introduction to geography people, places, and environment, 4e edward f. bergman william h. renwick
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Introduction to Geography People, Places, and Environment, 4e Edward F. Bergman William H. Renwick. Chapter 4: Biogeochemical Cycles and the Biosphere Victoria Alapo, Instructor Geog 1010. Biogeochemical Cycles. - PowerPoint PPT PresentationTRANSCRIPT
Introduction to GeographyPeople, Places, and Environment, 4eEdward F. BergmanWilliam H. Renwick
Chapter 4: Biogeochemical Cycles and the Biosphere
Victoria Alapo, Instructor
Geog 1010
Biogeochemical Cycles
Pathways by which energy & matter are transformed & recycled in Earth systems. See Fig. 4-1, pg 133 (next slide).
In the Atmosphere, hydrosphere, lithosphere e.g. water cycle.
Law of conservation of energy and matter – “matter cannot be destroyed or created under ordinary conditions, but it may be changed from one form to another”.
Two important biogeochemical cycles Hydrologic cycle Carbon cycle
Hydrologic Cycle
Flows (cycles) of water among land (lithosphere), sea (hydrosphere) and air (atmosphere). See next slide, but use the simpler version for exam.
Water changes between 3 states, but the amount remains constant. Gas Solid Liquid
All living things are primarily water
Water Storage and Sources on Earth
Water Budget An accounting of inflows and outflows of water
within a given system over some time period.
Evapotranspiration Sum of evaporation and transpiration Seasonal variation
Low in winter High in summer
Local water budgets Compares precipitation and evapotranspiration
Vegetation and Hydrologic Cycle
Trees and forests require large amounts of water. E.g. one tree in the Amazon can transpire an average of 1000 liters per day into the atmosphere!
Therefore, trees play key role in returning rainwater to the atmosphere So deforestation affects water balance of
regions. Ex. Amazon, and other parts of the world.
The Carbon Cycle
Processes that cycle carbon and oxygen between the environment and living things (next slide). Photosynthesis
Determined by climate/ more in summer Respiration
Opposite reaction of photosynthesis (Oxygen is used) Combustion
Coal, oil, natural gas Industrial Revolution
The lithosphere stores carbon (from 1000s of years e.g. coal).
Soil
Is a dynamic, porous layer of mineral and organic matter
Six principal components of soil Rocks and rock particles Humus Dissolved substances Organisms Water from rainfall Air
Soil Formation
Weathering The first step in soil formation Mechanical and chemical
Soil horizons (next slide) Layers of substances found in soils Formed through vertical movement of water,
minerals and organic matter
Soil Horizons
Types of Soils
Soil orders 11 orders (next slide)
47 suborders 230 great groups 1,200 subgroups 6,000 families Thousands of soil series There’s nothing simple about “ordinary dirt”!
USDA Natural Resource Conservation Service maps (soils maps used in Planning Commissions & by farmers).
Ecosystem
Includes all living organisms and the physical area in which they exist
Fundamental elements Producers Consumers Decomposers Material/energy needed for production
Food Chains
Food that plants produce are distributed via a food chain (distribution)
Trophic level – each step in the food chain.
Biomagnification – e.g. when persistent chemicals remain in animal tissues and magnifies as it goes up the food chain. As in the case of humans, lions, etc.
Food Chains
These 3 are all “consumers” (i.e. they’re just types of consumers):
Herbivores Carnivores Omnivores
What category does a “Venus fly trap” fall in???
Community Succession Sequence – how comm. succession happens Succession – each plant community is succeeded
by a new one until… Climax community – when the community or
environment becomes stable
Biomes Named for dominant vegetation/climate
Major Biomes
Forest Tropical & temperate rainforest (based on location). Boreal – needle leaf/coniferous evergreen found closer
to poles e.g. Alaska & Canada. Called Taiga in Russia. Savannah – Woodland & Scrubland
Location of the Serengeti National Park (“Safari”) found in Tanzania & Kenya – also a world heritage site.
Grassland – Prairies Desert Tundra
Human & Natural Effects on the Environment
Humans influence ecosystems 37% of land area = cropland or pasture
(see next slide) Desertification – when a previously non-
desert area becomes one over time. E.g. fringes of the Sahara, etc. See further slide. This could be due to misuse by humans or because of global warming.
Desertification Hazard
The most severe desertification hazards are in northern Africa, central Australia, and the southwestern parts of Africa, Asia, North America,
and South America (the fringes of the major deserts of the world).