Nutrient Cycling

Biogeochemical Cycles

Energy vs. Matter Energy flows throughout an ecosystem in ONE

direction from the sun to autotrophs to heterotrophs

Matter is recycled

WHY?

Biogeochemical Cycles “Matter can cycle through ecosystems

because organisms don’t USE it, they TRANSFORM it.”

Matter/Nutrient cycled includes: Water Nitrogen Carbon Phosphorous

Water CycleProcesses involved:

Evaporation-water changes from liquid to atmospheric gas

Transpiration- water evaporates OUT of plant leaves

Also, condensation, precipitation, runoff…

Carbon Cycle Key ingredient of living tissue, found in many

places Found in animal skeletons, rocks, carbon

dioxide, carbohydrates, etc. Processes Involved That Take Up and Release

Carbon: Biological- photosynthesis, respiration,

decomposition Geochemical- erosion, volcanic activity Mixed- burial and decomposition coal and

petroleum Human Activities- mining, cutting and burning

forests, burning fossil fuels

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Nitrogen Cycle All organisms require nitrogen to make amino

acids Occurs in many forms: N2 (78% atm gas),

Ammonia (NH3), Nitrate and Nitrite (NO3- and

NO2-) are found in waste products and

fertilizers Processes involved:

Nitrogen Fixation: conversion of nitrogen gas into ammonia by bacteria (occurs in the roots of legumes) also can occur thru lightning

Ammonia can be converted into nitrates and nitrites, which are taken up by plants and enter the food web

Denitrification: bacteria in soil convert nitrates into nitrogen gas

Phosphorous Cycle All organisms require phosphorous to create

DNA and RNA Does not enter atmosphere, not very common Exists inorganic form in land rock and soil

minerals and ocean sediment Processes involved:

Erosion: sediment washes into rivers, streams, and ocean

Absorption: Plants and marine organisms take up the phosphorous and it moves through the food web