1. Chapter 4 Terrestrial Biomes & Aquatic Ecosystems

2. Terrestrial biomes Named for predominant vegetation Also have characteristic animals

3. Boundaries? No sharp boundaries between biomes Intergrades

4. Importance of climate Prevailing climate is most important factor in determining what kind of biome will develop Precipitation, temperature are most important

5. Desert biomes <10 inches (<25.4 cm) of rain per year Cool Temperate Tropical

6. Grassland biomes 10-30 inches (25.4-76.2 cm) of rain per year Tundra Temperate grassland Tropical savanna

7. Forest biomes >30 inches (>76.2 cm) of rain per year Taiga or coniferous forest Temperature deciduous forest Tropical rain forest

8. Aquatic ecosystems Initial categories based on salinity Freshwater Marine Estuary

9. Freshwater - nonmoving Standing waters Lakes Ponds Significant stratification in community structure Light Temperature

10. Freshwater - moving Moving waters Rivers Streams Communities change from headwaters (source) to mouth as environment changes

11. Headwaters vs. mouth Headwaters Cool High current velocities Few nutrients Mouth Warmer Slower More turbid More nutrients

12. Marine Vertical and horizontal changes Light Temperature Nearshore Open ocean

13. Estuary Freshwater rivers merge with oceans Mixing zone Very high productivity Threatened by pollution

14. Climatograph

15. Climograph Temperature, precipitation not sole determiners Overlap among different biomes on plot suggests that other factors also are important Seasonality of precipitation Temperature fluctuations around mean Soil composition (based on geology)

16. Deserts Lands where evaporation exceeds rainfall High evaporation rate 7-50X precipitation

17. Deserts Occur in 2 distinct belts between 15-35° N & S latitude Result primarily from worldwide circulation of air masses (dry over deserts) ~25% of world’s land mass

19. True deserts <10 inches of rain per year Semi-deserts may have 2-3X that, but have high evaporation rates Low humidity results in very hot days, but cool or cold nights Life is keyed to rainfall events Infrequent, but usually heavy when they occur

20. Desert life Plants, animals are either drought evaders or drought resistors

21. Evaders Plants survive dry periods as seeds, but germinate, grow, and reproduce after rainfall Animals may hibernate (cold) or estivate (hot) Dormancy during dry period E.g., spadefoot toad emerges to reproduce in pools formed after rain E.g., birds migrate in and out

22. Resistors - plants Plants develop deep roots to become independent of rainfall events (woody shrubs) or are succulents to store water in stems (cactus)

23. Resistors - animals Behavioral adaptations Come out only at night - spiders, scorpions, rodents, predators

24. Resistors - animals Physiological adaptations No need to drink Kangaroo rate with super kidneys gets all water from seeds

25. Grasslands Tropical savannas - grasslands with scattered individuals trees Central S. Amer., Central & S. Africa

26. Savannas 3 distinct seasons Cool-dry, hot-dry, warm-wet Frequent fires suppress trees, maintain grasses and forbs Herbaceous, low-growing annuals & perennials (dicots) Regrow from roots or seeds every year

27. Savannas Large herbivores (zebras, giraffes) and burrowing animals most common Most active during the rainy season

28. Temperate grasslands Similar to tropical savanna, but occur in cooler regions N. Amer. prairie (French for plains) Russian steppe Hungarian pusztas S. Amer. pampas African veldt

29. Temperate grasslands At one time covered 42% of world land surface Much under cultivation today Excellent soils Rich topsoil layer

30. Temperate grassland climate High rates of evaporation Periodic severe drought Rainfall ~25-75 cm/year Too light to support forest, but too heavy to encourage desert

31. Temperate grassland grasses Sod-forming Kentucky bluegrass Bunch grasses Big, little bluestem

32. Temperate grasslands Most require periodic fires for maintenance, renewal, elimination of incoming/invading woody growth Animal life dominated by grazing and burrowing species

33. Tundra Northernmost limits for plant growth, and at high altitudes Plants generally low-growing Mat or shrubby

34. Arctic tundra Encircles north pole Brief warm summers with nearly 24 hrs of sun/day Presence of permafrost Water-logged soils - low evaporation Shrubs, sedges grasses, mosses, lichens

35. Alpine tundra At high elevations at all latitudes Variable daylength, many of the same restrictions, plant species

36. Tundra animals Migratory, well-suited for cold climate Musk oxen, caribou, reindeer Lemmings, white fox, snowy owl

37. Tropical forests Equatorial, mean temp. ~25°C, 12 hrs sunlight per day Rainfall highly variable-determines type of tropical forest present

38. Types of tropical forests Thorn forests - furthest from equator, prolonged dry season

39. Tropical deciduous forest More rainfall nearer equator, distinct wet, dry seasons Lose leaves during dry seasons Types of tropical forests

40. Tropical rain forest >250 cm of rain per year Perpetual midsummer conditions Uninterrupted plant growth Types of tropical forests

41. Tropical rain forests Contain as many species of plants and animals as all other types of ecosystems combined 4 mi 2 area - 750 species of trees, 1500 species of flowering plants

42. Tropical rain forests Typically stratified into 5 layers Each layer has characteristic plants, animals May reach height of 80 m

43. Tropical rain forest soil Very poor - little or no topsoil Easily weathered Subsoil with iron-based clay - laterite Major problems with slash-and-burn agriculture

44. Tropical rain forests today Deforestation

45. Loss of forests at present rate will mean disappearance within next 15-25 years Major problems will result from climate change, loss of species of medicinal, economic importance

46. Temperate deciduous forest Eastern N. Amer, N. Europe and east Moderate temps., moderate moisture levels 5-6-month growing season

47. Temperate deciduous forest Dominated by broad-leaved deciduous trees Relatively nutrient-rich soil provides for good growth Typically have 4 layers present Ground, shrub, sapling, canopy Rich diversity of plant, animal life

48. Taiga Boreal forest, coniferous forest Harsh winters with lots of snow

49. Taiga Dominated by conifers - spruce, pine, fir, hemlock Best suited for short growing season because they are not deciduous Can carry out photosynthesis whenever temps. rise above freezing Needle shape, waxy cuticle conserve moisture

50. Thin, acidic, develop slowly Pine needles break down slowly in cool climate Taiga soils

51. Taiga animals Primarily seed, insect eaters, or those that feed on plants in or near water Squirrels, birds, elk, moose, deer, beaver, porcupine, grizzlies, wolves

52. Standing freshwaters Lakes and ponds

53. Standing freshwaters Significant stratification in community structure Light Photic zone Phytoplankton, zooplankton Aphotic zone Detritus, decomposers

54. Moving freshwaters Longitudinal zonation in physical, chemical characteristics Change in producers, benthic (bottom dwelling), fish assemblages

55. Marine 3/4 of world’s surface, major impact on climate, wind patterns, algae supply most of world’s oxygen

56. Marine

57. Photic, aphotic zones (vertical) Intertidal, neritic, oceanic zones (horiz.) Intertidal-wetted, dried from tides Neritic-shallow regions over continental shelves Oceanic-beyond shelves - deep zones Pelagic-open water Benthic-sea floor Abyssal zone-deep benthic - cold, high water pressure, no light

58. Deep sea fishes

59. Estuary Freshwater rivers merge with oceans

60. Estuary Not very diverse - few species tolerant of salinity Very productive - oysters, crabs, fish, waterfowl Most in danger from water pollution