AP Environmental Science Unit 1

Ecosystem

a particular location on Earth with interacting biotic and abiotic components

Biotic compoenents

are any components of ecosystems that are living, such as plants, animals, and bacteria

Abiotic

components are any nonliving parts of the ecosystems, like rocks, soil, and air

Biosphere

combination of all ecosystems on Earth

predator-prey relationship

one animal will kill and consume another animal

Predators

at a higher trophic level, play an important role in regulating much larger prey populations.

to avoid being eaten, prey have evolved behavioral, morphological, and/or chemical defenses

prey can hide (behavioral), Camouflage or attack (morphological), or be poisonous (chemical)

Symbiotic relationship

at least one of the species benefits from the relationship

symbiotic relationships can be

mutualistic (both benefit), commensalistic (one benefits, one unharmed), or parasitic (one benefits, one harmed)

competition occurs when

organisms must share a limited food resource. Whether it be water, shelter, food, nutrients, or light, coexistence is dependent on access to resources

Species who share common resources are able to resource partition, or

divide needed resources according to survival needs

If two species eat different parts of the same plant, they can share that

niche without overlapping the depleting populations

evolution

will favor the species with access to more resources, while species forced to over-artition will begin to die off

a keystone species

is one that plays a large role in its ecosystem despite being quite low in population. The removal of a keystone species can have cascading effects on the ecosystem, leading to significant changes in abundance and distribution of other species.

ecosystem engineers

are special types of keystone species that create or maintain habitats for other species

biome

is a geographic region that is characterized by a certain climate and diverse presence of plants and animals

terrestrial biomes

are any biomes that exist on land. They are usually characterized by plant growth, temperature, and precipitation

Aquatic biomes

are biomes that are characterized by the presence of water. Divided into two main categories, marine and freshwater, they are characterized by salinity, temperature, oxygen levels, nutrient levels, and amount of light

Tundra

• It gets less than 10 inches of rain per year, relying instead n snow for present moisture

• Trees cannot grow in these conditions, and are instead replaced by mosses and other small, low-growing plants

• permafrost (a part of the ground around 3 feet deep that remains permanently frozen)

Boreal forest (taiga)

• large coniferous forest biome; found in the high latitudes of the Northern Hemisphere, including parts of North America, Europe, and Asia

• Long, cold winters and short, cool summers

  • It is home to tall trees with dense leaves that form canopies which cover the ground below

Temperate rainforest

• are a coastal biome that has moderate temperatures and high precipitation

• soil is low in nutrients due to frequent rainfall

Woodland/shrubland

• hot and dry summers combined with rainy winters create weather extremes such as droughts and wildfires

  • this abiotic factor necessitates that species that live here must have drought-resistant evolutionary traits

tropical rainforest

• warm and wet biome that lies near the equator

• hot and humid, and receives a large amount of precpitation

• the soil the biome is nutrient poor

tropical seasonal forest/ savanna

• dry and hot seasons with few green trees or plants

• biome s found in sub-saharan africa

• warm temperatures promote decomposition which leads to rich soil composition, the dry climate prevents many large plants from growing

subtropical desert

• very hot and very dry

• almost no nutrients

  • precipitation can be as low as one inch in parts

Topical =

hot

temperate =

moderate

boreal/tundra =

cold

rainforest =

wet

seasonal forest/grassland =

wet and dry

desert/tundra =

dry

freshwater biomes

lakes , ponds, rivers streams:

• with low salinity in the water

marine biomes include

oceans, coral reefs, and estuaries

• have high salinity

Streams and rivers have

• flowing fresh water

• rivers are usually wider and carry larger amounts of water than streams

• water is constantly flowing, algae and aquatic plants are rate

  • higher amounts of oxygen, which supports the presence of freshwater fish

lakes and ponds

• have standing freshwater, with an end deep enough to prevent emergent vegetation

• lakes are usually larger than ponds

lakes

• are classified by how productive they are

lakes with a high level of productivity are called

eutrophic

moderately productive lakes are called

mesotrophic

Oligotrophic lakes have

low levels of nitrogen and phosphorus and are the least productive

littoral zone

is the shallow area of water near the shore where most of the photosynthesis occurs

below the littoral zone is called the limnetic zone

which goes as deep as sunlight can penetrate

below the limnetic zone is the profundal zone

which is too deep for sunlight to reach and therefore supports very few organisms

freshwater wetlands

• they are submerged in water for part or all of the year, but they are shallow enough in most parts to support emergent vegetation.

