Sustaining the Urban Forest
Contents |
Introduction
Forest cover in urban and developed areas is vital for a number of reasons. The canopy of trees can intercept falling rain, slowing the rate of storm run-off and thus reducing soil erosion and water quality problems. Trees in urban areas provide natural cooling in summer when the urban heat island effect and the demand for space cooling is greatest. Trees also draw pollutants and carbon dioxide, a greenhouse gas, from the atmosphere, thereby buffering climate change and improving local air quality. Strips or bands of extensive tree cover running through urban areas can provide both habitat and migration corridors for wildlife.
Conversely, the loss of forest cover can lead to faster storm drainage, less moisture retention, less shade for natural cooling, less habitat for wildlife and poorer air quality. Furthermore, the forests in the urban areas of southern Ontario may have – or support – tree species that are not commonly found anywhere else in Canada, which is a significant consideration for the conservation of Ontario’s biodiversity.
Researchers and urban forest advocates have put forward various concepts that help underscore the importance of the urban forest. Research shows that the continuity between the tree canopy of urban centers and outlying forested areas helps to ensure wildlife needs are met and certain ecosystem functions maintained. Some researchers have noted that human settlements should be regarded as that part of the forest where people live. After all, most of Ontario’s land mass was forest-covered at one time, which adds validity to this view. Another more utilitarian, but nevertheless valid, outlook is that urban trees are a vital layer of infrastructure, not unlike roads or sewers, which require planning to develop and maintenance for continued proper “operation.” In fact, some researchers have correlated tree cover in drainage basins with improved local surface water quality, noting that drinking water treatment costs decline as tree cover increases. Because of the pollution-abatement attributes of trees, the urban forest has been likened to “green infrastructure.” The following definition of urban forestry from an expert in the field captures many of these concepts:
- Urban forestry is the sustained planning, planting, protection, maintenance, and care of trees, forests, greenspace and related resources in and around cities and communities for economic, environmental, social, and public health benefits for people.
Despite the importance of urban forest cover, there is little direct regulation by the provincial government in this area. The make-up and maintenance of virtually all urban forests are handled either by the local municipality, Conservation Authorities, or thousands of individual landowners. The Ministry of Municipal Affairs and Housing has some authority over forests and natural heritage under the Municipal Act, the Planning Act and the Provincial Policy Statement. The Ministry of Natural Resources has a great deal of regulatory involvement in forestry matters on Crown land in Ontario, but has only a very small staff with forest expertise that could be applied to urban areas. It has also been suggested that the Ministry of Culture could play a greater role, under the Ontario Heritage Act, by ensuring key representative trees are given greater protection.
The federal government’s Canadian Food Inspection Agency (CFIA) has taken the lead in controlling certain threats to forest health in urban and settled areas. CFIA has been designated the authority through the Plant Protection Act and Ash-Free Zone Regulations to set quarantine zones, to oversee cutting trees that have become infested with the emerald ash borer, and to undertake other measures. CFIA acted similarly in the case of the Asian long-horned beetle infestation in Toronto. Natural Resources Canada, a federal ministry, helps to finance tree planting across Canada through support to a not-for-profit group called the Tree Canada Foundation.
However, the regulation of municipalities and urban affairs is very much a provincial, not federal, function in Canada, and therefore the question of what, if any, role the province should play in promoting and protecting urban forests is a valid one. The key provincial law governing municipalities in Ontario is the Municipal Act, which includes provisions that permit municipalities to pass tree bylaws, e.g., to prohibit or regulate the destruction or injuring of trees.
Some recent trends affecting urban forests and trees on private lands
Invasive species
In Essex and Chatham-Kent Counties, about 80,000 ash trees have been destroyed to limit the spread of the emerald ash borer, with the projected final number being over 100,000. Also, the ECO reported last year that by spring 2004, over 15,000 trees near the Asian long-horned beetle infestation area in north Toronto were felled. MNR intends to ensure that trees are returned to the landscape, using $1 million committed through its Forestry Futures Trust. The ministry has been in discussion with CFIA, Conservation Authorities, the City of Toronto, Essex County and others to ensure a tree-planting program goes ahead. MNR also works cooperatively with the federal Canadian Forestry Service on forest health in Ontario.
Declining canopy
In the central section of Toronto, the extent of the urban forest has shrunk from 22 per cent in 1992 to 16 per cent in 2004, in spite of having a tree advocacy office and program led by a municipal councillor. In late 2004, Toronto extended a bylaw throughout the entire city, requiring residents to purchase a $100 permit for removing most trees greater than 30 centimetres in diameter from property they own.
Bylaws under the Municipal Act
Municipalities updating tree bylaws could begin integrating biodiversity considerations, woodlands conservation and landscape-level issues into tree conservation policy. The Regional Municipality of Halton is moving in this direction through its 2004 draft tree bylaw, which prohibits, for example, destroying or injuring trees in Carolinian Canada sites (see Biodiversity and Genetic Importance, next page) and in areas of natural and scientific interest.
