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Chapter 11
Controls on Ecosystem Structure and
Function
© 2013 Elsevier, Inc. All rights reserved.
From Fundamentals of Ecosystem Science, Weathers, Strayer, and Likens (eds).
Figure 11.1 Biotic control of an aquatic ecosystem from the top of the food web. The trophic cascade hypothesis
proposes that top predators may control the abundance of organisms lower in the food chain. By reducing the
abundance of their prey (planktivorous fish), this in turn may allow an increase in the abundance or size of
organisms among the prey’s food source (zooplankton), which can lead to grazing down phytoplankton
populations and increase water clarity and concentrations of dissolved nutrients (Trophic cascade available at:
http://biology-forums.com/index.php?action=gallery;sa=view;id=2029.)
© 2013 Elsevier, Inc. All rights reserved.
From Fundamentals of Ecosystem Science, Weathers, Strayer, and Likens (eds).
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Figure 11.2 Autogenic (a, b, c) and allogenic (d, e, f) ecosystem engineering. (a) Oak (Quercus rubra) forest
near Millbrook, NY, changes microclimate and affects soil biogeochemistry and understory species. (b) Smooth
cordgrass, Spartina alterniflora, in a tidal marsh in the La Plata estuary near Playa Peninos, Uruguay. The marsh
attenuates storm surges, increases sedimentation, and retains organic matter affecting biogeochemistry and
creating protected habitat for other species. (c) Reefs of tube-building polychaetes, Ficopomatus enigmaticus, an
exotic species in Mar Chiquita coastal lagoon, Argentina. The reef in the foreground is ca. 3 meters across, and it
alters hydrodynamics and increases sedimentation, providing shelter for many invertebrates. (d) Riparian forest
area transformed by the dam-building activity of beaver, Castor canadensis, in Tierra del Fuego, Chile, where it
is an exotic species. The dam alters hydrology, sedimentation, and light levels and so affects biogeochemistry
and species habitats. (e) Mound made by leaf-cutting ant, Atta sexdens, in the “blanqueal” area near Fray
Bentos, Uruguay; ants bring saline soil from depth to the surface, eliminating most vegetation on the mound. (f)
The Southwestern Atlantic burrowing crab, Neohelice (Chasmagnathus) granulata, in Mar Chiquita coastal
lagoon, Argentina, buries litter in excavation mounds and prevents litter export as a nutrient subsidy to adjacent
estuary. (Photos: (a) Jorge Gutiérrez; (b) Cesar Fagúndez; (c) Martín Bruschetti; (d), (e) Clive Jones; (f) Pablo
Ribeiro. From Gutiérrez and Jones 2008.)
© 2013 Elsevier, Inc. All rights reserved.
From Fundamentals of Ecosystem Science, Weathers, Strayer, and Likens (eds).
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Figure 11.3 Cause-and-effect relationships representing a physically engineered ecosystem. The solid arrow for
autogenic engineering is the physical manifestation of organismal structure inserted into the abiotic milieu. The
dashed arrow for allogenic engineering represents the action of the engineer on other living or nonliving
structures. (From Jones et al. 2010.)
© 2013 Elsevier, Inc. All rights reserved.
From Fundamentals of Ecosystem Science, Weathers, Strayer, and Likens (eds).
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Figure 11.4 Biotic (vegetation structure) and abiotic (wind speed, cloud frequency, cloud liquid water content)
factors interact to affect fog water capture. For a given elevation and climatic region, greater vegetation height
and surface area will increase the fog capture.
© 2013 Elsevier, Inc. All rights reserved.
From Fundamentals of Ecosystem Science, Weathers, Strayer, and Likens (eds).
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Figure 11.5 Control on ecosystems can come from (a) outside or (b) inside the ecosystem.
© 2013 Elsevier, Inc. All rights reserved.
From Fundamentals of Ecosystem Science, Weathers, Strayer, and Likens (eds).
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Figure 11.6 Examples of different kinds of functional relationships between controlling variables and ecosystem
characteristics.
© 2013 Elsevier, Inc. All rights reserved.
From Fundamentals of Ecosystem Science, Weathers, Strayer, and Likens (eds).
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Figure 11.6 cont’d. Examples of different kinds of functional relationships between controlling variables and
ecosystem characteristics.
© 2013 Elsevier, Inc. All rights reserved.
From Fundamentals of Ecosystem Science, Weathers, Strayer, and Likens (eds).
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Figure 11.7 Both positive and negative feedbacks to climate, via atmospheric carbon dioxide, are possible with
warming of a tallgrass prairie. An enhancement of root and soil respiration and a positive feedback to climate
could result from stimulation of soil microbial activity associated with higher temperatures. This positive feedback
would be weakened if there is acclimatization such that soil (root-plus-microbial) respiration does not continue to
increase with increased warming. In contrast, if greater microbial activity leads to enhanced nutrient availability
and plant growth, this could result in greater carbon sequestration in plants and soil—and a negative feedback to
carbon dioxide concentrations in the atmosphere. (From Luo et al. 2001.)
© 2013 Elsevier, Inc. All rights reserved.
From Fundamentals of Ecosystem Science, Weathers, Strayer, and Likens (eds).
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