• Their soils are often saturated, which allows for specialized living conditions and lots of present nutrients

• they prevent blooding and drought with extensive rainfall intake and filter pollutants from the water

salt marshes

• they are often found along the coast in temperate climates

• salt marshes are often located along estuaries, which freshwater river meet salt water

• prevent flood and extreme coastal erosion

  • productive biomes for plants and algae

mangrove swamps

• located in topical and subtropical areas

• mangrove trees can survive in salt water as well

intertidal zones

• are narrow bands of coastline between the levels of high tide and low tide

• during high tide, the zone is submerged in water, so conditions are relatively stable

• during low tide, the water recedes which exposes the organisms to harsh conditions

coral reefs

• are found in warm, shallow waters

• corals are made up of tiny animals that produce limestone to form a hard external skeleton

• coral relies on photosynthetic algae for food

open ocean

• contains deep ocean water that sunlight cannot penetrate

the ocean is divided into three distinct layers

• photic zone: is the layer of ocean that sunlight can penetrate, allowing photosynthesis to occur

• aphotic zone: is below the photic zone, where photosynthesis can no longer take place

• benthic zone: the muddy bottom of the ocean

matter moves across the earth in cycle called

biogeochemical cycles

carbon cycle is the movement of

carbon across the earth

carbon is a vital element that is essential for life on earth, and the carbon cycle plays a crucial role in regulating the

amount of carbon dioxide (CO2) in the atmosphere

the carbon has two stages:

the fast stage and slow stage

fast stage (carbon cycle)

which is associated with living organisms

slow stage (carbon cycle)

is associated with dead organisms (fossil carbons)

plants intake CO2 and convert it to oxygen in a process known as

photosynthesis

(carbon cycle) when photosynthesis occurs, CO2 from human activity and other natural process is

regulated and converted to oxygen, essential for the Earth’s health and human survival

large reservoirs of carbon

oceans or landfills are called carbon sinks

carbon sinks help to

retain and mitigate large amounts of carbon through storage

carbons reentry into earth’s soils and ground is at a much

slower rate than harvesting of fossil fuels

there are two mini-cycles that take place in the ocean (carbon cycle)

• the first process: that occurs in the ocean is carbon exchange: the ocean absorbs some CO2 from the atmosphere, and it releases roughly the same amount of CO2 back into the atmosphere

  • the second process: occurs in the ocean is sedimentation. The C2 combines with calcium ions in the water to form calcium carbonate, which sinks to the bottom of the ocean and accumulates, if left undisturbed, it can cause accumulation of carbon, but upon disturbance hat carbon is reintroduced to the atmosphere and continues its journey through the carbon cycle

Nitrogen is a

macro-nutrient

Nitrogen is an important compotent of

proteins, DNA, and toher biomolecules and is necessary for rowth and developet of all living organisms

nitrogen fixation

allows nitrogen gas to be converted into a form that can be used by plants and animals, such as ammonia (NH3) or nitrate (NO3). Nitrogen fixation can happen in two of different ways: biotic and abiotic

In the biotic pathway (nitrogen cycle) nitrogen-fixing bacteria such as bacteria

in the roots of certain plants convert nitrogen gas into ammonia (NH3), which then quickly bonds with hydrogen ions to become ammonium (NH4)

biotic pathway (nitrogen cycle: nitrification)

ammonia and other compounds become nitrite (NO2) and later nitrate (NO3). Bacteria in soil and water allow this step of the nitrogen cycle to happen. It is important for bacteria to keep the amount of nitrate at bay to prevent pollution or overabundance of algal blooms in bodies of water.