Protecting heritage trees
The Ontario Urban Forest Council called for expanded protection for trees of significance by clarifying their definitions in the Ontario Heritage Act so that heritage trees could more readily be designated for protection. The Ministry of Culture announced in 2004 that it was introducing amendments to the Act through Bill 60, although the ministry says it’s up to municipalities to identify and preserve properties, including those with trees.
Greenbelt Act, 2005, and Places to Grow legislation
MAH’s Greenbelt Act, 2005 (see The Greenbelt Act, 2005, and the Greenbelt Plan), does not set specific targets for forest cover, nor specific goals such as planting native instead of alien tree species. Under its Places to Grow legislation, the Ministry of Public Infrastructure Renewal is considering where urban and economic growth should be permitted in Ontario and how – for instance, by promoting intensification and compact development (see pages 46, 53). Such decisions will have a significant impact on the space available for urban trees in the highly populated areas of southern Ontario.
MNR leaves the nursery business
The 2002/2003 ECO annual report expressed concern that the supply of nursery trees of native tree species had become less reliable in Ontario because of MNR’s exit from nursery operations. Cities such as Windsor and Hamilton have considered establishing their own nurseries in order to diversify the range of native tree species in their areas or simply to ensure the availability of native stock.
Special Needs of Trees in Urban Centres
Maintaining the forest cover in urban centres is becoming an increasing challenge, especially for trees situated near roads, in parking lots and on boulevards. Paved surfaces, road salting and soil compaction from traffic adversely affect roots and drainage. For decades, municipalities have been relying on hardy and often non-native tree species like gingko and the black locust because they can withstand such harsh conditions. Now, some urban foresters are building soil structures beneath sidewalks to foster the root expansion that is critical for tree growth. This costs more, but it also promotes a better survival rate and may allow a greater range of tree species to be planted. Even with better soil structures, though, watering and additional maintenance may be required to keep newly planted trees alive.
U.S. cities like Chicago have created very detailed rules about the sizes of tree to be planted in new developments; the required soil volumes, guard rails and protections; the amount of tree cover relative to paved surface; and the spacing of trees for property frontages. Larger urban centres like Toronto, Mississauga, Hamilton, London or Windsor could consider imposing these rules. Working out such rules would be a worthwhile initiative in light of the province’s plan for urban intensification under its Places to Grow initiative.
The perceived burden and cost of maintenance may make private landowners reluctant to plant or replace trees on properties. Native tree selection may help ease this reluctance – species like pin oak are drought tolerant, thus reducing watering needs, and smaller native trees such as serviceberry or redbud may reduce leaf clean-up or concern about sprawling limbs or roots. If the province and municipalities procured large amounts of native tree stock, native species could become more common and more affordable at private nurseries as a consequence. Also, recognition of the value of urban trees through the property tax assessment system could provide private property owners with the incentive needed to maintain trees on their property. Finally, as mentioned, some urban forests are aging and dying, often without a replacement plan or budget at the local level. For all of these reasons, greater resources and attention will need to be paid to the trees of urban Ontario in order even to maintain the forest cover that exists at present in certain areas of the province.
Conclusion
The forests of urban southern Ontario deserve more attention for a number of reasons. The environment of many urban areas can be harsh for tree growth, and in many cities the tree population is aging. Much will be needed to overcome these adversities, including research, funding, communication, and enhanced regulatory protection. On the positive side, urban park space and privately owned trees could make a continuing contribution to Ontario’s biodiversity and allow for partial restoration of native ecosystem conditions.
MNR’s primary involvement with urban forests, and indeed, with most of the forests of southern Ontario, is in coordinating and providing information and advice to municipalities, Conservation Authorities and nature groups about forest health and ecosystem issues through programs like the Natural Heritage Information Centre and through strategies like the Southcentral Region Forest Strategy. The Ontario Tree Seed Plant is MNR’s most “hands-on” activity in relation to the forests in this part of Ontario. MAH’s principal role in urban forest matters is the delegation of tree bylaw-making powers to municipalities under the Municipal Act. While these roles are helpful, the provincial government should consider a more active role in supporting urban forests, especially since the province has already become involved through its financial support for tree replacement because of losses from invasive species outbreaks.
| Recommendation 13:
The ECO recommends that MNR and MAH develop a coordinated urban forest strategy to protect urban and heritage trees, working together with municipalities, ENGOs and local agencies. |
| This is an article from the 2004/05 Annual Report to the Legislature from the Environmental Commissioner of Ontario. |
Citing This Article:
Environmental Commissioner of Ontario. 2005. "Sustaining the Urban Forest." Planning our Landscape, ECO Annual Report, 2004-05. Toronto, ON : Environmental Commissioner of Ontario. 201-205.
