Biogeography 2

Soil Organic Carbon
Carbon part of the soil’s organic matter which also includes Ca, N, and other important elements
Soil’s organic matter provides nutrients, binds particles together, and enhances water retention
Residence Time
Describes the average time a molecule will spend in a specific reservoir within a biogeochemical cycle
Carbon in the atmosphere
Carbon dioxide (five years) and methane (ten years)
Methane is released by wetlands, cows, and termites
Carbon in the ocean
Dissolved inorganic carbon used by phytoplankton
Huge carbon sink
Photosynthesis provides 1/2 world’s oxygen
Carbon in the lithosphere
Lithosphere has a residence time of millions of years
Stored in limestone and kerogens (fossilized organic material)
Nitrogen fixation
Describes the natural and synthetic processes that convert nitrogen in the atmosphere into ammonia
Lightning and Legumes
Law of the Minimum
Growth is controlled by the scarcest resource (limiting factor) not the total amount of resources available
Nitrogen in Fertilizer
Created green revolution, synthetic nitrogen supports 1/3 population
Harmful Effects of Nitrogen
Transported down rivers to common location, causes algal blooms
Hypoxia and Dead Zone
Hypoxia is low oxygen conditions, dead zone is hypoxic area that can’t support life
Phosphorous in lithosphere
Phosphorite is main source, produces phosphate
Recycling of Phosphorous
P used 46 times terrestrially, and 800 times by marine life, then sinks to bottom and rejoins lithosphere
Crushed rocks combined with sulphuric acid to produce phosphoric acid
Human production of P
Doubles P production
Devil’s Element
Creates an explosive, superphosphorus creates radioactive waste (phosphogympsum)
Wicked Problem
Difficult problem to solve because of contradictory goals
Groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups
o “…actually or potentially interbreeding…” means that the offspring of the species need to be able to produce their own offspring
o “…reproductively isolated…” means that even if interbreeding produces fertile offspring, if they live in separate habitats they’re separate species (lions, tigers, and ligers)
o Range or Distribution of species refers to the geographical area where that species can be found
Domesticated animals have had their behavior, life cycle, or physiology altered by being under human control for many generations
Happens through selective breeding
Silver Foxes
Soviet scientists picked friendliest foxes to breed (about 1% were picked to breed)
After about 50 generations foxes were very dog-like (friendly, floppy ears, shorter legs and tail, spotted coats, and barking)
Geographical area where that species can be found
Population/Population Density
Population: All the organisms of the same species who live in the same geographical area
Pop. Density: Number of individuals within a certain area
Environmental Tolerance Diagram
Population density v some limiting factor
Zone of Optimum: Region in the center
Zone of Stress: Towards the sides
Zone of Intolerance: Species can’t live in this environment
Generalist v Specialist
Generalist can live in a variety of environments (wide population distribution)
Specialist can live in a limited range of environments (narrow population distribution)
Fundamental v Realized Niche
Fundamental: Complete range of environments without competition or predation
Realized: Accounts for predation and competition (smaller than fundamental)
A role or function a species inhabits in an ecosystem
Organisms eat a restricted variety of food
Focus on the best food and have limited competition, but may have difficulty finding food
Organisms consume several different organisms
Usually large animals
Not tied to one location, but food might not be nutritious
Population dynamics
Changes in the size and age composition of populations and the biological and environmental processes that influence that change (Wolf Moose graph)
Self Regulating System (Predator/Prey)
A system that regulates itself, because a change in one thing will trigger a change in another thing to maintain balance (Predator-Prey graph)
Negative Feedback
When the output of a system acts to oppose the changes to the input of the system
The initial change is counter-acted by the response
A biological interaction where a predator (an organism that is hunting) feeds on its prey (the organism that is attacked).
Apex Predator
Have no predators of their own
Keystone Species
Has a disproportionately large effect on its environment relative to its abundance
A temporary event that causes a major chance in the structure of an ecosystem
Primarily affects plants
The process where one group of plants and animals is replaced by another
Primary Succession
Describes the growth of plants at a location that has never been previously colonized
Pioneer Species characteristics
High growth rates, small, high dispersal, rapid population growth
Secondary Succession
Occurs after plant life on a colonized surface is affected by a disturbance
Interference Competition
When one species interferes directly with others attempting to forage, reproduce or establish themselves within a habitat
Agriculture vs Succession
Agriculture attempts to prevent succession in fields
Three Proposition About Competition
1. Every organism on the planet needs resources to grow, reproduce and survive
2. Resources are limited
3. Organisms can’t acquire a resource if another organism consumes or successfully defends that resource
Ecological Competition
Negative interaction that occurs whenever the fitness of one organism is reduced because of the presence of another
Intraspecific Competition (Interference and Exploitation)
Competition between members of the same species (Interference=Direct=Stealing/Killing, Exploitation=Indirect=Getting rare resources first)
Interspecific Competition (Interference and Exploitation)
Competition between different species (Interference=Direct=Stealing/Killing, Exploitation=Indirect=Getting rare resources first)
Territorial Organisms
Defend an area against members of their own species (exploitation competition)
Population density curves and competition
Density curves can’t overlap, so curves shift to accommodate competition, or one species dies out.
Five Major Domesticated Species
Pigs, Cows, Horses, Sheep, Goats
Descended from aurochs (big scary cows with sharp horns)
Domesticated by humans
Production of 1. Wheat 2. Rice 3. Corn
1. China, India, US
2. Asia (China and Indonesia)
3. US (IOWA!)
4 Main Problems with Agriculture
1. Land intensive (takes up space and clear cutting)
2. Emits greenhouse gas (largest source of greenhouse gas)
3. Water intensive (drains aquifers)
4. Pollutes water(fertilizer leads to excess nutrients)
Two Solutions
1. Shift away from meat (will slow deforestation and won’t reduce food supply)
2. Stop expanding agriculture’s footprint
Three Major Crops
Wheat, Rice, and Maize (Corn)
All domesticated from other plants to be better (larger, tastier, more nutritious)
Excess biomass
Soil Seed Bank
The soil of most ecosystems contains large numbers of seeds that are usually dormant
Substance rich in nitrogen and phosphorous
Phosphorous deficient
Abnormal dark green leaves
Nitrogen deficient
Smaller plants
Nitrogen burn
Too much nitrogen, interferes with water retention in plants
Algal Bloom
Rapid increase in algae population
Artificial N fixation
Uses Fe as a catalyst to combine nitrogen with 3 hydrogens
Black Carbon
Small dark particles formed by the incomplete combustion of organic matter