chapter 4: characteristics in ecosystems - biology 20hillabybiology20.yolasite.com/resources/biology...
TRANSCRIPT
1. ABIOTIC FACTORS IN TERRESTRIAL ECOSYSTEMS
abiotic factors are the non-living components of an ecosystem
affect the type and number of organisms that can live there
Describe abiotic components that cause the two terrestrial
ecosystems below?
2
I. Physiographic Factors
physical features of a geographical area
a) Latitude - higher latitudes: less solar energy input, varied day
lengths with seasons
b) Altitude - higher altitudes: cooler temps, more wind, poorer soil
c) Topography - physical features of land (ex: mountains, river
valleys). May affect precipitation.
3
II. Climatic Factors
a) Light - amount affects the rate of photo-
synthesis and therefore food chains
b) Temperature - limits the type of organisms
that can survive
c) Moisture - certain plants and animals are
adapted to dry environments
d) Wind- affects soil; increases heat and
water loss by organisms
e) Fire - periodic burning is necessary in
some ecosystems ---> unlocks nutrients
stored in biomass of trees; increases
sunlight to forest floor
4
III. Edaphic Factors
factors related to soil
soil contains both organic and inorganic matter
site of decomposition of dead organic matter; matter returns to
producers
vegetation slows soil erosion and prevents water runoff
Abiotic factors are called limiting factors because they restrict or
limit the number and types of organisms able to survive in a particular
environment.
belts of climate determine result in distinct vegetation patterns the
vegetation of a region determines which consumers can and will continue
to exist there
these zones are called biomes
5
2. Abiotic Factors in Fresh Aquatic Ecosystems (p104)
1. Oxygen lakes and ponds get some
O2 from atmosphere, but most from photosynthetic plants
fast flowing rivers get major source of O2 from aeration
lowest acceptable limit is 5 ppm (5 parts of O2 per million parts water)
conc. of O2 in the water decreases as the
temperature increases
6
2. Carbon Dioxide
respiration by living organisms is the major source
the surface contains very little but the bottom has higher levels due to respiration by decomposers; mostly bacteria
3. pH
healthy range is usually between 6.7 to 8.6
acid rain can cause pH levels to drop, making aquatic enviro. unable to support life
4.Temperature
each species has a preferred temp.
with most species, an increase by 5C is harmful
as the water temp goes up, the ability to hold O2 goes down, yet the animal needs more O2 --------> or dies
5. Light
increased light means increased P/S and higher plant productivity 7
3. Structure of Lakes and Ponds
Read pages 105-106 and make notes on Seasonal Variations
in Canadian Lakes: define epilimnion, hypolimnion, thermocline.
(plants have roots)
(light)
(too dark for photosynthesis)
Benthic zone 8
4. Wetlands 9
• Bogs are usually located in regions where temperatures are cool for much of the year
• Marshes and swamps are usually located near coastal areas in warmer climates
• Swamps and marshes differ in the size of plant life they will support
• Marshes have small plants such as reeds, cattails, and grasses
• Swamps contain such larger plants as cypress trees and Spanish moss
• A variety of waterfowl and shorebirds live in swamps and marshes
• These wetlands also provide shelter to animals such as muskrats, frogs, turtles, snakes, alligators, fish, and raccoons
• Large numbers of insects, such as beetles, dragonflies, and
mosquitoes, are common in bogs
• Bogs also have a variety of plants that grow well in the organically
rich, partially decayed plant material called peat
• Peat forms much of the bog soil
• One of the most unusual bog plants is the pitcher plant
10
Section 4.3 Tasks
Read Pages 101-107 in your textbook
Complete Section 4.3 Questions – Page 107 - #’s
1-4, 7
Make some notes on “Seasonal Variations in
Canadian Lakes” – Nelson page 105-106
11
Section 4.3 Questions (Page 107)
1. The amount of organic matter in an ecosystem can increase through
runoff from soil, surface waters, fertilizer use, release of sewage emissions,
litter from plant material, animal wastes, and die-offs of plants and/or
animals, etc.
2. It is possible to have two ecosystems with identical rainfall and
temperature support different plants. For example, Europe and North
America both have deciduous forest ecosystems with similar temperatures
and rainfall. Both have tall trees, shrubs, ferns etc., but since they are in
different geographic locations, the species of each plant type might be
different.
3. The oxygen concentration in the hypolimnion is high initially due to spring
turnover. The oxygen concentration gradually falls as the oxygen is
consumed by bacteria that decompose dead plant and animal materials. In
extreme situations, oxygen may be completely consumed.
12
P107 Continued…
4. The lower, cooler layers of water have no source of oxygen input, so it is
gradually consumed. The surface layers receive more oxygen when wind
and waves disturb the surface, allowing oxygen to dissolve.
7. Trout can exist only in cooler, oxygen-rich waters. They survive below the
thermocline in lakes that stratify and remain high in oxygen, not in
shallower, warmer waters. Catfish are always found close to the bottom
since they are bottom feeders. They can live in shallow, warm waters and
can also tolerate low oxygen levels. Neither of these situations can support
trout.
