Transcript PPT Slide

BIOL 4120: Principles of Ecology
Lecture 5: Biome Concept in
Ecology
Dafeng Hui
Room: Harned Hall 320
Phone: 963-5777
Email: [email protected]
Topics
5.1 Climate is the major determinant of plant growth form
and distribution
5.2 Climate determine the boundaries of terrestrial biomes
5.3 Walter climate diagrams distinguish the major climate
biomes
5.4 Temperate climate zones have average annual
temperature between 5 and 20oC
5. 5 Boreal and polar climate zones have average
temperatures below 5oC
5. 6 Climate zones with tropical latitudes have average
temperatures exceeding 20oC
5.7 Biome concept must be modified for freshwater
aquatic systems
5.8 Marine aquatic systems are classified principally by
water depth
Biomes are classified according to
the predominat plant types and
climate
Concept of Biomes:
F.E. Clements and V.E. Shelford, 1939
Combining broad-scale distribution of both plants and
associated animals into a single classification
Biomes: classified according to the predominant plant
types
Campbell 1996: the world's major communities,
classified according to the predominant vegetation
and characterized by adaptations of organisms to that
particular environment.
Biomes reflect adaptations of dominant
plant life forms
Three general plant forms: trees,
shrubs, and grasses.
Why are there consistent patterns in
the distribution and abundance of
three dominant plant life forms that
relate to climate and physical
environment?
Biomes reflect adaptations of dominant
plant life forms
These three forms represent different patterns of carbon
allocation and morphology
Grasses: less C to production of supporting tissue (stem) than
do wood plants (shrubs and trees), more to photosynthetic
tissues (leaves)
Woody plants: shrubs allocate lower percentage to stem than
trees.
Trees: more to stem, advantage of height and access to light,
cost more for maintenance and respiration.
As environmental conditions become adverse for
photosynthesis (dry, low nutrient, cold T), trees will decline
in both stature and density until they are no longer able to
persist as a component of the plant community.
Forests
Within broad classes of forest and woodland ecosystem (trees
are dominant or co-dominant), leaf form is another
plant characteristic.
Based on longevity of leaf
Deciduous (live for only one year or growing season)
• Winter-deciduous (temperate regions, low winter T)
• Drought-deciduous (subtropical and tropical, leaf shed on
dry periods)
Evergreen (live beyond a year)
• Broadleaf-evergreen (tropic rainforest, no distinct growing
season, year-round photosynthesis)
• Needle-leaf evergreen (growing season is short or
nutrient availability constrains photosynthesis and plant
growth)
Economic model to explain adaptation of leaf form: cost to
produce leaf and gain from photosynthesis.
Concept of Biomes:
Major terrestrial biome types (eight , nine,
and varies):
Tropical forest, temperate forest, conifer forest
(taiga and boreal forest), tropical savanna,
temperate grasslands, chaparral (shrublands),
tundra, and desert.
5.1 Climate is the major determinant of
plant growth form and distribution
Since organisms are adapted to the physical environments of
their biomes, ranges of species are limited by these
physical conditions
In terrestrial environments, temperature and moisture are the
most important variables, particularly for plants.
Related species may differ in their ecological tolerances,
and distribute Differently
5.2 Climate defines the boundaries of terrestrial biomes
(Walter)
Robert Whittaker,
Cornell Uni.
Biomes and
climate
Boundaries
between biomes
are broad and
often indistinct
Other factors:
topography, soils,
and exposure to
disturbances such
as fire
Nashville, TN
Mean temperature: 14.9 oC, annual precipitation: 122.3 cm
Source: US Climate Data
Temperate seasonal forest
Robert Whittaker,
Cornell Uni.
Biomes and
climate
Boundaries
between biomes
are broad and
often indistinct
Other factors:
topography, soils,
and exposure to
disturbances such
as fire
BIOL 4120: Principles of Ecology
Lecture 5: Biome Concept in
Ecology
Dafeng Hui
Room: Harned Hall 320
Phone: 963-5777
Email: [email protected]
Recap
Climate and soil
Soil profile, soil weathering process, soil order
Biomes
Climate is the major determinant of plant growth form and
distribution
Climate determine the boundaries of terrestrial biomes
5.3 Walter climate diagrams
distinguish the major
terrestrial biomes
Precipitation and temperature
interactively determine
biomes
To permit ecologically
meaningful comparisons of
climates between localities,
Walter developed a climate
diagram to illustrate seasonal
periods of water deficit and
abundance.
Each climate zone has
a typical seasonal
patterns of T and P.
