The flux of energy and matter through ecosystems Flashcards
Primary Production
process by which solar energy is converted to plant biomass
what is primary production usually measured in?
dry biomass or carbon per unit of ground area
Gross Flux
total amount of CO2 fixed by plants
Net Flux
all material left behind after plants have respired
Net Primary Production depends on…
temperature, moisture, solar radiation and nutrients
Net Primary Productivity over succession
Increases rapidly at first than levels off as climax community is approached
Why does net primary production change the way it does over succession?
taller plants block out light to others
space becomes limiting
Leaf Area Index (definition)
total one-sided area of leaves per unit of ground area
What can leaf area index be used to predict?
the gross primary productivity
Leaf Area Index (formula)
LAI = leaf area (m2)/ ground area (m2)
Destructive harvesting
e.g.) grasslands, shrublands and croplands
rate of change = plant production
Allometric equations
e.g.) trees
mathematical relationship defined by some measure of size between an easy-to-measure parameter and component of NPP -> e.g.) stem diameter, foliage
Allometric requires a…
large data set
Allometric equations are…
very approximate
Allometric equations ignore…
seasonal changes
Whole-canopy gas exchange
smaller vegetation better (large expensive)
small area
Eddy co-variance (technique)
is a key atmospheric measurement technique to measure and calculate vertical turbulent fluxes within atmospheric boundary layers.
Remote sensing: airborne techniques
- vegetation density and structure
What does LIDAR stand for?
Light Detection and Ranging
How does LIDAR work?
measuring time delay between transmission of a laser or radio pulse and detection of reflected signal
Remote sensing: satellite techniques
reflectance of IR or near IR can be used to estimate biomass
Net Primary Productivity
radiation use efficiency (RUE)
photosynthetically active radiation (PAR)
fraction of PAR absorbed
- global estimations of NPP
decomposition
the breakdown of matter by living things
what does decomposition do?
- releases nutrients for plant, microbial and animal consumption
- facilitates soil formation
UV radiation causes…
photo-oxidation
why are plant poor quality food?
- hard to digest - lignin, cellulose
- toxic secondary metabolites - tannins
- physical deterrents - thorns
forest degradation
reduced density of forest area
partial disturbance
deforestation
reduced area covered by forest
<10% crown cover
drivers of deforestation and forest degradation
- industrial/commercial extraction of forest products
- uncontrolled anthropogenic wildfire
- clearing for land
biofilm
sticky like glue
prevents cell grazing
helps control extracellular enzymes
retain moisture
