Energy Flow & Roles

Producers a.k.a. autotrophs Can make their own food May use energy from the Sun May use chemical energy (chemosynthesis) Ex. Plants, algae & some types of bacteria

Consumers A.k.a. heterotrophs Include: Herbivores (1st level) …carnivores (2nd level) …omnivores (3rd level) … scavengers (also 3rd level) …decomposers / detritivores (4th level)

Food Chains Must start with a producer – A producer makes it’s own food! Continues to include all levels of consumers Shows WHO eats WHO

Food Webs Several food chains together Shows how every organism is interdependent Everything depends on producers

Energy Pyramid Made of “Trophic Levels” Each step of energy transfer ONLY 10% 90% of Energy is lost as heat or respiration

Producers are at the base Decomposers are at the top Shows DECREASING ENERGY FLOW!!!

Populations

Characteristics of Populations (3 of ‘em!)

1 - Geographic distribution 3 types:

2 - Population Density Low High

3 – Growth Rate: Birthrate Death-rate Immigration Emigration

If birth rate , & death rate Population increases If birth rate & death rate Population decreases

Types of Growth

Has unlimited resources J -shaped Exponential Growth Has unlimited resources J -shaped

Logistic Growth Normal S – shape It stops increasing at carrying capacity

How many organisms a given area can support Determined by: Carrying Capacity How many organisms a given area can support Determined by: Space and food

Limiting Factors LIMIT population growth 2 Types: Density –Dependent & Density-Independent

-1- DD: Competition Food Water Sunlight Space (Valley / mtn./ dam) Soil type

Examples of Competition Male lions for control of female prides plants for water, nutrients and light

-2- DD: Predation Predators eat prey Prey is eaten Predators help the ecosystem by reducing the size of prey populations and….. Allow for BIODIVERSITY

-3- DD: Parasitism & Disease

-4- DD: Stress & Crowding

Density Independent 1. Weather / temperature 2. Natural disaster 3. Seasonal cycles (rainy /drought) 4. Human activities (clear cutting forests, damming rivers)

Human Impact on the Environment Includes: Soil Erosion (from agriculture) Runoff & flooding (thru deforestation) Pollution (untreated sewage)

Interrupting nutrient cycles (burning trash; not recyclable) Population growth (depletes resources)

What is the WORST things humans do???? Habitat destruction!!!! Might be done by invasive species Causes a loss of biodiversity

Succession

Succession The process of how ecosystems form over a long period of time

Begins by hardy invaders called the pioneer species This includes lichens & mosses Progresses to a stable climax community (endpoint of succession)

Two Types

1 -Primary succession no previous growth Requires thousands of years Requires the creation of soil Occurs when new land is formed Ex. after volcanic eruption After a glacier melts

2 - Secondary succession develops after existing ecosystem has been disturbed More rapid – reaches climax within two centuries Ex: forest fire Natural disaster abandoned farm field

Biggest difference between primary and secondary is time, due to the presence/ absence of soil. Soil is made by the decomposition of rock; broken down by lichens and mosses (pioneer species).

Cycles That Occur in Nature

Water cycle Moves between atmosphere, oceans & land 1 – water evaporates from the ocean 2 – water evaporates from the leaves of plants during transpiration

3 - enters atmosphere as a gas (water vapor) 4 – Vapors condense to form clouds 5 – when large enough, water will fall back to earth as precipitation

6 – Water travels as runoff or seepage

7 – Plants remove water from root uptake Water is always equal in the cycle The amount never changes

Concerns (due to humans) Groundwater depletion due to irrigation Unsafe drinking water due to pollution or animal waste (causes 80% of diseases in undeveloped countries)

Carbon cycle

Photosynthesis: CO2 is taken in by plants & converted to sugar

Cellular Respiration: how energy from sugar is released

Erosion & volcanoes: releases CO2 in the air & ocean

Decomposition: carbon is released from dead stuff stored underground as fossil fuels

Human Activities: Mining Burning fossil fuels Cutting / burning down forests **We ADD to the carbon cycle !!

Nitrogen cycle Nitrogen –make up proteins and DNA Where is most of it stored? In the atmosphere!! (79%) Plants and animals cannot take nitrogen from the atmosphere

1. Bacteria converts nitrogen gas (N2) into ammonia in a process called: Ammonification 2. A different bacteria converts ammonia into nitrates and nitrites needed by plants to make proteins process called nitrogen fixation

3. Plants take in nitrogen (as nitrates and nitrites) 4. Consumers (including us) get nitrogen by eating producers 5. Organisms die, they return nitrogen to soil as ammonia

6. Some ammonia may be taken up by producers 7. Nitrates are converted into nitrogen gas by bacteria in a process called denitrification 8. Nitrogen gas returns to the atmosphere

Human activities can also add Nitrogen: Use of fertilizers (travel by runoff) Dumping raw sewage Burning fossil fuels & wood Leads to eutrophication (algal blooms)

Phosphorus Cycle 1 – stored in rock (land & ocean floor) & soil 2 - Released by weathering & erosion 3 – travels in runoff

4 – enters the ocean & gets used by some marine animals 5 – travels through the food web 6 – returned to soil through waste

Why do we need phosphorus? Along with calcium, you need it to make bones #1: it is a part of DNA

Phosphorous Cycle