The evaluation of the danger that a tree presents, either due to its state of health or its location, to people or property is called Tree Risk Assessment. Techniques have emerged based on the book by Matheny & Clark [7] matrix of three factors that contribute to the degree of risk, namely: (i) potential for failure (ii) size of the defective part and (iii) target rating (frequency with which something or someone can be damaged or harmed). Subsequently, others have developed a Quantified Tree Risk Assessment ("QTRA") system that calculates risk numerically with reference to the economic implications of damage to trees and published social norms of acceptable, tolerable, and unacceptable risk.[8]​ The International Society of Arboriculture updated its approach in 2012 with a qualitative (word-based) matrix known as Qualitative Tree Risk Assessment ("TRAQ").[9]​.

To comply with the tree owner's legal duty of care to occupants, visitors, passers-by or neighbours, where regular observation or monitoring of the condition of the tree is not possible, inspections of the tree should be carried out by a competent person at appropriate intervals and their risk reduction recommendations should be applied.[10]​.

Phytosanitary care

Phytosanitary care (PHC) is a multidimensional management strategy for the care of trees and plants to preserve the vitality of urban and community forests.[11] Arborists and Plant Health Specialists apply a wide range of techniques by selecting and integrating treatment options that protect and improve the health, structure and appearance of plants in the landscape.[11][12]

"APS tries to prevent problems before they start"[12]​ It is a holistic approach to plant management that focuses on the interaction of plants with living and non-living components of the landscape. Typically, APS is a service activity that relies on the relationship between the arborist and the client to make management decisions based on the health of the tree, the client's goals, and the professional training and recommendations provided by the arborist.[11]​[12]​.

Although APS evolved from Integrated Pest Management (IPM), the objectives and emphasis of each system vary. APS focuses on managing the specific, individualized needs of a plant and its growing environment.[12]​ APS involves identifying the stressors that affect the health of a plant or tree to create a care profile that reflects the client's goals of maintaining healthy plants and trees within an environmental context**.**.

• - Surveillance.

• - Development of thresholds (economic, aesthetic, psychological, biological and ecological).

• - Identification of the main stress factors.

• - Cultural manipulation and plant resistance.

• - Use of multiple management options.

• - Customer service.

• - Key concepts about plants.

• - Key concepts of stress.

• - Cultural control: plant selection, cultural practices that promote soil health, soil pH balance, pruning, sanitation.

• - Biological pest control: suppression of the pest population through predators, parasites and pathogens, increase of beneficial organisms to complement existing populations.

• - Chemical control: fungicides, insecticides, acaricides, bactericides, repellents, herbicides, systemic or contact pesticides.

• - Alternative pesticides: biological control products, insecticidal soap, horticultural oils, botanical products, insect growth regulators, microbial-based products and microbial agents.

• - Mechanical management: physical removal of pests from a plant (for example, plucking bagworms from an evergreen shrub), installing physical barriers to deter pests, pruning infested parts of the plant, etc.

Assessment of the detrimental effect of construction activities on a tree can be based on three factors: severity, extent and duration. Fundamentally, the activity must avoid the crown of the tree and the volume of rooting that it needs to maintain its vitality. Severity is related to the degree of intrusion into the rooting zone and resulting root loss. The extent is related to a percentage of a factor such as the crown, roots or bark, and the duration is based on the time that the activity interferes with the normal functions of the tree.

Various organizations, such as the International Society of Arboriculture, the British Standards Institute[13]​ and the Tree Industry Association (formerly the National Association of Arboriculturalists), have long recognized the sensitivity of tree health to construction activities. The effects are significant because they may lead to loss of monetary or recreational value due to damage to trees and subsequent repair or replacement costs, or to legal action for breaches of government ordinances (in the UK, laws, regulations and planning policies) or community or subdivision restrictions.

In the US, protocols for managing trees before, during and after construction activities are well established, tested and refined. It involves the following basic steps:.

• - Review of construction plans.

• - Preparation of the corresponding inventory of trees.

• - Application of standard construction tree management protocols.

• - Evaluation of the potential for damage to trees.

• - Development of a tree protection plan (which provides for measures to prevent and repair damage before, during and after construction).

• - Development of a repair plan.

• - Implementation of tree protection zones (TPZ).

• - Evaluation of the damage suffered by trees after construction.

• - Application of the repair plan.

In the United Kingdom there is a similar protocol.[13]​.

• - Arboriculture.

• - Horticulture.

• - Plant health.

• - Tree protection zone calculator.

• - Identification of a dangerous tree.

