As companies get behind the tree-planting movement, here's how to get real climate results

Reserva Natural Guapiaçu, Rio de Janeiro State, Brazil
Robin Chazdon
A native tree nursery for large-scale restoration of Atlantic Forest at Reserva Natural Guapiaçu, Rio de Janeiro State, Brazil.

This article originally appeared on Ecosystem Marketplace, a Forest Trends initiative.

The world is rallying around planting trees for climate action. Even President Donald Trump is on board, announcing at the World Economic Forum that the United States would join the One Trillion Trees Initiative.

In the next 10 years, you likely will see the largest effort in history to regreen the planet. The United Nations has declared 2021-2030 the Decade on Ecological Restoration. Initiatives including the Bonn Challenge, the African Forest Landscape Restoration Initiative and dozens of corporate and government commitments will replant, restore and preserve hundreds of millions of acres of land around the world.

These efforts contribute to keeping global warming under 1.5 degrees Celsius. Climate scientists have shown that reducing emissions is no longer enough to stay below this threshold. We need negative emissions — to actively remove carbon from the atmosphere in addition to our already-planned emissions cuts.

Investing in natural carbon sinks such as forests is our best — and currently our only — strategy for affordable carbon removal. Natural climate solutions such as restoring and preserving forests and other high-carbon ecosystems, switching to climate-friendly agriculture and practicing sustainable forest management can cost-effectively achieve more than 37 percent of the emissions reductions we need to stay under 1.5 degrees C.

It’s important to point out that tree-planting is not our only natural climate strategy. A major new study released this week shows that protecting existing tropical forests is still the largest pathway we have for cost-effectively mitigating emissions.

Nor can we forget that history is littered with failed tree-planting projects. China, home to some of the world’s largest reforestation campaigns in history, lost as many as 86 percent of trees planted between 1952 and 2005. Millions of trees have been planted in the Sahara since the 1980s, but it still isn’t green.

How do we make sure this tree-planting movement is different? Forest Trends has worked for nearly two decades in the Amazon planting trees as part of larger agroforestry and forest management systems developed hand-in-hand with indigenous peoples. Here are some basic guiding principles for making smart investments in forests that we’ve learned.

Learn to think at the speed of a tree, the breath of a forest

When forests and other ecosystems are damaged, they take decades or even centuries to fully recover, if they ever do. For that reason, it is vitally important right now to protect existing forests and healthy working forest lands than to plant new trees.

The best way to maximize carbon sequestration, water filtration, flood regulation, wildlife habitat and the other benefits trees give us is to keep existing forests healthy and intact. Then, we can build on this foundation through wise restoration and reforestation efforts.

Plant the right species in the right place, and remember a forest is more than just a stand of trees

Many tree-planting efforts fail or have unintended consequences because they create forests where forests didn’t exist before — for example, in grasslands and arid areas. You also need good science to understand how ecological functions interact or pose trade-offs.

For example, planting trees can reduce local river flows (at least initially) but sometimes has the opposite effect during the dry season. And the outcome depends a lot on previous land uses (for instance, if the land previously was plowed for farming), degree of soil disturbance and the eco-region we’re working in. Meanwhile, planting non-native species can hurt biodiversity.

For reasons such as these, projects need to take a whole-ecosystem approach. When we think about forests here at Forest Trends, we see them inherently multifunctional: a virtual (supermarket) of products and services. With a single conservation investment in a forest (PDF), you can sequester carbon, purify water, recharge aquifers, absorb floodwaters, provide a home for wildlife and ensure a sustainable supply of wood fiber, food and other products for people. When we plant trees and maintain forests, we need to capture and monitor these other services (carbon, water, biodiversity) and drive our economic system to value these precious assets.

Partner with local communities to ensure that seedlings survive and communities benefit from projects

"There is a saying in forestry: It is not about trees, it is about people," Nestor Gregorio, a research fellow at Australia’s University of the Sunshine Coast, told the Washington Post. "If people will find trees important, then they will look after the trees."

It’s like birthing and successfully rearing a child. Tree-planting projects succeed when locals have the right decision-making power, skills and incentives to protect their forests. Tree-planting projects fail when NGOs, companies or other funders parachute in, plant trees and leave.

We have seen that supporting indigenous and forest communities to thrive in their homelands is one of the most effective safeguards against forest loss. But these communities need effective partnerships to keep their forests standing. They also need support in creating sustainable economic enterprises that provide alternatives to deforestation.

Be humble

We are changing global ecosystems so drastically (the Amazon forests may tip over into savannah thanks to climate change and mega-scale conversion to agricultural production; some ecosystems may never recover in the Australian bush after this winter’s fires) that the analogs we have used to understand system change in the past no longer apply. We are seeing more novel ecosystems, and we can’t rely on the past for much guidance on how our restored and newly planted forests will behave.

For example, climate change is already changing rainfall patterns in many areas and we need to take that into account when, for instance, selecting the right species to plant. We should have an eye on restoring the ecological functions, but not necessarily the same ecosystems.

We cannot fix climate change with a one-and-done push to plant a trillion trees, but a global forest restoration effort can teach us a lot about respecting the incredible complexity and richness of our planet and its ecological systems.

Plant a tree but grow a green economy

We are losing forests around the world because our economy values a tree more when it is cut down or when a forest is converted for timber than when it is part of a standing forest. Forest Trends’ mission is to demonstrate value in both. Until we embed sustainability into our economy, tree-planting will be a Band-Aid on a deeper problem.

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