BIOL 104K - Ecosystem Conservation & Human Society EXAM

Millennium Ecosystem Assessment (2005)

- What was it? A major international research initiative launched by the UN in 2001, with the final report published in 2005.

- Purpose: Over 1,300 of the world's leading biological scientists evaluated the state of the Earth's ecosystems and provided summaries and guidelines for decision-makers.

- Conceptual framework: The MEA introduced a framework that linked ecosystem services (the benefits that people obtain from ecosystems) to human well-being. These services were classified into four categories:

1) Provisioning services

2) Regulating services

3) Cultural services

4) Supporting services

- Findings: Human activity is having a significant and escalating impact on the biodiversity of world ecosystems, reducing both their resilience and biocapacity. It measures 24 ecosystem services concluding that only four have shown improvement over the last 50 years, fifteen are in serious decline, and five are in a stable state overall, but under threat in some parts of the world.

- Examples: 1) 20% of the world's coral reefs were lost and more than 20% degraded. 2) 35% of mangrove area has been lost in the last several decades.

Provisioning services (MEA)

- Goods produced or provided by ecosystems.

- Food: Crops, livestock, fisheries, aquaculture, wild foods

- Fiber: Timber, cotton, hemp, silk, wood fuel

- Genetic resources

- Biochemicals

- Freshwater

Regulating services (MEA)

- Benefits obtained from regulation of ecosystem processes.

- Air quality regulation

- Climate regulation: Global CO2 sequestration

- Erosion regulation

- Water purification

- Disease regulation

- Pest regulation

- Pollination

- Natural hazard regulation

Cultural services (MEA)

- Non-material benefits obtained from ecosystems.

- Spiritual and religious values

- Knowledge systems

- Educational values

- Inspiration

- Aesthetic values

- Social relations

- Sense of place

- Recreation and ecotourism

Supporting services (MEA)

- Services necessary for the production of all other ecosystem services.

- Nutrient cycling

- Soil formation

Biomass

The total mass of organisms in a given area or volume.

Describe the rate of change in the structure and functioning of the world's ecosystems in the second half of the twentieth century versus at any other time in human history.

The structure and functioning of the world's ecosystems changed more rapidly in the second half of the twentieth century than at any other time in human history.

Impact on poor and marginalized people (MEA)

- Poor people are most dependent on ecosystem services and most vulnerable to degradation of the services.

- Per capita food production declining in sub-Saharan Africa.

- Number of undernourished people worldwide increasing.

- Water scarcity affects 1 in every 3 people worldwide.

- 1.1 billion people lack access to improved water supply.

- Malaria responsible for 11% of the burden of disease in Africa.

Economic and health costs of degradation can be substantial (example)

The cost of collapse of the cod fisheries in Canada is $2 billion in income support and retraining and loss of tens of thousands of jobs.

Changing the economic incentives

- Environmental problems can't be solved so long as ecosystem services are treated as free and limitless. Therefore, we need to measure ecosystem service values and incorporate these into cost-benefit analyses, such as in determining whether destroying mangroves to build a shrimp farm is a profitable action.

- Agricultural and fisheries production subsidies cause ecosystem service degradation. There is an opportunity to shift subsidies to payments for ecosystem services.

Levels of biological organization (only what we are concerned with in BIOL 104K)

- Organism

- Population

- Species

- Communities

- Ecosystem

- Biome

- Biosphere

The tree of life (3 main groups)

- Eucarya (such as people)

- Bacteria

- Archaea (such as thermophiles, which are often found in extreme environments)

Diversity of life underestimate (1992)

- Scientists massively underestimated the numbers of bacteria.

Diversity of vertebrate animals

- 55% fish and aquatic vertebrate species.

How many multicellular species are there?

- Bugs rule.

- Mammals make up a tiny fraction.

________________ rule the multi- + uni-cellular world.

Bacteria

Human microbiome

- The complete collection of microorganisms in the human body's ecosystem.

- The human genome has 23,000 genes whereas the human microbiome consists of 1,000,000+ genes.

- The number of human cells is tiny compared to the number of bacterial cells in the human body.

- The amount of human DNA is tiny compared to the amount of bacterial DNA in the human body.

Diversity of life (current)

- Bacteria comprise over 75% of organism species.

- Animals, fungi, and protists evenly split up the remaining 25% of organism species, with plants comprising a tiny sliver of the pie.

How can so many species coexist?

- Each species differs in the ecological niche it occupies.

Fundamental niche

- The full range of environmental conditions (biological and physical) under which an organism can exist.

Realized niche

- Where species actually occur and is usually smaller than the fundamental niche because of interactions with other organisms (competitors, predators, etc.).

Barnacle experiment (1950's)

- Connell focused on two species of barnacles found on the rocky shores of Scotland: Chthamalus (smaller) and Balanus (larger).

