Temperatures are rising around the world, including in Canada, and that is concerning not only for human beings but for all forms of life, including trees. Heat stress can be as dangerous for trees as it is for people. The damage can be so extensive that tree removal in Kitchener becomes necessary. Nevertheless, there are things you can do to help trees cope with the stress more effectively.
Do Trees Have Ways of Cooling Themselves?
As the human body regulates its temperature in hot weather through perspiration, trees cool themselves through a process called transpiration. Trees have small openings in their stems, flowers, and leaves from which water evaporates to cool them down. The hotter the temperature, the more trees have to transpire to keep cool.
Both human beings and trees can experience heat stress due to dehydration. Trees absorb water from the soil through their roots rather than drinking water, but if the soil is too dry, they have insufficient resources with which to cool themselves through transpiration.
What Temperature Is Too Hot for Trees?
It depends on the type of trees and the climate they are adapted to. Obviously, trees in tropical regions have evolved to tolerate warmer temperatures. For trees in temperate regions, such as Ontario, between 70 and 85 degrees Fahrenheit is the ideal growing temperature. Photosynthesis slows down when the temperatures rise above 94 degrees Fahrenheit, and trees start to die if the temperature extends above 115 degrees Fahrenheit.
How Do Trees Get Too Hot?
Generally speaking, the temperature of a tree is roughly equivalent to the temperature of the air around it, meaning that the tree can suffer if the air temperature gets too high. However, there are situations in which the tree’s temperature can rise above that of the ambient air temperature.
For example, hot air rises through the process of convection. The movement of hot air can increase the tree’s temperature. A tree can also absorb heat that is radiated from nearby structures or surfaces or sunlight reflected from the soil surrounding it. Even sunlight reflecting from the surfaces of the tree itself can raise its temperature.
What Are Some Signs That Trees Are Experiencing Heat Stress?
At first, the signs of heat stress in trees can be very subtle. Branches may start to droop, while leaves may start to wilt and turn yellow, especially near the trunk at first. The leaves may show signs of scorching around the edges or rust-coloured spots. Eventually, the leaves die and start to fall off. A tree experiencing heat stress may have a sparse-looking canopy because of a lack of new growth. The bark of the tree can be burned from reflected heat and form lesions that leak sap. This is most prominent on the southern side of the tree.
What Can You Do To Help Protect Your Trees?
As the temperatures increase, there are some things you can do to prevent heat stress in your trees:
1. Water the trees regularly to prevent the soil from drying out. To prevent runoff, water the trees slowly, and to make sure it reaches all the roots, water deeply.
2. When the weather is hot, avoid pruning healthy branches to prevent unnecessary stress on the tree. If it is safe to do so, you can also postpone pruning dead branches until the temperature cools.
3. Organic mulch helps to lower the temperature of the soil and keep it moist. You can spread the mulch out to the edge of the canopy in a layer two to four inches thick. However, spreading mulch too close to the trunk can promote mould growth.
Some trees are more susceptible to heat than others, especially those that are very young, very old, or already unhealthy. If you have done everything you could and the tree has still died, the next step is to ask yourself, “Where can I find tree cutting services near me?” Find out about tree removal from Martin’s Tree Service.
Steve Martin
I have a profound interest in trees and their natural beauty. I grew up on a hobby farm ten minutes north of Waterloo and spent many winters in the bush collecting firewood to heat our family home. It was definitely work, so I wasn’t always eager as a young boy to help my father and big brother, but I learned to love the process... READ MORE
FAQs
This heat can radiate and reflect into a landscape and onto trees, causing tremendous heat loading. Excessive heat loading causes large amounts of water to transpire, initiates metabolic problems, and can generate heat lesions just above the ground/tree contact juncture (root collar/stem base area).
How much heat can a tree withstand? ›
Trees find optimum growing conditions across a range of temperatures from 70oF to 85oF. Hot temperatures can injure and kill living tree tissues. A thermal death threshold is reached at approxi- mately 115oF.
Can a tree recover from heat stress? ›
After the heatwave has passed, look closely at your trees to see if they are recovering. If you don't notice any signs of improvement, contact a Certified Arborist for a consultation. Keep in mind that heat stress can have lasting effects on a tree – some symptoms may not appear until years later.
What temperature is too hot to plant a tree? ›
So, how hot IS too hot for plants? The general answer is around 90 degrees F, with some exceptions to the rule. This means that when temps rise above 90 and remain there for a lengthy spell: Leaves wilt.
