Ecology (BIOL 265) Exam 3

BIOL 265 : Ecology Fall 2025

Biogeochemical Cycles

All nutrients or elements flowing from the nonliving to living and back to non living components of the ecosystem in a cyclic path.

• Bio-living

• Geo-rocks and Soil

• Chemical-Processes

Movement of water and other material throughout the abiotic and biotic environments

Origins of cycles: Gaseous

Major reservoirs are atmosphere and oceans, global cycles in nature.

Origins of cycles: Sedimentary

Major reservoirs are soil, rocks and minerals. Elements or nutrients within the sedimentary cycle.

Both Sedimentary and Gaseous cycles

Driven by flow of energy through ecosystem.

Tied to water cycle.

Both involve biological and non-biological processes.

Diagram of Biogeochemical Cycle

Inputs come from the atmosphere or rocks and minerals (inorganic material)

Outputs come from respiration, denitrification, assimilation and excretion (within the forest with animals and plants)

Both happen at different scales through the ecosystem.

Total Inputs - Total Outputs + Total Sources - Total Sinks = The change in Mass

Internal Cycling + Examples

Recycling of nutrients within ecosystems. Measured as pools and fluxes

Lakes = Large short-term recycling

Forests = most of nutrient stored as biomass.

Movement goes from the living matter (pool) to the dead organic matter, this moves (flux) to the soil where it then goes back to the living matter.

Main Carbon Reservoirs

1) Atmosphere

2) Terrestrial biosphere (plants, animals, freshwater, soil)

3) Oceans (inorganic, living, non-living)

4) Geological (fossil fuels)

Chemical, Physical, Geographical, Biological

Atmospheric Carbon

Regulation for Earth, supplied by Earth’s biological and geological processes. Naturally with respiration or plants, animals, and eruption. Unnaturally with fossil fuel burning :<

Terrestrial Biosphere

Freshwater, soil, plants, and animals. Photosynthesis biomass and atmospheric and soil. Tons of internal cycling. Soil centered. Mainly turns into minerals to form inorganic dissolved carbonates and brought up when needed.

Soil Organic Carbon + Potential Solution

Allowing for the measurement of organic and inorganic carbon. Allows for atmospheric carbon balance as plants use and store. Balance Reservoir.

C Sequestration in Soils, allowing for offset of emissions. Stop Messing with the Soil.

Oceans

Primary source of carbon storage within cycle. This is with organisms, plankton photosynthesis. CO2 dissolves in Sea water and is responsible for absorbing a third of CO2 emissions.

Ocean Acidification with an increase of CO2. H+ Ions lower the pH.

Ocean Acidification weaken the calcium shells on Ocean organisms.

Aragonite Saturation - Allowing to see which parts are more acidic that others. Anything with calcium is attracted to the H+, messing with everything.

Geological Carbon

Stored CO2 underground which happens in different ways (Coal). Pools of carbon which is old. These are held in small pore spaces. There are able to hold large amounts of CO2 for long periods of time.

Carbon Operation

Varies daily and seasonally with tightly linked to energy flow. (Breathing of the Earth). Carbon increases within cooler months and declines with photosynthesis in the summer months.

Carbon is linked to…

Photosynthesis within plants and respiration with both plants and animals.

Nitrogen

Floating around the atmosphere at N2 Gas. Nitrogen is limited in ecosystems because bonds = difficult to break. Converted from microbes and enter the biological cycle.

• Plants grow better with the help of Nitrogen.

Nitrogen Fixation

Process that happens with multiple mechanisms. N2 Gas becomes usable to plants. It is an anaerobic process changing the N2 into organic N for primary producers, Bivalves and Predators.

• Lightning and Radiation accounts for 10% of nitrate entering.

Ammonification or Remineralization

Converting N2 gas into Ammonia from Bacteria.This can be used by Plants, from aquatic bacteria (Contain enzyme nitrogenase, Anaerobic) with algae blooms. This is anaerobic or aerobic. It becomes inorganic from being organic. The organic nitrogen becomes NH4+

Nitrification

Oxidation of ammonium. This is aerobic and converts it to NO3. It can be used by plants.

Benefits of Nitrification

N Levels with fixation allow for plant growth as well as nitrogen primary production.

Denitrification

This is an anaerobic process. The nitrate or nitrite (inorganic) gets converted back to N2 gas.

Phosphorus

Essential Material for DNA, Bones, Teeth and Phospholipids.

Phosphorus Cycle

No atmospheric reservoir and is tied to water instead. Weathered materials cycling from land to sea. This can be Organic or Inorganic.

• Cycles via water, soils, sediments and organic tissues.

This is also linked to biological activity such as absorption and assimilation.

Limitations of Phosphorous

Multiple organisms are P-limited and this affects growth and reproduction negatively.

Benefits of Phosphorous

Increasing phosphorous allows for plants to create a defense, such as latex making it difficult for Insects to invade.

Decomposition

Dead animals, feces and other excreted products and dead plant material

• Done with bacteria and Fungi

Breakdown of chemical bonds formed during the construction of plant and animal tissue.

