In Inquiry 1, you learned about the types of forests found across the planet. You also learned how much of Earth’s land area is covered in forests, and where forest area is growing and shrinking. You also learned about primary forests.

Primary forests are those with native tree species and little evidence of human activities. Primary forests are usually rich in biodiversity (Figure 1). Biodiversity is the variety of life and life processes. When a natural ecosystem is diverse, it has a variety of living organisms.

FAO wanted to know how much biodiversity the world’s forests contained in 2010. This can be complicated, because there are many ways to measure biodiversity. Biodiversity can be measured within an ecosystem, a plant or animal community, a species, a population, among individuals, and among genes. FAO decided to collect three pieces of information as an indication of a country’s forest biodiversity.

These 3 pieces of information included:

1. The number of hectares in primary forests.
2. The number of hectares of forests set aside to conserve the forest’s biodiversity.
3. The number of hectares of forests in protected areas. Protected areas are areas set aside by law to conserve biodiversity and other natural and cultural resources.

FAO and the National Correspondents also planned to identify the number of hectares of forests affected by natural or human-caused disturbances.

Worldwide, more than one-third of the world’s forests are primary forests (Figures 2 and 3). This includes tropical rain forests, which are Earth’s most diverse forests. FAO found that the percentage of primary forests has decreased yearly by 0.4 percent since 2000. This is about 40 million hectares, or the size of 12 football fields lost every minute. The decline was caused mostly by logging and other human disturbances. This does not mean that the forests had disappeared, however. It could mean that the primary forest had been modified by human activity so that it could no longer be classified as primary forest.

Almost twelve percent of the world’s forests are set aside for the conservation of biodiversity (Figures 4 and 5 and Table 1). The area of these forests increased by 63 million hectares between 2000 and 2010.

Worldwide, 13 percent of the world’s forests are located within protected areas (Figure 6). Since 1990, 94 million hectares of protected areas have been added globally. Two-thirds of these protected areas were added since 2000.

FAO found that over the past 20 years, more of the world’s forests are being set aside to conserve biodiversity. On the other hand, it found that the area of primary forests worldwide has declined over this same period.

Biodiversity can be threatened by invasive insects and some kinds of forest fires. Nearly 35 million hectares of forest land were damaged by insects worldwide (Figure 7). In particular, the mountain pine beetle attacked over 11 million hectares of forest in Canada and the western United States (Figure 8).

Largely because of the increase in worldwide trade, insects are moving from country to country.

The changing global climate has also made many areas more favorable for insects. This has caused an increase in damage from insects worldwide. Unfortunately, many countries did not collect information about damage from insects.

One percent of all forests were affected by forest fires in 2010 (Figures 9 and 10).

This estimate may be low, however, as only 78 out of 233 countries reported information about forest fires. Events such as fire, drought, wind, snow, ice, and floods are usually considered natural disturbances. As the global climate changes, the number and strength of these disturbances have been increasing. This has resulted in a greater threat to forest biodiversity in these areas.