22: Ecological Successions Flashcards
What is ecological succession?
gradual replacement of one community by another in response to environmental changes
What is primary succession?
community is developing in a site previously unoccupied by living organisms, a barren habitat with very little topsoil
- habitat with no previous life on it
- going where no one has ever gone before
- start from a point in which there is no life at all
What are examples of area where primary succession would occur?
areas after a volcanic eruption, earthquake or after a glacier has been moved out
What are lichens?
a pioneer species, contribute to the formation of soil
What contributes to soil formation?
biological factors (like lichens), together with physical and chemical factors
How is soil formed?
through weathering of big rocks
What 3 factors cause weathering?
- biological
- lichens (produce acid), tree roots - chemical
- acid helps corroding, crumbling, breaking down the rock
- water dissolves rock, erodes the rock little by little - physical
- wind, rain, thermal expansion and contraction, water freezing
- ex: thermal expansion and contraction produces breakage, crumbling
What is secondary succession?
occurs in an area where vegetation and soil were already present; begins in an area where natural vegetation has been disturbed but soil remains
What are examples of areas where secondary succession can occur?
abandoned farmlands, cut forests, forest fire
Which of the following events is likely to precede primary succession?
a. tsunami
b. deforestation
c. a wildfire
d. a volcanic eruption that creates a new island
e. a flood
d, a volcanic eruption that creates a new island
What is a primary/old growth forest?
forest that has not been disturbed for a long time (at least 200 years)
What can be seen in a primary forest?
- usually uneven-aged
- trees of different ages and heights - many different species
- have few invasive species
What is a secondary forest?
forest that has regrown after some human disturbance
- result of secondary succession
What can be seen in a secondary forest?
- usually have less diversity of species
- may be even-aged
- if all trees were planted at the same time - may lack very old and very tall trees
What are tree plantations/farms?
they are managed by humans, and it only contains one or very few species that are commercially valuable
What is monoculture forestry?
a single type of tree is grown
What percent do the types of forests make up?
70% of forests are secondary growth
25% are primary growth
5% are tree plantations
The first species to inhabit an area after a disturbance are called?
pioneer species
What is the location of the tropical rainforest?
areas near the equator
What is the climate of the tropical rainforest?
precipitation is plentiful, strong sunlight and maintain a relatively constant temperature year round
- warm and wet conditions
What do the trees of the tropical rainforest look like?
grow in different layers
1. emergent layer (tallest trees)
- grow and emerge into direct sunlight
2. canopy
- tall trees that receive 95% of sunlight
3. epiphytes
- use trees to live, grow on tall trees for support
4. understory
- trees and shrubs that are adapted to shade grow here
What is the soil of the tropical rainforest like?
decomposers break down matter quickly and return nutrients to the soil but plants quickly absorb them; nutrients are removed so efficiently from the soil
- water running in soil can be as clear as distilled water
What is the location of the temperate deciduous forest?
located between 30 and 50 degree north latitudes (east and west sides of continents)
What is the climate of the temperate deciduous forest?
range of temperatures can be extreme
- growing season lasts for only 4 to 6 months
- summer temperatures can soar to 35 C
- winter temperatures fall below freezing
What do the trees look like in the temperate deciduous forest?
drop their leaves each fall; vegetation changes with the seasons
- grow in layers
- ex: maple oak and birch dominate the forest canopy
- small trees and shrubs cover the understory
- this forest gets more light on the floor than the floor of rain forest does
What is the soil of the temperate deciduous forest like?
contains more organic matter and nutrients than soil in a tropical rainforest
