cut down and burned in order to clear land for temporary
agriculture; the land is used until its productivity declines at which
point a new plot is selected and the process repeats; this practice is
sustainable while population levels are low and time is permitted for
regrowth of natural vegetation; conversely, where these conditions do
not exist, the practice can have disastrous consequences for the
environment.

Soil degradation - damage to the land's productive capacity because of
poor agricultural practices such as the excessive use of pesticides or
fertilizers, soil compaction from heavy equipment, or erosion of
topsoil, eventually resulting in reduced ability to produce
agricultural products.

Soil erosion - the removal of soil by the action of water or wind,
compounded by poor agricultural practices, deforestation, overgrazing,
and desertification.

Ultraviolet (UV) radiation - a portion of the electromagnetic energy
emitted by the sun and naturally filtered in the upper atmosphere by
the ozone layer; UV radiation can be harmful to living organisms and
has been linked to increasing rates of skin cancer in humans.
Water-born diseases - those in which bacteria survive in, and are
transmitted through, water; always a serious threat in areas with an
untreated water supply.

Environment - international agreements: This entry separates country
participation in international environmental agreements into two levels
- party to and signed, but not ratified. Agreements are listed in
alphabetical order by the abbreviated form of the full name.

Environmental agreements: This information is presented in Appendix C:
Selected International Environmental Agreements, which includes the
name, abbreviation, date opened for signature, date entered into force,
objective, and parties by category.

Ethnic groups: This entry provides an ordered listing of ethnic groups
starting with the largest and normally includes the percent of total
population.

Exchange rates: This entry provides the official value of a country's
monetary unit at a given date or over a given period of time, as
expressed in units of local currency per US dollar and as determined by
international market forces or official fiat.

Executive branch: This entry includes several subfields. Chief of
state includes the name and title of the titular leader of the country
who represents the state at official and ceremonial functions but may
not be involved