Rose

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Why is length important?

  For full protection, the windbreak needs to extend the entire length of the area needing protection to account for changing wind directions.

Doubling the length of a windbreak will generally increase the area protected by 4 times Windbreak protected area Windbreaks 12

Why is width important?

Width influences:  Density  Wildlife values  Trapping capacity and efficiency Windbreaks 13

Why is continuity important?

 Wind speed increases in a gap  Gaps in the windbreak can result in damage or complications downwind

(% of open wind speed)

14 Windbreaks

Types of windbreaks Windbreaks 15

Types of windbreaks: field Windbreaks 16

Types of windbreaks: farmstead Windbreaks 17

Types of windbreaks: livestock Windbreaks 18

Types of windbreaks: specialty

Living Snow Fence Irrigation efficiency Odor

Windbreaks

Dust

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Multi-purpose windbreaks  Bio-energy feedstock  Food security  Wildlife  Income products 20

Summary  Windbreaks are an agroforestry practice  Windbreaks provide multi-functional benefits  Windbreaks can be designed to meet site needs and land owner objectives Windbreaks 21

For Additional Information A number of web sites are available to provide more detailed information on windbreaks. Here are a few:    

USDA National Agroforestry Center

http://www.unl.edu/nac/windbreaks.htm

The Center for Agroforestry

http://www.centerforagroforestry.org/practices/wb.php

Association for Temperate Agroforestry

http://www.aftaweb.org/entserv1.php?page=1

USDA Natural Resources Conservation Service http://www.nrcs.usda.gov/wps/portal/nrcs/home

Windbreaks 22

Acknowledgements This presentation was developed by the USDA National Agroforestry Center (NAC), Lincoln NE. NAC is a USDA partnership between the U.S. Forest Service and the Natural Resources Conservation Service.

A partnership of: National Agroforestry Center

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