How do tall trees carry water from their roots to the leaves?

How do tall trees, such as redwood, carry water from the roots to the leaves? Donald J. Merhaut, of the Monrovia Nursery in Azusa, California, talks in detail about transportation in tall trees: « Water is often the most restrictive factor for plant growth. As a result, plants have developed an efficient system of water absorption, transport, storage, and use. To understand the transport of water in plants, it is first necessary to understand the tubular (plumbing) of the plants. Plants have a wide network of canals, composed of wooden containers (xylem) and bark (phloem).

This pathway of water and nutrient transport can be compared to the vascular system that carries blood through the human body, and as with the human vascular system, wooden vessels and bark extend throughout the plant. These conductive tissues begin at the roots and extend through the trunk of the tree, branching into the branches, then branching into each leaf.

« The bark tissue consists of living cells that have long been attached to each other. Bark tissue is responsible for transferring nutrients and sugars (carbohydrates) produced by the leaves to metabolically active plant areas (which require sugars for energy and growth): wooden containers are also made of stretched cells, and these cells die as soon as they are formed, but the walls remain intact and act as an excellent pipeline for transporting water from roots to leaves. A single tree contains many fabrics or wooden container elements through which it extends. The diameter of the typical wooden container can only be several microphones.

« The physiology of water absorption and transport is also not very complex. The main driving force for absorbing water and transporting it to the plant is to pass the water (perspiration) from the leaves. The process of evaporation of water through specialized openings in the leaves called pores (stomata). Evaporation creates negative pressure from water vapor in the peripheral cells of the paper, and once this occurs, water is attracted to the sheet of vascular tissue, the wooden vessels, replacing the water that is available from the paper.

This cloud of water or tension in the wooden containers of the leaf will extend along the entire length of the wooden container column in the tree and in the wooden containers at the roots due to the cohesive forces (cohesion) that bind the water molecules along the sides of the wooden containers (remember, the wooden container is a continuous water column). From the leaf to the roots). Finally, the negative water pressure at the roots will result in increased absorption of water from the soil.

« If the leaf decreases, as is usually the case at night or in cloudy weather, the decrease in water pressure in the paper will not be as much as before, and therefore there will be a decrease in water demand (there will be less tension) in wooden ships.

The water loss from the paper (negative water pressure, or discharge) is similar to the application of a straw suction force. If the discharge or suction force created in this way is large enough, the water will rise through the straw.

If the straw is large in diameter, you will need more suction to lift the water, and if you have a very narrow straw, less suction power is needed.

This association occurs because of the consistent nature of the water on both sides of the pot (sides of wooden containers): because of the narrow diameter of wooden vessels, the degree of water tension (discharge) required to push the water up by wooden vessels can be easily obtained by normal rates of erosion that occur most of the time in the papers.

Alan Dickman, Director of the Program of Study in the Department of Biology at the University of Oregon at Eugene, provides the following answer to our question:

« Once present in the root cells, water enters a system of interconnected cells that make up the tree’s wood and extend from the roots through the trunk, branches, and leaves. The scientific name of wood fabric is wooden containers, which consist of several different types of cells, the cells that provide water (with dissolved mineral nutrients) are long and narrow and become non-living when they begin to carry water, some of which have open holes in their tops and bottoms and are stacked in a form It is like a concrete sewer pipe.

The other cells are tapered at their ends and do not have complete holes. But all cells have holes in their cell walls, through which water passes. Water moves from one cell to another when there is a pressure difference between the two cells.

« Since these cells are dead, they cannot actively participate in pumping water. It may seem possible that living cells at the roots can generate significant pressure in the root cells, and to some extent, this process occurs.

But the common experience tells us that the water inside the wood is not under positive pressure, but in fact, it is under negative pressure or suction. To be convinced, think about what happens when you cut down a tree or dig a hole in the trunk. If there is positive pressure in the leg, you expect a stream of water to turn off, and this rarely happens.

