Primary Productivity in Terrestrial Systems
Solar radiation vs temperature
--> tightly linked in aquatic systems
--> but, in terrestrial
--> large range of temps among areas with same
solar radiation
eg Arizona - desert to alpine
AET - Actual Evapotranspiration
- moisture into atmosphere
--> evaporation from ground
--> transpiration from plants
Function of
--> solar radiation
--> temperature
--> rainfall
AET
Net Primary Production
Net Primary Production
Tennessee
North Carolina
Massachussetts
New York
Wisconsin
Length of photosynthetic period
Boreal coniferous
Deciduous
Pine
Temperate Coniferous
Evergreen Broadleaf
0
10
20
30
40
Net primary production
Leaf area duration
Gross Primary Production
Solar radiation, temperature and moisture
--> good for predicting global patterns of
primary produciton
Local?
--> nutrients
--> fertilizer increases yields in crop plants
Old Growth Forests and Salmon
--> nutrient input
--> black bears consume tonnes of salmon each year
--> 8 dragged 1600kg each from river to forest
--> up to 100m away
--> consume only fraction of each carcass
--> feces
--> up to half of N in samples originated in ocean
Secondary Production
Biomass from plants
Herbivory
Detritus
Energy from Plant
Not Used
Digested
Feces
Urine
Resting E
Consumed
Metabolizable Energy
Activity
Maintenance
Growth
Reproduction
Production
How can you estimate secondary production in an animal
community?
Gross energy intake --> watch the animal
Assimilated energy --> gross E in minus e in urine and feces
Assimilated = Respiration + Production
Estimate Respiration
- measured in a lab
Basal metabolic rate
--> not really a good estimate
Maintenance and activity rates can be much higher than basal
--> temperature is very important
Net Production
--> growth of individuals in a population
--> Population size
Production = Growth + Birth
BIOMASS --> calories
Ecological Efficiencies
Assimilation at trophic level n (P+R)
0
Production
2
4
6
Production Efficiency =
Net productivity at trophic level n (P)
0
2
4
Respiration (log cal/m2/year)
6
Group
Insectivores
Birds
Small mammals
Other Mammals
Fish and social insects
Other Invertebrates
Herbivores
Carnivores
Detritivores
Nonsocial Insects
Herbivores
Detritivores
Carnivores
Production Efficiency
0.86
1.29
1.51
3.14
9.77
25.0
20.8
27.6
36.2
40.7
38.8
47.0
55.6
No. of Studies
6
9
8
56
22
73
15
11
23
61
49
6
5
Birds and mammals --> 97-99% of assimilated energy
--> RESPIRATION
Proportion to Respiration
Production efficiency --> not constant within a species
Food Consumption
Community Level Efficiency
Lindeman’s =
Consumption =
Assimilation at trophic level n
Assimilation at trophic level n-1
Intake at trophic level n
Net productivity at trophic level n-1
Consumption
0
Efficiency
10
20
30
Lindeman’s
1-2
2-3
3-4
Trophic Level
1-2
2-3
3-4
Trophic Level
What limits 2o production?
Why only 10 or 20% efficient ?
Primary production
Bottom up
2nd law of thermodynamics
Predation
Top down
Great Central Lake Salmon
--> salmon spawn and die locally
--> large fishery - removes fish
Solution --> fertilize the lake
NUTRIENTS
Increased primary productivity 10X previous level
Zooplankton biomass
Increased zooplankton biomass
1970
1969
Time of year
Interesting observation
--> phytoplankton biomass did not peak at time
of fertilizer addition
--> but zooplankton did
Average mass (g)
1970
1969
Time of Year
Thousands of fish
100 200 300 400
Great Central
0
Sproat
56
60
64
68
Year
72
76