chapter 53 - ecosystems and global ecology Flashcards
define ecosystem
one or more communities in an area + abiotic components
what are ecosystems tied together by?
flow of nutrients
define primary producer/autotroph
plants!
can synthesize its own food from inorganic sources
total energy captured = gross primary productivity
gross primary productivity (GPP)
total energy produced by autotrophs
used in 2 ways:
1) to stay alive through cellular respiration
2) growth and reproduction (net primary productivity)
Net Primary Productivity can be calculated as
NPP = GPP – R
R = energy used is cellular respiration
basically total energy minus energy used to stay alive
net primary productivity (NPP)
total energy used for growth and reproduction
builds biomass
why can so little solar energy be captured?
mostly due to light and temperature changes
- visible light only a fraction of the wave length
spectrum
– low or zero during winter
– stalled if too dry (stomata will close, plant can’t take in nutrients)
– enzyme efficiency varies with temperature
proportions of solar energy used
GPP uses 0.8% of total available solar energy
Cellular respiration (heat loss, waste) 55%
NPP 45%
nutrients cycle
sunlight -> primary producer
primary producer -> primary consumer
primary consumer -> secondary consumer
secondary consumer -> tertiary consumer
tertiary consumer -> decomposer
decomposer -> primary producer
energy dissipates as it flows through system
all produce heat
grazing vs decomposer food chain
difference in primary producer
Grazing: live plants
Decomposing: dead plants
10% rule
generally 10% of energy is transferred among trophic levels
biogeochemical cycle
paths that an element takes as it moves from abiotic systems through organisms and back again
- decomposition of detritus may limit how fast nutrients cycle through an ecosystem
detritus decomposition rate depends on…
3 factors
- ABIOTIC CONDITIONS (O2, temperature, precipitation)
- QUALITY OF DETRITUS (as a nutrient source for fungi that accomplish decomposition)
- ABUNDANCE + DIVERSITY of detritivores PRESENT
abiotic factors effecting nutrient cycling
temperature + climate
- nutrients cycle faster in tropical wet forests (smaller organic matter layer)
- slower in cooler climates (larger organic matter layer)
why is there more live biomass consumed alive in the ocean than on land?
?
in what places on earth is NPP highest? lowest? why?
highest on land near the equator because there’s more light available to photosynthesize
lowest in the ocean because water absorbs light, less photosynthesis
detritus
region in soil that contains waste and dead organisms
sources of local nutrient import and export
1) rocks weather - ions released and at as nutrients
2) nutrients blow in on soil particles or as solutes in streams
3) carbon added when primary producers fix carbon
4) nitrogen added when nitrogen fixing bacteria N2 in atmosphere to usable N
what is local nutrient import and export
nutrients constantly cycled within an ecosystem and can be exported to another
for an ecosystem to function normally, nutrients must be replaced
major nutrient import/export agents and 4 major ways they can be replaces
export: farming, logging, burning, soil erosion
1) ions released as rocks weather
2) nutrients arrive on soil particles in wind or solutes in streams
3) carbon added when primary producers fix carbon via photosynthesis
4) nitrogen added when nitrogen fixing bacteria convert N2 into usable nitrogen
explain the global water cycle and human’s impact on it
- Ocean evaporation + precipitation
- more evaporating, net gain of water into atmosphere - Vapour moves over continents
- joined by evaporation/precip cycles from lakes and water lost from plants
- more precipitation than evaporation - Water moves back to oceans via streams and groundwater
*no net gains or losses of water *
HUMAN IMPACT: groundwater depletion, pavement reduces water percolation, agriculture lowers water holding capacity
name global biogeochemical cycles
water, nitrogen, phosphorus and carbon cycles
water numbers
97.5% water in ocean
2.5% freshwater in icecaps and glaciers
0.5% freshwater in lakes, rivers and groundwater
different types of aquifers
layers of rock, sand or gravel saturated with water underground
closed: nonporous rock above
open: can be recharged with water from above
