Principles of Ecology Chapter 13

Ecologists Study Relationships Interactions and Interdependence Ecology – the scientific study of interactions among living things and their surroundings Basically, ecology is the study of nature’s houses. It can involve anything from single cells to entire planets.

Ecologists Study Relationships Biosphere - part of a planet (the earth) in which life exists including land, water, and air A biosphere is the largest of the “houses” in a biosphere. For the earth it can extend from 8 km above the earth to 11 km below the surface of the ocean

Ecologists Study Relationships Populations – individuals that live in the same area Species – a group of individuals that can interbreed

Ecologists Study Relationships Communities – assemblages of different populations that live together Communities are within the ecosystem (Ex. A reef in the ocean)

Ecologists Study Relationships Ecosystem – a collection of all organisms that live in a particular place with their nonliving, or physical environment Scientists often study species, populations, or communities in an ecosystem. the collection of components and processes that comprise, and govern the behavior of, some defined subset of the biosphere. The term is generally understood to refer to all biotic and abiotic components, and their interactions with each other, in some defined area, with no conceptual restrictions on how large or small that area can be. The breakdown is from largest to smallest – communities (assemblages of different populations) to populations (groups of individuals that belong to the same species and live in the same area) to species (A species generally consists of all the individual organisms of a natural population which are able to interbreed, generally sharing similar appearance, characteristics and genetics due to having relatively recent common ancestors.)

Ecologists Study Relationships Levels of Organization Biome – a group of ecosystems that have the same climate and similar dominant communities Within a biosphere is a biome. a biome is a major regional group of distinctive plant and animal communities best adapted to the region's physical natural environment, latitude, altitude, and terrain. A biome is made up of communities at stable steady state and all associated transitional, disturbed, or degraded, vegetation, fauna and soils, but can often be identified by the climax vegetation type.

Ecologists Study Relationships Ecological Methods Observing – first step Long term studies more beneficial-ecological change takes time Surveys Direct Indirect Determining Population Size Catch and release Quadrat Sampling Ecologists can do visual surveys – direct or indirect Direct – used for species that are easy to follow; watch with the naked eye or with tools like binoculars or scopes Indirect – used for species difficult to track; use signs of presence like feces or urine or a recent kill Radio Telemetry – used to monitor populations-animal fit with a radio collar that transmits a radio signal and used to track the animal Catch and release – used to determine population size – catch and mark members of population; then re-catch later and determine number of tagged to untagged Quadrat sampling – dividing the plots into retangular frames-count the number of plants in each plot and then use a computer formula to determine the total number of plants in the entire area

Ecologists Study Relationships Experimenting – used to test hypotheses Can do in the field or lab Lab-more control, not a true reflection Field-More accurate, difficult to determine cause and effect relationships Lab-controlled setting used to focus on a very specific part of the ecosystem Field-performed where the organism lives

Ecologists Study Relationships Modeling – gain insight Computers Mathematical models Use actual data to simulate Data collected using satellite technology

Biotic and Abiotic Factors Living and Non-living components Biotic - living factors Abiotic - nonliving things

Biotic and Abiotic Factors Biodiversity The assortment, or variety of living things Dependent on temperature, moisture Keystone Species – species that have a large impact on ecosystems Rainforests cover less than 7% of the earth’s surface, but contain 50% of the earths plant and animal species Beavers are a keystone species-they build dams which reduce water flow, which allows a greater variety of fish to live in the pond-fish attract birds such as herons and kingfishers-insects live in the trees-these insect attract other birds-shrubs grow on the edges of ponds attracting even more birds-animals that prey on bird eggs or the birds themselves are attracted to the area

Energy in Ecosystems Producers – organisms that make their own food Autotrophs – organisms that use energy from the sun or chemicals to make food All the energy on earth comes from the sun. Only 1% of the energy that comes from the sun that reaches the earth is used by living things for energy.

Energy in Ecosystems Energy from the sun Photosynthesis – Autotrophs use light energy to power chemical reactions that make energy Uses CO2 Makes O2 and Carbs On land, plants are the main autotrophs. In the water, algae is the main photosynthesizer. There are some baceteria (cyanobacteria). Cyanobacteria are major producers in the ocean producing oxygen.

