Before the forest grew, in the early few years of my life by the sacred mountain Arunachala in south India, some mornings I would look up at the peak shrouded in cloud, and optimistically hope that rain might fall. Invariably though, I was disappointed.

The reasons are obvious, now that I’ve watched the mountain for so long. Invariably, the prospect of rain would evaporate – literally – as soon as the sun rose and beat down on the dry rocky slopes. The temperature for seven months of the year averages a daily maximum of over 35 degrees, and often much more. Hot – parched and dry at first, in March, building up to stifling and humid pre-monsoon, then simply sauna-like until the relative respite once the monsoon has passed by December. Comparatively mild for the next three months until the build-up process begins again.

As soon as that sun heated the dry stony surfaces the hot, dry air rising up as ‘transpiration’ but without the moisture that the word suggests. As soon as that air merged with the clouds – pfff – the cloud would thin and vanish. No rain until the pre-monsoon showers may offer respite from the dry heat.

Well it should be obvious, shouldn’t it. If there were trees all over the mountain, then of course the same sun hitting the same mountain, would have a completely different impact. And it does! Now, twenty five years later (that’s a very short time, ecologically speaking), with the path now totally in shadow, it’s a completely different walk on the mountain. Instead of sweating and suffering, it’s a very pleasant walk, shaded and relatively cool, since any air moves across vast areas of leaf surfaces. Leaves are transpiring constantly, releasing moisture as they ‘breathe’, and just a water moving across a pond cools the air, the same thing happens with the trees.

But the effect is so much greater than that. These days, if there are clouds enveloping the peak, when the sun strikes the mountain, the trees transpire, the water evaporates, meets with the clouds, condenses until they can no longer hold all that extra moisture, and it falls as rain.

The Water Cycle – NOAA

So the trees have, in effect, ‘made’ the rain, and springs run where they have not run since many years. This is a transformation of the local climate of the mountain, and countless individual microclimates have been created or radically enhanced, just by planting the trees.

And where any microclimate exists, plants and animals, birds and insects, reptiles and the countless soil life begins to occupy that site, all perfectly ‘selected’ by nature. It’s a huge accelerator factor: one new plant species arrives, and there are specific creatures associated and attracted by that species will arrive. Each of those in turn has other associates, and the explosion begins.

I am told that the bird census at Arunachala counted something like 220 different species last year, an increase of many times over since the last count many years ago, when the mountain was so barren. Without doubt all those birds have relationship with so many other creatures and organisms, not to mention their unintentional import of yet more species from other zones away from the mountain. Such a spectacular increase in species also represents a geometrical increase in the transformers of organic material, and hence of soil fertility. So the ability of the mountain to germinate more plants, and increase the soil volume is also vastly augmented.

It all seems quite ‘miraculous’, but of course there is a divine order in the apparent chaos, and my incredulity is only a reflection of my own inability to fully comprehend the capacity and speed of Nature to heal herself. And also to accept the potential of our own human role to be agents of that acceleration.