Summary Comments

Emergy and UEVs are useful measures that may be applied to systems of all scales to better understand hierarchy, control, development, stress, and ultimately ecosystem health. UEVs measure the convergence of biosphere work into processes and products of ecosystems and offer the opportunity to scale ecosystems and their parts based on the energy required to develop and maintain them. Systems are hierarchically organized and composed of physical structure (i.e., wood, biomass, detritus, animal tissue, etc.) and information found not only in genetic makeup of components but in the relationships and connections between individuals and groups of individuals. Because of the demands of thermodynamic costs with each transformation, the energy, materials, and information associated with higher hierarchical levels of systems are relatively small in comparison with lower levels. A failure to account for

Table 6 Computed unit emergy values for the Everglades graminoid marsh in rank order of transformity

UEV

UEV

Ecosystem component

(sejJ1)

Ecosystem component

(sejJ1)

Periphyton

3.56E + 03

Small frogs

1.07E + 05

Labile detritus

6.43E + 03

Muskrats

1.08E + 05

Flagfish

1.24E + 04

Medium frogs

1.09E + 05

Floating vegetation

1.25E + 04

White-tailed deer

1.10E + 05

Utricularia spp.

1.51E + 04

Salamander larvae

1.11E + 05

Living sediments

1.59E + 04

Catfish

1.18E + 05

Other macroinvertebrates

1.91E + 04

Gruiformes

1.28E + 05

Apple snail

1.97E + 04

Large frogs

1.30E + 05

Mesoinverts

2.02E + 04

Alligators

1.34E + 05

Macrophytes

2.08E + 04

Spotted sunfish

1.36E + 05

Poecilids

2.23E + 04

Cichlids

1.36E + 05

Lizards

2.67E + 04

Warmouth

1.38E + 05

Tadpoles

2.91E + 04

Rabbits

1.41E + 05

Crayfish

3.04E + 04

Other large fishes

1.45E + 05

Freshwater prawn

3.87E + 04

Turtles

1.51E + 05

Bluefin killifish

4.14E + 04

Largemouth bass

1.52E + 05

Chubsuckers

4.26E + 04

Snailkites

1.62E + 05

Mosquitofish

4.35E + 04

Raccoons

1.63E + 05

Other small fishes

4.37E + 04

Grebes

1.76E + 05

Shiners and minnows

5.35E + 04

Salamanders

1.79E + 05

Killifishes

5.68E + 04

Cape Sable seaside sparrows

1.85E + 05

Large aquatic insects

6.37E + 04

Fishing spiders

1.99E + 05

Terrestrial inverts

6.74E + 04

Passerines

2.13E + 05

Topminnows

7.51E + 04

Gar

2.17E + 05

Blue-spotted sunfish

8.38E + 04

Rats and Mice

2.28E + 05

Pigmy sunfish

8.42E + 04

Bitterns

2.40E + 05

Opossum

8.63E + 04

Otters

4.00E + 05

Dollar sunfish

8.71E + 04

Minks

4.38E + 05

Redear sunfish

8.83E + 04

Nighthawks

5.39E + 05

Snakes

9.62E + 04

Panthers

1.35E + 06

Ducks

1.01E + 05

Bobcats

3.30E + 06

Other centrarchids

1.03E + 05

After Brown MT, Cohen MJ, Bardi E, and Ingwersen WW (2006) Species diversity in the Florida Everglades, USA: A systems approach to calculating biodiversity. Aquatic Sciences 68(3): 254-277.

quality differences can result in an overemphasis of the importance of lower-order components at the expense of the importance of higher-order components and their control actions. The UEV may offer a useful indicator of the cybernetic role of components within ecosystems.

See also: Ecological Network Analysis, Ascendency; Ecological Network Analysis, Energy Analysis; Exergy.

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