- Chthamalus were found mostly in the upper intertidal zone, where they could tolerate longer periods of exposure to air (desiccation).

- Balanus were found mainly in the lower intertidal zone, where they could take advantage of being underwater most of the time.

- Connell wondered if these differences in distribution were due to environmental tolerance or biological interaction (competition).

- Connell performed removal experiments: When Balanus was removed from the lower zone, Chthamalus was able to survive and grow in the lower intertidal zone, suggesting that Balanus was outcompeting Chthamalus in the lower zone. When Chthamalus was removed from the upper zone, Balanus still failed to colonize that area, indicating that Balanus couldn't tolerate the harsher, drier conditions of the upper intertidal zone.

- Demonstrated that both abiotic (environmental tolerance) and biotic factors (competition) shape species distributions.

Warbler study (1950's)

- MacArthur's study is a classic example of how niche differentiation reduces competition between closely related species.

- While all 5 closely related warbler species lived in the same spruce and pine trees, they foraged in different parts of the trees and exhibited distinct feeding strategies.

Competitive exclusion principle (CEP)

- An ecological concept that states that two species cannot coexist in the same ecological niche for long if they compete for the same limited resources. One species will eventually be driven out or become extinct due to the competition unless they can reduce competition by partitioning their niches.

Character displacement

- The phenomenon where closely related species that coexist in the same geographic area (sympatry) evolve distinct traits to reduce competition for resources.

- In contrast, when the species are living in separate areas (allopatry), their traits are often more similar because they are not directly competing for resources.

- In some cases, this can drive speciation: As two populations diverge more in their traits, reproductive isolation may occur, leading to the formation of new species.

Autotrophs vs. heterotrophs

- Autotrophs: "Self-feeders" that obtain carbon from inorganic source (CO2) and produce organic compounds (glucose). They are essential in synthesis of living matter.

- Heterotrophs: Organisms who must obtain their energy source by ingesting or absorbing nutrients from other living things (organic sources).

Energy flow vs. biomass of different trophic levels

- Producers are the foundation of the food chain and typically have the largest biomass in an ecosystem. Their biomass represents the amount of stored energy available to the next trophic level (herbivores). This sets the carrying capacity for higher trophic levels.

- Only ~10% of the energy stored in producers is transferred to herbivores. The other ~90% is lost as heat, metabolic processes, waste, or remains in parts of the plant that the herbivore can't digest. The biomass of herbivores is much smaller than at the producer level because the loss of energy between trophic levels limits their biomass.

- Again, only ~10% of the energy stored in herbivore biomass is transferred to carnivores. This limits the amount of energy available to carnivores, resulting in further reduction of biomass. This explains why apex predators are relatively few in number compared to herbivores and why ecosystems cannot support large populations of carnivores.

Carrying capacity

Largest number of individuals of a population that a environment can support.

Top-down vs. bottom-up control

- Top-down: Predators regulate the abundance of herbivores and producers.

- Bottom-up: The availability of resources for producers influences the abundance of all other trophic levels.

Net primary productivity (NPP)

- The amount of energy or carbon that a plant accumulates over a period of time. It's calculated by subtracting the amount of energy or carbon lost through respiration from the total amount of energy or carbon gained through photosynthesis.

- Highest in regions near the equator and decreases at greater latitudes (regions farther from the equator).

- The open ocean and tropical rainforest ecosystems account for nearly 50% of the Earth's net primary production.

Size-selective predation

- Predators often select prey by size.

- Predator size could be influenced by prey size or vice versa.

- Pack hunting is an exception to this rule.

Advantage of large body size

- Larger, heavier predators can go for larger, heavier prey.

- Predation of herbivores changes sharply at around ~150 kg. Herbivores below this weight experience a high rate of predation while herbivores above this weight are very infrequently preyed upon due to the fact that such few predators can take on large herbivores such as an elephant.

Biological magnification (DDT, Mercury)

- Toxins become more concentrated in successive trophic levels.

- DDT is a synthetic pesticide that was widely used after WWII to control mosquitoes (to combat malaria) and agricultural pests.

- DDT does not easily break down, remaining in the soil, water, and organisms for many years.

- In bird populations, DDT caused them to lay thin-shelled eggs that would break before hatching, leading to drastic population declines.

- Mercury levels in seafood are often a concern to humans due to biomagnification through trophic levels.

r/K selection theory

- Opportunistic strategy: Organisms that follow the r-selection strategy tend to maximize their population growth rate (r) in environments where resources are abundant but unpredictable, or where population density is low and the environment is frequently disturbed.

- Equilibrium strategy: Organisms that follow the K-selection strategy focus on maintaining populations close to the carrying capacity (K) of their environment. These species are adapted to stable, predictable environments where competition for resources is high, and survival depends on efficiency rather than rapid reproduction.

