It is easy to lose sight of the forest for the trees – to take for granted the myriad ways in which forests and trees are vital to the world’s health.

John Heilprin Rolf Amiet

Rolf Amiet, John Heilprin, Switzerland, swissinfo.ch

For this year’s celebration of world forests, the United Nations emphasizes that forests are key to supplies of fresh water, the basic building block of all life. Three-quarters of the world’s accessible fresh water comes from forested watersheds and wetlands.

A third of the world’s largest cities get a major part of their drinking water from protected forest areas. One of every five people on the planet depends on forests for their livelihood, according to the UN. Forests shelter 80% of the animals, plants and insects that live on land.

About a third of Switzerland – and a third of the Earth – is forested. The total area in Switzerland is increasing, particularly in the Alps. Each year, with a rising world population that is now up to 7.125 billion, the world loses 13 million hectares of forestland, which is converted to agriculture and other uses.

An area nearly equal in size to South Africa – 129 million hectares of forestland – was lost in the quarter century since 1990, the UN reported last year. The deforestation accounts for 12 to 20% of the global heat-trapping gases that contribute to climate change.

Forests now cover 30.6% of the world’s land areas, or 3.999 billion hectares, down from 31.6%, or 4.128 billion hectares, in 1990. More forest areas are gaining protection, however, as nations get better at forest management.

By Rolf Amiet, photo editor; John Heilprin, writer