Transcript Document
Chapter 5 Biomes & Biodiversity • • • • • Biomes Biodiversity How Do We Benefit from Biodiversity? What Threatens Biodiversity? Human-Caused Reductions in Biodiversity • Protecting Biodiversity Cunningham, Cunningham 2002 Part 1: Biomes Biomes • Broadly defined life zones • Environments with similar climates, topographies, soil conditions, and biological communities • Distribution mainly dependent on temperature and precipitation – only at broad scale used to determine distribution of biomes Biomes of the World – where humans mostly live? Less rain, Cold Does temperature or precipitation limit human habitation of an area? Lots rain, Hot Cunningham, Cunningham 2004 FAO 1999, WRI 1998-1999 Ice, rock, desert etc. = 32% Forests, woodlands = 33% Potential ~ 66% RESOURCE EXTRACTION; Humans use ~40% of all global net primary production GLOBE Pastures = 23% Ag = 10% Built land = 2% UNITED STATES Forests, woodlands = 28% Desert = ~ 14% Built land = 6% Ag = 28% Pasture, Rangeland = 31% NY Times Oct. 4, 2002, p. A19, E. Becker ~ 87% RESOURCE EXTRACTION Why is the tundra least dominated by humans (0.3%)? Why are the tropical forests only 25% dominated by humans? Why is 4/5 of the area of temperate broadleaved forests dominated by humans? Where do most humans live and survive the best? Deciduous forests Why Washington not dominated by deciduous forests? - NEEDS ENOUGH RAIN DURING GROWING SEASON since not grow during winter and WA have dry August Evergreen Forest Grow year round and in winter; grow in nutrient poor soils Lower human population levels – difficulty finding food (bark of tree not good, past considered desert for animals since few big game animals) Largest trees in world are evergreen, locations where sequester carbon in forests Mixed Forest Mixed DeciduousEvergreen Forests More people live in dry •Lots vines tropical forests than wet. Why? •Lots big trees •Multilayer habitat with different species •Lots of species Dry forests – •soils more nutrient rich •fewer insects, parasites and fungal diseases so healthier for humans •can use fire TROPICAL RAIN FORESTS •Plants adapted to get rid of water •Lots of species High protecting themselves species by forming chemicals diversity, at high levels & highly Large tree toxic (but value for biomasses pharmaceutical, Lotsdrugs) vines, epiphytes TEMPERATE RAINFOREST, WASHINGTON •large pieces of dead wood •lots habitat in dead wood •endemic species on wood •live > 1,000 yrs •resistant to disease •not fire susceptible when large •high carbon sequestration rates - important for mitigating rising CO2 levels •Thin needle like leaves, waxes, minimize moisture loss TEMPERATE CONIFEROUS FOREST (Old growth Douglas-fir) Alaska Arctic tundra •Small trees •Old trees but very small •Boggy environments •Animals hibernate or migrate Black spruce forest •High diversity in microbial community (not animals or plant levels) Photo: K Vogt Layers of Ice Photo: H Bormann TUNDRA Alaska - permafrost SAVANNA - Serengeti National Park Impalas in African savannas http://www.summitelgin.org/grassland_web/Tropical%20Grasslands/Animals.html Dry, thornshrubland, Africa West Africa Deserts. The Encroaching Wilderness. Ed. Allan and Warren. 1993 Oxford University Press