How to choose the right trees for a changing environment

Climate change is threatening trees in cities and forcing urban planning changes.

Climate change is destroying trees in cities, just as it has done to over 10 million hectares in British Columbia’s Canadian province.

Trees in urban areas are at risk from heatwaves or lack of rain, both of which are predicted to increase over the next decade. Many trees can be found in cities and towns. However, it is difficult to document the criteria for species selection and climate-risk assessments. Planning and tree selection are crucial.

Urban forests are composed of trees, shrubs and other plants. They can be grown in greenways, parks, and streetscapes as well as existing native vegetation. They are beneficial to humans because they reduce heat, absorb air pollution, provide habitats for wildlife, and improve health.

These forests surround built environments such as concrete structures and streets. They also act as pedestrian walkways and bike routes, which all increase the effects of climate change. People enjoy looking at trees, which is also important. These green spaces can be used to strengthen our connection with nature and improve mental health, especially during pandemic lockdowns.

While urban forests are affected by climate changes, they are essential in making cities liveable and resilient. Planting and conserving trees, especially large ones can reduce urban heat. They shade buildings and pavements and provide natural cooling. Urban trees also help via transpiration — the evaporation of water that is released to the air through plant leaves — resulting in localized cooling. As governments and communities gain more insight into the changing climate, cities all over the globe are building resilience through urban greening. Climate projections are not easily accessible and have not been widely used in urban landscape planning. Because of their slow growth, tree canopy coverage must be increased for many decades.

But so far, local government decisions are more often based on what’s been historically planted, which may no longer suit — contributing to the failures of urban species in extreme climate conditions today. For example, 53 percent of the 1,342 tree varieties currently in 22 Australian cities (which is more than half) are susceptible to high temperatures or low rainfall in at most one city.

Uncertainties around decision-making are exacerbated by the lack of data about urban plants’ environmental tolerance. Municipalities and councils do not keep consistent records on the failure rates of trees, new or old. Instead, staff, contractors, community members and others share anecdotal information. However, it is not available publicly and has limited applicability to other areas. Urban forests are typically closely stewarded and managed — including by watering through periods of drought — combatting some of the negative effects of climate change. This can help tree species to survive in areas where they are not natural. Due to global water shortages, irrigation is not sustainable in many areas. We must choose the right trees for the right place. Identifying and quantifying factors that cause poor growth or death can maximize resources and minimize financial losses to local governments and residents. It will be necessary to increase our knowledge about urban plants’ heat tolerance and drought tolerance in order to maintain urban forests that can withstand changing climates. This will also require efficient maintenance of urban plants and detailed monitoring over time.

The future protection of the hotter cities will depend on how we plan today.

(This story was not edited by Devdiscourse staff. It is generated automatically from a syndicated feed.