Trees and forests are often seen as symbols of nature, and for good reason. They are of great importance to both the earth and humans. More than three-quarters of the world’s terrestrial biodiversity occurs in forests. Forests filter and manage rainwater, provide shade, absorb pollution, regulate climate, provide oxygen, and soothe our spirits.
Approximately 38 percent of the planet’s 166,000 tree species are now at risk of extinction in the face of threats such as deforestation, ecosystem degradation and pests, according to an October study. evaluation From IUCN. Scientists agree that increasing the amount of tree cover on Earth would have positive benefits for the climate and ecosystems, but how to go about doing so is complex.
In an interview with Yale University Environment 360Jake M. Robinson, a restorative genomics researcher at Flinders University in Adelaide, South Australia, said reforestation efforts, if done poorly, can fail, reduce biodiversity and negatively impact local populations. He said there is.
“When you plant trees in ecosystems where they shouldn’t grow, you remove the biodiversity that has evolved in the gaps,” said Robinson, author of the recently published book. Treewilding: Our past, present and future relationship with forests. “Tree-planting campaigns are important, but getting them right is even more important.”
Jake M. Robinson
Provided by Flinders University
Yale University Environment 360: How have the earth’s trees changed since humans began transitioning to an agricultural society about 10,000 years ago?
Jake M. Robinson: At that time, about 45 to 60 percent of the Earth’s surface was covered by forests. Things have changed rapidly. Our forests have gone from about 6 billion hectares to 4 billion hectares. In the past 10,000 years, we have lost a third of the planet’s forests. About 50 percent of that loss has occurred in the past 100 years or so. That’s how much it has sped up since the Industrial Revolution. But the nature of forests is also changing. A small amount of native forest remains, but most of it is monoculture plantation.
e360: Is there a consensus on how much of the Earth should be covered by forests for a healthy planet?
robinson: No, there is no consensus. Some people believe that ecosystems should be returned to the state they were in before human intervention began. Another view is that we need to restore the functions and processes of ecosystems and the biodiversity they support, not necessarily to their ideal state thousands of years ago. Not. They want us to realize that humans are part of the ecosystem too, and that it’s okay to change the land. Indigenous peoples have been changing ecosystems over tens of thousands of years.
e360: Tree planting activities have begun in earnest. You write that the area of planted forests worldwide increased from 170 million hectares in 1990 to 293 million hectares in 2020. How did this happen?
robinson: This was partially driven by the events of 2019. science studywhich is quite controversial in the field of restoration ecology. They basically ran some models and showed that 900 million hectares are available to support forests, and about 1 trillion more trees could be planted there. That simple idea went stratospheric. The authors were not advocating planting literally a trillion trees, nor did they mean to suggest that other important ecosystems, such as grasslands, don’t exist. It was all well-intentioned, but mostly due to poor communication.
“Restoration seems like a fairly simple idea…but probably the majority of ecosystem restoration projects fail.”
e360: What’s wrong with the idea of ”planting 1 trillion trees”?
robinson: Repair seems like a very simple idea, but it often fails. In urban areas, approximately 30 percent of planted trees die within the first five years of life. Planting trees in ecosystems where they shouldn’t grow can remove the biodiversity that evolved in that niche. Arguably, the majority of ecosystem restoration projects fail or fail to achieve their stated goals. Many people already live on the land set aside for tree planting, so there is a large social element as well. You may end up replacing them. Tree planting campaigns are important, but it’s even more important to plant the right trees in the right places and do it right.
e360: Do you have any significant examples of thoughtful and successful tree-planting projects?
robinson: There is a place in Oaxaca, Mexico that I would like to focus on. Hundreds of years ago, the Coistlahuaca area was home to 100,000 indigenous people, supported by forests, but today it has fewer than 3,000 inhabitants. The land is degraded by agriculture and poor land management and cannot feed them. Twenty years ago, soil was essentially rock. Local communities had to break up rocks so they could hold water. And they planted these small nurse species (an exotic tree called Greg’s pine, which adapts to adverse conditions and doesn’t reproduce) just to revitalize the ecosystem. These trees died and their carbon went into the soil. This is an ongoing project and not yet a thriving ecosystem, but it just shows that you can start from scratch.
A pine tree planted as part of a reforestation program in Oaxaca, Mexico.
