BIOB50H3 Chapter Notes - Chapter L#4: Advanced Land Observation Satellite, Hightide, Liana
CHAPTER 3: pages 50-78 – THE BIOSPHERE
- biological diversity in central NA (the Great Plains) is much lower than the Serengeti of
Africa (which is very diverse)
- if not for climate change, the ecosystems might be similar 18k years ago, ice sheets
covered NA over last 12k years, ice receded and vegetation grew contained species
of grass, sedges, and low-growing herbaceous plants
animals were greatly different before used to be a large collection megafauna
(species >45kg) similar to Serengeti (included wooly mammoths, horses, camels,
saber-toothed cats, cheetahs, lions etc.) many of the large mammals of NA then
suddenly went extinct
hypothesized that it might have been changes to the climate, that led to changes in
habitat or food supply
oanother hypothesis: arrival of humans may have hastened the demise of
animals controversial
INTRODUCTION
- living things are found in many place eg. Ravens can fly over 26k feet, fangtooth fish
swim 8km below ocean surface
- most living things live in a range of habitats that cover the earth’s surface, and within
200m of the oceans
- the biosphere: the zone of life on Earth, is located between the lithosphere (earth’s
crust) and the troposphere (lowest layer of atmosphere)
TERRESTRIAL BIOMES (3.1)
-Biomes: large-scale biological communities shaped by the physical environment in
which they are found categorized by most common growth forms of plants distributed
across large geographic areas (note: categorization does not take into account
taxonomic relationships among org., instead relies on similarities in the morphological
responses of org. to the physical env.)
- A biome includes similar biotic assemblages on distant continents (w/ similar responses
to climate in diff. locations)
- Biome provides a biological unit for modellers simulating the effects of env. Change on
biological communities
- There are 9 biomes: tropical rainforest, tropical seasonal forest, savanna, desert,
temperate grassland, temperate shurubland and woodland, temperate deciduous
forest, temperate evergreen forest, boreal forest, and tundra
- Terrestrial communities vary a lot (eg. Tropics to cold, dry tundra)
Tropical forests have many green layers, lots of diversity (eg. Borneo 10k plants
species), trees about 75m tall
Polar regions scattered, tiny plants, dry soil about 100 species, plants about 5cm
tall
- Terrestrial biome are classified by the growth form (size and morphology) of the
dominant plants
Characteristics of their leaves (eg. Deciduousness [seasonal shedding of leaves] or
succulence [development of water storage tissues]) can also be used
find more resources at oneclass.com
find more resources at oneclass.com
- Use plants not animals b/c plants are immobile thus: if they are to
successfully live in a site, they must be able to cope w/ its env.
Pressures, and biological pressures (eg. Comp. for nutrients, light etc.)
- Plants have
many diff. growth forms
in response to diff.
selection pressures of the
terrestrial env. eg.
Aridity, temp, solar
radiation, nutrient poor
soils, crowding by
neighbours etc.
eg. Deciduous
leaves protect against
exposure to subfreezing
temp (or dry period),
trees and shrubs invest in
woody bark to increase
height and protect from
damage from snow/wind
perennial grasses keep most of bases underground facilitates
tolerance to subfreezing, dry, fire etc.
- similar plants grow @ similar climates (even if not evolutionarily related)
- evolution of similar growth forms among distantly related species in response to similar
selection patterns is called convergence
Terrestrial biomes reflect global patterns of precipitation and temperature
- tropics (23.5* N and S)have high rainfall and warm temp. in subtropical regions,
rainfall is seasonal, w/ wet and dry seasons
- major deserts are at 30* N and S (zones of high pressure)
and at the rain-shadow effects of mountains
- locations of terrestrial biomes are correlated w/ these
variations in temp. and precipitation
temp. influences plant growth form distribution
temp. + precip. Together influence availability of
water + rate of water loss in plants
water + soil temp. are important in determining the
nutrient level in soil
-association between climate variation and terrestrial
biome distribution can be seen in a graph of temp. vs
precipitation (though this approach fails to take into
account seasonal variation and extreme temp. are greater
determinants of species distribution)
find more resources at oneclass.com
find more resources at oneclass.com
eg grasslands/shrublands actually have greater distribution than graph suggests (can
actually live in regions with more precipitation but drier periods)
The potential distributions of terrestrial biomes
differ from their actual distributions due to human
activities
-land use change: effects of land conversion
and resource extraction done by humans,
whose effects are apparent on the land surface
- earliest forms of humans affecting terrestrial
ecosystems could be 10k years ago setting
fires to forests to increase game population
- last 150 years = worst mechanized
agriculture + logging + exponential increase in
human population (primarily agriculture,
forestry and livestock grazing)
b/c these changes, the potential and
actual distributions of biomes are different
temperate biomes (mostly grasslands)
have been transformed
TROPICAL RAINFORESTS
- found in low-latitude tropics (10*N and S), where precipitation > 79 inches annually
- typically exp.
Warm,
seasonally
invariant
temperatures
abundant precip.
Is spread evenly
through year or
may occur in 2 main peaks, associated with the
movement of the Intertropical Convergence Zone
- seasonal rhythms are typically absent from this biome, and
plants grow continuously during the year
- have lots of plant biomass contain about 50% of Earth’s
species and about 37% of terrestrial pool of Carbon in
about 11% of earth’s terrestrial vegetation cover
-occur in: central and south America, Africa, Australia, and
Southeast Asia
- has lots of broad-leaved evergreen and deciduous trees
- light is key factor in vegetation structure of this biome selection pressure to either
grow taller than neighbouring trees, or to adjust to lack of light
- have 5 layers of plants in this biome
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Chapter 3: pages 50-78 the biosphere biological diversity in central na (the great plains) is much lower than the serengeti of. Animals were greatly different before used to be a large collection megafauna (species >45kg) similar to serengeti (included wooly mammoths, horses, camels, saber-toothed cats, cheetahs, lions etc. ) Many of the large mammals of na then suddenly went extinct. Hypothesized that it might have been changes to the climate, that led to changes in habitat or food supply: another hypothesis: arrival of humans may have hastened the demise of. Introduction animals controversial living things are found in many place eg. ravens can fly over 26k feet, fangtooth fish swim 8km below ocean surface. Most living things live in a range of habitats that cover the earth"s surface, and within. 200m of the oceans the biosphere: the zone of life on earth, is located between the lithosphere (earth"s crust) and the troposphere (lowest layer of atmosphere)
