A tree is a woody plant that usually is more than 3 meters tall and has one main stem. Although trees have different shapes and sizes, they all have the same basic parts. Each of these parts, from the highest leaves in the crown to the tiny rot hairs buried in the soil, play an important role in the tree's function and survival.
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| Parts of tree |
The stem (trunk)
It consists of heartwood which is the deadwood of the stem, sapwood which is the living wood (xylem), cambium, and bark.
The heartwood is the older part of the wood and consists of dead cells. Its function is only to strengthen the stem. The cells in the heartwood are very often filled with resin and oil, which makes it very rot resistant. This resin has a darker brown and sometimes black color and makes the wood very attractive for various purposes such as furniture and other carpentry. The heartwood of Juniperus communis is extremely rot resistant.
The sapwood (xylem) provides transport for the tree sap (= water plus nitrogen and minerals) which is carried up from the root to the leaves/needles.
The cambium is a layer of cells inside the inner bark. It is found in between the sapwood and the bark. The cambium produces both the xylem (sapwood) cells and the phloem(= inner bark) cells. The cambium layer is responsible for increases in tree diameter, by creating annual rings, and responds to injury by producing callus tissue each year a tree essentially grows a new "coat of wood" over the older wood. This is where the growth in diameter occurs and where the annual rings in the wood and the bark is formed. The annual rings found in tree stems are the result of variations in growth rate and in the type of wood produced early and late in the growing season. The annual rings are also reflecting the actual weather conditions every year; with a favorable summer, the rings will be wider. When counting the rings we can determine the age of a tree. Many trees are hundreds of years old, and a few live thousands of years. Thus the annual rings provide valuable information on climate and conditions for growth.
The bark layer is made up of dead bark (cortex) cells and protects the tree from insects and diseases, extreme heat and cold, and injuries. In the inner bark (phloem) layer, the sugar which is produced in the leaves is carried down to the branches and stem and root, where it is converted to starch which in turn can be used by the tree for its growth in all parts.
The Root
The root of the tree supports the stem and crown and it also anchors the tree to the soil where it grows. The root also serves as storage for the organic material produced by the leaves. The root also absorbs water and nutrients from the soil. Trees' root systems are made up of large, permanent roots (which mainly provide anchorage and transport), and many small, temporary feeder roots and root hairs. It is these small parts of the root system that are the primary water and nutrient absorbers. Roots of most species of trees are invaded by soil fungi to form root-fungus structures called my mycorrhizae. The mycorrhizal association is beneficial to both the tree and the fungus. The tree supplies carbohydrates/organic material and other growth requirements to the fungus, and the fungus increases water and mineral uptake (particularly phosphorus P) of the host tree by increasing the total absorptive area of the root system.
The Crown
The crown consists of all the leaves or needles, flowers and fruits, and all smaller or bigger branches. One important function of the crown is to carry the leaves in such a way that they are efficient receivers of the energy from the sunlight. The flowers and fruits are almost always found in the crown. The final form of a mature tree is determined by the dominant growth in the crown of some buds and shoots at the expense of others, a phenomenon known as
apical dominance
Conifer trees are with few exceptions (Larix spp.) evergreen and they have needle-shaped leaves. In most conifers, the trunk or main stem grows more each year than the other branches, and the branches attached to the stem grow more than smaller branches. This results in a very orderly growth habit that forms a conical tree growth and is very typical on conifer trees as Pinus spp and Abies spp.
Deciduous trees have green flat leaves that are falling off in the autumn. Most deciduous trees do not show strong apical dominance and therefore typically exhibit less orderly growth. Instead, many shoots grow at the same rate, many branches are developed, and it sometimes becomes difficult to identify the main stem. These species usually have large spreading crowns.
Regeneration
Like all plants, the trees are always producing male and female flowers. Very often the two sexes of flowers grow on the same tree. After being fertilized by the pollen the female flower produces fruit with seeds, bigger or smaller. Very often the seed has 15wings, as on Pinus spp and Picea abies, Betula spp, Acer spp, and others. Sometimes the seed is bigger, like coconuts, walnuts, hazelnuts, oak nuts, and others. The seeds are produced in great numbers to secure that at least some of them will survive and become a new tree. The regeneration of trees from seed in this way is called natural regeneration and is by far the most common in nature.
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| Leaf and seed of the oak tree |
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| The Oaktree germination |
The trees can also have vegetative regeneration. The new shoots or new small trees are growing up from the roots of a big tree. In fact, it is considered to be the same plant as the mother tree. Such regeneration is common for Populus spp and Salix spp.
In Kosova, new shoots are commonly growing from the stump when the original tree is cut. These small shoots are called coppices and the regeneration is called coppice regeneration. Coppice regeneration is quite common for the oaks (Quercus spp) The oak however also produces a great number of big seeds that fall on the ground.
Tree planting
This practice is designed to establish trees where the existing vegetation is inadequate and on open lands where conversion to the forest is desirable and feasible. When there is a general abundance of trees and a richness of native species and where the moisture and fertility of soils are good, the trees naturally regenerate well and tree planting is not necessary
To produce the forest plants, the seed is collected from mature trees of good quality and sown in a forest nursery. After 2–4 years, the plant is big enough to be planted in the forest and to survive in natural conditions. This method of securing the forest regeneration after the felling of the big trees is relatively costly, but it gives a very good quality forest when the production of plants, the planting work in the forest, and the subsequent silviculture activities are done professionally.
Reference :-
https://www.academia.edu/38283510/Introduction_to_forestry
Picture Collected From :- Pixvay
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