How Can Trees Help Us Beat the Heat?

Thanks for the A2A. A nice tree can certainly create a more pleasant place for contemplation than sitting in the scorching Mohave desert under a cactus!

The Role of Trees in Urban Environments

Trees provide essential shade, which helps in cooling the ground and the surrounding air. The concrete, metal, and asphalt surfaces of urban cities absorb heat and radiate it back, making these areas particularly warm. Paris, for instance, has become a classic example of how urban heat can be exacerbated, with its extensive pavement and limited greenery. This is why the city's famous phrase 'canicule' or heat wave has taken on a new significance.

Urban Cooling Solutions

MIT's Senseable City Lab has devised an innovative solution to address this issue. They have created a 'Green Umbrella' project, which not only highlights the need for more green spaces but also sheds light on how trees can effectively cool urban areas.

Complicating efforts to plant more trees in cities is the competition for limited space. For example, in Athens, a traditionally hot and paved city, proposals to plant trees are constantly met with the demand for parking spaces. Practically speaking, one must often choose between these competing demands.

The Impact on Boreal Forests

Beyond urban settings, trees also play a crucial role in cooler and more temperate regions, such as boreal forests. In these areas, planted seedlings rarely develop roots deep enough or with the same soil penetration and moisture exploitation capabilities as those that grow naturally from seeds. This natural process, known as self-sowing, is characterized by a high survival rate among seedlings that thrive under a forest canopy, where temperatures are cooler and humidity levels are higher.

Forest management over the past century has largely focused on clearcutting, site preparation, and the planting of fertilized and chemically protected seedlings, which have been shielded from pests and herbivores. These practices, while effective in establishing tree growth, may not be well-equipped to deal with the extreme heat and moisture stress caused by climate change. In this context, naturally emerging seedlings and saplings that grow beneath a forest canopy are better suited to survive harsh conditions.

Selective Harvesting and Forest Sustainability

Forestry practices that emphasize clear cuts and plantations often work against the fundamental aspect of sustainability observed in nature, which favors self-saucing and the survival of the fittest. To maintain forest sustainability in the face of severe climatic warming, it is essential to adopt a more sustainable approach. This includes selective harvesting and focusing on maintaining a closed-canopy environment and allowing shade-tolerant species to regenerate.

While both methods—commercial clearcutting and regulated planting—can coexist, the emphasis should be on both to address the complex issues of forest management in a changing climate. By adopting a balanced approach that respects the natural processes of forest growth and regeneration, we can better ensure the long-term sustainability of our forests.