With an average elevation of 5000 meters, this area is known as the Third Pole of the earth. Here, ice-covered peaks rise like forests above a vast stretch of deserted snow fields. Either blessed by God or spared by Nature, clusters of Chinese tamarisk trees had impossibly managed to survive in the folds of the valley, their stems and branches having the color of rusty iron and their leaves spreading out like soft feathers. Occasionally they produce dense tiny flowers crowded into the shape of rice ears, beaming in spite of the heat and thin air on the plateau. Symbolizing the spirit of the plateau, they are the closest to the sun of all green tree species. It takes a whole century for them to grow into a small cluster. Riding on my horse through the grayish tamarisk trees on my medical-service rounds, I was even convinced that they would exist as long as the snow-covered plateau itself.

One day, our company quartermaster ordered all of us to go to cut firewood.

At first I thought I'd misheard him. Where on this plateau could we find firewood?

The answer was that we would drive a hundred kilometers to some tamarisk trees, dig them out and carry them back as kitchen fuel.

I was shocked, "Aren't we going to kill off the only trees on the plateau?"

The quartermaster retorted, "You need to eat, right? Food needs to be cooked, right? To cook we need firewood, and the only firewood is tamarisk, OK?"

I said, "Tamarisk trees are not firewood. They are living. They have a life. We can use gasoline or coke. Why do we have to wipe out the only green color from the plateau?"

He explained, "To haul a truckload of oil up to our place, we burn two truckloads of oil on the road; for a jin of coke, we pay the price of 6 jin of wheat flour; and tamarisk is free of charge. You do the math!"

The soldiers took up their spades, picks and axes, and a large tamarisk-digging contingent set out.

Tamarisks usually grow on sand dunes. On top of a solid sand dune there may stand a proud tamarisk tree, whose roots, like the many tentacles of an octopus, extend all the way to the indented edges of the dune.

I wonder why the tamarisk trees do not grow on the leeward side of the dunes to avoid the many setbacks of life. A veteran soldier said I put the cart before the horse. It is not that the trees choose to grow on top of dunes, but that the trees fix the sand to cause a build-up of dunes. With the growth of the trees more drifting sand is fixed, and finally a big sand dune is formed. The wider their roots spread, the bigger the dune can be.

Ah, the tamarisk tree is just like an iceberg. Above the sand we see only one tenth of it while a mammoth amount of strength lies underneath.

The branches and leaves of tamarisk do not make good firewood, while its roots are strong and tenacious, and can join sand grains, into a cohesive whole as hard as concrete. When lit up, they burn steadily to produce a huge amount of energy, as if releasing in an eruptive manner all the radiation they've exacted from the sun over the past millennia. Even in the burning flames, the blocks of roots, like dauntless heroic spirits, still manage to stay in their intertwined shapes.

To dig out the roots called for a terrifying amount of work. The tamarisk trees and the land had long formed an inextricable relationship. We had to spend days scooping most of the sand out of a dune, thus leaving the dinosaur-skeleton frame of the tree standing there with its bare roots over the open wilderness. Then men of Herculean strength were summoned. Wielding sharp axes they hacked continuously at the roots, a living tree-root sculpture, until these last links with the earth were severed and the whole tree toppled down.

The year passed. All the tamarisk trees in sight were dug out except those most aged ones.

The digging job took ever longer, for even the strongest men were no match for the unyielding stems and roots. So we resorted to a modern technique – break them with explosives!

A tunnel was dug to the root area. Having put the explosives in place, we ignited the long fuse and lay down at a safe distance. After a moment of dead silence, there was a loud bang. Even the most weather-beaten tree would be blown up into the sky and fall down in pieces.

We camped out in the open. We saw on some sand dunes large hollows, left by the sand-fixing tamarisk trees which had been pulled out the previous year. The gaping holes looked like the eyeless sockets of a wounded face staring angrily at the sky. However, this heart-rending scene would not last long: two years later even the dunes themselves would disappear. It is as if there never had been a tree that had survived the hardships over thousands of years and fixed a large heap of sand.

I was told by someone who had recently been to Ali that the tamarisk trees are no longer to be found there, their stems, roots, leaves and everything of them have vanished in fire and smoke.

Sometimes in the depth of night the images of the aboriginal inhabitants of the highlands would pop into my head: where in the clouds are their spirits anchored now? I also think of the sand dunes once fixed firmly by the trees: have they been blown to all corners of the world? Indeed, the sand grains on our roofs can be carried far and wide on the wind.