Go green and plant a few trees this Earth Day. Your kids and their kids will thank you.

Studies have shown that schools with tree coverage have a low prevalence of asthma and lung diseases amongst their learners. In addition to this, children with Attention Deficit Hyperactive Disorder are able to concentrate for longer periods.

This year’s Earth Day theme is ‘Trees on Earth’ and it will be celebrated on 22 April 2016. The Earth Day Network (EDN) aims to plant 7.8 billion trees by 2020 to honour its 50th anniversary. This can be translated to a tree for every person on.

Currently, the earth is losing approximately 15 billion trees every year because many of them are being cut down. This can be compared to losing 48 soccer fields every minute. The EDN believes its initiative will be able to serve as a foundation for a cleaner, healthier and more sustainable.

However, it is important that the right trees are planted and not over watered since South Africa is a water-scarce country trying to recover from the effects of the recent El Niño.

The CSIR has embarked on a number of projects to boost the understanding of the exact water requirements of specific trees and crops. This includes calculating the water-use of irrigated crops, trees, as well as invasive alien plants.

According to CSIR hydro-scientists, stands of indigenous tree species tend to use less water than fast-growing introduced tree species from other countries. Groundwater-dependent alien invasive plants, like the Prosopis, can consume up to 50 L of water per tree per day. “Higher stand level water use by Prosopis invasion is more a consequence of higher plant densities rather than high individual tree water use, explains Dr Sebinasi Dzikiti, CSIR eco-hydrology expert.

Prosopis is unfortunately found in communities that mostly depend on ground water for survival, consequently limiting the availiabilty of water for people dependent on these water sources.

In the agricultural sector, farmers tend to move from flood-based irrigation to high-pressure micro-sprinkler and drip irrigation systems. But, Dzikiti explains, the problem is deciding when to irrigate and with how much water. The study the CSIR is conducting will provide accurate crop water use information so farmers can develop guidelines for precise irrigation scheduling and water resource management in apple orchards.

“For example, field measurements show that a 14 year old ‘Pink lady’ apple tree, growing in an apple orchard in the Western Cape, uses between 20 to 30 L of water per day in summer,” explains Dr Mark Gush, a CSIR hydroscience expert. “This amounts to 4 000 L of water per tree over the growing season and means that each tree requires about 27 L of water to produce an apple,” says Gush.

The researchers used the heat pulse velocity sap flow technique, which measures how fast the water is travelling through the stem of a plant. Based on these measurements, they are able to calculate the actual volumes of water transpired by the trees. The energy-based technique, which requires equipment to be mounted above the vegetation, measures the water use of an entire field or orchard. Other methods include in-field vegetation water use monitoring techniques, remote-sensing methods for estimating evapotranspiration, modelling approaches and water-use impact indices and tools.

Because of the CSIR research, farmers will be able to produce more fruit using less water, which means improved agricultural water-use productivity and a more sustainable agriculture sector. Now that we are armed with the knowledge of what type of trees to plant and how much water to use, let us go out there and plant the right trees in our communities this Earth Day. Remember, it is for the future generations.