Planting trees is often a go-to action for benefiting the planet, but it turns out that it really matters what types of trees you plant – and where. Tree diversity, or the amount and distribution of tree species in a forested area, is very important for things like growth, biodiversity and building resilience to the effects of climate change.
A new study shows that it also makes a big difference in the carbon cycle which is the balance created by carbon being absorbed by ecosystems and then returned to the atmosphere through decomposition.
Unforthuantely, tree diversity is on the decline globally, and is a particular problem in Canada. Tree diversity is a term used to describe three specific aspects of the forest environment. The first two aspects are species richness, which is measured by the number of trees in an area, and evenness, which describes how equally the species are distributed. The last aspect comes down to the actual trees and the different functions they perform in the forest.
Different species of trees have distinct physical characteristics; in turn, those characteristics give them different capacities to adapt to certain challenges — and that ensures the forest is resilient to stress, said environmental scientist Devon Earl.
While sustaining forest biodiversity helps to improve resilience to climate change, diversity can also help to mitigate further warming, according to a new study on carbon storage in natural forests across Canada, published in Nature.
“This is the first study to demonstrate that tree diversity can increase soil carbon sequestration in natural forests,” said Scott Chang at the Univeristy of Alberta.
According to the study, increasing species evenness increases soil nitrogen and carbon by 42 and 30 per cent respectively. And by increasing the functional diversity – that is the variety of physical characteristics within the forest – enhanced soil nitrogen and carbon by 50 and 32 per cent, respectively.
Chan also said that more diverse forests often have more biomass production. Attributes like root depth and canopy height play a role in how forests grow and thrive, he added.
Earl explains, after an area is logged, forestry companies tend to plant a single species that they want to cut again in the future. Also, companies will often use the herbicide glyphosate to suppress the growth of deciduous trees and other plants.