succession of plants
31Fire ecology — The Old Fire burning in the San Bernardino Mountains (image taken from the International Space Station) Fire ecology is concerned with the processes linking the natural incidence of fire in an ecosystem and the ecological effects of this fire.… …
32United States — a republic in the N Western Hemisphere comprising 48 conterminous states, the District of Columbia, and Alaska in North America, and Hawaii in the N Pacific. 267,954,767; conterminous United States, 3,022,387 sq. mi. (7,827,982 sq. km); with… …
33Devonian Period — Interval of geologic time from 417 to 354 million years ago; it was the fourth period of the Paleozoic Era. During the Devonian, a giant continent was situated in the Southern Hemisphere (see Gondwana), and other landmasses were located in the… …
34Permian Period — Interval of geologic time, 290–248 million years ago. The last of the six periods of the Paleozoic Era, it follows the Carboniferous Period. During the Permian, the continents joined to form a single supercontinent, Pangea. Hot, dry conditions… …
35Europe, history of — Introduction history of European peoples and cultures from prehistoric times to the present. Europe is a more ambiguous term than most geographic expressions. Its etymology is doubtful, as is the physical extent of the area it designates.… …
36evolution — evolutional, adj. evolutionally, adv. /ev euh looh sheuhn/ or, esp. Brit., /ee veuh /, n. 1. any process of formation or growth; development: the evolution of a language; the evolution of the airplane. 2. a product of such development; something… …
37cañada — /keuhn yah deuh, yad euh/, n. Chiefly Western U.S. 1. a dry riverbed. 2. a small, deep canyon. [1840 50; < Sp, equiv. to cañ(a) CANE + ada n. suffix] * * * Canada Introduction Canada Background: A land of vast distances and rich natural resources …
38Canada — /kan euh deuh/, n. a nation in N North America: a member of the Commonwealth of Nations. 29,123,194; 3,690,410 sq. mi. (9,558,160 sq. km). Cap.: Ottawa. * * * Canada Introduction Canada Background: A land of vast distances and rich natural… …
39Mexico — /mek si koh /, n. 1. a republic in S North America. 97,563,374; 761,530 sq. mi. (1,972,363 sq. km). Cap.: Mexico City. 2. a state in central Mexico. 6,245,000; 8268 sq. mi. (21,415 sq. km). Cap.: Toluca. 3. Gulf of, Mexican, Golfo de México /gawl …
40Stone Age — the period in the history of humankind, preceding the Bronze Age and the Iron Age, and marked by the use of stone implements and weapons: subdivided into the Paleolithic, Mesolithic, and Neolithic periods. [1860 65] * * * First known period of… …
