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Sometimes we forget the importance of forests, but they provide many ecosystem services

Unsplash image of Yong Chuan Tan

Forests provide a very important type of wealth for humanity, the so-called ecosystem services, which are several benefits, such as food, raw materials, beautiful landscapes, climate regulation, biodiversity, tourism and so on.

An indispensable ecosystem that is interconnected with most others is forests. They cover only 30% of planet Earth, but about 80% of all living things on Earth live in this type of environment. Green areas, especially native forests, play a fundamental role in the four categories of ecosystem services: provision, regulation, cultural and support (learn more about this topic in the article: "What is Payment for Environmental Services (PES) and how it is it works?"). Forests are responsible for regulating several factors such as preservation and control of water systems, erosion, soil quality, climate control, protection of biodiversity, among others.

Water

Forest vegetation is directly related to water-producing areas, such as hydrographic basins that have a vegetated area and offer a greater contribution to the production of quality water (understand more about the topic in the article: "Forests are essential for the future and stability of the global climate").

Forests maintain the proper functioning of water flows, as they are responsible for returning part of the rainwater to the atmosphere. When it rains, a portion of the water is retained in the crowns and evaporates, while another part is absorbed by the roots and used by the trees and also evaporates through the transpiration of plants - this phenomenon is called evapotranspiration. With this system, forests return part of their water to the atmosphere to continue the hydrological cycle.

And the rest of the water? The root system of trees (their roots) and the organic matter deposited in the soil increase their porosity and, consequently, the infiltration of the remaining water is facilitated. Infiltrated water is stored in the inner layers of the soil and in rock formations that act like a sponge, gradually releasing water into the groundwater. This control carried out by the forests establishes a regular flow throughout the year, avoiding floods or droughts.

Forests also control the chemical composition of water through physical and biological filtration, improving its quality and dispensing with high costs for water treatment.

Ground

In addition to the interception of raindrops by the tops of trees, the forest floor is covered by a layer of leaves and branches (burlap) that reduces the impact of rain on the ground. As previously mentioned, vegetation provides good water infiltration into the soil, while in a deforested area, rainwater flows directly through the soil at a higher speed and without much permeability, carrying sediment and causing floods.

The litter and the shade of the trees in the forests keep the humidity in the place, preventing the soil from drying out. Vegetation is one of the main factors in slope stabilization and erosion control; its root system works like a net, firming the soil grains, preventing mass movements. Even in vegetated areas, erosion occurs naturally, at a rate of about 162 kg/ha/year, but in cities like São Paulo, where there are few green areas, the erosion rate increases a lot, ranging from 6.6 t/ ha/year to 41.5 t/ha/year! All these factors help to control erosion and load sediment into water bodies, preventing landslides and silting.

climate control

The interaction between forests and the climate happens through the contribution of temperature, solar radiation, precipitation and intervention in the composition of gases in the atmosphere. The vegetation cover influences the absorption, reflection and transmission of sunlight on the earth's surface. Tree tops intercept sunlight, absorbing or reflecting it, and thus alter the amount and intensity of radiation reaching the ground; this keeps the humidity and makes the temperature more pleasant. It is exactly for these reasons that, when we are inside a green area, we feel the cooler climate.

Forests are able to decrease the maximum temperature and increase the minimum temperature daily, making the temperature more constant, in addition to serving as a barrier to the wind. On a smaller scale, trees regulate microclimate and humidity. In urban regions, the temperature drops between 2°C to 8°C in vegetated areas.

Through photosynthesis, forests are able to store carbon, which is retained in their tissues. A tree is capable of absorbing 15.6 kilos of carbon and other pollutants in a year (learn more about the topic in the article: "What is the value of a tree?"). On the other hand, deforestation, mainly due to burning (the most common method), causes the release of CO2 accumulated in the biomass of trees and particulate matter, which impairs air quality. Healthy forests capture polluting gases in large quantities and contribute to climate control and air quality. Large forests like the Amazon affect the global climate, and smaller forests affect the local microclimate.

Biodiversity

Forests are the cradle of animal and plant biodiversity and are responsible for providing the necessary subsidies for their survival. They offer shelter, protection, food for species that live in it or that just stop by, like birds, for example.

For us, the biodiversity of forests has great economic value. It is estimated that around 4% of Brazil's GDP comes from services rendered such as obtaining firewood and charcoal, wood, paper and cellulose, among others. Biodiversity also offers active principles, drug production, scientific research and new technology solutions through synthetic biology.

All these ecosystem services provided by forests vary according to the type of species, soil, climate, slope, among other factors. But the importance of forests and native vegetation for the planet is indisputable and, unfortunately, we still don't know how to take advantage of what forests offer without destroying them.

Change in land use is the villain of forests - 37.7% of the world's land is devoted to agriculture. Between 2000 and 2010, around seven million hectares per year of vegetation were lost in tropical countries and around six million hectares per year were converted to agricultural land. To stop this unrestrained advance of agriculture on forests, it is necessary to implement public policies and change in land use, as provided for in the Paris agreement.

Sustainable agriculture, sustainable extractivism, PES (payments for environmental services) and reforestation with native forest are some techniques of environmental services that can be provided to try to contain the degradation of forests. What we can do is support the implementation of these techniques and consciously consume. Watch the video about the importance of forests:

Also check out a video (in English) about the International Day of Forests.