Micro Climate and microclimate manipulation – From 3

In the last post, it was found that air movement is an important factor to influence the microclimate of the forest garden and now we will investigate Air mixing a little closer. In many ways it is desirable to have so still air as possible. A small gust of wind can blow away the hot air and destroy the effect of both reflective surfaces and heat storage. Lähäckar (ned even though the), walls and other types of shelters are important elements to create a favorable microclimate, especially in exposed areas. In humid areas, it may require some mixing of the air to reduce the risk of fungal attack on plants.

The most dangerous wind for our utility plants is the north wind in the late winter and spring. Low temperatures are no major problems for most plants, as long as they are at rest. But in early spring, when they begin to come to life again, they lose much of their hardiness. The north wind that sweeps across the usually snow-covered expanses of northern Sweden is very cold and can easily be devastating, especially for fruit- and nut trees. While we want to protect the plants from the wind, it is early in the spring as stagnant air also may pose problems.

Night sky temperature is -270 ° C and starry nights, there is a transfer of heat from the relatively warm ground surface to the cold space in the form of heat radiation. The air is completely stationary, the temperatures closest to the surface sink quickly and the risk of nattfrost, that can easily beat out this year's apple harvest, is high. Therefore we would like to have some air circulation, which balances the temperature close to the ground during cold spring nights. In commercial plantations, this is accomplished sometimes with the help of giant fans, but this solution is hardly feasible in small-scale context. The easiest way to reduce heat radiation to the clear night sky is to place an object between us and the night sky. It need not be a thick blanket, but need only a millimeter thin surface to reflect heat radiation. That's why we use cloth in plantations and even eldrök (also used in commercial orchards) helps against late frosts. Since in our woodland gardens rarely appropriate with either smoke or cloth, we can instead take the help of so-called shelter trees, forming a screen between the worth protecting plants and the cold night sky. Alder is an excellent display tree, because it grows faster than most plants, it is easy to stutter up and is also nitrogen-fixing. Using the tree screen does not necessarily mean that the entire night sky needs to be shielded, but suffice it quite sparsely distributed tree, because the night sky visible surface is reduced enough, see illustration below.

It is important to remember that cold air is rarely complete standstill, without it "flows" like water down the slopes and can be just as water trapped in depressions and form what is called frostfickor. These occur if the running cold air is slowed down by a wall, lähäck or similar obstacle. Behind these structures may be significantly colder than around and plants that are in a frost pocket can suffer great harm. Frost pockets can be difficult to read the landscape and the importance of observation in the early morning after our call- and autumn nights to identify them. One can counteract frost pockets, make sure that air can flow freely, example through gaps in lähäckar or by planting them with a slight slope towards the contour line, so that air can continue to run along with them. Can not counteract frost pocket, can instead customize plant selection for the conditions. Fruit is best placed halfway down a slope: This avoids both frost pockets in the valley and wind exposure in the higher positions.

Finally, the soil moisture an impact on the microclimate. Water has a higher heat storage capacity than soil and wet soil therefore need more time to warm up than a dry soil. It is therefore a great advantage to drain waterlogged soils in spring (and ideally capture the drained water again before it leaves our land), so that the plants get an earlier start.

In conclusion we can say that we have great potential to influence the microclimate with often quite simple means in our woodland gardens. That way we can get a better crop of higher quality and grow plants that might not otherwise be able to be at our latitude. As always, we can find inspiration for good micro climate solutions in nature and I would encourage all readers begin to observe how microclimate affects how well the vegetation thrive in our environment.