Natural Root Grafts

We’ve all heard social networks help us to be healthy and successful. It ends up that trees have been networking quite intimately for a very long time.

Tree networking takes two forms. They frequently share nutrients indirectly, using soil microorganisms as go-betweens. And they fuse their root systems in natural root grafts, called anastomoses.

Exposed tree roots (Jennifer Boyer) CC BY 2.0

How do roots graft?

Natural root grafts occur when relatively small roots of two different trees come into contact with each other. As they grow, they fuse, creating mutually accessible cambium layers and vascular bundles that allow them to share water, nutrients, and the products of photosynthesis. 

Why does this happen?

More than 150 plant species exhibit natural root grafts, according to researchers. There is debate about whether this occurs due to overcrowding or if plants purposefully graft their roots onto neighboring roots. There is also debate whether this action is beneficial or verging on parasitism. Most researchers lean toward the mutually beneficial explanation. Potatoes and strawberries frequently graft their roots onto neighboring plants of the same species. Surprisingly, some natural root grafts are between different species.

Mature roots from two trees naturally grafted together to share water and nutrients (Wood Geek) CC BY-SA 4.0

Benefits of natural root grafting

Natural root grafting provides several benefits to all parties involved. Those benefits include improved stability and water and nutrient sharing. These benefits help keep neighboring trees healthy, making them more resistant to wind and herbivore damage. In one study, trees with natural root grafts were found better able to recover from a spruce budworm attack.

Tree root grafting allows groups of trees to share water and nutrients. It also forces them to share soil-borne pests and diseases, such as Dutch elm disease and apple proliferation. 

For me, this is yet another example of the amazing processes going on underground. I was stunned to learn that plants can hear. I wonder what will be discovered next.