Think All Tree Planting Is Good? Here’s What Science Says

Reforestation could be a climate solution that also benefits wildlife

When it comes to tackling climate change, planting trees often feels like a simple and natural choice. You plant a tree, the tree captures carbon dioxide, and we all live happily ever after, right? 

Well, not all tree-planting efforts are created equal, especially if we want to maximize their impact on wildlife. What if I told you that planting trees may not always be the best decision?

I remember having this conversation while working across an area that used to be a wetland and, after exploitation, was being evaluated on how to restore it. One of my friends commented that it’d be great if they just planted trees to help with carbon sequestration. 

After studying ecology for many years, I didn’t agree with their vision. Well, the animals in this area are adapted to living in a wetland, not a forest. Why should we change the type of ecosystem? Could we think beyond planting trees for its sake? 

To answer this question, a recent study published in Science dives deep into the effects of three popular land-based climate strategies — reforestation, afforestation, and bioenergy cropping — on over 14,000 animal species.

But wait? Aren’t those all the same? I know they sound very different, but there are some key elements that differentiate them. 

Reforestation involves restoring forests to areas where they historically existed but were cleared due to agriculture, urbanization, or other activities. Afforestation, on the other hand, creates new forests in regions where they did not naturally occur, such as grasslands or savannas. Finally, bioenergy cropping focuses on cultivating specific plants, like switchgrass or fast-growing trees, for renewable energy production. 

And what did the authors find? Reforestation, which restores forests to areas where they historically grew, comes out on top as the most wildlife-friendly option. But why?

Dr. Evelyn Beaury, one of the authors, put it plainly: “Reforestation is an obvious ‘win-win’ for biodiversity. Restoring lost forest provides habitat as well as reduces the impacts of climate change.”

But let’s go back a bit before we explore what the results mean to us. Those who read me often know I love looking at studies’ methodologies, so how was the study performed? 

To get a clear picture, the researchers modeled the impacts of these strategies on animal species ranging from tiny rodents to moose. To do so, they combined maps of current and projected habitats with climate data to see how strategies like reforestation, afforestation (planting forests where they didn’t naturally occur, such as in grasslands), and bioenergy cropping (farming plants for renewable energy) would affect species’ habitats by the year 2050. 

They measured how much land each strategy converted to new uses and how much it helped mitigate climate change, focusing on the balance between these two effects.

And going back, what did they find?

Let’s start with the good news. Reforestation increased habitat availability for most species while also helping stabilize the climate. It was especially beneficial in areas where forests once thrived but were lost due to agriculture or development. Iconic species like jaguars, red-bellied woodpeckers, and spotted salamanders all stand to benefit from these efforts.

In other words, reforestation isn’t just good for carbon sequestration and the planet; it’s great for the creatures living on it.

However, the story looks a lot different when we look at the other two strategies. Afforestation, which involves planting forests in places like grasslands or savannas, often harms biodiversity. This is because species adapted to open habitats, such as ostriches and lions, saw their homes shrink or disappear entirely. 

Similarly, bioenergy cropping came with its own set of challenges. While farming plants like switchgrass can help capture carbon, they often replace biodiverse meadows with monocultures. This shift was particularly hard on species like grouse and elk, which need their preferred species to survive. 

Additionally, the data revealed that habitat conversion (aka. changing one type of ecosystem into another) often caused more harm than the benefits gained from climate mitigation. 

In simpler terms, losing critical habitats, even with the intention to fight climate change, might do more harm than good in some instances. We’d be better off restoring the ecosystems to their natural stages, whether this means forests, grasslands, wetlands, and anything in-between. 

But what do these results mean to our conservation efforts?

This study is the first global assessment to look at how these strategies impact biodiversity alongside climate goals. As countries around the world adopt ambitious plans to achieve net-zero emissions, many rely heavily on planting trees or farming bioenergy crops. 

However, this research shows that taking action merely by thinking about the climate and not considering its impacts on other environmental aspects, such as species diversity, may create more harm than good in the long run. 

Dr. Beaury explained, “Plant-based mitigation strategies do not have the same effect on the climate or on biodiversity everywhere they are deployed. Our research suggests that we cannot assume plant-based solutions always indirectly reduce the biodiversity crisis.”

Don’t get the researchers wrong, though. This doesn’t mean abandoning climate solutions. Instead, it’s about using them wisely. 

Reforestation stands out as a way to restore balance, but afforestation and bioenergy cropping need careful consideration. In many cases, leaving natural ecosystems like grasslands and savannas untouched and letting them recover naturally at their own pace might be the better choice for wildlife.

And what can we learn from this study?

Climate change and biodiversity loss are deeply intertwined, and this study highlights the need to address both issues together. We need to remember that, ultimately, policymakers and conservationists are responsible for considering local ecosystems when deciding where and how to deploy these strategies. 

It’s not just about planting more trees; it’s about choosing the right strategies in the right places.

Reforestation, in particular, offers a promising path forward. It not only removes carbon from the atmosphere but also creates new habitats for countless species. 

However, it’s clear that one-size-fits-all solutions won’t cut it. Strategies need to be adapted to local conditions and ecosystems, balancing the needs of the climate and the creatures that call our planet home.

By taking this balanced approach, we can tackle two of the biggest challenges of our time — climate change and biodiversity loss — without making one worse. 

Thoughtful planning and science-driven decisions will be key to ensuring that our efforts to protect the planet truly benefit all who share it.

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