What effect does temperature have on the growth rate of trees? ›
Various tree species have different tolerances for temperature and precipitation, and these conditions can influence both the rate and pattern of tree growth. Warmer temperatures generally speed up the metabolic processes necessary for tree growth. However, extreme temperatures can be detrimental.
What happens if a tree gets too hot? ›
Signs of Heat Stress in Trees
Wilting leaves are typically the first thing you'll notice. As the tree becomes more stressed, stems and branches can start to droop. Irregular yellowing of interior leaves or needles. Failure to produce healthy-looking new growth, making the tree canopy look sparse.
What temperature can trees tolerate? ›
The approximate thermal death threshold for trees in a temperate zone is 115°F depending on their age, thermal mass, water tissue content, and the ability of the species to adjust. Optimum growing conditions for most trees range from 70°F to 85°F. Tree temperatures usually run around the air temperature (+ or - 4°F).
How do you help a tree in extreme heat? ›
WATER: During an excessive heat event, we recommend that you double your normal watering routine. This means that your new trees should receive 15 gallons of water at least twice a week throughout the heat wave, meaning a deep watering every three to four days when it's about 90-degrees or more for an extended period.
Can heat cause a tree to split? ›
In addition, frost cracks can form because constant heating and cooling can cause the water molecules to expand and contract to the extent of cracking the tree's bark. Luckily, the tree may not die. It'll often be able to recover by itself through the natural healing process.
Do trees drop leaves in extreme heat? ›
Heat or Drought Stress
The relentless summer heat and prolonged drought can put significant stress on trees. As a survival mechanism, they may prematurely shed their leaves to conserve vital moisture.
Most plants shut down during extreme heat, so if it is over 100 degrees, it may be best to wait to water even if your plant is stressed. Throw a damp sheet over it, or mist it lightly to bring the temperature down. Mist leaves with a spray nozzle to cool down plant and reduce transpiration.
Is it okay to plant a tree in July? ›
Yep. For the most part if you water well you can easily and successfully plant trees, shrubs, and perennials in summer. Water deeply every other day for the first few weeks. After this time reduce to about 2-3 times per week depending on your climate, soil, etc.
At what temperature should I cover my trees? ›
Cover your tree whenever the temperature is expected to drop below 32 degrees Fahrenheit. To trap in the earth's accumulated warmth, drape young or small trees with burlap, sheets, or tarps that extend to the ground, and use a frame or stakes to reduce contact between the cover and the leaves of the tree.
What is the optimum temperature for a tree? ›
For temperate plants the minimum temperature is about 40° C (40° F), the maximum 41° C (106° F), and the optimum 25° to 30° C (77° to 86° F). For tropical plants the minimum is 10° C (50° F), the maximum 50° C (122° F), and the optimum 30° to 35° C (86° to 95° F).
How does weather affect trees? ›
High winds, heavy rain and ice buildup place a lot of stress on a tree, which can lead to fallen branches or structural damage. To protect your tree against storms, it is important to incorporate regular pruning into your tree's maintenance.
How does climate affect tree growth? ›
For example, a warmer climate may increase tree growth in some forests but decrease it in others. Some forests may be able to respond to climate changes more successfully than others. For instance, forests that are fragmented into smaller patches may be less able to adapt than those that are well connected.
What tree can withstand extreme heat? ›
Acacia. Although it's an exotic tree, an acacia can adapt to almost any landscape. Additionally, these beautiful trees thrive in extremely warm climates, making them the perfect addition to your yard if you're concerned about heat resistance.
How to keep trees alive in extreme heat? ›
Water the roots of the tree by applying water directly to the soil (as opposed to overhead irrigation); this way you don't lose any water to evaporation. Refresh the mulch over your tree's root zone. If there is no mulch, a 2- to 3-inch layer can help insulate the roots from heat and minimize moisture loss in the soil.
What temperature damages tree leaves? ›
Freeze damage may occur if temperatures drop into the lower 20s or teens. This damage includes leaves that turn white, brown, and/or collapse. The extent of plant damage depends on temperature, plant species, exposure, and stage of plant growth.
Can heat break tree branches? ›
The tendency of some trees to lose large limbs during periods of high temperatures, like our North Texas summers, is generally called “sudden branch drop,” although it is also referred to as “high temperature limb failure,” and similar terms.
