Environmental Science 1021F/G Lecture Notes - Algae, Commensalism, Interspecific Competition

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ES1021G Lecture 4 February 5,
Biomes, Ecoregions and Ecozones (Freedman Chapter 8)
Earth’s major biomes and their characteristics
A biome is a geographically extensive ecosystem, occurring wherever environmental
conditions are suitable for its development (climatic conditions –ex. rainfall)
Biomes are characterized/identified by their dominant life forms; not by the species
that occur there. E.g. forest biomes are characterized by an abundance of trees
At far-flung parts of biomes, different species may dominate the
ecosystem – boreal forest ecosystem, at the northern border has different
species then the southern border. Species may not be similar to each
other, but have the same function
They may not even be closely related, but are similar in form and function
because of convergent evolution
Temperate – direct seasonality UWO campus in in temperate deciduous)
Boreal forest – coniferous trees, compared to temperate deciduous forests that
lose their leaves in the fall
ES1021F Lecture 4 October 5, 2011
Tundra – near arctic environment, low vegetation across many kinds of species
Desert different from savanna – desert is short grasses, dry; while savanna think
Very complex zonation of biomes – not only across land, but zonation can also occur
as you increase in elevation above sea level.
The occurrence of biomes is determined by the environmental regime in which they
oTerrestrial biomes are primarily influenced by temperature and precipitation
oFreshwater biomes are mostly affected by nutrient availability, water
transparency ( how deep can sunlight penetrate water), and depth (Erie is
more susceptible to eutrophication because it is not as deep, so it heats up
faster, causing algal blooms)
oMarine biomes are affected by nutrients and physical oceanography
ES1021G Lecture 4 February 5,
^ label it exam question – how the terrestrial biomes are zoned according to mean
annual temp. and precip. levels
Major terrestrial biomes
Tundra – vegetation of short stature, occurring at high latitude (arctic) and high altitude
(alpine)- short grasses, small plants
Boreal forest – northern subarctic (below latitudes of arctic) forest, usually dominated by
coniferous trees
Montane forest – a subalpine analogue of the boreal (higher altitudes, similar to boreal,
but altitudes are different) – lower down mountain then alpine tundra
Temperate forest – angiosperm-dominated forest (trees that flower) of intermediate
latitudes (seasonality) – can contain coniferous trees as well as deciduous that have a
distinct flower or seed
Temperate rainforest – old-growth coniferous forest in a high-rainfall climate (such high
rainfall that no longer have flowering trees)
Temperate grassland – short-, mixed-, and tall-grass prairie types are limited by soil
moisture (grasslands have deep soils, good for growing crops)
Desert – sparsely vegetated because of dry conditions (short plants, or plants that have
adapted to low precip. areas)- lowest biodiversity (even lower then tundra because
tundra has soil where microorganisms can grow, while dessert is sandy)
Tropical forest – various kinds of low-latitude forests in a warm, humid climate and
supporting extremely rich biodiversity (highest biodiversity of all terrestrial biomes)
Freshwater biomes (EXAM Q)
(not as extreme ends of the spectrum as terrestrial because water is more stable
then air, so enviro can only change so much)
Lentic – lakes and ponds
Lotic – rivers and streams
Wetlands (or mires) – shallow, continuously or seasonally wet habitats (waterlogged-
water table very high) [in between terrestrial and freshwater biomes, so factors that
affect both kinds of biomes effect wetlands]
oMarsh – highly productive and dominated by reed, cat-tail, bulrush, or other
tall graminoids (high level of biomass – productive ecosystem)
oSwamp – productive and dominated by tall shrubs or trees (trees here have
adapted by keeping some of their rots above water to allow for aeration)