37. LE 54-12a
Trophic level Dry weight
(g/m2
)
Tertiary consumers
Secondary consumers
Primary consumers
Primary producers
1.5
11
37
809
Most biomass pyramids show a sharp decrease in biomass at
successively higher trophic levels, as illustrated by data from a
bog at Silver Springs, Florida.
39. LE 54-12b
Trophic level Dry weight
(g/m2
)
Primary consumers (zooplankton)
Primary producers (phytoplankton)
21
4
In some aquatic ecosystems, such as the English Channel, a small
standing crop of primary producers (phytoplankton) supports a larger
standing crop of primary consumers (zooplankton).
41. In a bluegrass field in Michigan, only 3 top carnivores are
supported in an ecosystem based on production by nearly 6
million plants
Trophic level Number of
individual organisms
Tertiary consumers
Secondary consumers
Primary consumers
Primary producers
3
354,904
708,624
5,842,424
64. LE 54-19
Concrete dams and weirs
built across streams at the
bottom of watersheds
enabled researchers to
monitor the outflow of
water and nutrients from
the ecosystem.
One watershed was clear cut to study the effects of the loss
of vegetation on drainage and nutrient cycling.
The concentration of nitrate in runoff from the deforested watershed was 60 times greater
than in a control (unlogged) watershed.
Deforested
Control
Completion of
tree cutting
Nitrateconcentrationinrunoff
(mg/L)
1965 19681966 1967
80.0
60.0
40.0
20.0
4.0
3.0
2.0
1.0
0