No trees make deserts

No trees make deserts therefore trees are absolutely magical. Thanks to a large leaf area, a fully grown tree collect massive amounts of water. A mature tree can have an incredible 16 hectares of working leaf area – if you count both the outer surface and all the vessels within the leaves.

Trees are also shaped in such a way that when it rains, the water runs along the outer branches towards the trunk and down along it to the ground. Water will not drip from the crown until all the parts above the ground have been saturated. When the droplets finally hit the ground, they will be carrying nutrients from the surface of the tree along with insects and dust. This nutrient-rich water feeds the topsoil and the finer, shallower roots, while the water from the trunk feeds the deeper layers of soil and the more massive roots.

These thick, deeply buried roots pull different minerals from the ground – minerals which then gets transported up through the tree to the leaves. Once there, these nutrients are washed back down to the soil when it next rains. And so, the cycle goes. You could say that the tree feeds both itself and the ground surrounding it. Therefore, collecting rainwater under a tree gives you water that is significantly more nutrient-rich than just rain. Up to 50 times more nutritious than regular rain, to be precise!

The upper layer of soil and plant material underneath the tree – the so-called litter layer, or the
O horizon – helps to retain the water on its way down through the ground. The first 60 cm of the soil below the tree includes 15 per cent of the tree’s biomass (the roots) and 96 per cent of its water. This delay gives enough time for the roots to be able to take full advantage of the water before it continues down into the ground. Once the ground is fully saturated and the water has given life to everything in its path, the water continues down to the groundwater.

Different types of soils have different capabilities for retaining water. Roughly speaking, soil with no trees can hold 2.5–7 cm of rain per every 30 cm of depth, while the ground underneath a tree can hold up to 10–30 cm in the same volume of soil. Soil that is rich in organic matter, also known as humus, can hold up to one-third of its weight in moisture. One could say that there is a whole lake of recycled water within the forest’s layers of soil figuratively.

Interestingly enough, trees supply more of the water present in streams compared to what the rain does. This fact means that the water in a brook is cleaner than rainwater, assuming that the brook’s environment isn’t polluted.

Trees affect the climate

As said in the beginning no trees make deserts because a tree recycles roughly 74 per cent of rainwater. This recycling occurs partly by water evaporating from the leaves’ surface and partly by water from the ground; water that travels up through the tree, where it then evaporates. The rest – almost 26 per cent – of the water flows down into the ground to become groundwater.

From this evaporated water, or rather the water vapour, clouds are formed. However, before a cloud can produce rain or snow, the moisture must adhere to the surface of tiny, tiny little particles. Most of which are minerals, although airborne microbes also help out. In this, the trees play another vital role, as water vapour from trees contains large amounts of those same little water-creating particles.

Clouds formed over forests are a mixture of water vapour from the sea and water vapour from the trees, depending on how far it is to the sea or a lake. Along the coastline, the rain contains 100 per cent seawater, while further inland, as much as 50 per cent of the water in the rain comes from trees.

Unlike water vapour from seas and oceans, water vapour from forests contains significantly more organic particles and plant nutrients. That is precisely why no trees make deserts.

The farther you get from the sea, the trees ability to condense moisture plays an increasingly important role. A long way inland, where you are far away from any seawater, there would be no rain at all without trees.

Another effect on our climate is that trees affect temperature; because trees – and other plants – are in themselves several degrees warmer than the surrounding air. During the day, this leads to evaporation that in turn cools the tree down, which then makes its’ surroundings colder. The opposite happens at night, when the water condensates against the tree’s warmth, making its’ surroundings warmer than the air nearby.

This way, in turn, means that when hot, dry air enters a forest, it is cooled and moisturized. Vice versa, when cold, humid air enters a forest, it is heated up and dehydrated for it to evaporate on its way up through the canopies. Trees are, therefore, excellent at regulating both temperature and moisture.

Trees work together with the soil and mycorrhiza

Trees produce their weight in organic waste several times over their lifetime, which means that the trees produce most of their soil themselves. This fact aids the nutrient interaction – also known as mycorrhiza – between the plants’ fibrous root system and certain sponges (Mycelium). In the right conditions, these fibrous roots can extend an unbelievable 1000 metres away and 1500 metres down into the ground, which means that a tree can have a massive area to collect nutrients from. Concurrently, the fungi receive the starch they need from the trees.