13
Biotic Potential (p108)
Field mice can reproduce every 6 weeks and can have litters of 6
or more. A population of 20 mice could become 5120 mice in six
months! What factors prevent a population explosion of mice?
Biotic potential is the maximum number of offspring that a
species could produce if resources are unlimited
Regulated by four factors: birth potential (max #/birth),
capacity for survival (# reach reproductive age), breeding
frequency, and length of reproductive life (age of sexual
maturity and # of fertile years)
15
Limiting Factors and Carrying capacity 16
Recall that limiting factors are factors that restrict or limit the
number and types of organisms able to survive in a particular
environment
Limiting factors prevent populations from obtaining their biotic
potential
The carrying capacity is the maximum number of
individuals that can be supported by an ecosystem
At what level do the deer
reach their CARRYING
CAPACITY?
Density-Independent and Density Dependent Factors
17
Density-Independent factors affect a population regardless
of population density
Density-Dependent Factors affect the size of a population as
a result of population density
What are examples for each type of limiting factor? Unsure,
go to page 111, and copy table 2 into your notes!
Tasks to be completed:
Read Section 4.4 in your Text – Pages 108-111
Complete the Section 4.4 Questions – Pages 111-
112 – 1-2, 5
18
Changes in Terrestrial Ecosystems 20
Read Pages 113-115 of your textbook
Write down the main ideas on forestry practices
including clear-cutting, slash-and-burn, and
prescribed burns. Be prepared to discuss the pros
and cons for each technique!
Ecological Succession
The Process of Succession
•Describe the community in the picture on the
right.
•Ecological succession is a community change
in which new populations of organisms gradually
replace existing ones
•Succession occurs from natural causes
(competition, fire, earthquakes, etc) or due to
man (logging, mining, farming etc)
21
Primary Succession
•Succession that begins in an area where there is no existing community
•Causes of prim Succession: volcanic eruption, glacier retreat
•The first group of organisms to occupy an area undergoing primary
succession is called a pioneer community
•Pioneer organisms must be hardy and able to live on minimal resources
•Lichens are pioneer organisms
Primary Succession Animation
22
Steps in Primary Succession:
Soil formation
(lichens die/
break up rock)
Glacier Retreats
exposing Parent rock
Pioneer community
(lichens, mosses)
Enough soil = grasses
out compete lichens
Grasses die = more
soil = shrubs and
weeds take over
Increased soil =
shallow rooted
trees (pine)
Increased pine = more shade =
favorable for deeply rooted plant
(maple/ birch) Climax Community
23
Primary Succession:
Primary Succession Animation
24
Secondary Succession
•Secondary succession: occurs in an area where an existing community has
been partially destroyed
•Examples: Fires, logging, farming
•Occurs more rapidly then primary succession
•A community that achieves relative stability is called a climax community
•Climax communities tend to have greater species diversity than the
communities that precede them
25
Changes in Aquatic Ecosystems
1. Index Species
when water becomes polluted, there tends
to be a shift from MANY species of
moderate population density to a FEW
species of high population density ------>
index species
this decrease in the diversity of species
present is the best indicator of pollution
2. Eutrophication
definition: the natural process of SLOWLY
aging or increasing productivity of a body of
water
26
pollution increases the natural eutrophication process of water. Why?
Unnatural Eutrophication: a process in which nutrient runoff
from agricultural lands or livestock operations causes photosynthetic
organisms in ponds and lakes to multiply rapidly
Human-caused eutrophication wiped out fisheries in Lake Erie in the
1950s and 1960s
27
28
High levels of P
and N containing
compounds
(fertilizers/
detergents)
Algal Bloom
LAKE EUTROPHICATION
Algae die = food
for decomposers =
population grows
Decomposers break down material
and use up oxygen in lake
Low oxygen = other
organisms die out
•Water in which oxygen becomes too low to support animal life is called
eutrophic
•To protect Canadian lakes, ponds, and streams from becoming eutrophic,
some states no longer allow the sale of detergents containing phosphorus
compounds
•Dr. David Schindler is an ecologist who worked
at the Experimental Lakes Project in northern
Ontario
–He performed
several classic
experiments on
eutrophication that led
to the ban on
phosphates in
detergents
30
Classification of lakes by the nutrient input which also
determines the primary producers.
Oligotrophic lake: Nutrient-poor, photosynthesis-limited, clear water,
O2 rich.
Eutrophic lake: Nutrient-rich, high photosynthesis, murky water, O2
poor.
31
Tasks to be completed:
Read Chapter 4.5 in your textbook – Pages 113-121
Make your own notes on:
Forestry Practices – page 113 – 114
The effects of fire – page 115
Indicators of Water Quality – Pages 117
Biological Oxygen Demand (BOD) – Page 118
Complete Section 4.5 Questions – Page 122 – #5
Chapter 4 Review: P130 #1-8
32