Integrated Science Ch. 3 Communities, Biomes, and Ecosystems I. Limiting Factors - factors that affect an organism's ability to survive in its environment - temperature, rainfall, fire, food, predators, etc. A. Optimum Range: - area with least limiting factors B. Zone of Physiological Stress: - area with a few limiting factors C. Zone of Intolerance: - area where limiting factor is outside the range of tolerance Optimum Range Optimum Range Range of Tolerance Distribution of Douglas-fir * Microclimate II. Ecological Succession Mount St. Helens explosion, 1980 Same view, 20 years later II. Ecological Succession - the replacement of one community by another over time following disturbance - one community changes the physical environment so that it can't survive but another community can A. Primary Succession: - succession on land that has not been previously occupied - ex. lava, ash, bare rock - Pioneer species: mosses, lichen (build soil) Primary Succession Succession in a Pond (c) (a) (b) B. Secondary Succession - reestablishment of an ecosystem following disturbance (soil present) - ex. forest fire, clearcutting, flood, abandoned fields, hurricanes, mudslides Secondary Succession C. Climax Ecosystem - a mature community (until next disturbance) C. Climax Ecosystem - a mature community (until next disturbance) - occurs at the end of succession - can regenerate itself (plants can tolerate shade) III. Biomes: - large group of ecosystems with a similar climate and dominant plant life A. Terrestrial Biomes - most important limiting factors are temperature and precipitation Terrestrial Biomes High (Temperature) Low Climate Affects Biome Distribution Dry (Rainfall) Wet 1. Tundra Tundra Treeless region < 10 in. rain annually Permanently frozen soil (permafrost) Very fragile, scars last for centuries 2. Boreal Forest (Taiga) Boreal Forest (Taiga or Northern Coniferous Forest) Northern Canada and Eurasia Winters long & cold Evergreen coniferous trees with needlelike leaves Plant & animal diversity low 3. Temperate Deciduous Forests Temperate Deciduous Forest 30-60 in. rain annually, most during summer Mostly deciduous trees, bare in winter Leaf litter on soil High diversity of animals 4. Chaparral Chaparral Often in coastal regions bordering deserts Up to 30 in. rain annually, but all during cool months Summers hot & dry Small trees & large bushes (Temperate Rain Forest) Temperate Rain Forest Abundant rain Soil seldom freezes Usually coastal 5. Grasslands Grassland 10-30 in. rain/year Usually in centers of continents Shortgrass Prairie No trees except by rivers Periodic droughts Frequent fires Most fertile soil in world Overgrazing problems Sagebrush Desert or Shortgrass Prairie 6. Deserts Desert Usually found between 20-30° N & S latitude Less than 10 in. rain/yr. Boom & bust population growth after rain Very fragile ecology Sonoran Desert Arizona Flowers indicate recent rain Saguaro cactus unique to this desert 7. Savanna Savanna Grasses dominate; scattered trees Short rainy season <12 in. (30 cm)/year Long, severe droughts African savanna with many large animals Many species in danger of extinction 8. Tropical Seasonal Forest Tropical Seasonal Forest 9. Tropical Rain Forest Tropical Rain Forest Temp 77-86 °F Rainfall 100-160 in Biodiversity: 50-67% of all Earth’s species 6% of land area 40% now gone - Losing 70 acres/min > 2500 species go extinct annually Dominated by large, broadleaf, evergreen, complex forests B. Aquatic Ecosystems - major limiting abiotic factors: distance from shore (nutrients), salinity, depth (light), latitude 1. Freshwater Ecosystems: - rivers, lakes, ponds, groundwater - < 1% of earth's water 2. Transitional Aquatic Ecosystems a.Wetlands - marshes, swamps, bogs Marsh 2. Transitional Aquatic Ecosystems a.Wetlands - marshes, swamps, bogs Swamp 2. Transitional Aquatic Ecosystems a.Wetlands - marshes, swamps, bogs Bog 2. Transitional Aquatic Ecosystems b.Estuaries: - boundary between fresh and salt water 2. Transitional Aquatic Ecosystems b.Estuaries: - boundary between fresh and salt water - highly productive habitat for many animals - abundant nutrients and light - "nursery" for many animals 3. Marine Ecosystems: - vast and varied habitats - light penetrates only 100 - 600 feet (photic zone) Intertidal Zone Neritic Zone Open Ocean Photic Zone Zone Aphotic Zone Abyssal Zone Marine Ecosystems a. Intertidal Zone: - harsh environment: tides, waves, exposure to air b. Open-Ocean Zone: - low nutrients and fewer living organisms c. Neritic Zone: - between low tide and open-sea - abundant nutrients - most productive marine environment Coral Reef Kelp Forest 1) Photic Zone: - light penetrates up to 200m 2) Aphotic Zone: - no light 3) Benthic Zone - along the ocean floor 4) Abyssal Zone: - extremely harsh environment - cold, dark, high pressure ‘Black Smoker’ 4) Abyssal Zone: - habitat for bizarre fish and other animals Fangtooth Umbrellamouth Gulper Deep-sea Anglerfish Ecosystem Productivity Compared (Grams of biomass/meter2/year) Tundra (140) Tropical Rainforest (2200) Open OceanNeritic (125) (360) Estuary (1500) Boreal Forest (800) Temperate Deciduous Forest (1200) Grassland (600) Desert (90) Projected Effect of Climate Change on Forest Types The End