Transcript Ecology ppt - Glasgow Independent Schools

Introduction to Ecology:
The Biosphere
A. Interactions and Interdependence
1. Ecology: the scientific study of interactions
among organisms and between organisms
and their environment
2. Biosphere: portions of the Earth in which
all of life exists, includes land, water and air
a) Ranges from surface to 8 km above and 11 km
below
Levels of Organization
Biosphere
The part of Earth
that contains all
ecosystems
Biosphere
Ecosystem Community and
its nonliving
surroundings
Hawk, snake, bison, prairie dog, grass, stream, rocks, air
Community Populations that
live together in a
defined area
Hawk, snake, bison, prairie dog, grass
Population
Group of
organisms of one
type that live in
the same area
Bison herd
Organism Individual living
thing
Bison
Tissues, organs,
Groups of and organ systems
Cells
Brain
Nervous tissue
Cells
Nervous system
Smallest functional
unit of life
Nerve cell
Groups of atoms;
smallest unit of
Molecules most chemical
compounds
Water
DNA
Section 3-1
Producers
1. The Sun is the main energy source for life
on Earth.
– Less than 1% of all sunlight is used by living
things.
2. Some organisms rely on the energy stored
in inorganic chemical compounds
(chemosynthesis)
3. Autotrophs can capture energy from
sunlight or chemicals to produce food
(plants, some algae and bacteria).
a) Energy is used to combine simple
inorganic compounds into complex
organic molecules
a) Resulting organic molecules combine and
recombine to make living tissue.
b) Photosynthesis: light energy used to power
chemical reactions that convert CO2 and
H2O into O2 and carbohydrates (such as
sugar and starch)
1) Photosynthesis is responsible for adding
oxygen and removing CO2 from the
atmosphere.
2) Performed by plants, algae and some
bacteria (ex:cyanobacteria)
c) Chemosynthesis uses energy within
chemical bonds of inorganic molecules to
produce carbohydrates
1) performed by several types of bacteria
Consumers
1. Heterotrophs rely on other organisms for
their energy needs
a) herbivores consume plants
b) carnivores consume animals
c) omnivores consume plants and animals
d) detritivores consume organic remains
and dead matter
e) decomposers break down organic
matter
Feeding Relationships
1. Energy flows in one direction through an
ecosystem, from the sun or inorganic
compounds to producers (organisms that
can make their own food) through various
levels to consumers (organisms that rely on
other organisms for food).
Your body gets the energy and materials it
needs for growth and repair from the foods
you eat.
2. Food Chain: a series of steps in which
organisms transfer energy through feeding
Food
Chains
3. Food Web: demonstrates the complex
interactions between the organisms in food
chains in an ecosystem.
• The base of a food web is occupied mostly by
vegetation (producers) and fine organic debris
(decomposers).
• Herbivores (primary consumers) and carnivores
(secondary consumers) occupy the higher
levels.
• Omnivores occupy an intermediate level in the
food web.
4. Trophic level: each step in a food chain or
food web.
D. Ecological Pyramids
Shows the relative amounts of energy or matter
contained within each trophic level.
1. Energy Pyramid
a) Only ~ 10% of the energy in a trophic level can
be transferred to the next level (can range from
0.05 to 20%
b) The more levels that exist between a producer
and a top-level consumer the less energy
remains from the original amount.
2. Biomass Pyramid
a) Biomass: the total amount of living tissue
within a trophic level.
b) represents the amount of potential food
available for each trophic level
3. Pyramid of Numbers
a) Based on the actual numbers of organisms
at each trophic level.
Energy Pyramids
Energy Pyramid
Shows the relative amount of
energy available at each trophic
level. Organisms use about 10
percent of this
energy for
life processes.
The rest is lost
as heat.
Biomass Pyramid
Represents the amount of
living organic matter at each
trophic level. Typically, the
greatest biomass is at the
base of the pyramid.
Pyramid of Numbers
Shows the relative
number of individual
organisms at each
trophic level.
