Heartwood vs Sapwood : Know the Important Differences

    difference between heartwood and sapwood

    Heartwood and sapwood are two different types of wood that we get from trees. Heartwood vs Sapwood, the difference lies between their properties and usage. Heartwood is the mature, dark-colored wood that forms as the tree ages, while sapwood is the lighter-colored and softer wood closer to the bark. Heartwood is denser, more durable, and less susceptible to decay, making it a preferred choice for furniture and construction.

    On the other hand, sapwood is more flexible and easier to work with, making it a great choice for projects that require bending or shaping the wood. Understanding the properties of heartwood and sapwood can help you make informed decisions when selecting the right type of wood for your specific needs.

    What is Heartwood?

    Heartwood or duramen is the innermost part of a wood log/stem, formed of cells that are dead and known as inner wood.

    Sapwood cells that age and die become heartwood. In other words, the heartwood is formed of dead cells that are no longer used for transporting water and food through the tree stems. The formation of heartwood can be a long process and may take years for the tree to become fully grown.

    The cells of heartwood form a non-functional secondary xylem. As the tree grows, the stem keeps forming more xylem and the heartwood keeps getting more dead xylem. Because cells in the heartwood are very closely located, it is generally hard and strong. Xylem is what makes up the woody part of the tree, i.e. it is the core component of wood. The moisture content is typically lower than that of sapwood, which makes it more resistant to decay and insect damage.

    The dead cells in the heartwood contribute to the accumulation of chemical compounds such as extractives, resins, phenols, oils, and terpenes, which are responsible for the various properties of wood such as dark colour, durability and resistance to moisture, decay, insect attack, etc.

    As heartwood is the strongest part of a tree, it also provides structural support and keeps the tree standing in touch times. The crown of the tree, which includes the branches and leaves, also plays a crucial role in providing support and stability to the tree.

    Because heartwoods are strong and durable, they are used in many commercial applications and can have great demand based on their respective properties (of different species). Some uses of heartwood include construction, furniture, roofs, flooring, plywood, boatbuilding, musical instruments and many more.

    What is Sapwood?

    Sapwood is the original or the earliest form of a tree. Small plants are often called saplings because they only have sapwood and not heartwood. All cells in sapwood are alive and contribute to transporting water and nutrients to all parts of the plant/tree such as leaves.

    The xylem in sapwood is alive and functional. It is the woody part of the sapwood that contains vascular tissue.

    It is composed of a thin layer of alive cells that produce wood cells that form sapwood and bark cells that form the outermost part of a tree. Cells in the sapwood are always new and alive. As the sapwood cells get older and die, they become heartwood.

    Cells of sapwood do not contain any chemical compounds such as resin or oil, which is why it is light-coloured, soft and generally non-resistant.

    The bark of a tree is NOT sapwood. It is generally formed right under the bark. It’s the first thing you’ll see when you remove the bark of a tree.

    While it is not typically useful for commercial purposes, it performs a critical function in the tree, which is to transport water and nutrients to different parts of the tree as well as provide structural support.

    Even though sapwood is softer than heartwood, it still provides structural support to the tree.

    It is not as commonly used as heartwood. Because it is soft, applications such as carving are common.

    Heartwood Vs Sapwood

    differences between heartwood and sapwood

    There are many differences between heartwood and sapwood. Heartwood is the stronger and darker part of the wood that is also generally more useful than sapwood, which is typically weaker and light-coloured.

    The cross-sectional area of a wood log/stem is made of heartwood and sapwood, of which the latter occupies a smaller area as compared to heartwood, which generally occupies the largest portion of the wood.

    Position: While heartwood is the innermost, dense part of a tree, sapwood is formed of softer, outer layers between the bark and the heartwood. That means heartwood is present at the centre of the log, while sapwood is in the peripheral (outer) region.

    Synonym: Heartwood is also called the duramen, and sapwood is also known as the alburnum.

    Cells: Heartwood generally has older and almost all dead cells that are arranged very closely to give it a high density. The cells in sapwood are younger and alive and loosely arranged, which makes it have low density.

    Colour: Heartwood is generally dark in colour, but sapwood is light coloured, generally pale yellow to whitish depending on the species.

    Weight: They form the core of a tree. They are dense and are therefore heavier when compared to sapwoods, which are lighter in weight.

    Moisture presence: It is free of moisture, while sapwood contains moisture.

    Strength: Heartwoods are hard and strong. Sapwood is generally soft.

    Durability: Because heartwood is stronger than sapwood, it is generally more durable in terms of resistance to moisture and insect attacks. Sapwood is normally non-durable, with a few exceptions.

    Contents: Heartwood mainly contains dead cells and non-functional secondary xylem. It has more lignin. Sapwood contains living cells and functional xylem and has more cellulose.

    Purpose: Heartwood forms the core of a tree and provides structural support. It serves as an insulator. The main purpose of sapwood is to serve as a conductor and transport water and nutrients through the body and different parts of the tree.

    Commercial Uses: Heartwood has wide applications because of its high strength, density, durability and rich appearance. Sapwood is not widely used as a commercial wood, though it has applications in low-end projects.

    Conclusion

    Heartwood is denser and heavier than sapwood, and its cell composition changes as it ages, resulting in darker and stronger wood. Heartwood is also more resistant to decay and insect infestation, making it ideal for outdoor use. Sapwood, on the other hand, is less dense and weaker, and more susceptible to decay and insect damage. Its primary function is to transport water and nutrients from the roots to the leaves. These differences between heartwood and sapwood make them suitable for different purposes, so it’s important to know their properties when choosing wood for your project.

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