Abiotic forest health factors

Damage caused by non-living agents is referred to as an abiotic forest health factor.  Abiotic health factors include drought, wildfire, wind, hail, frost, mechanical damage, extreme temperatures and snowpress. Learn more about wildfire and drought.

Trees affected by abiotic damage are often susceptible to disease, infection and insect attack due to stress or wounding.

Symptoms of abiotic factors

The symptoms of abiotic factors can be similar to those caused by biotic factors (insects or pathogens) and like biotic agents, abiotic damage can decrease wood quality and reduce growth. Before assuming an abiotic factor is the cause of damage, affected areas should be checked for evidence of other factors including disease, animal or insect activity and feeding. This inspection may include looking for specific signs and/or symptoms of pests or pathogens such as cankers, fruiting bodies, root disease, decay characteristics, beetle galleries, webbing or girdling.

Generally, non-infectious abiotic damage can be found on a variety of plant species within a common area impacted by an abiotic factor, while symptoms and signs of forest pathogens are found only on specific hosts. 

When confirming abiotic factors, local climate records, topography and elevation, roads, potential for cold air ponding, and other disturbances should be considered when determining which abiotic factor caused damage.

Tree wounding and decay are instigated primarily by abiotic, mechanical damage such as snow breakage, wind and logging injury, but some decay can occur independently. Stem decay causes significant timber losses through breakage and degradation.  Broken branches and stems may result in growth reduction and provide a point of entry for disease. Severe stem damage may result in mortality or broken leaders.

To identify and learn more about tree wound and decay read Guidebook to Tree Wounding and Decay (PDF, 365KB)

Types of abiotic damage include:

Snow press

Snow press has been identified as one of the leading forest health factors in young plantations, particularly on lodgepole pine and Douglas-fir in the Interior Cedar Hemlock (ICH) and Engelmann Spruce Subalpine Fir (ESSF) zones.  Trees with smaller diameter, located in dense stands, or with stem or root disease are most vulnerable. Snow accumulation and compression may cause basal decay or discolouration of seedlings. Trees in leaf may incur more damage.

Hail

Hail damage symptoms consist of stripped branches, stem lesions, and scars and bruises on the upper surface of branches.

Frost

Frost damage is often the result of extreme cold temperatures during either late spring or early fall. Spring frost occurring late in the season can damage or kill buds and new growth. Other frost damage includes lesions on stems caused by frost killed cambium and frost ribs around older cankers. Frost heaving can eject first-year seedling from the soil breaking roots near the root collar. Frost damage in its many forms can result in reduced tree growth or dieback and in the case of seedlings, mortality.

Red belt

Red belt is the result of unseasonable warm conditions during the day and cold air at night. It can often be seen as a defined horizontal band of damaged trees across a large area. Moisture lost by trees during a warm day temperatures is not replenished due to frozen soil conditions exacerbated by low night temperatures. This causes desiccation resulting in a discolouration and eventual loss of needles. Trees often recover from the loss of needles and unopen buds are typically not damaged. Large areas of red belt greatly increase the wildfire hazard for a particular area.

Sunscald

Sunscald typically affects the southwest side of trees on open or pruned slopes. Affected bark becomes coppery or red in colour but fades by the end of the summer. Dead bark can shrink and slough off. Sunscald cankers may also form, varying in size from small patches to large areas covering the entire exposed side of a tree. Growth loss and mortality are seldom caused by sunscald.

Cedar flagging

Hot, dry summers can cause isolated branchlets to discolour to yellow or red, and die. This is a normal condition of western redcedar and does not have a detrimental effect on tree growth. Cedar flagging can resemble cedar leaf blight but the affected leaves do not have fungal fruiting bodies.

Road salt

Salt used on roads can cause damage to trees through direct splash on needles or the build-up of salt in the soil due to runoff. Contaminated run-off can flow a significant distance from the road particularly over frozen soil. Damage is most apparent in the spring before new foliage growth. Some conifers, and particularly Douglas-fir, can be killed by salt accumulation.

To identify and learn more about other abiotic forest health factors read the Field Guide to Forest Damage in B.C. (PDF, 6.5MB)