Download Spartina anglica - Washington State University

Ecology and the Biosphere
Chapter 50
Ecology - the study of the
interactions between organisms
and their environments
The interactions between
organisms and their environments
determine their distributions and
abundances
• Distribution = geographic range
• abundance=individuals per unit area
• environmental factors
– abiotic - non-living chemical and physical
factors
– biotic - living factors like other organisms
Figure 50.1 Distribution and abundance of the red kangaroo in Australia, based on
aerial surveys
Figure 50.2 Sample questions at different levels of ecology
Examples of ecological
questions:
• How do diving whales select their feeding
areas?
• What processes recycle vital chemical
elements, such as nitrogen, in a savanna
ecosystem
• What factors influence the diversity of tree
species that make up a particular forest
Factors affecting the distribution
of organisms
•
•
•
•
dispersal
behavior and habitat selection
biotic factors
abiotic factors
Biogeography
• The study of past and present distributions
of individual species
• continental drift and barriers contribute to
distinctive floras and faunas of the Earth’s
major regions
Figure 50.4 Biogeographic realms
Dispersal
• Example: Kangaroos may not be in North
America because they historically had no
way of getting there.
• To test this: species transplant experiments
Figure 50.6 Set of transplant experiments for a hypothetical species
• Transplant successful - distribution limited
because of dispersal problems
– inaccessible, not enough time to reach area, not
recognized as suitable living space
• transplant unsuccessful - distribution
limited by biotic or abiotic factors, I.e., for
some reason cannot survive there.
Invasive species
• In modern times, normal restrictions on
dispersal are lifted and invasive species can
proliferate
Figure 50.7 Spread of the African honeybee in the Americas since 1956
Figure 50.8 Expansion of the geographic range of the zebra mussel (Dreissena
polymorpha) since its discovery near Detroit in 1988
Spartina alterniflora and
Spartina anglica
• Saltmarsh grasses
native to the Eastern
U.S. (S. alterniflora)
and British Isles (S.
anglica).
• Invasive species in
Puget Sound and
Willapa Bay in
Washington State.
Spartina are physiologically
resilient and vigorous
• Physiological tolerance
– Wide range of salinities
– Waterlogged soils
• Anoxia
• Hydrogen sulfide
• Fast rate of spread - average 10-20% per
year (can be much greater)
Willapa Bay
• Spartina alterniflora
• 10,000 to 25,000
acres affected
• Nearly 4000 solid
acres
Puget
Sound
• Spartina
anglica
• ≈7000 acres
affected
– Solid acres:
•
•
•
•
Pink=<1
Peach= 1-5
Blue=6-100
Red=>100
1999
Managing the spartina problem
• >$10 million spent since 1990
– Affected areas have increased from a few
thousand to >20,000 acres
• Herbicide and mechanical control
– $2000 per acre per year
Distribution of hydrogen
sulfide in sediments
Oxidized zone
No hydrogen sulfide
Anoxic zone
Hydrogen sulfide-rich
Tolerating anoxic sediments
• Aerenchyma
• Anaerobic
metabolism
– Alcohol
dehydrogenase
• Sulfide
oxidation
Spartina anglica root
Biotic factors affect the
distribution of organisms
• Competition
– interspecific
– intraspecific
• Predation
• Mutualism - species helping each other
Figure 50.9 Predator-removal experiments
Limpet and urchin removal
experiments
• Results show that the herbivores limit the
distribution and abundance of seaweed
• limpets appear to be the main herbivores
• but why is there more seaweed when both
limpets and urchins are removed?
Temperature and water are major
climatic factors determining the
distributions of organisms
• Biome-a major type of ecosystem
Figure 50.10 A climograph for some major kinds of ecosystems (biomes) in North
America
Global climate patterns
Figure 50.12 What causes the seasons?
Figure 50.14 How mountains affect rainfall
Figure 50.15 Lake stratification and seasonal turnover (Layer 1)
• Winter
• cold water at
surface
• warmer deeper in
lake
• Spring - surface water warms and sinks
allowing mixing. Oxygen to bottom waters
and nutrients to surface waters
Summer -thermocline development
summer
• Thermal profile develops
• thermocline -separates cold bottom water
and warm surface water
Figure 50.15 Lake stratification and seasonal turnover (Layer 4)
Fall
• Surface water cools rapidly and sinks
• thermocline disappears
• remixing of lake water
Figure 50.16 Current geographic range and predicted future range for the American
beech (Fagus grandifolia) under two climate-change scenarios
Figure 50.17 The distribution of major aquatic biomes
Figure 50.18 Zonation in a lake
Figure 50.19 Freshwater biomes: Oligotrophic lake (left), eutrophic lake (top right),
stream flowing into a river (bottom right)
Figure 50.20 Damming the Columbia River Basin
Figure 50.21 Wetlands (top) and estuaries (bottom)
Figure 50.22 Zonation in the marine environment
Figure 50.23 Examples of marine biomes
Figure 50.23cx Black smoker
Figure 50.24 The distribution of major terrestrial biomes
Figure 50.25a Tropical forests
Figure 50.25b Savanna
Figure 50.25bx Savanna
Figure 50.25c Deserts
Figure 50.25d Chaparral
Figure 50.25dx Chaparral
Figure 50.25e Temperate grassland
Figure 20.25f Temperate deciduous forest
Figure 20.25g Coniferous forests
Figure 20.25h Tundra
Figure 50.26 A hierarchy of scales for analyzing the geographic distribution of the
moss Tetraphis
Figure 50.27 Most species have small geographic ranges
Figure 50.x1 Patterns of distribution in the biosphere