The magic of mulch
You will hear that there is as much tree under the ground as above. In fact, this is very true. Most tree roots grow in the upper 60 cm of the soil. The roots of a tree are essential for the health and stability of the tree. They absorb water and minerals and ensure the anchoring and storage of the tree.
The roots also have their requirements. Since they are underground, they cannot carry out photosynthesis and, therefore, cannot produce their carbohydrates, which must be transported through the phloem vessels directly under the leaf bark. They also breathe, which means they need oxygen. Oxygen comes from the air and reaches the roots through pores in the soil, which allows the exchange of gases through pores in the roots (lenticels) and along the channels in the wood (marrow rays) (the highlighted lines that can be seen in the oak). Therefore, tree roots are rarely found below 60 cm. Oxygen does not diffuse until now.
The roots of trees also depend on certain types of microorganisms to help them with their work. Carbohydrates that are transported down from the crown are not used by the tree. Some flow toward the ground where they are used by other organisms. In particular, a species of fungus known as mycorrhizas is essential for the health of the tree. Mycorrhiza (fungal roots) are a variety of fungi that have developed along with trees. Essentially, they grow on the roots of the trees (endomycorrhizas) or from shells (ectomycorrhizas) on the outside, and benefit from the carbohydrates of the tree, while the tree benefits from its greater capacity to absorb the minerals from the soil. Mycorrhiza are essential for the long-term health of trees. The area where trees, soil, and microorganisms interact is called rhizosphere.
In the natural environment of the woodland, the trees will shed branches and leaves that are degraded by various fungi, bacteria, and saprophytic (dying) animals. This increases the amount of organic matter in the soil. The organic matter helps to stabilize the pH of the soil, increases the nutrient retention capacity of the soil, also increases the water retention capacity of the free draining soils (sand, chalk, etc.) and increases the drainage capacity of the soil prone to water accumulation (clay). In short, it improves the texture of the soil and, in the longer term, helps to structure it with the help of small animals. The other result of the many small creatures that move on the ground is that they create channels for the exchange of gases. You can learn more here at https://www.treeservicefortworth.org/tree-disease.html.
Over millions of years, trees have evolved along with the creatures that live around them for mutual benefit.
In the garden environment, the soil can often lack organic matter. Foot traffic and cars traffic (mowers, etc.) cause soil compaction that crushes the channels in the soil on which the roots of the trees depend for water and air to reach them. Fertilizers and pesticides affect the nutrient content and poison the tree. All this can make the tree grow in a tough environment. In addition to roads or driveways can get worse. Soil compaction can be a major problem, and salt from winter waste can cause serious problems for tree organisms and soil.
A simple organic remedy
By using mulch wood chips, soil conditions can be significantly improved over long periods of time. It is not the quick solution offered by fertilizers and mycorrhiza injection, nor does it deal with compaction as quickly as with an airborne shovel, but in the long run, trees, shrubs, and general soil health can be beneficial. A layer of cut wood chips, as wide as possible on the crest of the root and about 75 mm deep, will almost certainly improve the health of your trees in the long-term
Won`t that encourage fungus into my garden?
A healthy tree must be able to withstand parasitic fungi. Healthy soil contains a variety of saprophyte and mycorrhiza fungi that compete with opportunistic parasitic fungi, such as honey fungi. This is not a panacea, but miracle drugs rarely preserve their miraculous status for a long time. This is based on good soil science and tries to restore the conditions experienced by trees in the forest.