Tree Care Glossary

Abiotic Stress: It can be defined as the adverse impacts created by the abiotic factors on the plant tissues. Abiotic stress is caused by nonliving factors that are in contrast to biotic stress, which is caused by living organisms. Plants cannot move, so they must endure abiotic stresses such as drought, salinity and extreme temperatures.

Abscission: From the Latin words ab (away) and science (to cut), it is a cell separation process by which plants can shed organs such as fruits, leaves, or flowers. The process takes place in specific locations termed abscission zones. In fruit crops like citrus, fruit abscission represents a high percentage of annual yield losses. Shedding of leaves in the fall is the most visually obvious display of abscission in nature.

Aeration: This involves punching holes into the soil and forcing air in to loosen it, most often near a tree’s root system. Aerating the soil in the root zone is one of the best and easiest ways to help a tree. It is commonly achieved with a plug aerator, which removes small plugs of soil from the ground to provide more space and aerate the soil around it. Young trees desperately need essential nutrients to grow, and an arborist may suggest options beyond soil aeration in case of poor soil nutrient quality.

Afforestation: Generally speaking, it is the process of introducing trees and tree seedlings to an area that has previously not been forested. Afforestation can be done through tree planting and seeding, naturally or artificially. The type of land planted could include areas that have turned into desert places that have long been used for grazing, disused agricultural fields, or industrial areas.

Arboriculture: The simplest definition of arboriculture is tree care. Arboriculture means growing, tending, studying, or removing individual trees and shrubs. It also encompasses woody plants and vines. The practice of arboriculture is executing those techniques used to maintain trees, such as selecting which trees to plant, applying fertilizer, and spraying to control insects and diseases.

Arborist: An arborist is an expert and a professional in the tree industry who has completed their AQF Level 3 qualifications in horticulture or arboriculture. The more technical definition is an arborist is a professional who studies, manages, cultivates, and cares for trees, shrubs, and other woody plants. An arborist is also known as a tree surgeon, arboriculturist, or tree expert. With the knowledge they acquired from this study and experience in the field, they work to preserve healthy trees and remove dangerous ones.

Bark: Similar to skin, bark is the outer covering of a tree. The term actually refers to several different tissue layers, including the cork, cork cambium and phelloderm. It adapts to protect the living tree from the environment and protects delicate tissues from diseases and insect attacks.

Basal Area (BA): A common term used to describe the average amount of an area, commonly an acre, which is occupied by tree stems. In other words, how much of the area of one acre is taken up in trees? BA is a measure of the capacity of certain stands of trees to increase annual ring growth.

Biennial Plant: As the name suggests, a biennial plant takes two years to complete their life cycle. In year one, they germinate, grow foliage and establish their roots. Then in year two, they flower, set seed and die.

Biodiversity: In its broadest sense, biodiversity is the term used to describe all life on Earth, in all its variety from all sources, including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part. Biodiversity is the most complex feature of our planet and it is the most vital. Without biodiversity, there is no future for humanity.

Biotic Stress: Biotic, by definition, is “resulting from living things”. Any biotic problem in a tree is going to be caused by living organisms such as bacteria, viruses, fungi, parasites, beneficial and harmful insects, weeds, and cultivated or native plants. Biotic stress causes the plant to become malnourished due to lack of nutrients, and this can cause its death. Not just on the farms but even post-harvest damage to the grains and fruits can be a result of biotic stress.

Boreal Forest: Also known as the Taiga or Snow Forests, it is the Earth’s northernmost forest encircling the globe across North America, Northern Europe, and Northern Asia. From a biological perspective, boreal forests are defined as forests growing in high-latitude environments where freezing temperatures occur for 6 to 8 months and in which trees are capable of reaching a minimum height of 5 m and a canopy cover of 10%.

Bracing: Simply put, bracing involves installing a long threaded rod through several branches or stems where they’re weak and likely to split. The rod gives more support than a cable and limits the degree of twisting that can happen during violent weather. This tree support technique, or any for that matter, cannot make a tree 100% safe, but it can mitigate the risks to a customer’s acceptable level.

