BIOL 4120: Principles of Ecology Lecture 22: Biogeographical Ecology

1
BIOL 4120 Principles of Ecology Lecture 22
Biogeographical Ecology

• Dafeng Hui
• Room Harned Hall 320
• Phone [phone]
• Email dhui_at_tnstate.edu

2
23 Terrestrial Ecosystems
23.1 Biomes and climate 23.2 Tropical forests
(Equatorial zone) 23.3 Tropical savannas
(semiarid regions with seasonal rainfall) 23.4
Desert 23.5 Temperate zone (Mediterranean
climate) 23.6 Forest ecosystems (Temperate wetter
regions) 23.7 Grassland ecosystems (Temperate
zone vary with climate and geography 23.8 Conifer
forests (cool temperature and boreal zones) 23.9
Arctic tundra (cold temperatures and low
precipitation)
3
Biomes are classified according to the predominat
plant types
4
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. Major terrestrial biome
types Tropic forest, temperate forest, conifer
forest (taiga and boreal forest), tropical
savanna, temperate grasslands, chaparral
(shrublands), tundra, and desert. three
general plant forms trees, shrubs, and grasses.
5
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
6
23.1 Terrestrial ecosystems reflect adaptations
of dominant plant life forms

• Why are there consistent patterns in the
  distribution and abundance of three dominant
  plant life forms that relate to climate and
  physical environment?

7
Terrestrial ecosystems reflect adaptations of
dominant plant life forms

• These three forms represent different patterns of
  carbon allocation and morphology
• Grass 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.

8
Forests

• Within broad classes of forest and woodland
  ecosystem (trees are dominant or co-dominant),
  leaf form is another plant characteristic.
• Based on longevity
• 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.

9
Ecosystems characteristic of warm, wet climates
with no distinct seasonality are dominated by
broadleaf evergreen trees (tropic or subtropical
rain forest). As conditions become drier, with a
distinct dry season, broadleaf evergreen habit
gives way to drought-deciduous trees (seasonal
tropical forest) As PPT declines further, trees
decline and giving rise to woodland and savannas
(shrub and grasses). PPT further declines, no
trees can be supported, giving rise to arid
shrubland and desert. Similar for T control.
10
Winter-deciduous
Drought-deciduous
11
Broadleaf evergreen in tropic rain forest in
Australia
Needle-leaf evergreen in Sierra Nevada, US
12
23.2 Tropic rain forest

• Location Equatorial zone between latitudes 10oN
  and 10oS
• T warm all year, annual mean Tgt18oC
• PPT rainfall occurs daily, min. monthlygt60mm
• Typical example Amazon basin of South America

13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
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, gt50 plant and
animal species 10-km2 contain 1500 species of
flowing plants and 750 tree species. Richest
area in Malaysia, 7900 species
17
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
18
Vertical stratification of a tropic rain forest
19
Plank-like buttresses
20
Tropical dry forest drought-deciduous
trees Africa, South America, Central America,
Australia, India, Southeast Asia
Undergo a dry season, influenced by the seasonal
migration of Intertropical Convergence Zone
(ITCZ)
21
23.3 Tropic Savannas

• Location Equatorial zone between latitudes 30oN
  and 30oS, Dry tropic and subtropical.
• T warm all year, annual mean Tgt18oC
• PPT distinct seasonality in rainfall, large
  interannual variation
• Typical example South America

22
(No Transcript)
23
Tropic Savannas

• Savanna means the treeless areas of South
  America
• An array of vegetation types representing a
  continuum of increasing cover of woody
  vegetation, from open grassland to widely spaced
  shrubs or trees to woodland
• Characteristics
• Occur on land surfaces of little relief, often on
  old plateaus, interrupted by escarpments and
  dissected by rivers
• 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-lay vertical structure (ground level grass
  shrubs or trees)
• Support a large and varies assemblage of
  herbvores, invertebrate and vertebrate, grazing
  and browsing.

24
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.
25
23.4 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, lt150 mm
• Typical examples majority in Northern
  Hemisphere, Sahara in Africa, Gobi in Asia,
  western North America

26
(No Transcript)
27
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
28
Hot desert a. Chihuahuan Desert, b. Great
Victorian Desert in Australia, c. Dunes in Saudi
Arabian desert.
29
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, species 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.

30
23.5 Temperate shrublands

• Shrublands shrub is dominant or co-dominant, but
  difficult to categorize
• Shrub no good definition, a plant with multiple
  woody, persistent stems but no central trunk and
  a height from 4.5 to 8 m.
• (Tree can grow less than 8m under severe
  environmental conditions)

31
Temperate shrublands

• Location between latitudes 30o and 40o, five
  regions
• T hot dry summers, cool, moist winters
• PPT 65 annual PPT falls during winter months.
• Five regions semiarid region of western North
  America, regions bordering Mediterranean Sea,
  central Chile, cape region of south Africa,
  south-western and southern Australia

32
(No Transcript)
33
Chaparral is the dominant mediterranean shrub
vegetation of southern California
Mediterranean vegetation (fynbos) of the western
cape region of South Africa
34
23.6 Forest Ecosystems

• 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
• Southern Hemisphere, temperate evergreen forest
  become predominant
• North America, deciduous forests consist of a
  number of associations (show later)
• Asiatic broadleaf forest found in eastern China,
  Japan, Korea is similar to the North American
  deciduous forest

35
(No Transcript)
36
Large scale distribution of temperature forest in
eastern US (showed before?)
37
Temperate forest in fall and spring
38
23.7 Grassland ecosystems

• Rainfall is very important 250 to 800 mm
• Other factors fire, and human activity (convert
  from forest to grassland)
• Area dropped from 42 to lt12 of original size
• Location mid-latitudes in mid-continental
  regions
• Typical prairies of North America, steppes of
  central Eurasia

39
(No Transcript)
40
Grassland in North America a. Tallgrass prairie
in Iowa, b. mixed-grass prairie c. shortgrass
steppe
Tallgrass prairie Big bluestem, gt1m Mixed-grass
prairie Needlegrass-grama grass Shortgrass
prairie Blue grama and buffalo grass
41
Aboveground primary productivity is related to
MAP (52 grassland) Grasslands are most productive
when MAPgt800 mm and MAT gt 15oC
42
23.8 Conifer forests

• Conifer forests needle-leaf evergreen
• Location Northern Hemisphere and mountain ranges
• Various composition wide range of climate they
  can grow
• Europe Norway spruce
• North America Rocky Engelmann spruce, subalpine
  fir Douglas-fir, ponderosa pine, lodgepool pine
  giant sequoia (in California Sierra)
• Boreal forest (11 of Earths land surface)
• Alaska and Canada in N. America, Euroasia
  (from Scotland to northern Japan)

43
(No Transcript)
44
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
45
23.9 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
• tundra up to 100 plant coverage, wet to moist
  soil
• polar desert dry soil, less than 5 plant cover
• Unique conditions
• permafrost isolate and protect soil OM
• vegetation simple form, slow growth, allocate
  more to roots
• transfer of heat

46
(No Transcript)
47
(No Transcript)
48
(No Transcript)
49
Principles of Ecology
What we covered in this course Ecology is study
of interaction of Organisms and environmental
conditions Organisms adaptation and evolution,
life history Environmental conditions Climate,
terrestrial and aquatic environments Subdisplinary
of ecology Population ecology growth,
competition, predation, parasitism Community
ecology structure and dynamics, influence
factors Ecosystem ecology Ecosystem energetic,
decomposition, biogeochemical cycle Global change
ecology climate change and ecosystem researches
Others biogeography, human ecology
50
Thank you!
51
(No Transcript)