Energy in Ecosystems Life without light One such bond is hydrogen sulfide, or iron monosulfide. Life without light Chemosynthesis – Use chemical energy to make carbohydrates Bacteria deep in the ocean

Energy in Ecosystems Consumers – Organisms that need other organisms for their energy and food supply These are also referred to as heterotrophs

Food Chains and Food Webs Feeding Relationships Food Chains – A series of energy transferring steps

Food Chains and Food Webs Types of heterotrophs Herbivores Energy from eating plants Carnivores Energy from eating animals Omnivores Both plants and animals Detritivores Feed on the remains of dead matter Decomposers Break down organic matter for energy Herbivores – cows, catepillars Carnivores – snakes, dogs, owls Omnivores – humans, bears, crows Detrivores – mites, earthworms, snails, crabs Decomposers – bacteria and fungi

Food Chains and Food Webs Specialist Consumer that primarily eats one specific organism Generalist Have a varying diet Snail kites eat only apple snails for food

Food Chains and Food Webs Trophic Levels – Each step in a food chain or web First level is producers Second level on is consumers-usually herbivores Tertiary consumers are usually carnivores Each consumer depends on the trophic level below it

Food Chains and Food Webs Food Webs – Feeding relationships among many organisms in an ecosystem form a network of interactions Decomposers will convert the dead plant material to detritus - is non-living particulate organic material (as opposed to dissolved organic material). It typically includes the bodies of dead organisms, fragments of organisms or faecal material, and is normally colonised by communities of microorganisms which act to decompose (or remineralize) the material.

Cycling of Matter The Hydrological Cycle (Water Cycle) Evaporation – Water changes from a liquid to a gas Transpiration – Evaporation from the leaves of a plant The water we need cycles between the ocean, atmosphere, and land. Water is evaporated from the ocean. It can also enter the atmosphere by a process called transpiration from plant As the water vapor rises due to heating from the sun, it eventually begins to cool and condensation occurs.

Cycling of Matter Clouds form from tiny drops of water collecting called condensation

Cycling of Matter Recycling in the Biosphere Biogeochemical cycles The transforming of matter by biological systems Energy moves in a one way fashion – Nutrients recycle Energy flows one way in a biosphere; matter is continuously recycled in and between ecosystems. Elements, compounds, and other forms of matter are passed from one organism to another and from part of the biosphere to another. The reason it continues to recycle through the biosphere is that organisms do not use up matter, they transform it. – It is either assembled into body tissues or excreted as waste.

Cycling of Matter Nutrient Cycles Nutrient – All the chemical substances that an organism needs to sustain life Nutrients cycle through an ecosystem just like a biogeochemical cycle.

Cycling of Matter Oxygen Cycle Most organisms use oxygen need oxygen Plants release oxygen Living organisms release carbon dioxide as a waste product

Cycling of Matter The Carbon Cycle Carbon is passed on from one situation to another throughout the biosphere Photosynthesis uses CO2 to make carbs Carbs are eaten by other organisms Organisms exhale CO2 during cellular respiration All organisms eventually decay and the carbon is converted to coal or petroleum Burning things releases stored CO2 into the atmosphere Remember, carbon is one if not the most important element to living things – it makes the macromolecules we need to survive.

Cycling of Matter The Nitrogen Cycle All organisms need nitrogen to make amino acids What do amino acids make? Proteins 78% of Earth’s atmosphere Nitrogen gas (N2) Other types: Ammonia (NH3) Nitrate (NO3) Nitrite (NO2) Nitrogen fixation – N2 to NH3 Denitrification - NO3 to N2 There are many types of naturally occurring nitrogen. Although N gas is the most abundant gas in the atmosphere only a few select bacteria can actually use it directly. They are usually attached to the roots of plants called legumes. They convert nitrogen gas to ammonia through nitrogen fixation Denitrification releases nitrogen from dead plants back into the atmosphere

Cycling of Matter The Phosphorus Cycle DNA and RNA need phosphorus This element does not go into the atmosphere Phosphorus works its way through the food web

Cycling of Matter Nutrient Limitation Ecologists look at the rate of production of producers – Primary Producivity Availability of nutrients can limit an ecosystem Limiting nutrient Ecosystem limited by one nutrient Nitrogen in the ocean is the limiting nutrient 0.00005% nitrogen If runoff causes a drastic increase in nitrogen, then an algae bloom occurs Farmers apply fertilizer because of limiting nutrients Algae bloom becomes a primary producer

Pyramid Models Ecological Pyramids – diagram that shows how much energy is transferred at each trophic level

Pyramid Models Biomass Pyramid Biomass – Total amount of living tissue in a level Represents the amount of potential food available at each trophic level

Pyramid Models Energy Pyramid Only about 10 % of the energy is transferred to the next trophic level More levels means less energy at the last level One tenth of the solar energy captured by grasses ends up stored in the tissues of cows. Only 10% of 10% (1%) is transferred to humans that eat the cow.

Pyramid Models Pyramid Numbers Shows how many individuals there are in each level