Photosynthesis

- CO2 + H20 --> Glucose + O2

- ~2% efficiency

Cellular respiration

- Glucose + O2 --> Energy + CO2

How much global NPP do humans use?

- ~40% NPP

Equinox

- The two days of the year on which neither hemisphere is tilted toward or away from the sun.

- Day and night is of equal length.

Winter solstice

- When the sun is at its southernmost point.

- In the northern hemisphere, shortest day and longest night.

Summer solstice

- When the sun is at its northernmost point.

- In the northern hemisphere, longest day and shortest night.

Earth wind patterns

Intertropical convergence zone (ITCZ)

- The area where the two Hadley cells converge and cause large amounts of precipitation.

- The ITCZ undergoes a seasonal migration. It occurs at a higher latitude in the northern hemisphere summer and at a lower latitude in the southern hemisphere summer.

Why is seasonal variation greater in the northern hemisphere?

- More land in the northern hemisphere and less open ocean.

Surface ocean currents

- Driven largely by trade winds and prevailing westerlies.

Thermohaline circulation (global conveyor belt)

- Movement of ocean water caused by density difference brought about by variations in temperature and salinity. As ocean water freezes at the poles it concentrates salt, and the colder, denser water sinks.

- An oceanic circulation pattern that drives the mixing of surface water and deep water.

- Plays a critical role in distributing heat, nutrients, and gases (like O2 and CO2) throughout the world's oceans.

- Helps redistribute heat across the planet. For example, the Gulf Stream carries warm water from the tropics toward Europe, contributing to the relatively mild climate of Western Europe.

- Helps sequester carbon in deep water for long periods, helping to regulate atmospheric CO2 levels.

Upwelling

- The movement of deep, cold, and nutrient-rich water to the surface.

How was catastrophe avoided in the Deepwater Horizon oil spill?

- They managed to contain and clean up the mess before it entered the gulf stream and got circulated through the Atlantic.

El Nino

- A climate phenomenon characterized by the periodic warming of sea surface temps near the coasts of Peru and Ecuador (every 7 to 14 years).

- Along the coast of South America, cold, nutrient-rich water typically upwells from the deep ocean to the surface, supporting marine life and fisheries. During El Nino, the warm surface waters suppress this upwelling, reducing nutrient availability and causing declines in fish populations.

- Fisheries can collapse and the warming water can cause coral bleaching.

- La Nina often brings opposite weather effects to those of El Nino, characterized by unusually cold sea surface temps near the coasts of Peru and Ecuador, and increased upwelling.

Biome type

- Described by climate + soil type.

Buttressed roots

- Common in tropical trees.

- Provides mechanical support.

- Shallow-rooted, covers large horizontal surface area for nutrient acquisition.

Tropical understory

- The layer of vegetation found beneath the canopy in tropical rainforests.

- This layer receives less sunlight than the forest canopy above it, but still supports a wide variety of plant and animal life adapted to the lower light levels and high humidity.

Epiphytes

Plants such as mosses, lichens, and orchids, that grow on other plants but do not take nutrients from them.

Tropical lianas

- Long, woody vines that are a prominent feature in tropical rainforests.

- They use trees and other structures for support to reach sunlight, which is scarce in the lower forest layers.

Tropical deciduous forest

- A biome with pronounced wet and dry seasons and plants that shed their leaves during the dry season to minimize water loss.

Chaparral vegetation (Mediterranean climate)

- Small trees and bushes adapted to a Mediterranean climate (hot, dry summers and mild, wet winters).

- Unique for its ability to thrive in hot, dry conditions and its remarkable adaptations to fire-prone environments.

- Have evolved to thrive after wildfires (fire-stimulated seed germination).

Continental climates

- The climate of the centers of continents, with cold winters and warm or hot summers.

- Characterized by large seasonal and daily variation in temperature.

Temperate deciduous forest

- A forest (or biome) that is characterized by trees that shed their leaves in the fall.

Boreal forest

- A forest biome made up primarily of coniferous evergreen trees that can tolerate cold winters and short growing seasons.

- Found in the upper regions of the northern hemisphere.

- Small leaves heat up less, leading to lower transpirational demand.

Tundra

- A vast, flat, treeless Arctic region of Europe, Asia, and North America in which the subsoil is permanently frozen.

- Very short growing season.

Ellesmere Island

- Located at 80 degrees North latitude.

- Moth takes 17 years to grow feeding off the grasses.

Why are mountaintops cooler and how do they "make" rain?

- Warm, moist air is forced upwards.

- Cooling occurs.

- If the dew point (100% humidity) is reached, rain falls.

Temperate rainforest

- The cool, dense, rainy forests of the northern Pacific coast; enshrouded in fog much of the time; dominated by large conifers.

Rainshadow

- A region having little rainfall because it is sheltered from prevailing rain-bearing winds by a range of hills.