III. Cycles of Matter
A. Recycling in Biosphere
1. Matter is recycled within and between
ecosystems.
a) Biogeochemical cycles: connect biologic,
geologic and chemical portions of the
biosphere through the conversion of
elements, chemical compounds and other
matter between organisms and their
environment.
b) Matter can cycle because biologic systems
do not use up matter – they transfer it into
living tissue or pass it as waste products
B. The Water Cycle
1. The process by which water is moved through
the biosphere
a) Evaporation: water changes to gaseous form by
absorbing energy
b) Transpiration: loss of water through leaves due
to evaporation
c) Condensation: changing of water from gas to
liquid by releasing energy
d) Precipitation: movement of water from
atmosphere to surface as rain, snow, hail or
sleet.
• It is estimated that a single drop of water
can take 4000 years to complete the water
cycle.
Water Cycle
Condensation
Precipitation
Evaporation
Transpiration
Runoff
Seepage
Root
Uptake
C. Nutrient Cycles
1. Nutrient: chemical substances required for
life functions and growth
a) nutrients are passed between organisms
and the environment through
biogeochemical cycles
1) Prevents dangerous levels of nutrients (too
high to too low)
2. Carbon Cycle
Important because carbon is the key
ingredient in all living organisms
a) Less than 1% of all C on Earth circulates
in the biosphere
1) ~ 71% in oceans as CO3 and Ca(CO3)2,
22% in fossilized carbon
b) 4 main processes for carbon cycling
1) Biological processes (e.g.: photosynthesis,
respiration, decomposition)
2) Geological processes (e.g.: volcanic
outgassing, absorption in
ocean/precipitation)
3) Mixed biogeochemical processes (e.g.:
creation of fossil fuels, limestone)
4) Human activity (e.g.: mining, burning of
fossil fuels and forests)
Carbon Cycle
CO2 in
Atmosphere
CO2 in Ocean
Global Warming
• Global warming is an observed increase in the
average temperature of the Earth's atmosphere and
oceans.
• Part of this increase may be due to natural
processes, and would have occurred
independently of human activity.
• The remainder is due to a human-induced
intensification of the greenhouse effect.
– The increased volumes of carbon dioxide and other
greenhouse gases released by the burning of fossil
fuels, land clearing and agriculture, and other human
activities, are the primary sources of human-induced
warming
Greenhouse Effect
• Greenhouse gases (GHG) are gaseous
components of the atmosphere that
contribute to the greenhouse effect.
• The major natural greenhouse gases are
water vapor (36-70% of the greenhouse
effect); carbon dioxide (9-26%); and ozone
(3-7%)
3. Nitrogen Cycle
Important because N is used to make amino
acids which are used to build proteins.
a) Occurs in many forms, 78% as nitrogen
gas (N2)
1) Ammonia (NH3), nitrate ions (NO3-) and
nitrite ions (NO2-) from dead and decaying
matter.
b) Nitrogen fixation: conversion of N2 (gas)
into NH3 by bacteria in soil or on legumes
(roots of certain plants)
1) Decomposers further converted NO3- and
NO2- ions which can be used by producers
to make proteins.
• C) decomposers return nitrates to soil as
ammonia to be used again
• D) soil bacteria convert nitrates into N2
(denitrification)
Nitrogen Cycle
N2 in Atmosphere
NH3
NO3and NO2-
4. Phosphorus Cycle
Important because used in DNA and RNA
a) Not very common, found in rock and soil
minerals and ocean sediments
1) Note that it is not found in the atmosphere
b) As rocks and sediments erode, phosphate is
released and may be dissolved in water
1) Used by marine organisms in the oceans
2) Some phosphate remains on land and
cycles between organisms and the soil
i) Plants absorb phosphate and bind it into
organic compounds
ii) Organic compounds move through the
food web
5. Nutrient Limitation
a) Primary productivity: rate at which
organic matter is created by producers.
1) Depends on recycling of available nutrients
– if any are in short supply it will limit an
organisms growth.
b) Limiting nutrient: a nutrient that is scare or
cycles very slowly and limits growth in an
ecosystem.
1) Fertilizer used to compensate for limiting
nutrients (N,P and K)
c) Oceans are (by their nature) nutrient-poor
compared to the land.
1) Algal bloom: an increase in the amount of algae
and other producers due to an increase of
limiting nutrient(s).
i) If there are not enough consumers, an algal bloom
can upset the health of an ecosystem by oxygen
depletion from bacteria during decomposition of
dead algae.