HU-205: Geography. Geography 04: Biogeochemical Cycles & Biosphere. Biomes. Global patterns in the biosphere

Transcription

1 HU-205: Geography Geography 04: Biogeochemical Cycles & Biosphere Biomes Global patterns in the biosphere Plant and animal types Similar distributions Soil Vegetation Climate Human impacts Population growth Consumption of natural resources 1

2 Biogeochemical Cycles Recycling processes that supply essential substances to the biosphere Connect Earth s subsystems Atmosphere, hydrosphere, lithosphere Law of conservation of energy and matter Both Energy and Matter are conserved in a closed system This means neither energy or matter can be created or destroyed only changed into other states. Two important biogeochemical cycles Hydrologic Cycle (water) Carbon Cycle (C and CO 2 ) 2

3 Hydrologic Cycle Flows of water among land, sea and air All living things are primarily water 3 states of water Gas Liquid Solid Changes of state Upward Changes Thawing: Solid Liquid Evaporation: Liquid Gas Downward Changes Condensation: Gas Liquid Freezing: Liquid Solid 3

4 Water: Where is it? 96.5% stored in oceans 2% stored in glacial ice 0.9% is saline groundwater 0.8% available as fresh water 0.014% in rivers and lakes 0.001% is contained in the atmosphere Water Budget Accounting of inflows and outflow within a given system Evapotranspiration Sum of evaporation and transpiration Evaporation: Change in state from liquid to gas Transpiration: Loss of water vapor from plants Seasonal variation Low in winter High in summer Local water budgets Compares water in vs. water out (precipitation vs. evapotranspiration) 4

5 Soil and the Water Budget Critical to water budget Stores water for evapotranspiration (ET) Soil texture Affects how much water soil can hold Infiltration capacity Good Poor Vegetation and Hydrologic Cycle Trees and forests require large amounts of water Trees play key role in returning rainwater to the atmosphere Deforestation affects water balance of regions Ex. Amazon Grasses Shallow roots Variable transpiration rates 5

6 The Carbon Cycle Processes that cycle Carbon (CO 2 ) and Oxygen (O 2 ) between plants and animals Photosynthesis In: Sunlight, water, CO 2, O 2, soil nutrients Out: Water, O 2 Extent determined by climate, seasonal cycles of solar radiation Respiration In: O 2, water, food Out: Water, CO 2 Opposite reaction of photosynthesis Combustion Fossil fuels: Coal, oil, natural gas Industrial Revolution begins extraction and combustion Lithosphere stored carbon Atmosphere (GHG s) 6

7 Deforestation Important influence on biosphere-atmosphere exchanges Biomass Stores carbon Forests and trees are key storage sites Deforestation through cutting and burning releases carbon into atmosphere Critical regions Central and South America West Africa Southeast Asia 7

8 Ecosystem Includes all living organisms and the physical area in which they exist Fundamental elements Producers Plants Consumers Herbivores, Carnivores, Omnivores Decomposers Bacteria, Fungi Material/energy needed for production 8

9 Food Chains Distribution Herbivores Carnivores Omnivores Trophic level Biomagnification Concentrating toxins up chain Community Succession Sequence Succession Climax community 9

10 Biodiversity Diversity of species How many different species? Stability of community How does the community interact? Coexist? Importance of size Benefits and detriments of community size Managed landscapes Introduction of artificial (human) controls Biomes Ecosystems grouped by: Plant types Animal types Named for dominant vegetation/climate Typically contain many ecosystems 10

11 Major Biomes Forest Tropical rainforest Temperate rainforest Boreal Savannah Woodland Scrubland Grassland Desert Tundra 11

12 Human and Natural Effects Humans influence ecosystems 37% of land area = cropland or pasture Desertification Local topography and geology Vegetation and evapotranspiration vary regionally Wind erosion 12

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