Tree Maintenance

Tree maintenance is crucial for ensuring the health and longevity of urban trees, which can directly support the sustainability of urban forests in Canadian municipalities. Depending on the geographic region, environmental conditions, tree age, and species, tree care can include a variety of practices. These include tree pruning, watering, mulching, fertilizing, cabling, bracing, and identifying and removing hazard trees. These practices not only enhance tree vitality but also help mitigate the stresses that urban trees face due to environmental stressors like drought, pests and pathogens, nutrient deficiencies, invasive species, and general damage due to physical stresses like weather or construction activities.

Maintenance Practices

Investment in the maintenance of newly planted and young trees pays off later by having healthy trees and reducing the cost of their management. Some of the most common maintenance practices used for young trees are watering, mulching, pruning to shape the tree for a strong structure, protecting the base of a tree and trunk from mechanical damage, inspecting for pests or diseases, and soil improvement like fertilization. Some of the most common practices to maintain older trees are regular pruning, protection of the root system from soil compaction, supplemental watering during drought conditions, and careful fertilization, which can enhance tree longevity and vitality (ISA, 2021a).

Tree pruning is one of the most common maintenance practices used to support the health, structure, and safety of urban managed trees. Pruning practices include structural pruning of young trees, removal of dead, diseased, or damaged branches, crown thinning, crown raising, pollarding, or in some cases, crown reduction to prevent tree conflicts with structure or utility lines. It is best to time pruning during the dormant season and avoid techniques like topping, which can harm the tree (see chapter: Hydro Lines and Corridors).

Cabling and bracing are structural support techniques used to stabilize trees with weak or multiple trunks, large limbs, or those subject to strong winds (Mayne, 1975; Vandergriff & Clatterbuck, 2005). These methods are particularly useful in urban settings where tree failure can pose significant risks to public safety and infrastructure (Purcell, 2017).

In urban growing spaces where natural water sources may be limited or inconsistent, regular and deep watering is essential for establishing young trees and the development of their root systems in the first few years (2 to 5 years). This is particularly relevant during drought periods, which are becoming more frequent due to climate change, and for newly planted trees, which are particularly at risk of drying out (Steil, 2022; Zuzek, 2018; UMC, 2023).

Mulching complements watering by conserving soil moisture, reducing weed competition, protecting trees from mechanical damage by mowers and trimmers, but also improving root development (Sun et al., 2023; Magditsch, 2021; Qu et al., 2019). Mulching also helps mitigate soil compaction, a common issue in urban environments that can impede root growth and water infiltration. Older trees might also benefit from mulching, which helps conserve moisture and improve soil health (ISA, 2021b).

Fertilizing urban trees is a targeted approach to addressing nutrient deficiencies often found in city soils. However, it is important to apply fertilizers judiciously, as over-fertilization can lead to water pollution and tree health issues (Appleton & Kauffman, 2021; Maine Forest Service, 2000; Bellis, 2023). In Canada, guidelines for urban tree fertilization emphasize soil testing and the use of slow-release fertilizers that match the specific needs of the tree species and site conditions (CFIA, 2024).

Identification and removal of hazard trees are critical for urban forest management practice. Hazard-rating systems, which assess the likelihood of tree failure and the potential impact on people or property, are employed by many Canadian municipalities to prioritize tree maintenance efforts (TRCA, 2006). By assessing key hazard identifiers such as limb damage, wood decay, and cankers, as well as situational conditions such as frequent use areas, proximity to infrastructure, and tree species failure potential, a decision can be made about the size of the hazard and the urgency with which action, such as pruning or tree removal, should be taken against the hazard. Taking a proactive approach in hazard tree management helps manage risks and allocate resources effectively (Gurney & Ward, n.d.; Pokorny et al., 2003; ISA, n.d.).

In addition to traditional maintenance practices, invasive insects and disease management is a growing concern in global and Canadian urban forestry (Sweeney et al., 2019). The spread of pests like the Emerald Ash Borer (Agrilus planipennis) has led to significant maintenance efforts to retain some trees and reduce tree loss, requiring municipalities to implement extensive monitoring, treatment, and removal programs. The City of Montreal, for example, has removed thousands of ash trees (genus Fraxinus) to manage this invasive pest.

Tree Maintenance and Relevant Guidelines 

Canadian municipalities follow national and provincial guidelines for urban tree maintenance, often supplemented by local bylaws and urban forest management plans. These frameworks provide a structured approach to tree care, emphasizing sustainable practices, climate resilience, and community involvement. For instance, the Canadian Urban Forest Strategy (CUFS) promotes best practices in urban forestry, including tree maintenance, and recommends that municipalities integrate urban forest management into broader city planning initiatives (Tree Canada, 2018).

At the provincial level, organizations like the Ontario Urban Forest Council, the British Columbia Urban Forest Network, and the Manitoba Urban Forest Council offer resources and guidance on urban tree care, while municipalities often have their own arboriculture standards and maintenance protocols. These include regular inspections, pruning cycles, and emergency response plans for extreme weather events.

Tree Maintenance and Human Resources

The effectiveness of tree maintenance programs depends on the availability of skilled professionals, including arborists, urban foresters, and municipal staff trained in tree care and management (Trees Are Good, n.d.). Continuous education and training are vital to ensure that the latest techniques and knowledge are applied in the field. In Canada, certification programs such as those offered by the International Society of Arboriculture (ISA) and other regional bodies are widely recognized and help maintain high standards in urban tree care.

Moreover, municipalities often collaborate with community groups and volunteers to support tree maintenance efforts, particularly in the context of tree-planting initiatives and public awareness campaigns. Canadian municipalities can effectively maintain and enhance their urban forests by engaging the broader public in tree care and maintenance, invasive species monitoring, and tree monitoring, contributing to healthier, more livable cities. For example, educating the public on how to prune and maintain their private trees contributes to urban forest health and the enhancement of tree canopy (Johnson et al., 2008; IUFC, n.d.). These partnerships are crucial in fostering a shared sense of responsibility for the urban forest and ensuring its more sustainable maintenance.