1
	2
																							3
			4
																															5
							6
																													7
8																						9
10
																					11				12
							13		14
																		15
									16
					17							18
			19
																															20
		21																									22
																													23
		24
							25
																	26
27
									28
29

Across 1. Reduction of the net primary productivity of grassland vegetation and grass cover from absence of grazing for long periods. 2. Virgin and old, second-growth forests containing trees that are often hundreds, sometimes thousands of years old. 4. Deliberate alteration of a degraded habitat or ecosystem to restore as much of its ecological structure and function as possible. 6. Agreement in which a certain amount of foreign debt is canceled in exchange for local currency investments that will improve natural resource management or protect certain areas 9. Extremely hot forest fire that burns ground vegetation and treetops. Compare controlled burning, ground fire, surface fire. 10. Method of forest management in which trees, sometimes of a single species in a given stand, are maintained at about the same age and size and are harvested all at once. 16. Research and scientific study devoted to restoring, repairing, and reconstructing damaged ecosystems. 19. Method of timber harvesting in which all trees in a forested area are removed in a single cutting. 24. Value of an organism, species, ecosystem, or the earth's biodiversity based on its usefulness to us. 25. A variation of clear-cutting in which a strip of trees is clear-cut along the contour of the land, with the corridor narrow enough to allow natural regeneration within a few years. 26. Value of an organism, species, ecosystem, or the earth's biodiversity based on its existence, regardless of whether it has any usefulness to us. Compare instrumental value. 27. Fire that burns decayed leaves or peat deep below the ground surface. Compare crown fire, surface fire. 28. Site planted with one or only a few tree species in an even-aged stand. When the stand matures it is usually harvested by clear-cutting and then replanted. 29. Managed grassland or enclosed meadow that usually is planted with domesticated grasses or other forage to be grazed by livestock.

Down 1. Method of forest management in which trees of different species in a given stand are maintained at many ages and sizes to permit continuous natural regeneration. 3. Multidisciplinary science created to deal with the crisis of maintaining the genes, species, communities, and ecosystems that make up earth's biological diversity. 5. Slightly smaller plot of land to harvest trees than a tree plantation. 7. Area where the earth and its community of life have not been seriously disturbed by humans and where humans are only temporary visitors. 8. Stands of trees resulting from secondary ecological succession. Compare old-growth forest, tree farm. 11. Cutting of intermediate-aged, mature, or diseased trees in an uneven-aged forest stand, either singly or in small groups. 12. Renewal of trees and other types of vegetation on land where trees have been removed; can be done naturally by seeds from nearby trees or artificially by planting seeds or seedlings. 13. Destruction of vegetation when too many grazing animals feed too long and exceed the carrying capacity of a rangeland or pasture area. 14. Forest fire that burns only undergrowth and leaf litter on the forest floor. Compare crown fire, ground fire. 15. Deliberately set, carefully controlled surface fires that reduce flammable litter and decrease the chances of damaging crown fires. See ground fire, surface fire. 17. Removal of trees from a forested area without adequate replanting. 18. Value of an organism to the changing society of an ecosystem. 20. old-growth forest. 21. Thin strips and patches of vegetation that surround streams. They are very important habitats and resources for wildlife. 22. Value of an organism based on species and role in the environment. 23. Land that supplies forage or vegetation (grasses, grasslike plants, and shrubs) for grazing and browsing animals and is not intensively managed.