September 26, 2020

Do you really know what forests are for?


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Deforestation is the cause of up to 20% of climate change, only behind fossil fuels. And the loss of forest each year, although it has slowed, is still too high.

From 2000 to 2012, 3.2% of the previous forest area in the world was lost. Something like a million and a half or 1.7 million square kilometers. 3 times Spain. And since 2012, with massive fires like those in the Amazon, Borneo or Australia, this figure will have increased.

The situation is worrying because forests are much more than the lungs of our planet, but also. Because it is true that when vegetation grows, a large amount of CO2 from the atmosphere remains fixed, and that slows down climate change.

What else do we owe to forests?

But this is not its only benefit. Forests also participate in a very important way in water cycles, increasing the humidity present. They protect the soil from erosion and are also an area of ​​great biodiversity.

For us, selfishly, they are also relevant and deserve care. Among other merits, trees reduce air pollution in cities, act as a sound barrier on roads, prevent landslides and floods, and even soften the severity of winds from storms and hurricanes.

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Reduce air pollution

In wooded areas within a city particulate matter in the air decreases up to 24%. This pollution comes mainly from the burning of fossil fuels (factories, cars, heaters…) or biomass (wood, burning fields…) and causes cerebrovascular damage, lung cancer or heart attacks. In total in the world, it causes more than 3 million deaths a year.

But trees, especially if they have a lot of foliage (and therefore a lot of gas absorption surface) are able to capture these particles effectively.

They cool temperatures in summer

The extreme heat that we experience in some cities in summer can also be mitigated by planting trees. In wooded areas the temperature drops to 2 ° C, considerably refreshing any city.

It has to do with albedo effect, or how much heat the ground is capable of reflecting. The asphalt city, dark in color, tends to absorb almost all the solar radiation that reaches it, heating up. In addition, the heat is released even though the sun is no longer shining, so even being at night it will cause an increase in temperature in the city.

Trees, unlike asphalt, are capable of reflecting more light, and that entails less heat capture than asphalt. In addition, and as is evident, they have the ability to provide ample shade, which also prevents the ground from getting hot in these areas.

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They give warmth in winter

But there is more. If the trees are deciduous they will give a nice wide shade in summer, but will not have leaves in the cold months, so the sun will affect the ground more, increasing the heat from the city, which reduces the use of heating.

Anyway, if what we are looking for (which we are looking for) is Let nature help us with the temperatures, ideally, what seems most effective and economically viable are green roofs. Use the roofs of buildings as gardens to achieve the benefits they provide when regulating the temperature of the building and the city.

In addition, it does not escape anyone that in many cities already formed, planting trees in most of their streets would require large urban projects, and yet doing it on rooftops would be much easier, more comfortable and would even achieve greater results.

Reduce noise

Another of the great benefits of trees in the city is the relaxation power they provide. Trees produce more happiness in people. Various studies relate the presence of trees and nature in general with greater personal, physical and mental well-being. Walking through a park with dense forest cover, we quickly forget that we are in the city. There is no traffic. There is no noise … because trees also have a great ability to retain sounds, making them a natural barrier to get away from urban debauchery.

They put a brake on the desert

In addition to cities, forests are of global importance in human life. The African Union and several organizations have been working since 2007 to make a Great Green Wall.

A misuse of the land is causing the Sahara to advance inexorably south. If we don’t stop it, millions of people from Senegal to Ethiopia would have to be displaced by the expanse of the desert. A fact that would lead to famines, droughts and the consequent migrations of people in search of survival.

Given this alarming situation, it was decided to carry out a massive tree planting project, involving the local population. And it seems to be succeeding.

Of course, it is not simply a matter of planting trees in the wild. It has been a well-designed decision in which the environment is respected to create a wall with appropriate and sustainable practices. And for the moment it is leading to achieve -at least in part- the objective.

A job well done in which iidentified which species were most valuable, well designed the planting of new trees and adapted production techniques from crops to the environment.

