Final Unit 3

Unit 3

• Ecosystem: A biological community of interacting organisms and their physical environment

• Energy: The qualitative property that must be transferred to an object to perform work on, or heat the object.

  • It flows through ecosystems (transforms)

  • Energy is finite; it moves and flows.

• Photosynthesis: the process of using light energy to convert carbon dioxide (inorganic carbon) to carbohydrates (organic carbon)

  • Plants and algae

  • Light to food conversion

• Cellular respiration: the process of breaking down the chemical bonds in food molecules (organic carbon) to harvest energy and release carbon dioxide (inorganic carbon)

• Food chain: a hierarchical series of organisms, each dependent on the lower level as a source of food

  • Primary producers/1st trophic level 

    • Transform energy from the sun 

  • Primary consumers/2nd trophic level 

    •  Herbivores

  • Secondary consumers/3rd trophic level 

    •  Predators (carnivores) 

  • Tertiary consumers/4th trophic level 

    • Predators (carnivores)

  • Decomposers  Feed on nonliving organic matter 

    • Feces/dead organisms

• Food web: the natural interconnection of food chains and a graphical representation of what eats what in an ecological community

• Keystone species: Named after the wedge-shaped keystone that holds arched structures together 

  • Removal causes collapse

• Matter: any substance that has mass and takes up space by having volume. 

  • Important elements to live include hydrogen, oxygen, carbon, phosphorus, nitrogen, and sulfur

  • Matter gets reused (cycles)

Carbon Cycle

• The planet-wide flux of carbon driven by life •

  •  Respiration: returns to the atmosphere 

  •  Photosynthesis pulls from the atmosphere

    • Net ecosystem production (NEP) • NPP – respiration of all nonphotosynthetic organisms = NEP Net flux of carbon into an ecosystem

    • Net primary production (NPP): Remaining organic carbon available to consumers after the plants and algae have fed themselves (through cellular respiration) 

    • Gross primary production (GPP)

Total carbon dioxide converted to total organic carbon

• Biogeochemical cycles: the ways in which chemical elements or compounds move between the biotic and abiotic components of an ecosystem

Nitrogen Cycle 

• Nitrogen fixation • N2 gas into ammonia (NH3 ) • Bacteria and lightning

• Nitrification • NH3 into nitrite (NO2-) then into nitrate (NO3-) • Bacteria

• Denitrification • Returns to the atmosphere • Bacteria

Phospours Cycle

• Dissolves in soil and water • From minerals and decomposing organic matter • Plants absorb from soil and water • Animals obtain through food • Eventually carried to ocean and sinks to bottom • Becomes sedimentary rock

• Humans have altered the phosphorus cycle 

  •  Mining 

  • Guano harvest 

  •  Manure spreading

• Biome: a large naturally occurring biological community of flora and fauna occupying a major habitat, e.g., forest or tundra

• Convergent evolution: the process where unrelated species independently evolve similar traits or features, often due to adapting to similar environments or ecological niches

• Terrestrial Biomes • Communities of similar organisms in a particular climate • Determined by atmosphere and climate • Temperature and precipitation are the most important variable

• Tropical zone • Average monthly temperatures normally above 20° C (68° F) except in the high mountains • On the equator, there is 12 hours of daylight and 12 hours of darkness • Pronounced lack of seasons (spring, summer, winter, fall

• Tropical rain forest • Annual rainfall greater than 2,000 mm (80 in) • Plentiful rainfall, warm climate • Enormous plant and animal diversity • Net primary production (NPP) greater than any other terrestrial biome

• Endemic species: those species that are found only in specific environments and specific geographic areas and do not occur naturally anywhere else in the world

• Tropical savanna • Occurs where rainfall is highly seasonal • Drought persists more than half the year • Dominated by grasses • Not enough precipitation for large amounts of trees • Fires are too frequent for large amount of trees • Supports massive herds of grazing animals • Climate overlaps with seasonal tropical forest

• Tropical seasonal forest • Annual rainfall 1,500–2,500 mm (60–98 in) • Wet and dry seasons

• Temperate zone • Over 60% of Earth’s land mass in temperate zone • Annual precipitation ranges from 200 to over 2,000 mm • Average monthly temperatures range 5–20° C (31–68° F) • Dominated by deciduous forest • Growing seasons range 4–10 months

• Temperate evergreen forest • Dominant trees keep leaves • Evergreen conifers • Generally less precipitation and warmer winters than temperate deciduous forest • Summer drier than winter • Mild temperatures year round

• Temperate deciduous forest • Dominated by broadleaf trees that shed leaves (why?) • Moderate summers and cold winters • Growing seasons last between last and first hard frosts • Little remains undisturbed