Branches: Sometimes referred to in botany as a ramus, they are the parts that grow out from its trunk and have leaves, flowers, or fruit growing on them. Large branches are known as boughs, and small branches are known as twigs.

Brush Chipping: Shredding debris leftover from tree trimming into wood chips, which can then either be removed from the property or used in landscaping to prevent erosion. Brush chipping is more than a way to dispose of debris from tree removal or dead wooding. It can also improve the look and safety of your property. Brush chipping is an expedient and excellent process when trimming or removing a tree. It’s less time-consuming and, therefore, more economical than hauling and less polluting than burning the brush.

Bud: Small lateral or terminal protuberance on the stem of a vascular plant that may develop into a flower, leaf, or shoot. New buds typically initiate in current-year shoots in the latter part of the growing season. Buds are responsible for primary growth and are created by meristem tissue.

Cabling: A method by which arborists provide structural support to trees, thus reducing stress damage on your tree from high winds, the weight of ice or snow, and heavy foliage. Tree cabling uses extra high-strength cables to hold a tree branch in place. However, cabling isn’t a substitute for proper trimming and pruning, nor can it save a branch or even a tree that is badly damaged or already dead.

Cambium: Is the layer of plant tissue responsible for the secondary growth of roots and stems. The cambium has several functions. In woody plants, it produces layers of xylem and phloem, consequently enhancing the stem’s diameter.

Canopy: Refers to the coverage amount of leaves and limbs that a single tree or group of trees cover. A tree canopy provides shade to your yard, a habitat for native animals, and a beautiful display of leaves. It can even create the ideal growing space for shade-loving trees and plants.

Canopy Cover: Refers to the coverage amount of leaves and limbs that a single tree or group of trees cover. Tree canopy coverage is often used to measure the benefits of trees. Measuring canopy cover helps us understand how much shade is provided and how much carbon dioxide is absorbed by our city’s trees. For example, Canopy cover in Canberra varies from suburb to suburb. Some older established suburbs have close to 40% canopy cover while some newer suburbs have below 10%.

Carbon Sequestration: Describes the process in which carbon dioxide (CO₂) is removed from the atmosphere and subsequently stored through biological, chemical, or physical processes. Though it is a process that happens naturally, it is increasingly encouraged and facilitated to mitigate the effects of climate change.

Chainsaw Safety: Prevents common Tree Felling Accidents. A chainsaw should never, under any circumstances, be operated without personal protective equipment (PPE). Use a chainsaw only if you feel comfortable with your experience and ability to handle one. Safety when it comes to chainsaws is a mix of personal protective equipment (PPE), training and proper maintenance.

Chlorophyll: Is a molecule used in photosynthesis, and it’s responsible for the green pigment. This compound is a photoreceptor, meaning that it captures sunlight and uses it for photosynthesis, a process by which sugars and other nutrients are created to feed the plant.

Cloning: The word clone comes from the Greek “klon,” which means twig. In plants, cloning is the production of a cell that is genetically identical to the parent. Simply put, cloning is the surest way to replicate successful plants. This is particularly beneficial for growing plants commercially since it ensures consistency generation after generation.

Collar: The collar is the folded bark tissue around the base of a branch. A branch collar is the attachment structure in woody plants that connects a branch to its parent branch or to the trunk. The collar is an important part of a tree’s anatomy and is especially important for those pruning trees to understand its purpose.

Cone: Cone, in botany, mass of scales or bracts, usually ovate in shape, containing the reproductive organs of certain nonflowering plants.

The cone serves as a woody container for the seeds, which are released from the cone only when environmental conditions are exactly right.

Coniferous: Are trees that grow needles and cones as opposed to leaves. Unlike deciduous trees, coniferous trees do not change colors during the winter. This helps explain why the Christmas tree we put in our home keeps its green color while all of the deciduous trees are leafless and brown during the winter.