In assimilation, nitrogen is in its

useable form, and gets absorbed by plant tissues. This nitrogen can be synthesized by consumers, or it can run into the ocean, providing aquatic ecosystems with enough nitrogen.

When organisms die,

decomposition occurs and organic nitrogen present in these organisms through the nitrogen cycle reverts back into ammonium. This is called mineralization, and the last step before nitrification can restart

At the end of the nitrogen cycle, certain species of bacteria take nitrates and convert them into nitrous oxide (N2O) and eventually back into N2. This last step is called

denitrification, and permits and cycle once again restart

Nitrogen cycle:

1. Nitrification: Nitrification is the process by which ammonia and other nitrogen compounds are converted into nitrite (NO2) and nitrate (NO3). Nitrification is carried out by bacteria in soil and water

2. Assimilation: Nitrate is taken up by plants through their roots and is incorporated into proteins, DNA, and other biomolecules

3. Mineralization: When organisms die, decomposition occurs and organic nitrogen present in these organisms through the nitrogen cycle reverts back into ammonium.

4. Dentification: Denitrification is the process by which nitrate is converted back into nitrogen gas. Denitrification is carried out by bacteria in soil and water.

Once nitrogen is in useable form, plants can

assimilate it, or incorporate it into their tissues. Consumers who eat the plants will also synthesize some of the nitrogen into their tissue.

When organisms die, decomposers break down their

tissues and convert the organic nitrogen back into inorganic ammonium. This process is called mineralization or ammonification.

Nitrogen is often classified as a ____

limiting nutrient, meaning its essentiality is coupled with the fact that it is scarce and hard to find. Since Earth is a closed system, there isn’t a way for us to create more of it, but plants still require nitrogen to grow

phosphorus is needed for

DNA RNA and ATP and is also a limiting macronutrient

Phosphorous Cycle

1. When materials like rock are weathered, organic phosphorus is released into surrounding environments. This means that natural processes such as natural disasters, rain, or wind cause rocks or other materials to break down, releasing phosphorus.

2. It is then transported between land and water through aquatic functions like rain or runoff

   1. After phosphorus has been transported between ground water and soil, living organisms can absorb it and use it for production of DNA and other important biomolecules, as discussed above. Though. similar to all other cycles, these absorbers will eventually die, and their decomposition will release phosphorus back into the environment to restart the cycle (if sedimentation occurs, this excess phosphorus remains stored in rocks or soil at the bottom of bodies of water)

Human impacts on the phosphorus cycle

• Phosphorus runoff can accumulate in groundwater, causing excess buildup with throws off the balance of specific ecosystems. As a result, these bodies of water experience eutrophication, where a body of water’s quality drastically decreases due to an excess buildup of nutrients (specifically, like nitrogen and phosphorus) . These dead zones are dangerous and can create problems for surrounding plant and animal life

Hydrologic cycle (water cycle)

1. Evapotranspiration is a term used to describe all water that, during the hydrologic cycle leaves Earth to enter the atmosphere as gaseous water vapor. Heat from the sun causes water to turn into water vapor and rise into the atmosphere, called evaporation (plants also can release water through transpiration, meaning that their leaves lose water)

   1. Once the water has evaporated into the atmosphere, it comes back down to the Earth in the form of precipitation (rain, snow, hail/sleet, etc)

Three different things that can happen when water is returned to Earth is

1. surface runoff: water slides from the land back into a body of water. Surface runoff doesn’t have to be immediate; snow can stay on a mountain for months before it returns into a body of water. Surface runoff helps to preserve the balance and presence of water reservoirs

2. percolation: the water will be absorbed by the ground and will become part of the Earth’s groundwater stores

3. uptake: plants can uptake water and use it for photosynthesis

Human impact on the water cycle

• cutting a forest, there won’t be trees to uptake the water which can lead to flooding and soil erosion.

