Chapter 5 How Ecosystems Work

Life depends on the sun!!! Photosynthesis: the process of converting light energy into chemical energy. Carbohydrates and Oxygen (products), sugar and air, help to support all life. Animals eat the plants, and so on, thus energy is transferred through the system Producers: makes its own food (autotrophs) Consumers (heterotrophs): get energy by eating producers

Exception to the rule: deep sea communities! Light is not available here, they do Chemosynthesis (basically using chemicals as a source of initial energy rather than the sun.) What eats What Producers, make their own: examples grass, ferns, trees Consumers, eats producers, there are 5 basic types Herbivore: eat only producers (cows, sheep, deer) Carnivore: eat other consumers (lions, hawks, snakes) Omnivore: eat both producers and consumers (humans, bears, pigs) Decomposer: breaks down organic matter from dead organisms (fungi and bacteria) Detritivores: heat dead things (vultures, crabs) ****not in your book!!!!!

Cellular Respiration: Burning the fuel PS gave us a source for sugars, now to use them CP is the process of breaking down carbohydrates to yield energy. Oxygen needs to be present Basically the reverse of PS

Excess energy is stored as fat Energy is transferred to organisms through a food chain.

Food chain: path of energy flow from one organism to another. Food Web: multiple food chains in an ecosystem Trophic level: each step of a food chain 10% rule: for each trophic level, only 10% of the energy available is passed on, 90% is lost.

4.Tertiary consumers eat secondary consumers. NOT IN YOUR BOOK, BUT EXPECTED TO KNOW!!!! Trophic Levels: The trophic level of an organism is the position it holds in a food chain. 1. Primary producers (organisms that make their own food from sunlight and/or chemical energy from deep sea vents) are the base of every food chain - these organisms are called autotrophs. 2.Primary consumers are animals that eat primary producers; they are also called herbivores (plant-eaters). 3.Secondary consumers eat primary consumers. They are carnivores (meat-eaters) and omnivores (animals that eat both animals and plants). 4.Tertiary consumers eat secondary consumers. 5.Quaternary consumers eat tertiary consumers. 6.Food chains "end" with top predators, animals that have little or no natural enemies.

Energy pyramids Each level represents a trophic level Producers make up the base (where most of energy is found)

The Carbon Cycle Process by which carbon is cycled between the atmosphere, land, water and organisms. Short and long term cycles Short: plants converting to carbs via photosynthesis; release of CO2 in cell respiration Long: carbonates (bones, shells, rock like limestone) The ocean and limestone two largest carbon “sinks” on the planet. How humans effect it: Burning fossil fuels (estimated 8.4 billion metric tons yearly) Cars, fires, etc…. CO2 is a greenhouse gas as well

The nitrogen cycle All organisms need nitrogen to build proteins Nitrogen gas is 78% of the gas in the atmosphere (unusable in this form) The process in which nitrogen is cycled between the atmosphere, soil, and organisms Nitrogen gas must be “fixed” Done so by bacteria (nitrogen-fixing bacteria) Nitrogen is converted to nitrogen oxide, which combined with water makes nitrates Decomposers are important because the can help release nitrogen from wastes and dead organisms.

The Phosphorus Cycle Needed to help form bones and teeth in animals Is the movement of phosphorus from the environment to organisms and then back Rarely occurs as a gas Found mostly in soil/rocks As rocks break down, it is released into the environment Also comes for decaying organisms Not soluble in water, typically settles, forming a layer of sediment These become rock over thousands of years… Think Ashley Phosphate road???? Was a phosphate (phosphorus) mine.

How ecosystems change. Ecological succession: is a gradual process of change and replacement of some or all of the species in a community. May take 1000’s of years As a new community arises it becomes more difficult for the original to survive Over enough time (if undisturbed by man) it will settle so that changes are very small, stable community. Two basic types of succession: Primary and Secondary Primary: previously did not support life. Example: rocks or sand dunes Secondary: occurs where life previously existed. Example natural disasters, or Human activities.

Primary: previously did not support life Primary: previously did not support life. Example: rocks, sand dunes, new islands Can be a very slow process Pioneer species: first species to colonize the new area, typically bacteria or lichens. Over time, they break down rocks, forming soils Remains of these provide nutrients for larger plants to take root.

Secondary: where life was previously Natural disasters Fire PEOPLE Climax community: final stage, stable community (can still change)

Other type of succession Old-field succ. Farmland is abandoned. Then basically same process as secondary. Fire and secondary succession, necessary due to the fact that many plants can’t release seeds with out fire and also an important tool for the environment to return nutrients to the soil