NUTRIENT BUDGETS

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NUTRIENT BUDGETS

• Consider the general sedimentary cycle

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Items to be calculated

• standing states and transfers
• turnover rate
• turnover time
• net flux input - output
• Biomass accumulation

20 kg/ha/yr
K in soil
400 kg/ha
20 kg/ha/yr
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EXAMPLE 1000 units in a compartment 10 units
go out each day.

• Turnover rate 10/1000 .01 or 1/day
• Turnover time 1000/10 or 100 days.
• Turnover time of Phosphorus in water (2 lakes)
• Area (km2) Depth (m) Turnover time (days)
• Water Sediments
• 0.4 7.0 5.4 39.0
• 2.04 3.8 17.0 176.0
• from Hutchinson

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Calcium example from Hubbard brook ecosystem
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Choosing the unit of study

• Consider size and measurability
• Consider the various possibilities for input and
  output

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The P forest cycle could be made into a budget.
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Forest budget
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Hubbard Brook - Ca Budget
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Hubbard Brook - N Budget
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Results of clearcutting

• Differences between Hemlock and Beech/Maple
  stands
• Transpiration stream interrupted
• Soil temperature increases increase in
  decomposition speed increased amounts of
  released nutrients
• rapid NH3 -gt NO3 H -gt increased acidity and
  solubility of Ca, Mg, Na, K

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As an ecosystem matures it increases in holding
capacity of nutrients.

• Very small amounts of nutrients are lost in
  mature systems.

• More nutrients are held in the biomass.
• Nutrients released are taken up rapidly by the
  standing stock.
• Mycorrhizal fungi tend to transfer nutrients.

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A budget is not a steady state

• Seasonal annual changes in net input and output
  
• Turnover time of Phosphorus
• Release and uptake from sediments

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DISTURBANCE
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EXAMPLE

• Hubbard brook
• undisturbed forest - estimated 8 kg/ha/yr of Ca
  were lost
• disturbed forest (cutover) - 3 to 20 times higher
  amounts were seen.
• some nutrients recover relatively quickly, some
  slowly.

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Hubbard Brook Experiment (Ca)
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NUTRIENT BUDGETS

• Where are the most common losses or gains?

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