The Biosphere - All Experiences

Ecology on a Living Planet

Our Living Planet: Stability and Change

biosphere: part of Earth in which all of life exists including land, water, and air/atmosphere

• organisms:

  • interact w each other and physical components

  • respond to and change their environments

The Science of Ecology

ecology: scientific study of interactions among organisms and between organisms and their environment

Ecology and Economics

linked bc humans are a part of the biosphere → depend on ecological processes to provide essential water and food, which can also be bought and sold

Levels of Organization

(most specific → most broad)

1. species: a group of organisms that can breed and produce fertile offspring

2. population: a group of individuals of the same species that live in the same area

3. community: assemblage of different populations that live together in a defined area

4. ecosystem: all the organisms that live in a place, together with their nonliving environment

5. biome: a group of ecosystems that share similar climates and typical organisms

Biotic and Abiotic Factors

an organism’s environment consists of the abiotic and biotic factors that affect it

Abiotic Factors

abiotic factors: physical or nonliving factors that shape an ecosystem

• sunlight

• heat

• precipitation

• humidity

• wind / water currents

• soil type

stable factors = stable environments, some change thru seasons

plantetarily → wind, ocean currents, and water overall determine the stability of ecosystems

Biotic Factors

biotic factor: any living part of the environment with which an organism might interact

• important factors include predators, prey, competitors

planetary → predator and prey populations + human populations drive stability

Biotic and Abiotic Factors Together

ex: “muck” in shores of sand and pond has nonliving sand and mud particles, but it also has decaying organic material serving as food for bacteria → if it was ever living or containing living stuff, it’s biotic

abiotic conditions are shaped by organisms too → trees affect the sunlight and temp the “muck” experiences. trees also provide wind protection → impacts humidity. plant roots determine soil erosion. the type of decomposing oak leaves changes acidity of soil.

Global Systems

system: a network of relationships among parts, elements, or components that interact with and influence one another through the exchange of energy, matter, or information

the earth is divided into four spheres

1. biosphere

2. atmosphere: a thin layer of gases that surround earth

3. hydrosphere: all of the water (salt/fresh, liquid/ice/vapor) above and below Earth’s surface and in the atmosphere

4. geosphere: all of the rock at and below Earth’s surface

these parts often interact with each other

algae (biosphere) photosynthesize in the ocean (hydrosphere) and release oxygen into the air (atmosphere) for humans and animals to breathe, in which they live on the (geosphere)

Climate and Weather

changes in weather and climate determine the success/failure of crops and the stability of populations and communities

weather: day-to-day conditions of the atmosphere, including the temperature, precipitation, and other factors

climate: average year-to-year conditions of temperature and precipitation in an area over a long period of time

these determine the type of organisms that grow in ecosystems

climate is influenced by solar energy, latitude, and wind and ocean currents

Latitude and Solar Energy

solar radiation hits Earth at diff angles and at diff times bc Earth is curved and tilted on its axis, causing seasons

equator → sun directly overhead (not spreading out)→ little changes in daylight

poles → sunlight spreads out as winter sun drops lower → shortest winter days

EQUATOR has most solar energy

climate zones are produced by uneven distribution of heat/sunlight, tilted axis = seasons

polar zones: between 66.5 and 90 degrees north and south latitude; very cold winters, barely warm summers

temperate zones: between 23.5 and 66.5 degrees north and south latitude; hot summers, cold winters

tropical zones: 2; between 23.5 north and 23.5 south latitudes near the equator; warm/hot throughout year

Solar Energy and the Greenhouse Effect

Earth’s avg temp is determined by amount of heat trapped in biosphere and the amount lost to space

• controlled by concentration of three gases - carbon dioxide, methane, and water vapor → greenhouse gases trap heat

• greenhouse effect: the process in which certain gases (carbon dioxide, methane, and water vapor) trap sunlight energy in Earth’s atmosphere as heat