Respiration of dead organic matter: litter and soil organic material

Detritivores

Organisms that consume dead things

• Tadpoles

• Millipedes

• Worms (the native ones)

Bacteria as well as Fungi

Processes of Decompostition

Leaching and fragmentation and results in change in physical and chemical structures. Big clean up operation.

Mass loss —> release of CO2 and means respiration occurred. This can be measured physically.

Litter bags

Pre and post mass can show rate of decomposition. Carbon is lost to the atmosphere as CO2 in the process of respiration (microbial).

Rate of decomposition

Calculates the rate at which nutrients are made available to primary producers. Largest bottom-up process

These are influenced by abiotic factors

• Temperature and Moisture

These are influenced by biotic factors

• Chemical composition of leaves and nutrient content and structure of leaves (lignin) can influence. Proteins and soluble C are decomposed fast.

These are higher in tropical ecosystems.

Photodegredation

Sunlight degrades organic molecules and assists in increasing rates of decomposition.

Mineralization (1) (reverse of immobilization)

Transformation of nutrients and other elements from organic matter into inorganic or mineral forms

• Organic N —> Ammonia

Leaching (2)

Nutrients are lost simply because material is dead.

Immobilization (reverse of mineralization) (3)

Microbes uptake and assimilate nutrient. Inorganic nutrients used for growth.

Net mineralization rate (ecosystem-level consequences)

rate of mineralization - immobilization

High nutrient = High productivity

Low nutrient = Low productivity

Dead Organic matter (OM)

Serves as energy source for microbial decomposers. Dead leaves will contain varying degrees of nitrogen. The quality of OM will vary.

C:N ratio

Low = High Protein

High = Low protein and high lignin.

(usually influenced by nutrients in environment)

Species with a high N% will have a higher N mineralization and High immobilzation.

Overall of Decomposition

Primary productivity determines rate of nutrient transformation from inorganic from to organic form (nutrient uptake)

• Soil / sediment —> plants and algae

Decomposition determines the rate of transformation of organic to inorganic form (N mineralization)

• Plant / Carcasses —> Soil / sediment

High Nitrogen mean high immobilization and high mineralization

Aquatic Nutrients

Lower nutrients that terrestrial environments. Diversify to extract nutrients.

Feeding Methods

• Shredders

• Collector gatherers

• Grazer Scrapers

• Collector filterers

Extracting something there is not much of.

Landscape Ecology

Study of relationships between spatial patterns and ecological processes over a range of spatial scales

Mosaic or Matrix

Most continuous area across a heterogeneous landscape (more of)

Patch

Homogenous area that differs from its surroundings (less of)

Landscapes

• Shape of habitats

• Patches of each

• Sizes

• Distance

• Borders

Larger patches…

Less population density….

support larger population sizes

due to larger size of area with less prone to extinction and more species.

Edges

Borders between habitats which is formed by natural features such and land to water and habitat disturbance like fire and human activity.

Edge Effects

changes in population or community structures that occur at the boundary of two habitats

Interior species

Specialized and adverse to disturbance.

Edge species

Generalists and tolerant to disturbance

Ecotone

Transition zone between two patches associate with change in vegetation and community

Metapopulations

A set of discrete subpopulations connected by occasional movement of individuals between them

Low Migration Rate

Smaller populations with smaller fragments of habitat will have a lower chance of survival and go extinct (unstable)(no recolonization)

Intermediate Rate of Migration

Unoccupied patches are recolonized following local extinctions, populations will persist.

High Migration Rate

Subpopulations act as a single large population, these are less likely to suffer extinction. 

Corridors

Area of habitat connecting two patches allowing for movement, gene form and mitigate loss of core habitat (interior).

Just connections between subpopulations.

Connectivity

Source-sink dynamics with sources that are high quality for population increase and sink that are lower quality with population decrease

Ecosystems Ecology

Study of interactions among organisms and their physical environment as an integrated system. Examining whole system process.

Ecosystem

Ecological system consisting

• All organisms in an area

• Physical environment for interactions with abiotic/biotic and pools/fluxes.

Hierarchy

Arrangement of organisms into a graded series of compartments

• Between Time and Space, how ecosystems function across the whole system.

• Studies are done at large spatial and/or temporal scales

  • Trophic levels

  • Microbes

  • etc.

High Biodiversity…

After a disturbance, the ecosystem would return back to its original state. Being able to withstand change and disturbance.

Ecosystem Resistance

• The ability of an ecosystem to absorb stress or disturbance.

• Populations or communities remain essentially unchanged.

• Maintain essential characteristics and processes.

Ecosystem stability

Little deviation from average state despite shifting environmental conditions. Looking at the changes.

Less Change = More stable; Resilient.

Ecological Services

Resilience and Stability measures with the products that are produced. Benefits that the environment supplies to humans. (O2).

• Pollination

• Climate Regulation

• …

Threshold

Level of Disturbance an ecosystem can withstand before it does not function or provide services.