5.4 Temperate climate zones have average
annual temperature between 5 and 20oC
Temperate seasonal forest biome (Climate zone VI)
Temperate rain forest biome (Climate zone V)
Temperate grassland/desert biome (Climate zone VII)
Woodland/shrubland biome (climate zone IV)
Subtropical desert biome (climate zone III)
Temperate seasonal forest
Forest ecosystems dominate the wetter regions of
the temperate zone
Deciduous forest covered large area of Europe and
China, but mostly converted to croplands, only
exist in eastern China
North America, deciduous forests consist of a
number of associations (next slide)
Southern Hemisphere, temperate evergreen forest
become predominant
Asiatic broadleaf forest found in eastern China,
Japan, Korea is similar to the North American
deciduous forest
Large scale distribution
of temperate forest in
eastern US
Grassland ecosystems
Rainfall is very important: 250 to 800 mm
Other factors: fire, and human activity
(convert grassland to desert by
overgrazing)
Area: dropped from 42% to <12% of
original size
Location: mid-latitudes in mid-continental
regions
Typical: prairies of North America, steppes
of central Eurasia
Grassland in
North
America
Tallgrass prairie
Big bluestem,
>1m
a. Tallgrass
prairie in
Iowa,
Mixed-grass
prairie
b. mixedgrass
prairie;
Needlegrassgarma grass
c. shortgrass
steppe
Shortgrass prairie
Blue garma and
buffalo grass
Aboveground primary productivity is related to MAP (52 grassland)
Grasslands are most productive when MAP>800 mm and MAT > 15oC
5.4 Temperate climate zones have average
annual temperature between 5 and 20oC
Temperate seasonal forest biome (Climate zone VI)
Temperate rain forest biome (Climate zone V)
Temperate grassland/desert biome (Climate zone VII)
Woodland/shrubland biome (climate zone IV)
Subtropical desert biome (climate zone III)
sclerophyllous: hard-leaved
vegetation
Desert
Area: 25 to 35%
Location: latitudes between 15 and 30o
Cause: Global air mass circulation
T: High in summer, could be cold in winter
PPT: low, <150 mm
Typical examples: majority in Northern
Hemisphere, Sahara in Africa, Gobi in
Asia, western North America
Deserts are not the same everywhere
Cold desert: Great Basin of North America, the Gobi, Takla Makan, and
Turkestan deserts of Asia
Species: sagebrush, shadscale, chenopods, etc
Hot desert: Mojave, the Sonoran, and Chihuahuan
Vegetation: none to some combination of chenopods, dwarf-shrubs,
and succulents
Hot desert: a. Chihuahuan
Desert, b. Great Victorian
Desert in Australia, c. Dunes
in Saudi Arabian desert.
Plants and animals in Desert
Survive of desert plants:
Adapted to scarcity of water, low primary productivity
Flowering only when moisture is present
Fast grow, flower, produce seeds and die
Deep-rooted (mesquite, taproots reach water table)
CAM pathway, special leaf structure
Survive of animals
Support a diversity of animal life (bettles, ants, locusts,
lizards, snakes, birds and mammals)
Grazing herbivores: generalists, consume a wide range of
species.
Desert carnivores, such as fox and coyotes, have mixed
diet include leaves and fruits.
5. 5 Boreal and polar climate zones have
average temperatures below 5oC
Boreal forest biome (Climate zone VIII)
Tundra biome (Climate zone IX)
Black spruce in North America
taiga (boreal forest)
Some coniferous forest. A. Norway spruce, b.
Rocky Mountaine subalpine forest, c. montane
coniferous forest in Rocky Mountains
Arctic Tundra
Tundra is treeless plain
Arctic tundra is a frozen plain, clothed in sedges, heaths, and
willows, dotted with lakes, and crossed by streams
Cold Temperature and low precipitation
Two types:
Polar desert: dry soil, less than 5% plant cover
Wet tundra: up to 100% plant coverage, wet to moist soil
Unique conditions:
permafrost: isolate and protect soil OM
vegetation: simple form, slow growth, allocate more to roots.
Arctic
tundra
Canada
Rocky
Mountains
alpine
tundra
5. 6 Climate zones with tropical latitudes have
average temperatures exceeding 20oC
Tropical rain forest biomes (Climate zone I)
Tropical seasonal forest/savanna biome
(Climate zone II)
Tropic rain forest
Location: Equatorial zone between
latitudes 10 oN and 10 oS
T: warm all year, monthly mean T>20
oC
PPT: Rainfall occurs daily, min.
monthly>60mm
Typical example: Amazon basin of
South America
Recap
Climate zone with temperate climate zones have average
temperatures between 5 and 20 oC
Boreal and polar climate zones have average temperatures
below 5oC
Climate zones with tropical latitudes have average
temperatures exceeding 20oC
Tropic rain forests in
Amazon (a), Malaysia (b),
and Northeast Australia (c)
High net primary
productivity (NPP)
High diversity of plant and
animal life
7% land surface, >50%
plant and animal species
10-km2 contain 1500
species of flowing plants
and 750 tree species.