• part of their nutrient cycles → impacted by natural and human-caused changes

  • concentrations increase → earth heats, concentrations decrease → earth cools

Heat Transport in the Biosphere

unequal distribution of heat = global wind and ocean currents

warm rises, cool sinks

→ Global Winds

heated area in warm areas expand and lose density → spreads north and south, losing heat → air cools and becomes denser, sinking → rinse and repeat

between places where are rises and sinks, air travels over the surface, creating winds

→ Ocean Currents

similar to wind process

cold water sinks cs its dense, but: some areas rise tho thru upwelling → surface waters r moved by winds, creating heat in currents → air passing over warm currents pick up heat → water cools

overall, wind and water currents determine humidity, temperature, ocean salinity, etc. and affect land and marine organisms

Energy Flow and Ecosystem Stability

Primary Producers

autotroph: organism that is able to capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer

primary producers: first producer of energy-rich compounds that are later used by other organisms

Energy from the Sun

photosynthetic primary producers (algae, plants, bacteria) get solar energy and use photosynthesis to convert carbon dioxide and water into carbs and oxygen

land → plants; freshwater → plants, algae, bacteria; sunlit water → algae; tidal flats → other kind of photosynthesis w bacteria

Life Without Light

deep dark oceans → water from vents has inorganic compounds like hydrogen sulfide

chemosynthesis: process in which chemical energy is used to produce carbohydrates

• chemosynthetic bacteria around vents live in worms and clams and supply host w carbs

studies underwater helped us realize chemosynthetic primary producers are common and live in many areas

• bacteria thrive in deep dark areas

Consumers

heterotrophs: organism that obtains food by consuming other living things; also called a consumer

consumers: organism that relies on other organisms for its energy and food supply; also called a heterotroph

decomposer: chemically break down organic matter, producing dead and decaying plant/animal matter

• mushroom

herbivore: obtain energy and nutrients by eating plant leaves, roots, seeds, or fruits.

detritivore: chew or grind detritus particles into smaller pieces

carnivore: kill and eat other animals

omnivore: eat both plants and animals

scavenger: animals that consume carcasses of other animals that have been killed by predators or have died of other causes

Food Chains and Food Webs

food chain: a series of steps in an ecosystem in which an organism transfer energy by eating and being eaten

• can be big or small

Food Webs

food web: network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem

→ Food Chains within Food Webs

lots of food chains make up a food web

→ Decomposers and Detritivores in Food Webs

decomposers release nutrients into soil for primary producers

without detritivores, nutrients would remain locked in dead organisms

Food Webs and Ecosystem Stability

difficult to determine stability bc it changes based on seasons, but think of 2 things:

1. the amount the system varies from its average state (variability)

2. the ability of the system to recover from different kinds of disruptions (resilience)

stability = function and energy flow of ecosystem

diversity can affect variability and resilience

• i.e. only one primary producer → environment changes → single food chain horribly disrupted

• multiple producers → “taking over niches” species

ecosystems can pretty easily adapt and recover from short-term natural events

Food Webs and Disruptions

long-term manmade disruptions like climate change or habitat destruction can permanently transform ecosystems

Trophic Levels

trophic level: each step in a food chain or food web

• 1st = primary, rest = consumers

ecological pyramid: illustration of the relative amounts of energy or matter contained within each trophic level in a given food chain or food web

1) Pyramids of Energy

only 10% of the energy that enters any trophic level is available to organisms at the next level because ts organisms mostly spend energy on processes such as respiration, movement, growth, reproduction, released as heat

2) Pyramids of Biomass and 3) Numbers

biomass: total amount of living tissue within a given trophic level

• kind of determined by energy available

• primary producers have most mass, higher consumers have least mass

number of organisms at each trophic level → number pyramid similar to biomass pyramid most ecosystems

• exceptions: consumers r smaller than the organisms they feed upon, like mosquitos on deer or insects biting trees

• same biomass, upsidedown number pyramid

Trophic Levels and Ecosystem Stability

structure determined by interactions between food chains

climate change → more extreme weather events like droughts or floods → disrupt flow of energy and cycling of matter, same for human-caused disruptions

Cycles of Matter

Recycling in the Biosphere

essential nutrients: chemical substance that an organism needs to sustain life

• CHNOPS = carbon, hydrogen, nitrogen, oxygen, phosphorus, sulfur

Biogeochemicals

biogeochemical cycles: process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another