Coppicing: Coppicing comes from the French word ‘couper’ meaning to cut. It involves cutting a tree at as low a level as possible to create what is known as a coppice stool. It exploits the natural growth pattern of trees: if the main stem has been cut or has fallen, it will send up shoots in a bid to survive. Many trees can withstand coppicing indefinitely, providing lumber for generations without dying.

Critical Root Zone (CRZ): Also called the “tree protection zone”, is often defined as an imaginary circle on the ground that corresponds with the “dripline” of the tree. This area is important to a tree because it is where the most critical tree roots are located beneath the ground. That is why it is also called a “protection” zone.

Crown: The tree “crown” or “canopy” is referring to the branches, leaves, and other foliage on top of the trunk. The crown is an incredibly important part of a tree, helping to filter out dust and particles from the air.It also helps to cool the air by providing additional shade. This reduces raindrops from impacting the soil below.

Crown Cleaning: This is the removal of defective limbs including those that are dead, dying, diseased, rubbing, and structurally unsound. Cleaning reduces the risk of branch failures, improves plant health and enhances tree appearance. An example of a crown cleaning specification might be, “crown clean to remove dead, dying and broken branches 1” diameter or larger”.

Crown Raising: The term ‘crown’ means the same as ‘canopy’ in arborist terminology. Also known as Crown Lifting, this refers to the pruning of some of the lower branches on the tree to increase the distance the crown or canopy is above the ground level. Good practice dictates crown raising should not normally include the removal of large branches growing directly from the trunk as this can cause large wounds.

Crown Reduction: It is one of the most common pruning techniques arborists use to control the size of the tree while maintaining the structure or shape of its crown. During this process, dangerous deadwood and crossing branches are removed or pruned to minimise the possibility of pathogens and disease infecting the tree. Crown reduction cuts should be as small as possible and in general not exceed 100mm diameter unless there is an overriding need to do so.

Crown Restoration: Is pruning conducted on topped or damaged trees over time. In this process, arborists will locate strong twigs in the crown of the tree that evenly covers the canopy. They will perform precision trimming to incentivize the growth of these twigs into branches. Over the next several years our arborists will select the strongest limbs and slowly remove the others until the crown has recovered.

Deciduous: The word deciduous means “to fall off” and refers to how a plant or tree’s leaves fall off in the autumn. Some may refer to these trees as “broadleaf” trees, as their leaves typically have a wide and flat shape. Examples of deciduous tree species include maple, oak, birch, and cherry.

Defoliation: It is defined as a widespread loss of leaves or stripping of leaves on a plant due to stress or disturbance from insects, disease, grazing animals like deer or rabbits, chemical runoff from herbicides or a natural event such as wind or rain.

Deforestation: Is the clearing, destroying, or otherwise removal of trees through deliberate, natural, or accidental means. Deforestation usually involves cutting down many trees without planting new ones in their place. Greatly accelerated by human activities since 1960, deforestation has been negatively affecting natural ecosystems, biodiversity, and the climate.

Dendrology: The term dendrology is derived from two Greek words meaning trees and discourse or study, or the study of trees. In common usage it has come to mean the taxonomy of woody plants. Dendrologists specialize in identifying woody plants and differentiating between species and subspecies that can show very subtle variations.

Drip Line: Defined as the area directly located under the outer circumference of the tree branches. When the tree canopy gets damp, any extra water moves to the ground along this dripline, something like an umbrella. This area is a tree’s CRZ (critical root zone).

Epicormic Shoots: Also known as “suckers”, these are fast growing branches that can emerge along the trunk and branches of a tree. Epicormic shoots usually arise from suppressed buds in the bark. These buds form on the growing shoot but fail to extend and then become embedded in the bark as the stem grows in thickness.

