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agroforestry – Land-use systems that combine agriculture and forestry practices to create a more holistic, integrated, profitable and sustainable system of food and fiber production.

alpaca – (Lama pacos) A small-sized relative of the llama. Alpacas stand about 1.5 meters tall and weigh about 50 kilograms. The alpaca is found in the Andes Mountains of Chile, Peru and Bolivia. It has been domesticated for 5,000 years, mainly for its long, fine, silky wool.

Amazonia – The watershed of the Amazon River and its tributaries. Amazonia covers about 40 percent of South America (7,050,000 km²) – half rainforest and the rest savannah ("campo") or scrubby woodland ("cerrado"). Amazonia covers substantial parts of Bolivia, Peru, Guyana, Suriname, Colombia, Ecuador and Venezuela, though most of the Amazon basin lies within Brazil. It is the largest tract of undeveloped forest and greatest single concentration of biodiversity in the world.

amphibians – A class of animals with backbones (vertebrates) that includes frogs, salamanders and caecilians. Amphibians have moist skin and do not have scales, feathers, or hair. Amphibians can live in water or on land. Most lay eggs in water and their larvae go through a complex metamorphosis process as they grow to adulthood and move to land. It is thought that amphibians were the first animals to venture out from the water and adapt to life on land.

anoas – Two species of small (150-300 kilograms), endangered relatives of the buffalo found only on the Indonesian island of Sulawesi: the lowland anoa (Bubalus depressicornis) and the mountain anoa (Bubalus quarlesi). They are unusual among buffalo because they rely on undisturbed forest. Anoas live alone or in pairs rather than in herds, except when the cows are about to give birth.

apalis – (Family: Sylviidae) Small (about 10 centimeters) warbler songbirds found in Southern Africa. Apalis eat fruit and insects. Many species are restricted to open grassland and scrub habitat.

aquaculture – The farming of freshwater and marine organisms including fish (such as salmon or tilapia), shrimp, oysters, mussels (and other mollusks), crustaceans, crocodiles, alligators, amphibians and plants. Land-based systems include fish raised in flooded rice fields; aquatic-based systems generally use floating pens to rear juveniles under captive conditions. Concerns with aquaculture include the escape of invasive species, which may spread disease, and pollution from high concentrations of organisms in "fish farms."

araucaria – Tall (up to 40 meters) evergreen trees, such as the monkey-puzzle tree of Chile or the Norfolk Island pine, native to Oceania and South America.

armadillo – Cat-sized, armored mammals, found in warm, dry areas of South America. They are related to sloths and anteaters. They dig burrows and dig for insects, although they occasionally eat plants, berries or bird eggs, or scavenge dead animals. Females give birth to identical quadruplets. Unlike other mammals, young develop from the same egg and a single placenta.

atoll – A nearly circular island initially formed by a volcano, which eroded leaving a coral island consisting of a reef surrounding a lagoon.