Where and when should we reforestation

Imagine that you are tasked with spending a billion dollars annually for 50 years to restore and preserve the maximum amount of Biodiversity forest on this planet. With 458 forest ecosystems around the world, the problem is figuring out which ones to invest in each year, in order to improve your money, and preserve as biodiversity as possible. It was this problem that the scientists set out to solve.

Humans have already changed 70% of the Earth’s surface. Since the beginning of agriculture nearly 15,000 years ago, a third of all forests have been destroyed. Half of this destruction occurred after 1900, and since 1990 420 million hectares of forest have been cleared. Today, only 15% of the surface of the continents is in reserves. Most of these areas have not been selected to ensure maximum biodiversity conservation, but are usually in areas of less economic importance.

Scientists estimate that it is necessary to preserve between 17 and 40% of the surface to prevent the collapse of living systems. In other words, in the most optimistic case, we have to stop deforestation and restore 2% of the planet’s surface if we want to continue to live in a land in a sustainable way.

For each of the 458 ecosystems, the scientists collected data on the richness of biodiversity, the portion actually deforested, the cost of reforestation per hectare, and the amount of areas actually protected. In addition, they considered the starting point of the reforestation process that was present in 2018 in each region, and the final point (maximum reforestation) of what was present in each ecosystem in 2000.

A risk factor was also assigned to each ecosystem based on the annual deforestation rate of that ecosystem between 2000 and 2018. Based on this data, a dynamic model was created that optimizes restoration in order to conserve the largest number of species at the end of 50 years. This model produces a list of areas to be reclaimed each year and can be recalculated by changing the amount invested annually and the number of years of the project. The goal of improvement is to obtain maximum conservation of forest biodiversity with the available funds and on time.

In general, the dynamic model ends up prioritizing restoration of the most threatened areas of smaller ecosystems with greater biodiversity, considering the cost of restoration in each area, leaving ecosystems at less risk for later years. The math equations are quite complex, but some of the results are worth understanding.

The model shows that $1 billion per year for 50 years could prevent the extinction of 23,680 tree species in 127 out of 458 forest ecosystems. This can be achieved by investing first in the forests found in Melanesia, South and Southeast Asia, the Anatolian Peninsula and the northern regions of South and Central America. One result of this model is that investing in forests in developed countries, such as Japan, North America and Europe, is not worth it, because the costs of reforesting these areas are very high and the money generates more species saved. If you invest elsewhere.

For those who are curious, at work there is a table of zones. The result of this improvement shows that with few resources it is possible to preserve a large part of the threatened forest biodiversity. However, this is a theoretical model, in which political difficulties between states and within each state are not taken into account. It assumes that all countries participate in the project and allows the reforestation of priority areas in their territory. This is far from what happens in the real world.

On the other hand, this is one of the first models that show what can be done in terms of forest restoration in a given time frame, with a realistic budget. This type of modeling can be used to prioritize forest restoration in a single country. It can be used to determine, for example, what to do in Brazil.

more information: When and where to protect forests. Nature 2022