• Point at which an ecosystem crosses into a new set of stable states

Combination of resistance, stability, and resilience (point at which an ecosystem changes (stable/unstable))

Ecosystem Function

Interaction of structural components within and across ecosystems

• processes that occur within an ecosystem

Metrics of ecosystem function

• Fluxes of energy and matter across trophic levels and primary production

Consequences of biodiversity

• Number and kinds of species

• Organismal traits

• Ecosystem processes

Traits may mediate energy and material flow directly. Traits may alter abiotic conditions (limiting resources, disturbance, microclimate)

Photosynthesis and N fixation

More plant species and the rates differs, this is regardless of atmospheric conditions (someone will)

Complementary Niche Space

Overlap in species roles, adding species could increase ecosystem functions linearly. Same or similar increases function.

Global Ecosystem

Ecological processes that occur or effect on a global scale.

El Niño - More storms, wetter climate, warmer

La Niña - Less Storms, dry climate, cooler

Humans and N Cycle

N is fixed to a certain extent

Changes in Carbon storage with different Nitrogen additions (effects on trees with Fossil Fuels increasing N levels in the ecosystems)

Leeched Fertilizers making ecosystems Eutrophic (Haber-Bosch (nitrogen synthesis))

Habitat Fragmentation

Leading cause of loss of biodiversity

• Habitat patches

• Decrease of core habitat

• Leads to decline in species, biodiversity and function.

Disjunction of Habitat and true loss of organisms.

More natural land = More pollen = More to eat

Earth’s Water Origins

Most of Earth’s water is within the oceans (96.5) with freshwater being the least (2.5). Even within Freshwater, most of it is in glaciers and groundwater with a small percentage on the surface. Surface water includes ground ice and permafrost, lakes, rivers / marshes, living organisms and atmosphere.

Surface Water

Water on the surface of the Earth as in oceans, ponds, lakes, streams, wetlands…

Groundwater

Water beneath the surface of the ground; mostly surface water that has seeped down into soil.

High Plains Aquifer

Geologic formation that contains sufficient amount of ground water availabilty. Principal aquifer with potable (drinkable) water. Most hydraulically connected geologic units of tertiary or quaternary age. In parts of Colorado, Kansas, Nebraska, South Dakota…

How do we get water??

From Lake Michigan where it is treated and brought to our taps. 700 million gallons of water a day!

Human Impact of the water table

Water is used to create loads of different products, most being meat products and least being tea and coffee. Using for production in products

Water Withdrawal

Rate of withdrawal > rate of recharge leads to the aquifer being depleted. Aquifers take thousands of years to fill (fossil ground water) making it a non-renewable resource.

Pollution

Water pollution includes water containing high levels of metals like arsenic. Metals can contaminate large areas of water quickly leading to major impacts on human health.

Water shortages

Precipitation is not equally distributed throughout the world. There is a large demand on water with the increase of human population and the supply is low due to pollution and waste, High demand in agricultural use which less water being diverted underground due to the high amount of impervious surfaces (pavement / roofs).

Drought

Exists when rainfall for a period of 21 days or longer is substantially below average. Dry spells and water shortage are linked to climate change.

Anthropogenic Litter (Garbage)

All trash lead to the great pacific garbage patch. It affects ocean organisms greatly. Different types of garbage which accumulates in rivers.

Plastics

Increased production significantly from 1950s onwards. Most of them can be recycled. As plastic is weathered with mechanical, microbial, and photodegradation, it becomes sedimentation. Sediments adhere to surfaces, and get passed up the food chain.

Microplastics

Small plastic pieces less than 5mm long (literally everywhere).

Pollution - Pharmaceuticals Hormone Disruptors

Chemical pollutants that alter the hormonal system of animals that ingest them. Low-level exposure can disrupt animal reproduction and development.

Pollution - Pharmaceuticals Prescription and nonprescription drugs

Urine of humans and animals released into surface waters are showing to kill or have affects on aquatic organisms.

Hormones making more female frogs from estrogen

Output Control

Treat pollutants from point sources

Input Control

Changing to non-polluting inputs at the point source (pollution prevention)

Throughput Control

Alter the production of waste by adjustments of substances flowing through a system.

Ways to increase water supply

• Stop polluting what we have

• Population control

• Water Conservation

• Reclamation of sewage water

• Development of Groundwater Resources

• Desalination of Seawater

• Changes in Crops

• Voting

Pathogens

Infectious, disease producing agents (Bacteria, Viruses).

Etiology

Study of the cause of disease.

Reservoir

Population where a disease is dormant or active, a source for infection. (Can become a vector).

Vector

Any organism that carries and transmits to host.

Non-infectious diseases

Those caused by genetic disorders, food, environment

Infectious Diseases

Those caused by infection of a host with an organism (pathogen).

Epizootic disease

Meaning its an outbreak where large amounts of animals die (epidemic)

Enzootic disease

Low occurrence (endemic)

Measures of parasite fitness

R0= Measure of parasite fitness

>1 = Epidemic

<1= Extinction

=0= Endemic

Zoonotic Disease

Transmitted between humans and animals

>60%

Not studied enough, unable to understand diseases further.

Disease Ecology

Understanding relationships between pathogens, hosts, and their environments.

Epizootiology

How and why diseases in wildlife populations occur.