Richest area in Malaysia,
7900 species
90% of all primate species live
in the tropical rain forest
orangutan (an arboreal ape)
Gibbons, langurs, macaques
(Malaysian)
Gorillas, and chimpanzees
(Africa)
Lemurs
Beetles, butterflies
Vertical stratification of a tropic rain forest
Tropical Savannas
Location: Equatorial zone between
latitudes 30oN and 30oS, Dry tropic
and subtropical.
T: warm all year, annual mean
T>18oC
PPT: distinct seasonality in rainfall,
large interannual variation
Typical example: South America
Tropical Savannas
Savanna: means the treeless areas of South America
Grassland with scattered trees.
Characteristics:
Occur on land surfaces of little relief, often on old plateaus,
dissected by rivers, soil poor in nutrients, especially P
Dominant species are fire-adapted, subjected to recurrent
fires.
Grass cover with or without wood vegetation is always present
Woody component is short-lived (less than a few decades).
Two-layer vertical structure (ground level grass + shrubs or
trees)
Support a large and varies assemblage of herbivores,
invertebrate and vertebrate, grazing and browsing.
Interaction between annual PPT and soil texture in defining biomes
Access by plants to soil moisture is more limited on the heavy
textured soils (clay) than sandy oil.
5.7 Biome concept must be modified
for aquatic systems
Terrestrial biomes: classified by growth form of
dominant vegetation reflects climate conditions.
Aquatic biomes: in many aquatic systems, there is
no “vegetation” form, only algae
Classified primarily by physical characteristics
such as salinity, water movement, and depth
Freshwater aquatic:
 Flowing water: Streams and rivers
 Standing water: lakes and ponds
 Wetlands
 Estuaries
Flowing water: streams and rivers
Lotic systems: flowing fresh
waters, such as streams
and rivers
Streams form wherever P
exceeds ET, and excess
water drains from the land.
Riffles: water runs rapidly
over a rocky substratum
Pools: deeper stretches of
more slowly moving water
Lack richness and diversity
Riparian zone: terrestrial
veg influenced by seasonal
flooding
Allochthonous: organic
material that enters the
aquatic system from the
outside
Autochthonous: home grow
its organic material.
Fluvial systems, as rivers
are sometimes called
Standing water: lakes and ponds
Layers of lake:
Littoral zone
Liminetic or
pelagic zone
Benthic zone
Lentic system: nonflowing water systems, such as lakes and ponds
Wetlands
Wetlands: terrestrial and aquatic communities come together
Lands consisting soil saturated with water and supports vegetation that
specifically adapted.
Include swamps, marshes, bogs (fresh water), salt marshes and
mangrove (associated with marine environments)
Plants can tolerate low O2
Important habits for a wide variety of animals, waterfowl, fish,
invertebrates
Protect coastal areas from ravages of hurricanes
Wetland sediments immobilize potentially toxic or polluting substances
dissolved in water and are thus natural water purifying plants.
Estuaries
Estuaries are
found at the
mouths of river
Mix of fresh and
salt water
Extremely
productivity
systems
Human inputs into freshwater
biomes
Acid rain and eutrophication
1. Acid rain: combustion of fossil fuels, sulfur
dioxide, nitrogen oxides
pH<4 in steams and rivers
2. Eutrophication: addition of limiting nutrients,
such as N, P to aquatic ecosystems.
runoff: sewage, industrial wastes,
fertilizers, animal wastes from agricultural lands.
Oxygen depletion
5.8 Marine aquatic systems are
classified principally by water depth
Variation in marine environments:
temperature, salinity, depth (which influence
light and pressure), currents, substrata and at
the edges of ocean and tides.
Depth:
Littoral zone (intertide zone): extends between
highest and lowest tidal water levels.
Neritic zone: extends to depth of 200m, high
productivity.
Oceanic zone: below neritic, sparse nutrient, low
production.
Benthic zone
Seafloor below
oceanic zone.
Photic zone:
With sufficient
light for
photosynthesis
Aphotic zone: no
light for
photosynthesis
Open ocean === desert
But in:
Coral reefs: shallow water
of warm ocean, T>20oC
year around
very productive and high
diverse
Like tropical rain forest in
terrestrial biome
Problem: global warming,
coral bleaching
Thank you!
Winter-deciduous
Drought-deciduous
Broadleaf evergreen in
tropic rain forest in
Australia
Needle-leaf evergreen in
Sierra Nevada, US
BIOL 4120: Principles of Ecology
Lecture 5: Biome Concept in
Ecology
Dafeng Hui
Room: Harned Hall 320
Phone: 963-5777
Email: [email protected]
Recap
Biomes, concept
Climate is the major determinant of plant growth form and
distribution
Climate determine the boundaries of terrestrial biomes
Walter climate diagrams distinguish the major climate
biomes
Temperate climate zones have average annual temperature
between 5 and 20oC