One of the most important roles trees play is in the hydrological (or water) cycle. Life can’t exist without water, so these natural systems are absolutely essential, and when they break down, we get an insight into what happens if we don’t protect the natural world. We can see this happen clearly through increases in droughts, which are prolonged periods of abnormally low rainfall leading to a shortage of water.
Droughts have always occurred, but they're now happening more often. In fact, we're seeing a negative cycle where these extreme droughts increase climate change, and, in turn, climate change causes more droughts.
The longer an area goes without water, the more plant life starts to die off, eventually reaching a tipping point where ecosystems can’t survive. This is known as desertification.
The ecosystems that die off during severe droughts have a huge role to play in regulating weather patterns and preventing droughts, so once tipping points have been passed in terms of biodiversity lost, it's hard for an area to get back to its former state.
The worst natural hazard?
According to UN’s food and agriculture organization, drought has affected more people worldwide in the last 40 years than any other natural hazard.
So how are people being affected? As you might expect, lack of rainfall affects water security. This in turn affects food security since crops and farm animals don’t have the water they need to survive.
Limited access to food and water is also causing more conflict over the resources that remain, as well as mass migrations from areas becoming uninhabitable.
When droughts reach the point where trees start to die off, temperatures can also rise dramatically in the affected areas. This increase in heat is where droughts start to impact global warming levels.
Do trees improve water quality?
There are quite a few misconceptions about tree planting and water, with many people backing the idea that trees are using water that would otherwise be available to people and crops. Is this true? Well, yes it can be, but not if reforestation or afforestation is done properly.
Poorly managed, non indigenous forests really can cause water security issues, but trees can also play a key part in combating water security. Let’s take a look at how.
What happens without trees?
Rainfall is already less likely to occur, and when it does, the water isn’t absorbed or diffused by trees and shrubs, and instead quickly runs across the ground and into rivers.
This water is not available for long since it doesn’t have a chance to soak deeper into the ground. Rapidly flowing water quickly picks up sediment, and potentially chemical runoff, making it a health hazard.
What happens when there are trees
The ground can absorb more water and intricate root systems slow its release into waterways, helping filter out sediment and providing cleaner water for local communities and those further downstream.
Why are people worried about trees’ impact on groundwater?
A study that showed anecdotal evidence of lower water quality due to deforestation also included concerns about eucalyptus trees planted near waterways using too much water. You might already have guessed that the trees they’re worrying about are not native to the area, so they do use a disproportionate amount of water.
In short, trees can be both the problem and the solution. The wrong trees can cause droughts and worsen water scarcity, but the right trees can improve groundwater levels and increase water quality.
How powerful are trees when it comes to water quality?
The difference trees can make to water supply is probably greater than you’d think. In fact, trees are such a powerful resource that countries worldwide are looking to invest in and protect forests near key water sources to save on more expensive tech solutions to clean or protect their water supplies.
As an example, when New York funded the protection of forests upstate to help regulate and clean their water supply, they avoided major water filtration expenses, ending up with cleaner water at a much lower cost. On top of that, they had the added benefit of protecting biodiversity.
This is a great example of how solutions that focus on protecting, reintroducing, and strengthening nature’s way of working are often the most powerful when done correctly.
It’s easy to get caught up in very black-and-white thinking around climate solutions, especially with new knowledge coming into the field all the time, but most of these issues - just like nature - are more complex than that.
It’s vital that we don’t back away from the complexities of dealing with water security. Clean water is going to be a bigger and bigger issue globally in the coming years, so we need to gain a deeper understanding of how to manage this vital resource.
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