These 10 golden rules for planting trees could help save the planet

There are around 60,000 tree species in the world, spread out across myriad ecosystems. Within these ecosystems, and around these trees, are countless other organisms ranging from the tiniest bacterium to the mightiest moose.

Between the trees, their landscapes and their peer flora and fauna, exist startlingly complex relationships that we're only just beginning to understand. The matter gets even more complex when you factor humans into the equation – around 2 billion people rely on forests alone, for work, food, shelter and water. Of course, trees play a massive role in sequestering carbon from our atmosphere.

It's perhaps no surprise then, that there are a healthy number of tree planting initiatives around the globe – run by businesses, governments and even individuals. Make no mistake: we need to be planting trees. But while many of these initiatives are certainly ambitious, it's important that we establish a set of best practices to get the most from the resources we put into restoring forests.

With our colleagues at the Royal Botanic Gardens, Kew, Botanic Gardens Conservation International (BGCI), and partners from around the world, we helped to develop a list of '10 golden rules' to improve tree planting efforts in terms of carbon sequestration, biodiversity and human livelihoods.

Right now, the world is losing areas of forest equal to the size of the United Kingdom each year. This means less carbon is sequestered, and in many cases, more carbon dioxide emissions. Old growth forests are massive carbon sinks, and it can take hundreds of years for them to fully recover.

A crucial first step to preserve trees around the world is to simply protect the ones we have already. Governments of all levels, and corporations, should actively combat deforestation.

Reforestation can be a truly daunting project, but at its core it needs to engage with local communities and the people who live and work with the trees themselves. Research suggests that many attempts at reforestation fail simply because they don't involve local communities.

The people living in the areas benefit from tree planting and forest maintenance, both economically through the creation of jobs, and in terms of health. They are also subject experts in the forests themselves, and the issues facing them.

For example, BGCI’s project to conserve Malawi’s national tree – the Mulanje cedar – not only resulted in more than 500,000 trees being planted, it also created more than more than 1,000 jobs for the local community, and trained over 200 people in nursery management and enterprise development to manage 10 community plant nurseries. Restoration works best when it has co-benefits for local livelihoods.

Forests and their relationships with humans, animals and other plants are deeply complex, and trying to understand the best ways to address many of the issues they face can be difficult. However, this interconnectivity means that by improving the health of the forest itself, you're improving the health of its neighbours and inhabitants.

Any reforestation project should be made to address multiple related goals, such as increasing biodiversity, helping local economies and reducing carbon emissions. However, there can be trade-offs, but priorities should be agreed upon by stakeholders at the beginning of the project, and based on science, the environment and the needs of the communities.

Not every plot of land is made equal when it comes to reforestation. Areas that were previously forested should be targeted. Some wild areas like wetlands, peatlands, and grasslands contribute a great deal of carbon sequestration, on top of their other ecosystems to humans and the environment at large. These are not suitable zones for tree planting efforts and planting trees in these places can displace biodiversity and do more harm than good. Target areas that either connect or expand on existing forests, or restore lost forests, thus helping improve their overall size and health.

Sometimes, it's best to let nature do the work for you. Natural regeneration is a process in which a forest, or other wooded area, regrows after a parcel of land is abandoned, or when a forest begins to mend itself after degradation. This is cheaper, easier, and in many cases, more effective. Carbon capture in naturally regenerated land can be 40 times greater than in plantations.

There are different levels of natural regeneration. The easiest is passive restoration, where no human intervention is involved. Low intervention includes protecting a region from fires, and selectively reintroducing native flora and fauna. But there are other cases – intermediate and high intervention – that involve more work. Whether natural regeneration is possible, and the amount of intervention required, will vary depending on the time since the area was cleared, land-use since clearance and distance from remaining forest patches.

Sometimes, natural regeneration is not possible, and human intervention needs to be part of the equation. In cases like this, it's essential to pick the right kinds of trees. Try to introduce only native species, including rare and endangered whenever possible, and bring in a good mix of species.

Reintroducing a wealth of biodiversity to a forest will help attract pollinators and restore habitats for a larger array of animals. These forests will also be more resistant to diseases, fires and extreme weather. Avoid invasive species at all costs.

A BGCI project in Uganda with Tooro Botanical Gardens (TBG), in just two years, has produced more than 260,000 seedlings of 100 indigenous species to support genetically and species diverse forest restoration. Reforestation is not just about getting trees in the ground: it’s about providing the building blocks of an ecosystem.

As climate change continues to impact ecosystems around the world, the best tree species for reforestation are those that are resilient. Pick seeds and seedlings with a healthy amount of genetic diversity, as this can make the population less susceptible to pests and climate change. Make note of how the region is expected to change in the future, and try to choose tree species that anticipate the climate reality.

Source trees, seeds and seedlings locally whenever possible. Establish a good, reliable supply chain for the reforestation project at every step of the process and plan this stage well before the beginning of the project.

Work with local communities, and train workers on the best practices for seed collecting, storing, planting, etc. Employing people from the area helps bolster local economies and makes use of their valuable experience and expertise in the region.

Start every project by reviewing scientific literature about the tree species and the region you want to grow them. Consult with the communities themselves so they can aid the process, and help you pick the right species and right places for them.

Then, try some small-scale trials before engaging in the process fully – it is essential to test the trees' effectiveness in the region before deploying all your resources. Keep monitoring your work through every stage of the process; keep a keen eye out on how the ecosystem is recovering, and change your processes as needed.

Forest restoration isn't a cheap process. However, there are many different ways to bring new income streams into a project, and help benefit the different stakeholders involved. For example, consider selling sustainably produced forest products, or setting up an ecotourism operation. There are many ecological benefits to reforestation, but fostering a forest's health and biodiversity can also help local economies.

We designed these golden rules with a few things in mind, such as the importance of local and indigenous knowledge, and bringing money into the communities involved. We've taken lessons both from modern scientific research in the field, and success stories within it. However, even with these tips in mind, it's worth noting that this process is a tricky one with many moving parts and solutions that will have to be local.

But, irrespective of how you're involved in the reforestation process – or even if you're just an enthusiast – you can help global efforts by following these golden rules and supporting the right kind of reforestation. BGCI and our global network spearheads several initiatives to conserve trees and restore forests, whilst sticking to best practice, including the Ecological Restoration Alliance of Botanic Gardens, the Global Trees Campaign and the Tree Conservation Fund.

Later this year, we will be releasing the Global Tree Assessment (GTA), the first-ever conservation assessment of all the world’s known tree species. This report will provide a conservation roadmap that will put our 10 golden rules to good use.

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