« In fact, aspiration in water-carrying cells comes from the evaporation of water molecules in the leaves. Each water molecule has electrically positive and negative charged parts. As a result, water molecules tend to stick together;

The water molecule evaporates through the pores of the paper, exerting a small pull on the adjacent water molecules, reducing the pressure in the water-carrying cells in the paper, which causes the water to be removed from the adjacent cells, and this chain of water molecules extends all the way from the leaves to the roots and even extends from Roots to the ground, so that the simple answer to the question of what pushed the water from the roots to the leaves is that the sun’s energy does this: the heat of the sun causes the evaporation of water, which releases the water’s chain of movement.

Ham Keillor-Faulkner is a Professor of Forest Sciences at Sir Sandford Fleming College in Lindsay, Ontario. He explains and tells us:

« Until trees turn into long, autonomous ground plants, they must develop the ability to carry water from the groundwater supplies to the top of the tree, a vertical distance that, in some cases, could exceed 100 meters (i.e., the height of a 30-story building).

To understand this evolutionary achievement, we must be aware of the structure of wood, some of the biological processes that occur in trees and the physical properties of water. Water and other materials for biological activity are transported in trees throughout the trunk and branches in thin hollow tubes in wood fabric, or wood fabric.

These tubes are called ship elements in solid trees or fallen leaf trees (which lose their leaves in the fall) and are called tracheids in soft or coniferous trees (those that retain most of the foliage produced during the last winter season).

Vascular elements are combined end-to-end through holes to form tubes (called vessels) ranging in size from a few centimeters to several meters in length depending on the species, with diameters ranging from 20 to 800 microphones. There are very small openings called pits along the walls of these ships that allow materials to move between adjacent ships.

The bronchi in conifers are much smaller, rarely more than five millimeters long and 30 micro sin diameters. They do not have perforated ends, so their ends are not connected to the ends of the other bronchial tubes. As a result, drilling in conifers, which are also found along the lengths of the sternum, plays a more important role.

This is the only way for water to move from one story to another as it moves to the top of the tree. To move water through these elements from the roots upwards, a continuous column must be formed. This column is believed to begin when the tree is a newly planted (germinated) seedling and to maintain it throughout the life of the tree by two forces, one pushing water upwards from the roots and the other pulling water upwards.

Thrust is obtained by two characteristics, namely capillary property (the fluid tends to rise in a thin tube because it usually flows along the tube walls) and root pressure. Poetic work is a secondary element of the payment process. Root pressure extends most of the force that pushes water at least a short distance to the top of the tree. Root pressure is created by water moving from its reservoir in the soil to the root tissue by osmosis (propagation by concentration gradient).

This procedure is sufficient to overcome the « hydrostatic » hydrostatic power of the water column and even the osmotic gradient in cases where soil water levels are low. The poetic act and root pressure can support a water column between one and three meters high, but longer trees, in fact, all trees, as they mature, require more strength. In some older models, such as some tree species such as redwood, Pseudotsuga menziesii and many other species in tropical rainforests, the canopy is 100 meters or more above the ground!

In this case, the additional force that pulls the water column from the vessels or bronchial tubes is evaporation and propylation (evapotranspiration), which is the loss of water from the leaves through openings called pores and the subsequent evaporation of this water. When water is lost from the

Leaf cells during the promendence, a slope develops, and the movement of water outside the cell increases the focus of this cell and thus increases the pressure of the suction force. This pressure allows these cells to absorb water from adjacent cells, which in turn take water from their neighboring cells, and so on – from leaves to branches to branches to stems to roots – while maintaining continuous clouds.

To maintain a continuous column, water molecules must also have a strong familiarity with each other. This idea is called the theory of coherence. Water, in fact, has an enormous cohesion. In theory, this coherence is estimated to reach a force equivalent to 15,000 atmospheric pressure forces.

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