Evergreen: In a literal sense, evergreen means that a tree remains “green forever” (or as long as it is living). Evergreens are trees and shrubs that keep their beautiful green foliage year-round. Moreover, evergreen plants and trees are those which do not lose their leaves at the onset of cold weather.

Exotic Species: The species of trees growing in an area which is different from their natural habitat or where they do not naturally occur are termed as ‘Exotic’. Also known as non-native and non-indigenous species, they can be introduced on purpose, or by accident. Exotic tree species grow faster than their indigenous counterparts. They can also be more profitable than native tree plantations in terms of timber.

Fertilization: It simply means adding material to soil (or sometimes directly to plants) that provides the elements plants need for tree growth, and contributes to the overall health and vitality of a tree. Trees, like all plants, require certain specific nutrients to survive. If nutrients are lacking, the tree may be unable to complete the process of photosynthesis, which is how plants make their energy.

Forest Management: Forest resource management, it is the process of protecting and maintaining a forested area. Forest management can include anything from low-intensity to high-intensity interventions using different practices, tools, and techniques. It often involves evaluating the soil, trees and vegetation within a forest ecosystem and performing a variety of complex tasks to improve land management practices.

Girdling: Also called ring-barking, it is the loss of a strip of bark from around a branch or trunk of a woody plant. Girdling is a technique that kills woody plants in place without cutting them down. It severs the bark, cambium, and sometimes the sapwood in a ring that encircles the trunk of a tree. In this sense, the word usually refers to the intentional killing of a tree.

Grafting: Is a technique that joins two plants into one. It occurs naturally in forests when two branches of two different trees (or sometimes the same tree) touch each other, merge, and continue to grow. In general, a wound is created on one of the plants, and the other is inserted into that wound so each plant’s tissues can grow together. As a technique used by humans for tree propagation, its use dates back to ancient times in many civilisations.

Habitat: A habitat is the natural home or environment of a plant, animal, or other organism. It is a place where a living thing can obtain everything it needs to survive like food, water, shelter and space to survive. Habitats consist of both biotic and abiotic factors.

Hardiness Zone: Hardiness zone tells us how cold minimum temperatures can be. More specifically, it is a geographic area defined to encompass a certain range of climatic conditions relevant to plant growth and survival.

Hazard Assessment: It is an estimation of the level of risk that a tree poses to persons or property due to failure to thrive. A professionally conducted tree hazard assessment is a preventative tree care service that is offered by arborist companies. If a risk is identified by this assessment, recommendations on how to improve health and safety are made (sometimes, this may mean complete tree removal).

Heartwood: In a branch, it is the main stem or root of sufficient diameter, the non-living inner wood. Although dead, it will not decay or lose strength while the outer layers are intact. Heartwood is the central supporting pillar of the tree.

Herbaceous plants: These are plants with no persistent woody stems above the ground. Unlike woody plants, such as trees, these plants don’t have a stem that will remain above the ground when their leaves die. They are mostly biennials and annuals, along with a few perennials. In unfavourable seasons, the top growth dies down to the ground.

Hydrozoning: The landscaping technique known as hydrozoning groups plants that require comparable amounts of sun, water, and soil in order to preserve water, enhance plant health, and safeguard the ecosystem. It minimizes both underwatering and overwatering, which means happier plants and less water waste.

Indigenous Species: Terrestrial and aquatic species that have evolved and occur naturally in a particular region, ecosystem, and habitat. In Australia, the term usually applies to species of trees that pre-date the arrival of European settlers. They represent a number of different life forms, including conifer trees, hardwood trees and shrubs, grasses, forbs, and others.

Irrigation: Applying controlled amounts of water to plants when they most need it is known as irrigation. Water and sunlight are essential for plants to develop because they promote photosynthesis. Irrigation benefits plants, because it stimulates deep roots, encourages blossoms and leaves, and systematically cares for your plants.

Lateral Roots: Un-tapered, rope-like roots that grow outward and form a network to support the tree. They absorb a lot of water and nutrients as well as anchoring the tree. In addition, they are the roots most likely to break up the sidewalk and to be damaged by lawnmowers.

