Environmental Science: Chapter 4 Ecosystems: How they change.
-
Upload
dorothy-stevens -
Category
Documents
-
view
224 -
download
1
Transcript of Environmental Science: Chapter 4 Ecosystems: How they change.
![Page 1: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/1.jpg)
Environmental Science: Chapter 4
Ecosystems: How they change
![Page 2: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/2.jpg)
Biotic Potential Vs. Environmental Resistance
![Page 3: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/3.jpg)
Predator-prey Balance:Wolves and Moose
![Page 4: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/4.jpg)
Steps in predation
Encounter
Attack
Capture
Ingestion
![Page 5: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/5.jpg)
Encounter
Ambush: Wait for prey to come to you. Burst speed. Pike, muskie, barracuda, gar
Rover: Actively search for food. Constant motion. Bass, yellow perch
http://fcn.state.fl.us/fwc/fishing/Fishes/gar.html
Lepisosteus osseus
![Page 6: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/6.jpg)
Attack: forward (most fish) or sideways (gar) lunge special grasping organs
http://insects.ummz.lsa.umich.edu/michodo/test/index.htm
Odonate larvae mentum extends to grasp prey
Capture:
prey have adaptation to avoid capture piscivores have lots of teeth
![Page 7: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/7.jpg)
Blue Whale 100 ft, up to 220 tons
http://www.calpoly.edu/~jiturrir/ED480/whales/baleen.html
predator – prey sizes
http://bio-images.bgsu.edu
~ 1mm
![Page 8: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/8.jpg)
Other factors effect population levels; ex. parasitism, weather
Time po
pu
lati
on
siz
e
predation
parasitism
Time po
pu
lati
on
siz
e
![Page 9: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/9.jpg)
Mechanisms of Population Equilibrium: Plant-Herbivore
![Page 10: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/10.jpg)
-Livestock grazing occurs on more federal public lands than any other commercial use
-Affects more than 260 million acres – an area the size of Texas and California combined
-Water diversions, predator control, vegetation manipulation and fencing
-In the US, livestock grazing has contributed to the listing of 22 percent of federal threatened and endangered species (almost equal to logging (12 percent) and mining (11 percent) combined)
Livestock grazing in western US
![Page 11: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/11.jpg)
=
Selective feedersMigratory
Non-selective Non-migratory
![Page 12: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/12.jpg)
Interactions between species: competition vs predation
resource consumer
+
-
predation
+
+
competition-
--
![Page 13: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/13.jpg)
intraspecific competition: between members of same spp
density dependent population regulation evolutionary change
Time
po
pu
lati
on
siz
e
K= # that resources can support
resources scarce, competition
![Page 14: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/14.jpg)
interspecific competition: occurs between members of different species
negative effect on both populations depends on adaptations of each population
spp 1 niche spp 2 niche
competition
realized niche
![Page 15: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/15.jpg)
Dry habitat, trees can’t compete w/ grass
![Page 16: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/16.jpg)
Territoriality: defense of a resource against individuals of the same species
-Examples: wolves, songbirds, bluegill
-Means habitat supports fewer individuals and less competition is result
![Page 17: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/17.jpg)
Tipping the Balance: Introduced Species
http://www.gdaywa.com/g5.php
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/AustralianRabbits.jpg
![Page 18: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/18.jpg)
-By 1940, three and a half billion American chestnuts had perished.
-American chestnut stock advertised as "blight free", means it was grown in an area where no blight is present, outside the natural range or inside a greenhouse.
Chestnut Blight
-Fungus which entered US on Asian nursery stock imported to New York ~ 1900
-Spread by wind, rain, birds etc…, enters through cracks or wounds, multiplies rapidly, making sunken cankers which expand and kill everything above the canker
-American chestnut was devastated throughout the natural range, the Appalachian hills and highlands from Maine to Georgia
![Page 19: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/19.jpg)
Introduced Species
• Why have these introductions resulted in a degradation of the ecosystems? (Think in terms of environmental resistance and biotic potential.)
![Page 20: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/20.jpg)
Disturbance and Succession
Equilibrium = No change
![Page 21: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/21.jpg)
• Ecological succession: transition between biotic communities– Primary- no previous biotic community– Secondary- previously occupied by a
community– Aquatic- transition from pond or lake to
terrestrial community
![Page 22: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/22.jpg)
Primary Succession
• Mosses invade an area and provide a place for soil to accumulate.
• Larger plants germinate in the new soil layer resulting in additional soil formation.
• Eventually shrubs and trees will invade the area.
![Page 23: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/23.jpg)
Relies on adjacent ecosystems
Rain of organic material, seeds, and spores accumulates in cracks
Some pockets moist enough to support scattered `ohi`a seedlings and a few hardy ferns and shrubs
Accumulation leaves, bark… converted by soil organisms into a thin but rich organic soil
A forest can develop in wet regions in less than 150 years
Dramatic examples: HI lava flows
![Page 24: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/24.jpg)
Aquatic Succession
![Page 25: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/25.jpg)
•Ecosystems can show resilience during a disturbance
Fire
![Page 26: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/26.jpg)
Disturbance
• Removes organisms, favors tolerant spp.
• Reduces populations
• Creates opportunities for other species to colonize
![Page 27: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/27.jpg)
Fire and Succession
• Fire climax ecosystems: maintained by fire; e.g., grasslands, pine and redwood forests
• What significance does this have for humans and where they live?
![Page 28: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/28.jpg)
Resilience Mechanisms After A Forest Fire
• Nutrient release to soil• Re-growth by remnant roots and seeds• Invasions from neighboring ecosystems• Rapid restoration of energy flow and nutrient
cycling
![Page 29: Environmental Science: Chapter 4 Ecosystems: How they change.](https://reader035.fdocuments.us/reader035/viewer/2022062308/56649ced5503460f949baa10/html5/thumbnails/29.jpg)
Ecosystem management: thinking about the entire system rather than trying to maximize harvest of few populations
Adaptive management: 1) be prepared to chance policy 2) bring in stakeholders 3) do experiments