Forests in countries like Brazil and the Congo get a lot of attention from environmentalists, and it is easy to see why. South America and sub-Saharan Africa are experiencing deforestation on an enormous scale: every year almost 5 million hectares are lost. But forests are also changing in rich Western countries. They are growing larger, both in the sense that they occupy more land and that the trees in them are bigger. What is going on?

        Forests are spreading in almost all Western countries, with the fastest growth in places that historically had rather few trees. In 1990 28% of Spain was forested; now the proportion is 37%. In both Greece and Italy, the growth was from 26% to 32% over the same period. Forests are gradually taking more land in America and Australia. Perhaps most astonishing is the trend in Ireland. Roughly 1% of that country was forested when it became independent in 1922. Now forests cover 11% of the land, and the government wants to push the proportion to 18% by the 2040s.

        Two things are fertilising this growth. The first is the abandonment of farmland, especially in high, dry places where nothing grows terribly well. When farmers give up trying to earn a living from farming or herding, trees simply move in. The second is government policy and subsidy. Throughout history, governments have protected and promoted forests for diverse reasons, ranging from the need for wooden warships to a desire to promote suburban house-building. Nowadays forests are increasingly welcome because they suck in carbon pollution from the air. The justifications change; the desire for more trees remains constant.

        The greening of the West does not delight everyone. Farmers complain that land is being taken out of use by generously subsidised tree plantations. Parts of Spain and Portugal suffer from terrible forest fires. Others simply dislike the appearance of forests planted in neat rows. They will have to get used to the trees, however. The growth of Western forests seems almost as unstoppable as deforestation elsewhere.

解析：C。根据题干中的the fastest forest growth可定位到第二段第一句。该句指出，几乎所有西方国家的森林都在扩张，而在历史上罕有树木覆盖的地区，森林的扩张速度最快。C项与此内容相符，其中used to have对应定位句中的historically had，the lowest forest coverage对应该句中的rather few trees，故C项为正确答案。

错项排除：A项利用原文第二段中于1922年获得独立（became independent in 1922）的爱尔兰设置干扰，但这只是个例，并不代表所有新独立的国家森林增长就最快，故A项排除。B项和D项利用第三段中政府由于对木材的需求而发放补贴设置干扰，但对木材有需求是政府发放的原因之一，政府发放补贴也只是促进森林增长的因素之一，文中没有说明这些因素与fastest growth（增长率最快）有必然联系，故B、D两项排除。