Leaf Scorch: Non-infectious, physiological condition caused by unfavourable environmental situations. Leaf scorch is caused by the failure of the tree to supply enough water to the leaves at a critical time, usually in July and August. If the water supply is deficient, the exposed leaves dry out and scorch. Though there might be multiple reasons for this condition, scorch is most often a direct result of an inadequate water supply.

Leaves: Leaves are the main locations of photosynthesis; they provide food for plants, which eventually provide sustenance and nutrition for all terrestrial creatures. Sunlight is absorbed by leaves, which then convert it into energy.

Line Clearance: This includes work in proximity to electrical hazards when the arborist is not employed by or working under contract to a utility-system operator. When working near power lines, municipal and commercial arborists usually have this in mind; however, they are not there to clear trees for the power company. Generally speaking, it refers to the cutting down of brush that is within ten feet of electrical power lines or the pruning, trimming, repairing, maintaining, clearing, or removing of trees.

Logging: The process of cutting down trees for wood. Also referred to as commercial logging, it entails cutting down trees for pulp or lumber that will be sold. The pulp is used to manufacture paper and paper products, and the lumber is used to construct furniture, houses, and other things. There are two main types of logging: clear-cutting and selective logging.

Monoculture: It is a farming system in which only one single type of tree is grown in a field at a particular time. Monoculture can refer to planted forests or other human-made ecosystems that primarily contain one species of plant, like lawns.

Mulching: It is the act of covering the soil with mulches in order to preserve moisture and improve the condition of the soil. Mulch protects your soil from the elements, keeps your tree’s roots protected, and stops you from falling. Proper mulching techniques can improve soil quality, moisture retention, and weed suppression. It can also prevent harm to trees and promote healthy growth.

Mycorrhiza: Basically, “myco” means fungus and “rhiza” means root. It refers to the symbiotic relationship between fungi and the roots of a tree. The fungi help trees or shrubs, and in return, the roots give the fungi carbon, carbohydrates, and other nutrients. This not only makes the trees more efficient, it makes the trees more efficient, it makes them better prepared to survive droughts and reduces their supplemental irrigation needs.

Needles: It may not seem like it, but needles are leaves. They do the same job that broad leaves do—capture sunlight, “inhale” carbon dioxide, and “exhale” oxygen—providing the tree with food and air for us to breathe. Instead of shedding every fall, though, needles can last three or four years!

Perennial Plant: A perennial plant will live for more than two growing seasons. Unlike their short-lived counterparts, perennials are typically cold-hardy plants that will return again in the spring. But in common use, the term usually describes smaller herbaceous plants rather than larger trees, bushes, and shrubs. Perennial plants can either be evergreen, meaning they keep their foliage all year round, or they can die back in winter before reappearing in spring from the same root base.

Pest Control: Pest control is the process of controlling, managing, minimizing or removing undesirable insects and other pests from trees. Mostly, beetles and borer cause damage to trees, but also include fruit flies and any other insect that feeds on trees.

Petiole: The leaf stalk that connects the blade(s) to the twig. The petiole is the stalk that supports a leaf in a plant and attaches it to the stem. Many people often call it a stem, which is incorrect. It allows the transport of the energy synthesized in the leaf to the rest of the plant as well as enables the transport of nutrients and water to the leaf.

Phenology: The word phenology is derived from the Greek word phaino, meaning “to show” or “to appear”. It refers to the “cyclical and seasonal natural phenomena in relation to climate, vegetation, and animal life. Phenology tells us about our food supply and ecosystem and also helps us determine if species critical to our survival will endure in our changing world.

Phloem: The inner bark, or “phloem” is the band of tissue outside of the cambium. It is responsible for distributing and transporting carbohydrates produced during photosynthesis. It lives for only a short time, then dies and turns to cork to become part of the protective outer bark.

