A common site for anyone that lives in the Great Plains of America are little spots of trees that appear randomly throughout the landscape. What many people don't know is that a great majority of those trees were not naturally grown there but were instead planted by both early and modern homesteaders of the plains. They were planted for many different reason throughout the years but one purpose especially keeps them being planted in a ecosystem that naturally could never support trees. They are planted in order to provide protection from the strong winds that sweep across the plains. With minimal topography and little natural tree growth the plains are the perfect area for wind to travel and pick up speed since there is nothing substantial to slow them down.
Tree's with their large trunks, broad expanses of limbs, and foliage are the perfect tool for providing long term shelter from the wind. Once established many varieties will provide not only protection for many years(sometimes up to 100 years depending on species) but can also provide habitat for wildlife, food for you and some nice shade on the hot summer days. In the past hundred years we have learned a lot about trees and how they interact with the Great Plains including what works and what doesn't work. So if you want to plant trees for a windbreak or just any trees in your yard that don’t already grow there it pays to do some research first to find out whether the tree will work.
Items to consider before any tree is planted include:
Goal of the Windbreak
Space to plant
Goal of the Windbreak
Before you can do anything at you have to to figure out what is the goal of the windbreak. There are many different designs to consider before you go any farther in the process. If your goal is to protect your house and yard you will want multiple rows of denser trees like conifers, shrubs, and some tall deciduous trees as well. If you want to catch snow before is clogs your drive way then you want something like a twin row of conifers designed to catch snow before it reaches your drive way. Sometime you want to spread snow out like on a pasture or a large back yard then in that case you will want a loosely planted row or two of deciduous trees and shrubs that will spread snow out over a large area. The three goals above are some of the most common in my experience but they are not a catch all. It will be up to the person who needs the windbreak to suss out exactly what they need.
Unless you are involved with some sort of agriculture be that ranching, farming, gardening or whatever, you most likely don’t know much about what that stuff is beneath your feet. Well that stuff beneath your feet in your yard is not dirt. It looks like dirt, smells like dirt and feels like dirt but it is not dirt. Dirt is something you brush off you pants or sweep up of the floor at the end of the day. What you have in your yard is a living, breathing, teeming with life, massive organism called soil. Soil and soil types are something that has evolved over thousands of years and its properties and characteristics must be taken into account. If you try and plant a tree that needs good drainage in your waterlogged back yard, it probably will fail without a lot of babying. I'm not saying it wont grow at all but who wants to put that much effort into a tree that is suppose to be working for you. So please please get familiar with the soil on your property it will save you so much headache in the end. Use resources like Web Soil Survey to find out what kind of soil you have. If you bring that information into a Natural Resources Conservation Service (NRCS) office which there is one in almost every county they will be be to help you with the next step which is tree selection.
It is by easier to match trees to soil then to try and modify soils to work for trees. You can temporarily do some soil modifications like liming to alter the pH but it is a process that you will have to repeat over the life of the windbreak. Knowing what soils you are working with will aid you in picking trees that will hopefully meet your goals and can grow in your soil. There are sources of information out there called WSG's or Windbreak Suitability Groups that pair your soil type with trees and shrubs that have been shown to grow successfully in that soil. Again a good place to go is your local NRCS office and they should have that info on file. If they don’t know they should be able to point you in the right direction.
Now tree windbreaks do take up some space which is one of there primary detractors as a windbreak tool. It can be 4-6 feet between plants in a row and 8 ft between rows for shrubs and even larger spacings for bigger trees even up to 15 feet apart. Now if you just want one or two rows that might be able to fit on most smaller lots but for a efficient and well designed house windbreak you will need 4-6 rows of many trees to give you the best bang for your buck. So make sure to take out a tape measure or if you know your pace use that to get a estimate of what kind of space you have to work with.
For windbreaks there is are two main tried and true designs that will work for most situations. You have the straight line windbreak. Which is just like it sounds it is a line of trees that extend however far you want them to in one direction. This design is common for snow catching and snow distributing windbreaks and are also called field windbreaks since that is where you see them most often. The other design is the L design were you have two legs of trees that run a 90 degree to each other. This design is usually used for houses, barns and livestock protection. Studies have show that windbreaks effect the wind typically up to 10H or 10 times the height of the tallest tree. This can vary a lot but it typically is a good rule of thumb that most designers use. One final thing to keep in mind about that 10H is that protection will not cover as far as you think it will. See Figures 1 & 2 below to better understand what I mean.
In Figure 1 you can see that the protected area does not extend outward the whole length of the windbreak. This is because wind curves past the edges of the windbreak and pushed back towards the center. Figure 2 shows the same effect just modified slightly due to the additional leg of tree's which enlarges the protected area.
By keeping in mind the above it will put you on the right path to successfully designing and planting a windbreak. There are many things to consider when attempting this so it is good to start early and get in touch with your local experts to help you out.
If you have any questions about what I covered here just let me know and I will do my best to find the answer for you.