Nutrient cycling communities Flashcards
Epilimnion
surface level on lakes
- most productive
- water movement; wind and waves
Thermocline
separating water layer
- keeps warm epilimnion and cold hypolimnion from mixing
- no mixing in the summer!! the warm water stays on top
hypolimnion
bottom cold layer
- no oxygen
- o2 got used up by bacteria at bottom of water
what happens to the lake layers in fall and spring
- surface water sinks to bottom
- bottom water rises to surface
- brings up nutrients to the surface
- temperature is equal from top to bottom as well as o2 levels
TROPICAL ZONES DON’T GET THE TURNOVER
what determines how productive the lake will be in the summer
the amount of wind
Terrestrial communities
1) tundra
2) temperate coniferous forest
3) temperate deciduous forests
4) prairie and savannah (grassland)
5) desert and semi-desert
6) tropical forest
tundra
- permafrost ~ 0.5 m
- ## surface soil thaws in summer
how many strata in tundra
3
- soil
- ground
- low shrubs
what are the seasonal migrants in the tundra
- waterfowl (shorebirds)
What kind of trees in the temperate coniferous forests
- monopodal growth (shaped like triangle)
- snow sluffs off
- ancient trees (in west coast and south america)
how many strata in temperate coniferous forests
4
- trees
- shrubs
- ground
- soil
why is there slow decomposition in temperate coniferous forests
because of the short summers and long cold winters
what forest has the greatest biomass/ha of all ecosystems on planet
west coast north and south america temperate forests
how long is seral stage recovery after clear cutting for coniferous forests?
1000 years
how many strata in temperate deciduous forests
5 strata
- upper canopy - large trees
- lower canopy (small trees)
- shrubs
- ground layer of herbs (ferns and mosses)
- soil
what community does lots of breeding and reproduction (seasonal migrants) happen in summer
temperate deciduous forests
how many strata in prairie and savannah
3
- sparse trees
- ground
- soil
how deep are roots in prairie and savannah
2 m deep
characteristics of savannah and prairie
- occasional trees
- high evaporation, long droughts
- burrowing of small animals (get out of heat)
what is the soil moisture protected by in savannah and prairie?
mulch
how many strata in desert and semi-desert?
3
- cactus
- ground
- soil
what kind of animals would u expect to see in desert
- animals that can burrow to get out of heat
- seed-eating mammals
- lizards
how many strata in tropical forests
6
- trees over 60 m
- trees up to 20 m
- lowest canopy trees
- shrub layer (tall herbs and ferns)
- ground layer (plants and seedlings)
- root and soil layer (shallow and poorly developed)
highest trees and soil layer are connected by vines
what community has the most taxonomic groups
tropical forests
how is the root layer in the tropical forests
poorly developed
- need the vines to connect the high trees to the ground
- very thin soil… when seed drops on it it can’t germinate
- deforestation is a big issue here
which community has the lowest nitrogen level?
tundra
which community has the highest nitrogen content for the root layer
grassland
which community has the highest nitrogen content for above ground
tropical equatorial forest (75% of the biomass is what you see)
what are the major causes for broad geographical distribution of communities?
- **uneven heating from earths surface
- different atmospheric circulation patterns (cooler and dryer vs wetter and warmer)
ferrell cell
cold air sinks (between arctic and tropical forests)
polar cell
air sinks (highest latitudes)
hadley cell
cold air sinks (tropical forest)
total number of species on the planet (estimate)
12, 000, 000
what species are 50% of total biomass
(viruses and bacteria)
> 1,00,000 species
as body mass increases
- there are less proportion of species; more species of smaller animals
global trends in species abundance
1) taxonomy and body size
2) aquatic vs. terrestrial
3) geographical correlates (latitude, depth and altitude)
current estimate for aquatic habitat species number
2,000,000 species
71%
predicted terrestrial species number (based on area)
700,000 species
29%
current observed terrestrial habitat species number
10,000,000 species
–> more than the predicted!!
geographical correlates of species richness
- species richness varies with latitude, depth and altitude
- looked at the number of copepods (marine) highest species richness in tropics
tree species richness in north america (geographical correlates)
- no trees really up north
- get more trees lower
- greatest tree diversity in florida… no rise in california
coral species
most coral at equator… not much anywhere else
fish species and geographical correlates
- more fish species when you get closer to the equator
what country has the most vascular plants?
