For those living in Japan, it's easy to forget that forests are not a given.

Travel in any direction from one of its cities and you'll soon come to the ocean or to hills and mountains, most of which are cloaked in forests. In fact, 67 percent of Japan is forested, an unusually high percentage among the world's nations.

Off in the distance, beyond the urban sprawl, these hills offer a verdant reminder that nature is always within reach on this archipelago. Unfortunately, their proximity can be as much a bane as a boon to city dwellers, but more on that later.

Last year, 2010, was the United Nations Year of Biological Diversity, and since forests — including boreal, temperate and tropical — are home to as much as 90 percent of terrestrial biodiversity, it is fitting that they get special attention: 2011 has been declared the U.N. International Year of Forests.

When the resolution to designate 2011 as such was adopted by the U.N. General Assembly in December 2006, it was with the understanding that "concerted efforts should focus on raising awareness at all levels to strengthen the sustainable management, conservation and sustainable development of all types of forests for the benefit of current and future generations."

More to the point, our planet's forests are under siege. This column offers a brief look at some of the issues and challenges that make up the global forest debate.

First, there is no concise definition of a forest. The U.N. Food and Agriculture Organization (FAO), which has been documenting changes in forest cover for more than two decades, surveys nations to gather information on "forests" and "other wooded land," particularly three classes of forest: primary forests, naturally regenerated forests and planted forests. Also included in the counting are mangroves, bamboo and rubber plantations.

Today, forests cover approximately 31 percent of Earth's total land area and 6 percent of the planet as a whole. The world's forests total just over 4 billion hectares, which averages out to about 0.6 hectares per person, according to the FAO's Global Forest Resources Assessment 2010 (GFRA).

The assessment also states that half of the planet's forests are found in five nations — Russia, Brazil, Canada, the United States and China; 10 countries have no forests at all; and 54 countries, with a combined population of 2 billion people, have forests covering less than 10 percent of their land.

Even with all we know about the benefits of forests — from soil retention and as sources of medicinal resources to the sequestration of atmospheric carbon — deforestation remains an alarming threat, with the primary cause being conversion of tropical forest to agricultural land.

Over the past decade, the GFRA reports, "Globally, around 13 million hectares of forest per year were converted to other uses or lost through natural causes, compared with 16 million hectares per year in the 1990s. Both Brazil and Indonesia, which had the highest net loss of forest in the 1990s, have significantly reduced their rate of loss, while in Australia, severe drought and forest fires have exacerbated the loss of forest since 2000."

In some parts of the planet, though, large-scale planting of trees is significantly reducing the steady loss of forests. "Afforestation and natural expansion of forests in some countries and regions have reduced the net loss of forest area significantly at the global level. The net change in forest area in the period 2000-2010 is estimated at minus 5.2 million hectares per year (an area about the size of Costa Rica), down from minus 8.3 million hectares per year in the period 1990-2000," notes the FAO report.

Still, a loss is a loss, and we continue to lose millions of hectares of forests each year. F orests are unique and invaluable banks for biological diversity — plants, animals and ecosystems — as well as for the carbon they sequester.

This is why the debate over clearing, planting and preserving forests has been a particularly prickly topic during the negotiations for a follow-up agreement to the Kyoto Protocol to the U.N. Framework Convention on Climate Change that was initially adopted in 1997 and went into force in 2005.

According to the 2010 GFRA, forests contain more carbon than the entire atmosphere. "The world's forests store more than 650 billion tons of carbon, 44 percent in the biomass, 11 percent in dead wood and litter, and 45 percent in the soil," it states. "But for the world as a whole, carbon stocks in forest biomass decreased by an estimated 500,000,000 tons annually during the period 2005-2010," warns the FAO.

So who has the most green? Well, according to the GFRA: "At the country level, the Russian Federation alone accounts for 20 percent of the total forest area in the world. Seven countries have more than 100 million hectares of forest each, and the 10 most forest-rich countries (the Russian Federation, Brazil, Canada, the United States, China, the Democratic Republic of the Congo, Australia, Indonesia, Sudan and India) account for 67 percent of total forest area."

In China, where deforestation was blamed for deadly flooding that ravaged the country in the summer of 2010, afforestation is being pursued with a vengeance: Forested areas increased by 2 million hectares per year in the 1990s, and by about 3 million hectares per year over the past decade, contributing to an overall increase in forest cover in Asia over the past 10 years, the FAO reports.

Unfortunately, one form of "forest" that is increasing is industrial monoculture, for example palm-oil plantations in Indonesia and Malaysia, similar to the monoculture cedar forests in Japan that cause so much suffering — again, more on that soon.

For decades, these two southeast Asian nations have been clearing forests to plant palm trees. On the landing approach to Kuala Lumpur International Airport in Malaysia, all one sees in every direction is palm plantations. Lovely and green from the air, but nearly lifeless up close.

Growing global demand makes palm oil profitable, but at a steep price.

"This cheap oil carries hidden costs. For the most part, palm oil is sourced from industrial monoculture palm-oil plantations that are notorious for pesticide use and poor working conditions," reports "Against the Grain," an Internet publication.

"Plus," it continues, "new palm-oil plantations are generally grown in tropical forests. In Malaysia alone, palm-oil plantations were responsible for 87 percent of the deforestation from 1985-2000. The conversion of forests to monoculture plantations leads to an irreplaceable loss of biodiversity and, in Malaysia, several species of mammals, reptiles and birds have been completely lost to palm-oil development."

Which brings us back to the price Japan pays for its own monoculture forests.

In Japan, where seasonal changes are enthusiastically marked each year with particular foods, distinct fashions, and ad campaigns for new seasonal beers, it is not unusual for foreigners to hear that the country is unique for its four seasons.

During my first few years in Japan, I would gently point out that nations throughout the northern and southern hemispheres share this characteristic. However, after a few more years and a bit more seasoning, I realized that, in fact, Japan has five seasons: summer, autumn, winter, spring and a rainy season that swathes much of Japan in musty dampness between June and July.

Now, after two decades living in the Tokyo area, I can say with conviction that Japan has six seasons, with the additional one straddling the end of winter and the beginning of spring.

This sixth season begins when the vast expanses of cedar trees across Japan begin to shed their pollen, blanketing urban areas in fine yellow dust that inflames the eyes and nasal passages of millions of residents who suffer cedar-pollen allergies.

According to a 2009 article in the medical journal Allergology International Vol. 58, No.3, between 10-20 percent of Japanese adults suffer from Japanese cedar pollinosis, the most common pollen allergy in the country.

From February into May, pollen swirls across Japan, finding its way into every nook and cranny of offices, homes — and people. Sufferers don masks, scarves, gloves and goggles; they get shots, take medicines, and use special air cleaners in their homes.

But to no avail. Almost 70 percent of Japan is forested, and 10-15 percent of this is monoculture Japanese cedar.

So don't envy Japan its forest cover, at least not until the cedars are thinned and healthy, diverse forests are cultivated in their stead. Et in Arcadia ego.

Stephen Hesse teaches in the Chuo University Law Faculty and is the director of the Chuo International Center. He can be contacted at [email protected].