Ch 8: Nutrient Regeneration in Terrestrial and Aquatic Ecosystems

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Ch 8 Nutrient Regeneration in Terrestrial and
Aquatic Ecosystems
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Objectives

• Terrestrial regeneration
• Intrasystem cycling
• nutrient regeneration in soil
• annual dynamics/balance the books
• Intersystem cycling
• inputs vs. outputs
• Aquatic regeneration
• nutrients productivity
• timing of regeneration
• sources of regeneration

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Intrasystem (within 1) vs. intersystem (between 1
2) cycling in ecosystems

Ecosystem 2
Ecosystem 1
Ecosystem 1
2
Input ?
?
?
?
?
Output ?
Input ?

? output
?
?
4
Generalized model nutrient cycle, including
regeneration, in terrestrial ecosystem.
Intra
Inter
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Intrasystem cycling
Figure 1

• Figure 1

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Nutrient regeneration occurs in the soil.

• Rate depends on rate of ecosystem processes (e.g.
  decomposition mineralization).
• Productivity depends on regeneration of nutrients
  from litter
• decomposition
• mineralization (organic --gt inorganic)
• uptake
• Nutrients added by weathering of rock slow
• Nutrient uptake from soil by plants fast

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Life in the soil and litterinverts, bacteria,
fungi
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Nutrient regeneration from litter by

• leaching of soluble substances
• maceration by large detritus feeders
• fungi breakdown cellulose/lignin--gt C,H,O
• mineralization (organic---gtinorganic) of P, N,
  and S by bacteria

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Depolymerization of large organic molecules in
soil regulates nutrient cycling. Microbes
plants compete for small monomers (e.g. amino and
nucleic acids)
Figure 2
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Leaf quality (e.g. toughness/chemicals) affects
regeneration.Climate affects nutrient
regeneration

• Decomposition rate and what seasons
• Weathering rate and what seasons
• Soil properties

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Soil properties

• Eutrophic (rich) soils
• in geologically active areas young soils
  
• rapid weathering of bedrock - adds
• fresh nutrients
• Oligotrophic (poor) soils
• in old, geologically stable areas old
  soils
• intense weathering if high temperatures
• and abundant water ---gt
• 1) high respiration ---gtacid pH
• 2) removes clay and cations (e.g.
  Ca)
• 3) reduces storage capacity for
  nutrients
• 4) high leaching of cations
• 5) nutrient-pool soils

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How does vegetation aid nutrient
retention?(lower movement from intrasystem to
intersystem cycling)

• 1 retain leaves for long time
• 2 withdraw nutrients from leaves before drop
  (reabsorption)
• 3 develop dense root mats near soil surface
• 4 grab nutrients quickly before leached away
• 5 store more nutrients in biomass, not soil

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Annual dynamics/budget of intrasystem cycle

• Storage
• Annual requirement
• make foliage
• woody growth
• leaching (throughfall and stemflow)
• Annual uptake by roots
• woody growth
• returns from
• leaching
• litterfall
• Reabsorption (before leaf fall)
• Balanced if
• annual requirement uptake reabsorption
  

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What 3 components of the annual requirement
account for the total requirement (114.3)?
What 2 processes provide resources to meet the
total requirement (114.3)?What 3 components of
annual uptake account for total uptake
(92.1)?Is the forest in equilibrium?Explain
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Intersystem cycling Nutrients gained (input) and
lost (output) by an ecosystem

Ecosystem 2
Ecosystem 1
Ecosystem 1
2
Input ?
?
?
?
?
Output ?
Input ?

? output
?
?
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Contrast intra- vs. inter-system cycling in a
terrestrial ecosystem.
Atmosphere
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Intersystem cycling
--gtInput from waterflow
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Nutrient inputs on land from

• Lithosphere (weathering of bedrock and
• soil)
• Atmosphere
• Wetfall (in precipitation)
• Dryfall (particles)
• Hydrosphere
• Human Activities

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What are two generalizations about nutrient
input from the atmosphere?
Figure 5
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Nutrient losses (output) on land to

• Atmosphere
• Streams and groundwater
• Which cycle links terrestrial and aquatic
  ecosystems?

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Nutrient Budgets

• Balanced (equilibrium) inputs outputs
• Unbalanced (non-equilibrium)
• inputs gt outputs ???
• outputs gt inputs ???

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Question Does the presence of vegetation affect
the rate of nutrient output (loss) from an
ecosystem?Hypothesis IF vegetation increases
soil stability and intrasystem recycling of
nutrients,Experimental design
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• What is the prediction?

Figure 6
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Hubbard Brook watershed and experimental sites
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Hubbard Brook Ecosystem Study How does
deforestation affect streamflow and nutrient loss
(output)?

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Weir (dam) method of gaining output data
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Method of gathering input data
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Results
What is the conclusion (as in discussion)?
Figure 7
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What are two patterns?(1 general and 1
qualifying) What stats to do?
Figure 8
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Watershed studies of precipitation and stream
chemistry

• How important is intrasystem cycling relative to
  intersystem cycling of nutrients?
• Is amount of nutrients in intrasystem cycle per
  year small or large compared to external inputs
  and outputs?

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What contributes to input? output?What are
two main conclusions?
Figure 9
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Summarize the pattern. What causes
variation in amount of input?
Figure 11
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Nutrients and Aquatic ProductivityWhat
accounts for the highest and lowest levels?
Fig. 12
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NPP of aquatic systems maintained by

• Transport of nutrients from bottom sediments to
  surface (in shallow water or upwelling)
• Recycling of nutrients within photic zone
• Import of nutrients from other systems

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Temperate lakes have annual cycles of nutrient
availability and productivity

• Summer stratified- nutrients depleted by
  sedimentation of organic material --gt lowers NPP
• Spring and Fall vertical mixing brings up
  nutrients to photic zone --gt
• increases NPP

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Productivity varies in temperate lakes
nutrient-limited
well-nourished, productive
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What element controls the trophic structure and
productivity of lakes?
CNP
CN
Figure 16
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Estuaries and salt marshes

• Extremely productive due to
• rapid local regeneration of nutrients
• external input of added nutrients
• Major exporters of C and nutrients to
• marine systems.

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Intra- vs. inter-system energy flow in a salt
marsh. 10 of GPP exported.
Figure 17