The evaluation of the danger that a tree presents, either due to its state of health or its location, to people or property is called Tree Risk Assessment. Techniques have emerged based on the book by Matheny & Clark [7] matrix of three factors that contribute to the degree of risk, namely: (i) potential for failure (ii) size of the defective part and (iii) target rating (frequency with which something or someone can be damaged or harmed). Subsequently, others have developed a Quantified Tree Risk Assessment ("QTRA") system that calculates risk numerically with reference to the economic implications of damage to trees and published social norms of acceptable, tolerable, and unacceptable risk.[8]​ The International Society of Arboriculture updated its approach in 2012 with a qualitative (word-based) matrix known as Qualitative Tree Risk Assessment ("TRAQ").[9]​.

To comply with the tree owner's legal duty of care to occupants, visitors, passers-by or neighbours, where regular observation or monitoring of the condition of the tree is not possible, inspections of the tree should be carried out by a competent person at appropriate intervals and their risk reduction recommendations should be applied.[10]​.

Phytosanitary care

Phytosanitary care (PHC) is a multidimensional management strategy for the care of trees and plants to preserve the vitality of urban and community forests.[11] Arborists and Plant Health Specialists apply a wide range of techniques by selecting and integrating treatment options that protect and improve the health, structure and appearance of plants in the landscape.[11][12]

"APS tries to prevent problems before they start"[12]​ It is a holistic approach to plant management that focuses on the interaction of plants with living and non-living components of the landscape. Typically, APS is a service activity that relies on the relationship between the arborist and the client to make management decisions based on the health of the tree, the client's goals, and the professional training and recommendations provided by the arborist.[11]​[12]​.

Although APS evolved from Integrated Pest Management (IPM), the objectives and emphasis of each system vary. APS focuses on managing the specific, individualized needs of a plant and its growing environment.[12]​ APS involves identifying the stressors that affect the health of a plant or tree to create a care profile that reflects the client's goals of maintaining healthy plants and trees within an environmental context**.**.

• - Surveillance.

• - Development of thresholds (economic, aesthetic, psychological, biological and ecological).

• - Identification of the main stress factors.

• - Cultural manipulation and plant resistance.

• - Use of multiple management options.

• - Customer service.

• - Key concepts about plants.

• - Key concepts of stress.

• - Cultural control: plant selection, cultural practices that promote soil health, soil pH balance, pruning, sanitation.

• - Biological pest control: suppression of the pest population through predators, parasites and pathogens, increase of beneficial organisms to complement existing populations.

• - Chemical control: fungicides, insecticides, acaricides, bactericides, repellents, herbicides, systemic or contact pesticides.

• - Alternative pesticides: biological control products, insecticidal soap, horticultural oils, botanical products, insect growth regulators, microbial-based products and microbial agents.

• - Mechanical management: physical removal of pests from a plant (for example, plucking bagworms from an evergreen shrub), installing physical barriers to deter pests, pruning infested parts of the plant, etc.

Assessment of the detrimental effect of construction activities on a tree can be based on three factors: severity, extent and duration. Fundamentally, the activity must avoid the crown of the tree and the volume of rooting that it needs to maintain its vitality. Severity is related to the degree of intrusion into the rooting zone and resulting root loss. The extent is related to a percentage of a factor such as the crown, roots or bark, and the duration is based on the time that the activity interferes with the normal functions of the tree.

Various organizations, such as the International Society of Arboriculture, the British Standards Institute[13]​ and the Tree Industry Association (formerly the National Association of Arboriculturalists), have long recognized the sensitivity of tree health to construction activities. The effects are significant because they may lead to loss of monetary or recreational value due to damage to trees and subsequent repair or replacement costs, or to legal action for breaches of government ordinances (in the UK, laws, regulations and planning policies) or community or subdivision restrictions.

In the US, protocols for managing trees before, during and after construction activities are well established, tested and refined. It involves the following basic steps:.

• - Review of construction plans.

• - Preparation of the corresponding inventory of trees.

• - Application of standard construction tree management protocols.

• - Evaluation of the potential for damage to trees.

• - Development of a tree protection plan (which provides for measures to prevent and repair damage before, during and after construction).

• - Development of a repair plan.

• - Implementation of tree protection zones (TPZ).

• - Evaluation of the damage suffered by trees after construction.

• - Application of the repair plan.

In the United Kingdom there is a similar protocol.[13]​.

• - Arboriculture.

• - Horticulture.

• - Plant health.

• - Tree protection zone calculator.

• - Identification of a dangerous tree.