• Chaparral • Dominated by summer drought • Evergreen shrubland and low woodlands • "Mediterranean" climate • Shrubs are sclerophyllous: “stony leafed" and have adaptations to resist water loss and wilting • Frequent fires, intense, fire adapted, smaller animals

• Temperate grasslands • 90% have been altered by agriculture and cattle grazing • Too dry for forests • Wet enough to not form deserts • Winters long and cold • Summers hot

• Polar biomes • Average monthly temperatures are very cold, less than 5° C (41° F) • Short growing seasons • Limited abundance and diversity of life

• Boreal forest • Cold and wet (wet during summers) • Growing season less than 4 months • Winters long, dry, and bitterly cold • Forests dominated by conifers • Permafrost

• Deserts • Occur worldwide • Extremely arid • Typically below 250 mm annual rainfall • Wide variation in daily temperature • May be cold or hot • Plants adapted for little water

• Tundra • Treeless landscapes • Dry, only 100–500 mm annual precipitation • Permafrost • Growing season shorter than 3 months • Winters are most harsh

• Biodiversity: the variety of life in all its forms and combinations at all levels of organization

• Landscape biodiversity: variety and abundance of species from place to place

• Endemic species: those species that are found only in specific environments and specific geographic areas and do not occur naturally anywhere else in the world

• Community biodiversity: number of species, their relative abundance, and arrangement in space

• Species richness: total number of species in an area 

•  Species evenness: relative abundance of the species in a community • 

• Relative abundance: the percentage of an organism in an area compared to the total number of organisms in that area

• genetic diversity: the genetic variation among individuals • Genetic variation allows natural selection to act 

•  Outbreeding: mating with nonrelated individuals • Maximizes diversity and allows for adaptation •

• Inbreeding: mating between closely related individuals

• Habitat and structural complexity: three- dimensional distribution of species and environmental features

• Existence value is a type of non-use value, meaning the benefit derived from the existence of a resource or species, rather than from its direct use or consumption

• As biodiversity increases, there is a higher likelihood that the ecosystem will include a species that has a large effect 

  •  Sampling effect 

• As biodiversity increases, different species will utilize and partition resources in a fuller and more efficient way than fewer species. 

  • Complementary effect

• Ecosystem functions and services • Previously discussed in Unit 1 • Biodiversity enhances primary production, nutrient uptake, nutrient recycling, and water use •

• Existence value • Intrinsic value and right to exist 

•  Ecosystem stability • Biodiversity buffers the effects of environmental change 

•  Economic value • Revenue generated from ecotourism (recall examples from Unit 1) and provides many commodities

• The Rivet Hypothesis: an ecological hypothesis that compares the effect of species loss on an ecosystem to the loss of rivets on an airplane wing

• Biodiversity hotspots: areas with unusually high numbers of endemic species associated with human threats that has reduced the amount of available habita

• Disturbance: an event or force, of nonbiological or biological origin, that brings about mortality to organisms and changes in their spatial patterning in the ecosystems they inhabi

• Species interactions • Predation limits the likelihood of a few dominant species reducing biodiversity

• Habitat loss: the process that renders natural habitats functionally incapable of supporting the species present

• Habitat fragmentation: the process of large areas of habitat being divided into smaller, isolated, and disconnected pieces

• Overharvesting: the act of harvesting a resource at a rate that is unsustainable, which can lead to the destruction of that resource

• Non-native invasive species: an introduced (non-native) species that causes harm to the environment

• Pollution: the introduction of harmful substances or energy into the environment at a rate that is faster than it can be diluted, decomposed, or stored

• Underbrush fuel accumulation, or the buildup of hazardous fuels like grasses, brush, shrubs, dead leaves, and dead logs, increases the risk of wildfires and can lead to more intense and difficult-to-manage fires 

  • Surface fuel and ladder fuel

• Fire suppression paradox: despite intended efforts to prevent wildfires, the long-term practice of fire suppression can actually lead to increased wildfire risk and severity due to fuel buildup, potentially resulting in larger, more destructive fires

• Increased fire risk: a greater amount of dry vegetation means more fuel for a fire to burn, increasing the potential for wildfires to start and spread rapidly 

• Larger and more intense fires: when a fire does ignite in an area with a high fuel load, it can burn with greater intensity and spread more quickly, making it harder to control and potentially leading to catastrophic damage 

• Damage to ecosystems: the natural role of fire in some ecosystems is to clear vegetation, promote biodiversity, and prevent the buildup of excessive fuel; suppressing fires can disrupt these natural processes, potentially harming ecosystems and leading to less resilient landscapes

• Climate change: long-term shifts in temperatures and weather patterns

• Migration and conservation corridors: connect several habitat fragments into a larger preserve

• Ecological buffers: a protected area that helps to protect sensitive areas from human activity and land disturbance

• Umbrella species • Species whose protection protects other species that require a similar habitat