Wolfgang Köhler/Lightrocket via Getty Images
e360: In other projects, people are very strongly in favor of using only native species.
robinson: yes. In Japan, there is a method called the Miyawaki method. The idea is to plant a mixture of carefully selected native species at very high densities, thereby promoting the growth of those species. This is essentially a way to quickly create a functional ecosystem. However, this high density is controversial as it is artificial. Many ecologists are not fans. But I think most of the time they are in urban areas where the ecosystem is quite different and novel and also has social benefits.
e360: The Great Wall of China initiative aims to plant a strip of trees across a vast area of tens of millions of hectares on the southern tip of the Sahara Desert. What’s going on?
robinson:it is [English forester] Richard St. Barb Baker’s ideas for stopping desertification. It may be a good idea, but you need to do it right. I think they’re planting trees in places they shouldn’t be planted, and there are some potential human rights issues as well.
e360: You’re talking about the concept of “nurturing” trees rather than “planting” them. What’s the difference? Why does it make sense?
robinson: Sometimes you can just walk away and let nature take its course. Nature finds a way and grows. But in certain situations, because we are seriously degrading the earth, it is necessary to create the right conditions for these trees and feed them. That’s one of the challenges we’re trying to tackle now: how to grow it at scale.
“You can tell the difference between degraded and restored ecosystems just by listening.”
e360: Of course, restoring or planting more forests leaves less land for growing food.
robinson:This is a big problem. I don’t use the word revolution lightly, but I think we need a revolution in our food system. Because agriculture is one of the main causes, if not the main cause, of ecosystem degradation on Earth.
One of the solutions I talk about in the book is “syntropic agroforestry.” This is simply the idea that we can allow forest ecosystems to thrive while producing food within them. You need to really understand the life cycle of trees and know how to stratify plants and how communities change over time. New Zealand farmer Klaus Lotz is doing just that. It’s like a tropical rainforest. He mainly focuses on fruits and vegetables, non-annual plants such as nuts and mushrooms. He says that although the yield per species is 10 percent lower per land area than in a monoculture system, the overall yield, including all produce, is actually higher.
e360: You too are a microbiologist by training. How important are microorganisms in forests?
robinson:Very important. And it’s not thought out enough. The trunk of a 5-ton tree contains approx. trillions of bacteria; Also included in leaves, seeds, roots, flowers, etc. According to my calculations, trees have between 68.75 and 99.9 percent microorganisms. That’s a little daunting. the tree is a holobiont [assemblages of a host and the many microbial species living in or around them]. Just as we now recognize the importance of the gut microbiome in human health, we need to recognize the importance of microbes in forest health.
Klaus Lotz’s Syntropic farm in New Zealand’s Northland grows food in the midst of lush forests.
permadynamics
e360: Are forest managers harnessing the power of microorganisms?
robinson: sometimes. Microbial inoculants are becoming increasingly popular. The idea is to create your own liquid culture of microorganisms and spray it on leaves or put it in the soil. [to enhance soil fertility and plant growth]or if you are planting trees, you can also include them with small plugs of seedlings.
e360: You also study soil acoustics. How can it help support forest soil health?
robinson: We created a slightly modified microphone that can be placed in the soil to detect moving creatures such as earthworms, spiders, ants, and millipedes. Just as a doctor uses a stethoscope to listen to a heartbeat, we can tell the difference between degraded and restored ecosystems just by listening. This is very eye-opening and I think it will become a useful monitoring tool in the future. we also recently discovered that white noise It can stimulate fungi and encourage their growth. We need to elucidate the factors behind this evolution. Why do they react? Maybe they “mistake” the sound of falling rain, which can cause movement.
Climate change is “impacting different forests differently. Many are shrinking their ranges, while some are actually expanding their ranges.”
e360: How will climate change affect forests?
robinson: It has different impacts on different forests around the world. While many forests are shrinking their ranges, some are actually expanding. Along 12,000 kilometers of northern tree line [where forests give way to tundra]most of which have expanded and only slightly receded.
e360: What do you think about helping trees move to new climate-friendly areas?
robinson:I am working on a “climate-adjusted production site survey” in South Australia. We essentially collect seeds from a climate gradient northward where conditions are already warm and then see if seeds from further afield perform better in changing conditions than seeds from local trees. I am. We do not have a strong opinion yet as it is in the experimental stage in our laboratory.
e360: Overall, do you think humanity is on the right track to restoring the planet’s forestlands?
robinsonA: I’m cautiously optimistic. There are a lot of people doing really good things. We have to have hope.
e360: What is the biggest and boldest action humans can take to restore the planet’s forests?
robinson: Protection and restoration, that’s part of the picture. and protect indigenous peoples and cultures that are least affected.
This interview has been edited for length and clarity.
