Surely this can only be a good thing? It depends. The problem as always is economics - the irony is that the tree planting frenzy is leading to more pollution not less as the wood is processed (an inherently dirty industry).
As always, you need to dig beneath the headline behinds China's forestation miracle to seek the unpalatable truth.
This interesting article from ChinaDialogue discusses the Chinese tree planting trend.
China's "Green Deserts"
China’s tree-planting movement continues down a worrying path. The planting of artificial, single-species forests has not abated in China; in fact, it has worsened. The country’s original distribution of trees: fir trees in the south, poplars in the north, has made way for poplars everywhere – north, south, east and west. There are even attempts to start poplar plantations on the southern tropical island of Hainan.
Why are poplars such a common choice? Put simply, they are profitable. Poplars can be sold in the cities and increasingly in towns; the wood is shaved into two-millimetre thick boards that are used in high-density materials for fitting out buildings and constructing cheap furniture. This huge market has lead to an entire industrial chain planting, felling, shipping, processing and selling poplars. One northern city has several hundred wood processing plants alone. Wood processing is a polluting industry, which releases toxic chemicals due to the glues that are used. These can also harm – or even kill – workers who are regularly exposed to them.
Many will ask why we should not cultivate this fast-growing tree. It has a wide range of uses, after all. However, a quick-growing tree does not mean long-lasting wood. The artificial boards that poplar is used for only last five or six years. They are cheap enough to be thrown away and replaced as China frantically remodels its homes and offices. As a result, we are rapidly exhausting our non-renewable materials, including sand, concrete, bricks, plaster and stone. The short life-span of poplar products mean they do not fix carbon dioxide from the atmosphere for any significant length of time, unlike furniture or building materials made with quality woods, which can last a century or more.
China has the largest area of artificial forests in the world, but ranks last in terms of these forests’ productivity. These single-species require the constant use of fertilisers and other chemicals. They are weak ecosystems that are vulnerable to disease and pests, which can devastate large areas. They are also unattractive; artificial forests in scenic areas and along roads and railways are nothing to look at.