Brazil
orchids geographical correlates
- each orchid has different # of insects that pollinate it
- lots in columbia and venesuala
where is the most amphibians
Florida
where is the 2 richest bird country
- columbia and peru
how does species richness differ with depth and altitude (geographical correlates)
- deep sea biodiversity is among the highest on the planet
- high evenness
where is the peak biodiversity (at which depth)
intermediate depths (2000-3000 m)
Explanation for trends in global species richness
Ocean - biological desert
- good productivity at the equator
- high chlorophyll a concentration
- in each of these continental regions: have different chlorophyll a concentration
- more productivity with wind @ surface
- most productivity at the edge of continents
- total biomass of the open ocean is 4 billion
where is the lowest and highest benthic biodiversity
lowest: East Mediterranean
highest: arctic
- subglacal deposits
- deepest layer of oceanic crust (bacteria have been found)
bird species and vascular plant species richness with altitude
as altitude increases, bird species richness and vascular plant species richness decreases
what is the total biomass of the ocean
4 billion tonnes
where is tree species richness highest
tree species richness increases as you get closer to the equator
what marine community has the highest world biomass?
Estuaries
what marine community has the highest MEAN net primary production?
Algal beds and reefs
what community has the highest world net primary production
open ocean
- because it is so big
difference in productivity and species richness… equator and up north/south MARINE
equator: low productivity, high species richness
up north/south: high productivity, low species richness
Explanations for trends in global species richness
- primary productivity (marine, terrestrial)
- Competition
- Climate variability
- Spatial heterogeneity
- Environmental age
- Geological time
Net mean primary productivity of ocean
0.125kgC/m2/year
what has a higher total biomass, marine or terrestrial
terrestrial
2 factors higher
Biomass distribuiton on earth
plants: mainly terrestrial
Animals: mainly marine
Bacteria and archaea are normally located in deep subsurface environments
what does the study reveal about total marine biomass pyramid?
says that it contains more consumers than producers
what animal taxa has the greatest biomass?
arthropods
what taxa has the greatest biomass?
plants
what does the study reveal about total terrestrial biomass pyramid?
says that it contains more producers than consumers
PET and AET
PET: potential evapotranspiration (amount of water that could be evaporated if there were no limitations)
AET: actual evapotranspiration, the actual water that is evaporated from a surface for any area
why is terrestrial primary productivity so good at equator
- temperature
- rainfall (more species richness with more precipitation)
difference in productivity and species richness… equator and up north/south TERRESTRIAL
- High productivity = high species richness
- low productivity = low species richness
what are good indicators of species richness
- latitude (only one that if it increases, species richness dec)
- PET
- precipitation
- AET
competition theory
- in the tropics, where there is competition for space… will end up with a lot of specialist species (more species)
- arctic will tend to have a lot of generalist species. Jack of all trades. Will have less species
what (r or k) species will tropics and arctic have
arctic has more r-selected species: lots of young, low probability of surviving to adulthood
- BROAD NICHES
tropics has more K: less offspring, higher survival rates
-NARROW NICHES
what did the paper say the storage effect was
- reduces the potential for competition by 0.25% for each degree closer to the equator. Underpinned by climate
- varies latitudinal
how is climate different near the equator
- longer growing seasons
Climate variability theory
- in the tropics the temperature change between seasons is much smaller (more opportunity for year round specialization); MORE SPECIES WITH LOWER TEMP RANGE
spatial heterogeneity theory (small vs. large species)
there are more smaller species than large ones
cactus theory
- same level of primary productivity in more complex cactus’s but there are also more insects in these
spatial heterogeneity theory (landforms)
the diversity of landforms is a measure of habitat diversity; few plant species lead to few herbivore species which leads to few predator species (vice versa)
AS TREE SPECIES RICHNESS INC, NUMBER OF REPTILES/AMPHIBIANS
Environmental age theory (dispersal)
species dispersed by winds are most common, then birds, then water
Great Britain frozen and recolonization
- great britain initially frozen over, took a long time to grow plant species
- no insects where no plants are
- environmental age is important for species diversity
how do you get cladogenesis?
geographical isolation + natural selection + geological time = cladogenesis
what is the length of time for origin of a new species?
- average 1 million years
potentially as short as 1000 years or less
What affects the earth at a continent level
- primary productivity
2. geological time
what affects the earth at a regional level
- primary productivity
- environmental age
- spatial heterogeneity
- climate variability
NOT geological time
What affects the local community (differences in species richness)
- competition
- predation
- spatial heterogeneity
diversity stability hypothesis
- more species = more stability
rivet hypothesis
- if you lose a few species not a big deal
- if you lose a significant amount of species will not have a stable community!!!
redundancy hypothesis
if you lose keystone or dominant species community will collapse