Photosynthesis: Photosynthesis is an important process that permits plants, including trees, to use their leaves to trap the sun’s energy in the form of sugar. Trees use this process to create food for themselves. As a by-product of photosynthesis, oxygen is produced and released by the tree.

Pollarding: Also known as “lopping” or “topping”, it is the technique of regularly pruning trees or shrubs back to a trunk to form a head of branches. It is normally started once a tree or shrub reaches a certain height, and annual pollarding will restrict the plant to that height. Naturally, the response of a tree after pollarding is to generate sprouts at the site of the cut.

Pollination: Pollination is the transfer of pollen from the male part of the flower to the female part of the flower. Some types of fruit trees may be pollinated with their own pollen and are considered self-fruitful. Tree pollination is a critical aspect of tree biology, biodiversity, and ecosystem health. Trees rely on pollination for reproduction, and without it, entire ecosystems could collapse.

Pruning: The term is often associated with the removal of unnecessary branches and sometimes even roots. Pruning helps protect against pests and diseases, and promotes strong growth. It helps trees establish a strong structure for growth, which allows them to thrive. Pruning also improves the sunlight that reaches lower branches, encouraging branching and greater fruit production.

Reforestation: It involves the natural or intentional regeneration of tree cover after forest loss. This can mean anything from supporting natural regeneration in an area that has been degraded to planting ecologically appropriate tree seedlings after forest fires. It helps to maintain the balance of all the ecosystem services – which may be economic, cultural, environmental or health-related – provided by forest areas.

Right-of-Way(ROW): Is the dedicated space for public infrastructure: streets, sidewalks, and utilities. The condition of a tree varies according to its location. If it’s within the public right-of-way, which is typically three roadways wide and under town authority for highway purposes, you cannot chop and split it into cordwood without a public official’s approval. However, some residents take street tree maintenance into their own hands.

Root Pruning: Is the process of slicing through the roots of an established tree that is going to be dug and transplanted. Roots are instrumental in transferring vital nutrients to the entire tree body. If they are closer to the tree, this process becomes easier. Root pruning is also necessary to transport plants. In this case, the roots are pruned in order for the tree to be moved to another location. Hiring an Arborist to execute this process will help your trees live longer and flourish.

Root System: The roots system of a tree is the support mechanism for all parts of the tree above ground level. Put it this way: without the roots, a tree wouldn’t survive. Without a healthy root system, a tree will be more susceptible to diseases and toppling over – both of which are not ideal outcomes. The size and spread of a root system relates to the size of the plant so generally the larger the plant, the more extensive its root system.

Sap: Filled with nutrients and minerals, sap is the blood of a tree. Tree sap is a sticky, viscous liquid that flows through a tree’s vascular system, carrying water, nutrients, and hormones to different parts of the plant. In fact, one of the most popular kinds of sap, usually from sugar maple trees, is boiled down into maple syrup. It is in all vascular plants, but it’s most prevalent in deciduous trees, such as maple, beech, and birch, and coniferous trees, like spruce and pine trees.

Sapwood: The tree uses sapwood as a conduit to carry water up to the leaves. New wood is sapwood. Inner cells become heartwood as they lose their vigor and are replaced by fresh rings of sapwood.

Seed: When beginning a new garden, seed is an inexpensive approach to grow a big number of new shrubs or trees. Trying to develop trees from seed is equally enjoyable, but it takes perseverance because it takes several years to create a giant tree.

Silviculture: In order to meet the various needs and values of landowners and society, including those for wildlife habitat, timber, water resources, restoration, and recreation, on a sustainable basis, silviculture is the art and science of managing the establishment, growth, composition, health, and quality of forests and woodlands. This is accomplished by applying different types of silvicultural treatments such as thinning, harvesting, planting, pruning, prescribed burning and site preparation

Soil Compaction: Soil compaction is caused by soil particles settling together, reducing or eliminating the amount of oxygen and water space available. Often you can tell by leaf color and size in the trees near the site that they are suffering due to disturbed soil.

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