Yes, it’s true. Trees make rain!

Scientists have evidence supporting the widespread perception that vegetation is an important factor in rainfall patterns.[1]

Plants release microbes and other microparticles, enabling water to condense and form clouds.

Vegetation stores water and increases water infiltration and storage in soil. With less runoff, more water is kept in our catchments for evaporation from the soil, leaf surfaces, and transpiration of water by plants. Cloud cover increases, boosting rainfall and reducing temperatures.[2]

On average, 40% or more of the precipitation over land originates from evaporation and transpiration.[4]

When forests are replaced by pasture or crops, less water is evaporated from soil and vegetation, suppressing precipitation.[5] Large-scale deforestation reduces rainfall in some areas by up to 30%.

When we grow more vegetation over large areas rainfall increases and transports moisture inland – the Biotic pump theory. Reliable rainfall in continental interiors of Africa, Australia and elsewhere, may, therefore, be dependent on “maintaining relatively intact and continuous forest cover from the coast”.[6]

Trees are giant air conditioners with no power bills” Daisy Ouya[3]

Here’s some of the evidence

For more than 60% of the tropical land surface, the air that has passed over extensive vegetation in the preceding few days produces at least twice as much rain as air that has passed over little vegetation.[7]

In southwest Australia, more rain used to fall on the western side of a 750 km long fence built to exclude rabbits. Today the land on the eastern side of the barrier gets higher rainfall than the west side. The reason – on the west side, most of the vegetation has been cleared for arable cropping.[8], [9]

 

More trees more rainThe effects of deforestation on rainfall[10]

 

Drought-proof farm front cover

If you’re asking yourself – “what’s the best thing I can do to drought-proof my property?” – you’ll get the answers in the Drought-proof your farm.

Digging dams, bores and putting in new water points? Using planned de-stocking and rotational grazing practices? Mulch, water-smart irrigation technology, and seasonal cropping in horticulture and arable production? Engineering solutions like swales, keylines, and Natural Sequence Farming?

They all help.

There is, however, a remarkably simple solution that tends to get overlooked – improving your water cycle.

It gets the rain in your rain gauge infiltrating and stored in your soil, rather than running off. Is cheap to implement right across your farm

>>Discover how to use this eco-logical approach

References

[1] Shukla, J and Mintz, Y, 1982. Influence of Land-Surface Evapotranspiration on the Earth’s Climate Science19 Mar 1982 : 1498-1501. Vol. 215, Issue 4539, pp. 1498-1501
DOI: 10.1126/science.215.4539.1498 (https://science.sciencemag.org/content/215/4539/1498)

[2] M. Kravcík et al., 2007, Water for the Recovery of the Climate – A New Water Paradigm. (http://waterparadigm.org)

[3] Daisy Ouya, 2017, insights for a hot world: trees and forests recycle water. Agroforestry World, Feb 2017 (http://blog.worldagroforestry.org/index.php/2017/02/09/cool-insights-hot-world-trees-forests-recycle-water/)

[4] Trees, forests and water: Cool insights for a hot world. David Ellison, Cindy E. Morris,et al. 2017. Global Environmental Change 43 (2017) 51–61 (https://www.sciencedirect.com/science/article/pii/S0959378017300134)

[5] Spracklen, D., Arnold, S. & Taylor, C. 2012, Observations of increased tropical rainfall preceded by air passage over forests. Nature 489, 282–285 doi:10.1038/nature11390 (https://www.nature.com/articles/nature11390)

[6] Makarieva, A. M.  and Gorshkov, V. G. 2007. Biotic pump of atmospheric moisture as driver of the hydrological cycle on land. Hydrol. Earth Syst. Sci., 11, 1013–1033, 2007  (https://www.hydrol-earth-syst-sci.net/11/1013/2007/)

[7] Spracklen, D., Arnold, S. & Taylor, C. 2012, Observations of increased tropical rainfall preceded by air passage over forests. Nature 489, 282–285 doi:10.1038/nature11390 (https://www.nature.com/articles/nature11390)

[8] Nair et al-2011-Journal of Geophysical Research Atmospheres (1984-2012) The role of land-use change on the development and evolution of the west coast trough, convective clouds, and precipitation in southwest Australia (https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2010JD014950)

[9] Charles Massey – Farming in the Middle East and Australia: lessons about a brittle climate. ABC Saturday Extra (https://radio.abc.net.au/programitem/pgE7ZdmYZ6?play=true)

[10] Aragão, L. The rainforest’s water pump. Nature 489, 217–218 (2012) (https://www.nature.com/articles/nature11485)