Photic zone

- Portion of the marine biome that is shallow enough for sunlight to penetrate.

Benthic zone

- Bottom of an aquatic ecosystem; consists of sand and sediment and supports its own community of organisms.

Aphotic zone

- Dark layer of the oceans below the photic zone where sunlight does not penetrate.

Hydrologic cycle

- The cycle through which water in the hydrosphere moves; includes such processes as evaporation, precipitation, and surface and groundwater runoff.

Amount of ocean water vs. fresh water

- ~97% of water on Earth is ocean water.

- Out of the ~3% of fresh water, ~2% is held in ice, and ~1% is groundwater. The remaining fresh water is found in lakes, rivers, and swamps.

Hoover Dam (1936)

- First impoundment on the Colorado River.

- Eliminated any and all seasonal variation of river flow.

Salton Sea

- A large, shallow, saline lake located in the Imperial valley of southern California.

- Created by accident in 1905 when an engineering mishap diverted water from the Colorado River into the Salton Basin.

- Primarily fed by agricultural runoff.

- The lake has no natural outlet, meaning the water only leaves by evaporation, which concentrates the salts and pollutants over time.

- Extremely harmful and even lethal to migratory birds that stop there along their migratory routes.

- A result of human intervention in attempts to irrigate the Imperial valley for agricultural purposes.

Eutrophication

- Excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life (algal bloom) and death of animal life from lack of oxygen.

- Each year immense amounts of nitrogen from human activities in the Mississippi watershed wash into the Gulf of Mexico, setting off a chain of events each summer that creates a vast "dead zone".

Consequences of groundwater pumping

- Earth fissures.

- In 2021, Hwy 191 in AZ collapsed due to groundwater pumping.

Zebra mussels

- Accidentally introduced to Great Lakes; clogs water-intake pipes and irrigation pipes.

3 processes which changed the composition of the atmosphere

1) Volcanic activity: Volcanoes spew out water vapor, CO2, nitrogen.

2) Chemical reactions: Rain water and CO2 combine to form carbonic acid which can be trapped in rocks.

3) Photosynthesis: Plants take in CO2 and exhale O2.

Great Oxygenation Event

- A time about 2.5 billion years ago, when a significant amount of oxygen appeared in the atmosphere.

Oxygen catastrophe (first major extinction event)

- Population of cyanobacteria exploded since they had an advantage, produced more oxygen faster than it could be absorbed, causing it to build up in the atmosphere, which wiped out the other organisms (oxygen was toxic to the anaerobic organisms living at the time). Methane had been acting as a greenhouse gas that kept the Earth warm, but the extra oxygen reacted with methane to form carbon dioxide and water, which don't trap as much heat. The thin atmosphere caused Earth's first ice age.

- Ozone layer: Protection from UV (without which the UV radiation would have caused unsustainable levels of mutagenesis or DNA damage).

Nitrogen fixation

- N2 takes a substantial amount of energy to break apart and make "usable" by biological processes.

- 3 processes are responsible for most nitrogen fixation on Earth: 1) Atmospheric fixation by lightning, 2) biological fixation by certain microbes (alone or in a mutualistic relationship with some plants and animals), 3) industrial fixation.

Rhizobial bacteria

- A nitrogen fixing bacteria that form mutualistic relationships with the roots of some plants.

Fallow field

- Leaving a field unplanted (but fertilized) to replace nutrients in the soil.

Monoculture

- Farming strategy in which large fields are planted with a single crop, year after year.

Industrial N-Fixation (Haber Bosch Process)

- 3-5% of world natural gas production is consumed (highly energy intensive process).

- Responsible for sustaining one-third of the Earth's population.

Effects of nitrogen-fertilization

- Dramatically decreases biodiversity.

Anthropocene

- The current historical era in which human activity is reshaping the planet in permanent ways.

Chlorofluorocarbons (CFCs)

- Chemicals that have the potential to destroy the ozone; ex.) hair-spray, refrigeration, etc.

Montreal Protocol (1987)

- International law to protect the depletion of the ozone layer.

- First time universal ratification was accomplished.

- Chlorine density in the stratosphere decreased after several revision iterations.

Albedo

the proportion of the incident light or radiation that is reflected by a surface, typically that of a planet or moon.

Why are there no dominant species in tropical forests?

- Janzen-Connell Hypothesis: The seeds or seedlings of a particular species are more likely to be attacked by predators, pathogens, or herbivores if they are near the parent plant or in areas where other individuals of the same species are concentrated.

- This creates a natural form of population control, where species cannot form dense populations, as higher densities lead to increased mortality rates. This process encourages diversity because it prevents any single species from overwhelming others by occupying too much space.

- The climatic stability in tropical forests allows for specialization and tighter niche packing due to year-round exploitation of fruits and a favorable climate year-round.

- A stable climate promotes more predators and pathogens, preventing dominance of a few top competitors.