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