• urbanization

• agricultural

the amount of energy that the producers in an ecosystem capture is called the

gross primary productivity. When plants take in sunlight, come of the energy is always lost through respiration. This means that, when an organism converts glucose from the sun into energy, come of it is rendered unusable since it escapes into the atmosphere.

net primary productivity

can be found by subtracting the amount of energy respired from the GPP. Since the net primary productivity factors in respiration, it can more accurately demonstrate the energy capacity of any given ecosystem.

very little energy is actually available to ecosystems, but after respiration occurs, and ecosystem’s productivity levels and richness levels can be

assumed according to their NPP

Ecosystems with higher levels of productivity are often associated with higher levels of species diversity and

ability to satiate the needs of more consumers on higher and higher trophic levels

detritivores

example dung beetles, obtain nutrients by actively breaking down dead tissues and waste

decomposers

such as fungi convert organic bacteria into small levels and molecules that can be recycled back into the ecosystem

the first law of thermodynamics

energy cannot be created or destroyed; it can only be transformed from one form to another

second law of thermodynamics

states that entropy increases every time energy is forced to reroute or change forms. Entrop is the amount of disorganization present in a system

trophic cascade

is a series of events in an ecosystem that occurs when a predator at the top of the food chain has an impact on the populations of organisms lower down in the food chain. For example, in a marine ecosystem, if the population of sea otters, which are a predator, increases, it can lead to a decrease in the population of sea urchins, which are a species of prey for sea otters. This decrease in sea urchins can result in an increase in kelp, which is a type of seaweed that sea urchins eat. The increase in kelp can then provide more habitat for other species, leading to ripple effect through the ecosystem

Which of the following statements is true of aquatic biomes

freshwater biomes are a vital source of drinking water

Which of the following biomes is best characterized as an area that forms the narrow band along the coast that experiences a range of environmental conditions (including daily changes in sunlight, temperature, and water)

intertidal zone

where is the majority of fresh water found on earth

ice caps and glaciers

In a given ecosystem, producers convert solar energy into 15,000 kcal of chemical energy stored in organic compounds. Which of the following is the most likely amount of energy available to secondary consumers

150 kcal

decomposers break down

organic matter

five different species of warblers, seed-eating birds, live in the same species of conifer trees. All of the birds migrate to coniferous forests during the summer, and different species reside in different areas in the same tree. They feed on the seeds of the conifer trees, but the different species do not mate with each other. Which of the following best explains why the different warbler species can all have habitats in the same conifer trees?

resources partitioning in the seeds reduces competition, and five different species can live in the same tree

In a fish species, the number of eggs that hatch and survive for one year varies depending on the number of eggs that were produced. As the number of eggs produce increases past the threshold number, the survival rate of the offspring decreases. Which of the following statements best explains why only a limited number of offspring can survive in a fish population?

the chance of survival decreases when there is intraspecific competition for resources among the surviving yearlings

which of the following best describes a symbiotic relationship?

intestinal bacteria inhabit the gut of humans

Which of the following best describes gross productivity in an ecosystem

gross primary productivity is the total amount of solar energy captured by producers through photosynthesis over time

Which of the following best describes the net primary productivity of an ecosystem?

net primary productivity is the amount of energy lost through respiration by producers subtracted from the gross primary productivity of an ecosystem.

Scientists calculated the net primary productivity at two different forest sites. Both forests have the same gross primary productivity. Forest A has a net primary productivity of 1,650 kcal/m²/year and forest B has a net primary productivity of 1,110 kcal/m²/year which of the following statements is best supported by the data

Forest A producers have lower rates of cellular respiration than forest B producers (since gross primary productivity is the same, forest B has a lower net primary productivity; therefore, it has a higher rate of celllular respiration)

This biome contains plants that are adapted to prevent water loss due to low average rainfall and high temperatures year round

desert