Tree Decomposition
The lifecycle of a tree varies depending on their species and their environment. Some trees can live hundreds of years because they continually produce new tissue and are able to adapt to their surroundings. The majority of trees however, die earlier than this due to disease, injury or unfavorable environmental conditions.
Tree decay is the process of rotting or decomposition. When this biological process occurs the wood’s cellulose and lignin convert to carbon dioxide and water and the remaining nutrients are released into the soil. It can be caused by many factors, including; wounds, stubs, scars and root damage.
Trees can also rot from the inside out, making it harder to spot the signs of decay. Three types of rot can be caused by fungi, these are; white, brown and soft rot.
Wounds – These occur when a tree is injured limiting its ability to take in water or food and protect itself from infection, infestation or disease.
Stubs – A stub is created when tree branches break off, such as in a storm, or die. This can cause a wound that may not heal resulting in a hole that will invite decay.
Scars – When bark is removed or dies off, scars can leave the inside of the tree exposed to decay. Animals can cause scarring when looking for food and humans can cause scarring by writing messages on the bark.
Root damage – When roots don’t get enough oxygen or the right amount of water decay can begin underground.
White, brown and soft rot – Each kind of rot causes the wood to appear differently. White rot is present when the wood appears to be lighter, this occurs when the fungi feed on lignin. Brown rot can make the wood look crumbly and browner in color, this is due to larger amounts of lignin being left behind. Soft rot occurs when a fungus uses enzymes and nitrogen in the soil to break down cellulose. Soft rotting logs are usually partially buried in the soil.
So, what does tree decomposition look like?
Many fungi make their way onto decaying wood using microscopic spores that can drift in the air. Fungi will often inhabit a tree, living with them their whole life, only to become active when the tree becomes stressed or old.
Most often, when you see a fungus on the side of a tree it means the tree is in some level of trouble. Fungi commonly spread by extending their network of branches and as they spread along a dying or dead tree, they release enzymes that break down the wood and allow the fungus to feed on it.
As decay advances, more organisms such as bacteria, slugs, beetles woodlice and millipedes come along to assist in the processes. These organisms are called detritivores, and as they feed on the wood, they open it up to moisture which helps it to fall apart and decompose even faster.
Once the rotten wood starts to mix with the underlying soil, earthworms and springtails consume it, furthering the process of decomposition.
Other signs of tree decomposition can include soft or brittle wood, where the branches or bark easily break off, and discolored leaves, when the leaves change color off-season.
The rate at which a tree decomposes varies on many factors such as tree species and age, climate as well as the number of fungi and insects present.
How do fallen trees provide life?
The nutrients a tree uses to build itself during its lifespan are spread into the soil when it dies and decomposes. This makes the soil richer for other plants to use around it, and they are essential for small trees to grow and replace the dead ones.
Fallen trees also sustain the many organisms, such as the fungi, beetles and earthworms. Which in turn feed the other animals that prey on them and so on.
Once a tree falls it also leaves behind more space in the forest so more light can reach the forest floor, allowing for other vegetation to grow.
Fallen trees that are hollow can also provide shelter for animals such as foxes and bears who make their dens in them.
Fun Activity
Have a look at one of the many fallen logs around Mighton Woods and see if you can spot the organisms that are playing their part in the decomposition of the wood.
Red and White Oak Trees
Oak (Quercus) is a slow growing hardwood tree that is widely distributed in the Northern Hemisphere. They have leaves that can be spirally arranged with lobed edges, toothed, or smooth, and a nut that is born within a cup called an acorn. They can be deciduous or evergreen. Oak trees have been found as old as 600 years and can reach a height of 145 feet.
Mighton Woods has both Red and White Oak trees and these are some of the major differences between the two;
Leaf shape: White oaks have soft, rounded edges on their leaves, whereas red oaks have a more striking and pointy leaf shape.
Size: White oaks grow to be much larger than red oaks. The former reaches up to 80 feet, while the latter rarely ever goes above 70 feet.
Growth rate: White oaks grow much more slowly than red oak species. Red oaks can grow multiple feet in a single year.
Bark texture: White oak trees have bark that features a much rougher texture than red oak trees.
Differences between the bark of Red and White Oak trees.
Oak trees are known as a keystone species within their habitat and are known to have associations and symbiotic relationships with other plants. These include Juniper Berries and Black Perigord Truffle. They are also home to many species of wildlife including insects, such as caterpillars, birds, such as woodpeckers and Jays, and small mammals such as squirrels.
Oak trees produce both male and female flowers on the same tree and are pollinated by wind. They bloom from mid to late Spring, and the female flowers produce an acorn.
Acorns
The acorn of the oak is the nut, which usually contains one seed, enclosed in a tough leathery shell, and borne in a cup-shaped cupule. After the acorns fall from the tree they are spread by small animals and birds.