• elements are recycled through all spheres biologically, chemically, and geologically

→ Biological Processes

activities of living organisms → eating, breathing, burning food, eliminating waste products

→ Geological Processes

volcanic eruptions, forming n breaking rock, major movements below surface

→ Chemical and Physical Processes

forming clouds n precipitation, water flow, lightning

→ Human Activity

mining burning fossil fuels, clearing land, burning forests, fertilizers

The Water Cycle

mostly hydrosphere, atmosphere, geosphere, sometimes biosphere

• water travels into atmosphere as water vapor from ocean and lakes (evaporates)

• condenses to form clouds

• precipitation falls

• runoff of water goes back to ocean and lakes

• some groundwater, some transpirtation

The Carbon Cycle

carbon is important bc:

• makes up DNA and RNA

• living tissues, ecosystems, ecosystem stability'

• calcium CARBONate is important for animal skeletons and some rocks

• CARBON dioxide is important for the atmosphere, dissolves in ocean

exchanges thru atmosphere and oceans:

• plants take in CARBON dioxide thru photosynthesis, use carbon to build carbs

• CARBs pass thru food webs to consumers

• animals use CARBON calcium and oxygen to make their skeletons

• organisms release CARBON dioxide thru cellular respiration

• organisms die → decomposers break down into carbon

geologic forces carbon concentration → carbon rock

• carbon dioxide released to atmosphere by volcanoes

• reservoirs found in ocean, rock, fossil fuels

• important for greenhouse gas effect

carbon-containing compounds of ancient organisms can become

• coal'

• oil

• natural gas

• “fossilized carbon” removed from atmosphere by photosynthesis

human activities like burning coal and trees

• disrupts cycle, releases co2 into atmosphere

• more co2, more heat trapped, higher temps, affects ecosystem stability

The Nitrogen Cycle

nitrogen has many uses:

• amino and nucleic acids

• makes up atmosphere

• ammonia, nitrate, and nitrite found in soil, waste, decaying matter

most nitrogen isn’t usable, so:

• nitrogen fixation: process of converting nitrogen gas into nitrogen compound that plants can absorb and use

  • bacterias do this

  • consumers eat producers → new nitrogen compounds

  • decomposers release nitrogen from dead animals

lightning causes atmospheric nitrogen fixation, humans do industrial fixation for fertilizers

denitrification: process by which soil bacteria converts nitrate into nitrogen gas

sm human activities disturb ts

• lots of fertilizers end up in soil and rivers → adding excess nitrogen and nutrients

• encourages more algae and plant growth bc usually not tm nitrogen, but disrupts ecosystem stability

burning fossil fuels also release nitrous oxide into atmosphere → winds carry, contribute to acid rain, affects stability

The Phosphorus Cycle

phosphorus is important cs:

• important for DNA and RNA

• DOESNT cycle through atmosphere

• phosphate rock or dissolved in fresh/salt water

phosphate released as rocks wear down

• cycles bw organisms and soil on land → plants bind into organic compounds

• dissolved phosphate moves into oceans → aquatic organisms use it for biological compounds

• humans use for fertilizer → disruptions

Nutrient Limitation

“The rate at which primary producers create organic material, the long-term survival of species, and ecosystem stability are all dependent on changing resource bases that can be limited.”

• even if sunlight and water r abundant, shortage of one thing like nutrients could affect stability

• limiting nutrient: single essential nutrient that limits productivity of an ecosystem

Nutrient Limitation in Soil

• nutrients work like a gear system - if ur deficient in one, the ecosystem is cooked

• ts explains why farmers use fertilizers bc they have many necessary nutrients for plants

• no carbon cs atmosphere

• tm affects environment tho

Nutrient Limitation in Aquatic Systems

• usually nitrogen is the limiting nutrient esp for algae and plants

• fresh water → phosphorus is limiting

• heavy rain causes fertilizers to run into ocean → disrupts natural delivery, abnormal excess growth of algae and plants in water

  • algal bloom → grow and reproduce far beyond normal rates