lec 17 Flashcards
Area-hypothesis (_________): _________
Considerable evidence supports this at _________
Such as the ___________ which is the______
- species area effect
- Larger areas have more species because they can support larger populations and a greater range of habitats
- regional scales
- equatorial region
- largest climatically similar region in world
tundra biome is the ________
but has _________
- second largest terrestrial region
- low species richness
That open ocean has
but has
- the largest area of any marine system, and the largest volume of any habitat
- fewer species than tropical surface waters
productivity hypothesis: _________
An increase in plant biomass _________
Evidence for this hypothesis is
- greater production of plants results in greater overall species richness
- support more herbivores and hence more predators, parasites and scavenger species
- Bird and mammal species richness increases with productivity in N.A.
metabolic theory
accumulating theoretical and empirical studies suggest that the single most important factor
- ecological and evolutionary rates are temperature dependent
- kinetics
Succession
temporal change in community structure at a given location
Steps in abandoning cropland going through succession
____________ colonize followed by _______
over time _________ are replaced by _______
eventually forming a _________
_____ begin to occupy the ________
Eventually _____________ dominate the landscape
- grasses and weedy herbaceous plants colonize
- shrubs
- shrubs are
- conopy forest
- hardwood trees
- the understory
- deciduous hardwoods
Each of the stages in succession is called a _______
a point on the ______________
These stages can often be recognized as _______
with ____________
Stages can be ________ and may last ______
- seral stage
- continuum of vegetation through time
- distinct communities
- characteristic structure and species composition
- missed
- years or decades
Succession
begins with a disturbance
- seen in both terrestrial and aquatic environments
Succession begin with _________
A force that __________
It may be
They all exhibit
- a disturbance
- alters a biological community and remoes or destroys organisms
- storms, fires, floods, drought or human caused
- different frequencies and intensities
Succession is seen in both
terrestrial and aquatic environments
pioneer species
early successional species
who are the initial colonists
pioneer species often have
- high growth rates
- smaller size
- a high degree of dispersal and colonization
- high rates of per captia population growth
Climax species
late successional species which arrive later
climax species often have
- longer lifespans
- a larger size
- lower rates of dispersal and colonization
- lower rates of per capita population growth
- the patterns of species replacement through time are not random
Succession types
primary succession and secondary succession
primary succession occurs at _______
This type of succession occurs in a
- a location that was not previously occupied by a community; a newly exposed surface,
- baron lifeless environment
secondary succession occurs at
this type of succession can build
a location that was previously occupied by a community and then underwent a disturbance that removed all or part of the existing community
- on the remainder of the previous community
sand dune
an inhospitable site that can undergo primary succession
sand is __________
unlike soil ________ it has
- a product of weathered rock deposited by wind and water
- minimal nutrients and ability to retain water
successional stages of sand dunes
__________ stabilize the dune with _________
Then _________ colonize
Subsequently ______ invade: first ________, then _____
Trees that ________________ rarely succeed the pines and oaks except in __________
During succession _________ can _____ making it more _____________
- pioneering species such as grasses
- extensize rhizomes
- mat forming shrubs
- trees
- pine(conifers)
- oak (hardwoods)
- more moisture
- depressions or other areas where moisture accumulates
- colonizing species
- change the environment
- hospitable for other species
fire is ___________ in many ecosystems
Some __________ require fire for ________
- a key and natural disturbance causing secondary succession
- coniferous trees
- reproduction
reasons to let the forests burn: ___________
Fire suppression in forests permits __________ which is very susceptible to
- major forest fires can be avoided by having frequent small fires
- the build up of dead wood
- burning, especially during lighting strikes during summer
many national parks conducted
controlled burns to maintain natural disturbance and succession and to prevent large and intense forest fires
equatorial region
largest climatically similar region in world
tundra
second largest terrestrial region, low species richness
open ocena
largest area of any marine system
- largest voluem of any habitat
- fewer species than tropical surface waters
productivity hypothesis
greater production of plants results in greater overall species richness
an increase in plant biomass
support more herbivores and hence more predators, parasites and scavenger species
metabolic theory
accumulating theoretical and empirical studies suggest that ht esingle most important factor is kinetics
Succession
temporal change in community structure at a given location
Steps in abandoning cropland going through succession
grasses and weedy herbaceous plants colonize, followed by shrubs
- over time shrubs are replaced by pine trees, eventually forming a conopy forest
- hardwood trees bein to occupy the understory
- eventually deciduous hardwoods dominatt he landscape
seral stage
a point on the continuum of vegetation through time
- can be recognized as distinct communites with characteristic structure and species composition
succession
begins with a disturbance
- seen in both terrestrial and aquatic environments
disturbance
a force that alters a biological community and remoes or destorys organisms
- may be storms, fires, floods, drought or human caused
- exhibit different frequencies and intensities
Succession types
primary succession and secondary succession
primary succession
occurs at a location that was not previously occupied by a community; a newly exposed surface, occurs in a baron lifeless environment
sand dune
is an inhospitable site that can undergo primary succession
many national parks conducted
controlled burns to maintain natural disturbance and succession and to prevent large and intense forest fires
ecosystem engineer
another type of keystone species that creates, modifies and maintains habitats
biological diversity
the variety or number of organisms that make up the community
species richness
total number of species in a community
species diversity
the number of species in a community relative to the number of individuals
Time hypothesis
Communites diversity or gain species with time
By the time hypothesis,
Temperate regions have less diversity because _______ and have only recently ___________
Species have not ______________ in temperate regions
- they are younger
- recovered from glaciation
- time to evolve and exploit regions
One would expect marine organisms to be able to rapidly _______________ after glaciation
But the richness of marine organisms follows the same ________
- recolonize the temperate and polar regions
- polar-equatorial species gradient