Acorns provide food for wildlife including small mammals, birds and insects. However, the tannic acid in the acorns (which gives it a bitter taste) is toxic to large animals such as cattle and horses. Kidney damage and gastroenteritis can result if the acorns are eaten in large quantities.
Red and White Oak Acorns
Interesting Facts
Fossils of oak leaves dating back to the Middle Eocene (33 to 45 million years ago) period have been found.
Acorns can be eaten by humans after they have been boiled to remove the tannic acid.
Leaf Challenge – Can you find these different leaves and acorns?
Maple Trees
Red Maple (Acer rubrum) is one of the most common and widespread deciduous trees native to North America. They can grow in moist and dry soil, in dry ranges to swamps, and can live up to 150 years. It is a medium to large size tree, reaching heights of 90 to 120 ft. The trunk has a diameter ranging from 16 to 60 inches, with the branches mostly growing further up the tree.
Red maples are easily identifiable due to their leaves, which are typically 2 to 4 inches long and wide, with three to five palmate lobes with a serrated margin. The upper side of the leaf is green, while the underside is whitish and can be hairy. The lead stalks are usually red and can be up to 4 inches long.
Red maple leaves change color during Fall from green to a brilliant red and then brown. The most spectacular fall colors are seen in the northern parts of the country where it is cooler.
During early spring the flowers of the Red maple appear, usually before the leaves. They are unisexual, with the male and female flowers appearing in separate clusters. Flowering usually only occurs when a tree is older than 8 years, but has been seen in trees as young as 4. The fruit of the Red Maple are called Samara. These Samara have an enclosed seed at one end and a thin, dry, winglike projection at the other. They spin and resemble a helicopter wing when they fall from the tree.
Interesting Facts
Native Americans used Red maple bark as a wash for inflamed eyes, hives and muscle aches. Pioneers also used the bark to make brown and black dyes.
Red maple can be used for the production of maple syrup, however Sugar and Black Maple trees are more commonly used because the Red Maple flowers earlier making the sap taste bad.
Red Maple leaves are toxic to horses, the exact toxin is unknown but it is believed to be an oxidant that damages red blood cells, resulting in the deaths of about 50 to 70 % of affected horses.
Pitch Pine
Pitch Pine (Pinus rigida) is a small to medium size tree that is native to Eastern North America. It is irregular in shape and grows to a height of 20 to 98 feet. They grow rapidly when they are young, up until around 50 years, then growth slows, and can live for about 200 years.
The branches are usually twisted and the needles are in bundles of three, and about 2 1/4 to 5 inches in length. Pine cones are long and oval in shape and have prickles on the scales. The cones usually take 2 to 3 years to mature and the seeds within the cones are dispersed during the Fall to Winter.
Pitch pine has the ability to regenerate if the trunk is damaged by fire or is cut. The bark, which consists of thick and irregular plates, can protect the inner layers from heat. The tree can also re-sprout using epicormic shoots from its damaged areas. Pitch pine provides housing and food for many wildlife species. Birds nest in its branches, deer consume the new sprouts and small mammals and birds eat the seeds.
White Pine
The Eastern White Pine (pinus strobus) is a large pine tree that is native to eastern North America. It can grow almost anywhere, including well-drained or sandy soil, humid climates, boggy areas and rocky highlands.
In a mixed forest the white pine can grow to height that tower over other hardwood trees. It can grow up to 3 ft annually between the ages of 15 to 45 years, with slower growth noted before and after this time. Trees as tall as 157 ft have been found across North America. White pines grow so tall in fact that during the 17th and 18th centuries they were used as masts for ships and were known as “Mast Pines”.
The branches of the white pine are spaced on average every 18 inches on the trunk with 5 or 6 branches appearing like wagon wheel spokes. Mature trees are often 200 years old but some have been found to be as old as 500.
The Leaves or needles are soft, flexible and bluish-green to silver in color and are regularly arranged into bundles of five. The needles are 2 1/2 to 5 inches long and are shed at the end of the second growing season.
Seed cones are slender and long with a rounded apex that contain seeds which are dispersed by the wind. Cone production peaks every 3 to 5 years.
White pine cones are usually 4 to 8 inches in length and slightly curved. The scales are thin and never prickly.
White pine bark – when young the bark is smooth and greenish grey in color. As the tree matures, the bark will turn a greyish-red with layers of scales forming ridges that are broken into irregular blocks.
In younger trees the measurement of growth can be seen on the trunk between the branches. The distance between each set of branches indicates how much the tree has grown. This can be affected by weather conditions, such as a drought when the tree will grow less, leaving a shorter space between the branches.
White pine trees are valuable to the wildlife within the forest because they provide food and shelter for numerous forest birds, small mammals and insects who eat the bark, buds, foliage and cones.
Can you guess the age of the trees?
While walking the trail see if you can determine the age of the smaller trees by counting the spaces between the branches on trunk.