[QA] Will planting millions of trees save the planet?

This question seems to be coming up more and more lately. In short, no. It won’t have anywhere near the impact some people seem to think it will. It’s really important, but it must be one of action of many, many more. Large-scale tree planting must consider the whole ecosystem, taking into account factors such as whether the species being planted are native to the area and appropriate to the soil and climate. This ensures that they not only survive, but don’t become invasive and harmful to the health of surrounding ecosystems. If afforestation is poorly planned or undertaken in the wrong context, evidence suggests that it can cause extensive harm to biodiversity, ecological functioning and ecosystem productivity. _It seems obvious but we should also be making sure these lands where we’re planting can’t later be cleared again.

Research proposes that locations selected for restorative actions should optimize all of the potential benefits of the activities to be undertaken; for example, proper site selection for tree planting could integrate with regenerative farming systems, providing shade, improving water retention, and possibly yielding additional income sources to people on farms or grasslands. Importantly, there should be prior consultation with all of the groups who may be affected, including Indigenous peoples.

Short of the story – tree planting is complex and that action alone certainly isn’t going to change the world. There are many other things we need to do in conjunction. Plenty of these projects have also failed spectacularly (check out our carbon offsets article that goes into detail on some). Do we need more trees? Way more. Importantly we need to stop deforestation… and start replanting (but do it right!). We also need to be incorporating trees in our design of lands, homes and cities far more so that it doesn’t become a (nearly impossible) task later down the line._ But tree planting sure isn’t a quick fix to our problems.

Source: Aronson et al. (2020) A world of possibilities: six restoration strategies to support the United Nation’s Decade of Ecosystem Restoration.