As we all learned in high school, trees produce oxygen through photosynthesis, making them one of the main oxygen producers on land. But what many of us misunderstand is when it comes to the whole Earth. percentage of trees’ contribution to oxygen production.

As you know, trees shed their leaves in the fall. This begs the question: how can a tree without leaves produce oxygen? Or does it produce? If not, how can we keep breathing? The answer to these questions is not so simple, because there are many factors that influence the global oxygen cycle, and trees are only a small part of them.

First, let’s learn the shocking truth: Trees are not our planet’s main oxygen producers.

One of the first questions we should ask ourselves is: how much oxygen trees actually produce and how this relates to the total amount of oxygen in the atmosphere. According to some estimates, trees account for about 30% of terrestrial photosynthesis, that is, they produce about 30% of the oxygen given off by terrestrial plants. The rest comes from other plant species such as grasses, crops, shrubs and mosses.

More importantly, only terrestrial photosynthesis responsible for half. The other half is in the oceans. algae, phytoplankton and cyanobacteria It comes from marine photosynthesis performed by These microscopic organisms are often “lungs of the planetThey are called ‘because they produce about 50% of the oxygen we breathe.

Algae, phytoplankton and cyanobacteria

So if we add up all the sources of oxygen production on Earth, we can roughly calculate the total oxygen supply of the trees. We can say that it contributes about 15%. In other words, the fact that trees drop their leaves and stop producing oxygen for a few months does not cause a noticeable change in oxygen levels. But that doesn’t mean trees are unimportant, of course.

Another question to ask is how much oxygen the trees consume and how this affects the net oxygen balance.

Like all living organisms, trees need oxygen to breathe; meaning they use oxygen to break down sugars and release energy for growth and maintenance. Trees all year round, dormant in winter or they breathe even when leafless.

The amount of oxygen that trees consume; it actually depends on several factors such as their size, age, species and environmental conditions. But in general, trees consume about half of the oxygen they produce. This affects the oxygen balance of the trees. a net positive effect It shows us what it has, but not as much as we think.

For example, a mature leaf tree can produce enough oxygen for 10 people in a season for a year, but it also has the ability to consume enough oxygen for 5 people in a season for a year. So the net effect is a tree can support 5 people with oxygen production for a year. In addition, trees pass their leafless period by lowering their own respiration rate and consuming less oxygen. This has a positive effect on the net oxygen balance.

What about other sources of oxygen production and consumption? Is there a time when they stop too?

It turns out that the seasons have a similar effect on them. For example, grasses and crops also stop growing and photosynthesising in winter, but they also reduce respiration, like trees. Likewise algae and phytoplankton in the oceans to the presence of light and have seasonal cycles of growth and decline depending on the food source.

So, in general, the seasons affect both oxygen production and oxygen consumption in a balanced way, meaning oxygen levels don’t change much throughout the year. In fact, according to measurements from the Scripps Institution of Oceanography in California, atmospheric oxygen levels have been relatively stable since 1991, It fluctuates slightly between 20.94% and 20.96%.

(And don’t be surprised, it’s about 78% of Earth’s atmosphere.) nitrogen/nitrogen forms.)

What other factors affect the Earth’s oxygen level?

Of course, the seasons are not the only factor that affects oxygen levels. There are many natural and man-made factors that influence the global oxygen cycle, such as volcanic eruptions, wildfires, fossil fuel combustion, land use change and climate change. While some of these factors have a positive effect on oxygen levels, many have a negative impact.

volcanic eruptions

Volcanic eruptions can release large amounts of carbon dioxide and sulfur dioxide into the atmosphere, which can then react with oxygen, lowering oxygen levels. Not only that, but the volcanic ash and dust released from the eruption, because it blocks sunlight It also reduces photosynthesis.

forest fires

Similarly, wildfires can consume large amounts of oxygen by burning biomass, but they can also stimulate new growth and photosynthesis by removing dead wood and releasing nutrients. Burning fossil fuels can also consume large amounts of oxygen from burning coal, oil and gas, as well enough carbon dioxide to increase plant growth and photosynthesis can also increase.

Land use change

Land use change can also affect oxygen levels by changing the amount and type of vegetation on the Earth’s surface. For example, cutting down trees can reduce oxygen production but by removing decomposing organic matter can also reduce oxygen consumption. In the opposite scenario, i.e. planting trees with afforestation, oxygen production can be increased, but adding decomposing organic matter can also increase oxygen consumption.

climate change

Finally, climate change can also affect oxygen levels by altering temperature, precipitation and wind patterns that affect photosynthesis and respiration. High temperatures can increase breathing rate and decrease oxygen levelsbut also can also increase evaporation rate and water vapor contentthat can retain heat and can increase the rate of photosynthesis.

As you can see, there are many factors that affect oxygen levels in complex and sometimes counterintuitive ways. However, the total impact of these factors is very small compared to the total amount of oxygen in the atmosphere. In fact, according to a study by climate scientist Chris Poulsen of the University of Michigan, oxygen levels between 10% and 35% in the last 500 million years, It has changed little in the past 10 million years.

In conclusion, we can say that trees drop their leaves and reduce oxygen production, It does not affect our oxygen balance.