A space technology reveals that planting native species of trees and flowers can lower the daytime temperature in summer to 4.5ºC, a natural solution for heat waves.
Only by planting native species of trees, shrubs, flowers and grasses can the daytime temperature of a garden or geographic area be cooled by more than 4ºC in a decade.
It has been discovered by research from the University of Waterloo that used a new thermal camera from the International Space Station (ISS) called Ecostress to collect images: they show that temperature decreases over time when native species of biodiversity are restored in areas of southern Ontario, eastern Canada.
“We discovered a decrease of 4.5ºC in summer daytime temperatures for 12 years and we discovered that this change depends on biodiversity,” explains Jonas Hamberg, principal investigator of the study, in a release.
New space technology
The Hamberg team is one of the first to work with the new Ecostress technology, which was launched on the International Space Station in June 2018. The space station’s unique orbit allows the instrument to capture data on the same areas at different times. of the day. When the mission team analyzes the data, they gain a new insight into how plants behave throughout the day and can project their environmental impact in years.
Through three experiments, the researchers tested whether the relative surface temperature decreased over time in 31 initially agricultural fields that were converted to oak forests between 2006 and 2013.
They also observed whether the variation in daytime temperature decreased over time since forest restoration, and whether plant species diversity affected the relative change in surface temperature by controlling biomass and shade.
For their analysis, the researchers used both thermal images of those territories acquired by Landsat satellites since 2002, and the Ecostress thermal instrument located on the ISS.
Local temperature de-escalation
In those spaces restored with native trees, the scientists observed an average decrease in temperature of 1.5 percentage points per year since the restoration of the forests.
They also detected a decrease of 4 percentage points of diurnal temperature difference per year since the restoration of the same fields.
Finally, they determined that increasing an effective number of plant species diversity lowers the relative temperature by 5 percentage points.
These results correspond to a decrease in daytime temperature of 4.5 ° C for 12 years, a decrease in the variation of daytime temperature of 5 ° C in 8 years and a decrease of 0.3 ° C per additional plant species, the researchers explain. in an article published in the magazine Ecological Indicators.
Preparing increasingly hot summers
Hamberg hopes his work will foster thoughtful reforestation and restoration practices in Ontario and around the world.
He points out that, given the recent heat waves, people should think about planting local native species in their own outdoor spaces, and governments should do the same by planting new areas within their respective jurisdictions.
“I have advised local governments to restore natural areas with various native plants and trees because it is a very effective way for us to adapt to a warmer summer climate locally,” said Hamberg.
“Native species adapt to the local environment and can better cool their environment. For example, native tall grass species have deeper roots and can draw water for cooling, just like water-cooled air conditioning does, long after non-native grass grasses have turned yellow and dry. ” concludes.
Surface temperature as an indicator of plant species diversity and restoration in oak woodland. L. Jonas Hamberg et al. Ecological Indicators, Volume 113, June 2020, Article 106249. DOI: https://doi.org/10.1016/j.ecolind.2020.106249