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Retain water

The consequences it has are multiple. Why forests, with their leaves, protect the soil from erosion by rain, in addition to nourishing it. They also attract animal species that stopped seeing each other years ago. And, perhaps more importantly, if it is carried out correctly and ends up achieving a large wooded area, could positively affect the entire region by recycling rainfall.

The Sahel is an area with little annual rainfall, but when the rain falls it is very abundant. What happens is that if it falls on a wasteland, with eroded soil, the water does not have much infiltration capacity and it evaporates quickly. In addition, this can cause landslides and promote flooding.

However, if there is a forest, the water infiltrates more, is captured by the trees and is released little by little into the air with evotranspiration.

Evotranspiration is a sum of the water evaporated in forests and the water transpired by trees. A single tree throughout the day can transpire hundreds of liters of water that come out into the air. Thus, forests greatly increase humidity, which moves with the winds to interior areas of the continent.

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Make it rain

On average, 40% of the precipitations come from this evotranspiration. And in some places in South America, through the Amazon, it reaches up to 70%.

At the same time, they are capable of capturing water from fog and ambient humidity. And what is more shocking, forests seem to attract rain directly.

Let’s not forget that the rains start when the atmospheric humidity condenses. And this occurs when it becomes saturated with water, favored by molecules that act as nuclei of condensation. Well, in forests, volatile organic compounds produced by microorganisms can act as these condensation nuclei, so we could even say that the forests themselves make it rain.

The benefit of mangroves

The presence of vegetation allows millions of people to continue living in their homes. But not only because of the rain and food.

Mangroves are a kind of forest between sea, land and fresh water, which protect much tropical and subtropical coast of the temporary inclemencies.

Hurricanes, cyclones or typhoons join a new threat, rising sea levels, making human life difficult in many regions.

As well, the presence of a vast vegetation surface reduces the intensity of storms, since the mangroves literally absorb the energy they have. In the Caribbean and Southeast Asia, both areas prone to major storms, mangroves are present in much of the coastline. AND if there is mangrove, the winds and tides that reach land are weaker than if they had found a flat path.

But with the rise of the sea, these situations will worsen, putting the lives of billions of people at risk. Areas such as Indonesia, Bangladesh or the Philippines, countries with poor infrastructure, are on red alert. And there the protection of the mangrove can be essential.

In addition, the mangroves prevent coastal erosion, act as filter feeders for rivers at their mouths and are home to thousands of animal species.

Similar effects also occur on the emerged surface. Cities surrounded by forests and jungles will suffer less from storms than others built in areas devoid of leafy vegetation cover.

The forests also have their cross?

However, there are times when forests seem not to have such a beneficial effect.

In boreal areas, the growth of forests increases the local temperature due to the already mentioned albedo (the percentage of radiation that any surface reflects).

It is easy to understand that ice and snow, white in color, are able to reflect almost all the sunlight that reaches them, so their surface is practically not heated. But even so, as temperatures rise, the ice has begun to melt.

Forests and vegetation begin to populate areas that were previously covered with snow for most of the year. And as plants grow, they absorb much more heat than snow, which directly causes an increase in local temperature. So it is given again another feedback phenomenon: the more vegetation grows, the more the temperature rises that melts ice and snow, allowing more vegetation.

At a global level its implication is not yet clear: the growth of boreal forests captures large amounts of CO2, but the greater capture of solar radiation can increase global temperature.

This issue still requires further investigation, but for now it is known that the key lies in preserving existing temperate and tropical forests and, in optimistic scenarios, leaving more soil free for growth.

Nonetheless, we are losing forests at an alarming rate.

The causes, among many others, are a greater use of surface for livestock or for the wood industry, as well as increasingly extensive fires.

Massive deforestation will cause rains to drop by up to 30% in some regions. Less rains mean more droughts, more stressed plant areas, greater increase in fires.

Climate change and forests feed back on each other.

Without forests, our life would be much more complicated.



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