„Plant a tree, save the world“- Impact of all new trees on the climate

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There are hundreds of tree species we know and those we don´t, but we put hope into trees. They are planted for many purposes, including prevention of erosion and drift sand control, for the supply of fuelwood and other products. And while they are growing they absorb carbon dioxide from the atmosphere through photosynthesis and store it as carbon in the form of wood and of course they release oxygen. That is the fact we know since primary school. Younger trees make it quickly, but when they reach their “stabile” age (that is the point where the amount of absorbed carbon is equal to the amount lost through respiration) or even before that point they should be cut down and replaced with young trees. With this cycle and good management it is possible to take a lot of carbon from the air.

We live in the age when the carbon dioxide is released though many inventions (cars, factories, power plants…) so it is important that trees are able to do their part for us. But our society still needs more place for crops and livestock. Therefore a lot of our forests are gone. We cut them down to make more space, to make paper or just for new highway. So if we are thinking about planting new trees and avoiding further deforestation we should be right and it seems to be really simple way how to decrease carbon dioxide from the air. But we need to think about it much more complex. We have to consider all possibilities and impacts with planting new forests.

We have to know that besides carbon dioxide there is solar energy that has to be taken into consideration, when we are talking about rising temperature. What is on the earth´s surface, really matters, because it influences how much energy is reflected back to the space and how much energy stays. It is the same with us, black T-shirt absorbs more energy (temperature raises), so in the summer we prefer wearing white clothes. The dark-colored trees absorb more solar energy and temperature raises. Planting too many dark green trees (needle-leaved trees/conifers) has a real impact on temperatures.

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Forests now are mostly managed by people not by themselves. In my opinion people don´t think about the right type of tree for the specific area, but only about bigger and faster production of timber that has bigger commercial value. So that is why we have changed kinds of trees in forests. In Europe about 85% of forests are now managed by people. In 200-years-period forests in Europe have expanded, OK, that is great, but they are able to store less carbon as they used to store in branches, roots, leaves and soil. Scots pine and Norway spruce are planted because they grow fast. And that is why evaporation has increased and reflecting the solar energy back has decreased. (But for example in the tropical regions, though, water evaporating from trees increased cloudiness, which helps keep the planet cool.) Everything depends on the region we are talking about.

Kinds of trees like spruce or pine are darker, so they absorb more heat than broadleaf trees like beech or oak. So these forests are not as good for fighting with climate changes as the combined forests could be. For Example grassland or snowfields reflect more sun, so they are keeping temperatures lower. Nowadays forests are more one-type oriented, so they are not so helpful, but when this information spreads, the importance of combining species and thinking about right choice of trees for region, I really hope it won´t be only about money.

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We can see that a lot of countries have the “reforestation or planting trees” in their programs. Tree planting and plantation forestry are well established both in the private and public sectors. Most of these forests are established in areas that were previously not under forest cover. Trees are also planted as part of efforts to restore natural forests as well as in agroforestry, which involves increasing tree cover on agricultural land. Plantations and restored forest ecosystems are a key strategy for fighting with climate changes, biodiversity loss and desertification.

Many researchers believe that as the needle-leaved trees are harvest, more broadleaved trees should replace them. I think that the real challenge is to manage existing situation into future´s benefit, while minimising risks of negative impacts. We have to think about regions too. Not every solution for Europe fits also for tropical regions. It is really important to tailor a plan for concrete location, because every our decision has an impact. Maybe not right now, but in few years it can make a big difference. Think green, but think twice. 🙂

Renata Smolkova

Sources:

http://neobiota.pensoft.net/articles.php?id=7015

http://www.forestry.gov.uk/forestry/infd-869ga8

http://www.bbc.com/news/science-environment-35496350

http://scienceline.org/2016/04/the-wrong-kinds-of-trees-could-make-global-warming-worse/

https://www.bobvila.com/articles/plant-a-tree/#.WInHsn3vm-c

https://www.vassar.edu/archives/2012/11/07

http://www.countryliving.com/life/travel/g3252/beautiful-forests/

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