Decomposition and Nutrient Cycling

Decomposition and Nutrient Cycling

8/8/2012 2:26:00 PM

Last class Energy from the sun 90% lost/10% retained through each “system”  

the lost portion – reflected back into the atmosphere as heat

Nutrient cycling – infers that nutrients stay within the biosphere two main processes that drive...... – primary production and decomposition primary production- photosynthesis – input – carbon dioxide – inorganic output- carbohydrates – organic decomposition – input organic , output inorganic Nutrient Transformations***** Mineralization – usually what we think of when we think of decomposition. When chemicals eat minerals and create ammonia – organic inorganic Immobilization (essentially reverse of mineralization) – as they need nutrients for own metabolic process. Take inorganic (i.e ammonia) , and build it in there system as organic food. Inorganic organic net mineralization rate 

if it is positive – mineralization rate is higher. So organic output

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if negative – mineralization rate is lower, so inorganic output

Hot and Humid = higher mineralization/decomposition rates Internal Cycling – matter recycles, energy gets lost 

recycling of nutrients between organic and inorganic forms f orms driven by primary production and decomposition

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decomposition

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decomposers or dertrivores break down organic matter into soluble organic compound. They need organic matter for energy and nutrients

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decomposition rates depend on – hot and humid environments,

learn chart ***** in bottom up control, energy flow though the ecosystem is determined primarily by the 

- supply of resources limiting NPP (net primary production***)

Lab Exam – same format – no change describing the population (lab) 

give a set of numbers describing the weight of deer o

should be able to do mean median mode, SD, and histogram plot

predators and prey (termites) biodiversity (spiders) – notes 

difficult to define different organisms as species by simply using morphological means

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sexual dimorphism – 264 (construct a table like this one

explain results for Soil lab Soils determine the ecosystem n many ways NO strict scientific definition of soil certain types of soil are more likely to be found in certain climatic zones. Soil = stomach of mother earth great plains of the US 

grasses o

w/ roots over a meter deep

Soil Profile on page 279 Saturation capacity –refers to the amount of water a soil contains when all the spaces btwn soil particles are filled with water (San has the highest – relatively large particles cannot be packed as tightly as other soils- there can

be a lot of water in sand, but because particles are very big, water can flow through very fast) –Silt has an intermediate saturation capacity, and clay has very little saturation Water likes to stick to itself. Field capacity – will tell you how much water remains in the soil after it has been saturated and gravity has pulled all it can down through the soil column. 

clay has highest field capacity – clay have very small particle size, lots of surface area for water to stick too. SO clay holds more water for longer periods.

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Sand has a low field capacity – sand has very large particle size, little surface area for water to stick too. So sand hold less water for small periods of time

Wilting point –

8/8/2012 2:26:00 PM

8/8/2012 2:26:00 PM