Ek & Ruda · Title: Microsoft Word - Ek & Ruda.doc Author: Kardell Created Date: 7/26/2004 4:30:00 PM
EK 4.C.4 The diversity of species within an ecosystem may influence the stability of the ecosystem
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Transcript of EK 4.C.4 The diversity of species within an ecosystem may influence the stability of the ecosystem
Biomes & Succession
EK 4.C.4 The diversity of species within an
ecosystem may influence the stability of the
ecosystem
The biosphere is divided into regions called BIOMES that exhibit common environmental characteristics.
Each biome is occupied by unique communities or ecosystems of plants and animals that share adaptations which promote survival within a biome.
Biomes
High temperatures and heavy rainfall
Tall trees with wide canopy that allows little light to reach forest floor
Epiphytes – vines that grow on trees to reach the sun
Tropical Rainforest
Grasslands with scattered trees
Tropical regions – high temperature but receive much less water than a rainforest
Hi Temp & Lo Water
Savannas
Receive less water than savannas
Lower temperatures than savannas
Temperate Grasslands
Warm summers, cold winters, and moderate precipitation
Deciduous trees shed their leaves during the winter
Temperate Deciduous Forrest
Hot & dry
Growth of annual plants is limited to short periods following rains
Plants and animals adapt to hot dry conditions
Deserts
Coniferous forests
Winters are cold
Precipitation is in the form of snow
Taigas
Ground freezing winters
Thawing of upper soil layers in summer results in soggy soil
Permafrost – deep soil is permanently frozen
Tundra
Ponds, lakes, streams and rivers
Fresh Water Biomes
Estuaries, intertidal zones, continental shelves, coral reefs, and pelagic ocean
Marine Biomes
The change in composition of species over time.
Describes how one community with certain species is gradually and predictable replaced by another community consisting of different species.
As succession progresses, species diversity and total biomass increase.
Climax Community – final successional stage of constant species composition is attained which remains unchanged until destroyed by some catastrophic event.
Ecological Succession
Physical and biological conditions influence the pace of succession – in both cases, the conditions which make a habitat attractive to resident species may no longer exist, making the habitat more favorable to a new species. Changes include:Substrate texture – change from solid rock, to sand, to
fertile soilSoil pH – decrease due to the decomposition of organic
matterSoil water potential – ability to retain water varies based
on substrateLight availability – full sunlight to partly shady to total
shadeCrowding – increases with population growth
Ecological Succession
Occurs on substrates that never previously supported living things.
Occurs on volcanic islands, on lava flows, on rock left behind by retreating glaciers
The first organisms to colonize a newly exposed habitat are called pioneer species
Primary Succession
Primary Succession Rock & Lava
1st pioneer species is typically lichens; hyphae of fungal component holds onto rock and absorbs moisture; lichen secretes acid which breaks down rock into soil; as soil accumulates more and more species can move in
R-selected species will be replaced by K-selected species
Primary SuccessionSand Dunes – begins
with the appearance of grasses adapted to taking root in shifting sands; grasses stabilize sand to allow for new species to follow
Dunes of Lake Michigan are an example
Secondary Succession
Process begins in habitats where communities were entirely of partially destroyed by some kind of damaging event – this event does not destroy the soil which allows secondary succession to proceed at a faster rate.
Secondary SuccessionSuccession on abandoned cropland – begins
with the germination of r-selected species from seeds already in the soil; trees follow
Secondary SuccessionSecondary
succession of lakes and ponds – begins with a body of water, progresses to a marsh-like state, then a meadow and finally to a climax community of native vegetation.