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：A。根据题干中的encouraged forest growth可定位到第三段，该段阐述了促进这些国家森林面积增长的因素：农场遭到废弃，以及政府的政策和补助。A项中的government在第三段第四句中复现，advocacy对应该句中的policy and subsidy，故A项为正确答案。

错项排除：原文第三段第五句中虽然提到政府需要木材建造船只和房屋，但没有提到使用木材作为燃料，故B项错误。原文中没有提到宜人的气候或环保运动有利于森林的增长，故C、D两项排除。