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ecology > Lecture 20: Nutrient Supply and Cycling > Flashcards

Lecture 20: Nutrient Supply and Cycling Flashcards

1
Q

Biogeochemistry

A

the study of the physical, chemical, and biological factors that influence the movement and transformation of elements

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2
Q

Nutrient Requirements

A

all organisms have similar nutrient requirements, but amounts and specific nutrients needed vary

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3
Q

Structural Compounds of Plants

A
  • Carbon (C) is the main component
  • Nitrogen (N) is largely in enzymes
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4
Q

C:N Ratios

A
  • Reflect biochemistry
  • Animals have lower C:N ratios
  • Humans have a ratio of 6
  • Plants have a ratio of 10-40
  • Organic matter with a high ratio will have a low net release of nutrients
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5
Q

plants

A
  • Require a set of essential nutrients
  • Some species have specific requirements
  • plants that host N-fixing bacteria require cobalt
  • plants in selenium-rich soil require colbalt, but it is toxic to most plants
  • may resorb as much as 60–70% of the nitrogen and 40–50% of the phosphorus in their leaves before they fall
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6
Q

C4 and CAM Plants

A

require sodium

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7
Q

Animals

A
  • All require sodium
  • mostly get nutrients in food as large, complex molecules
  • Some are broken down; others are absorbed intact
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8
Q

Nutrients

A
  • derived from abiotic sources such as minerals in rocks and gases in the atmosphere
  • may be cycled within an ecosystem, repeatedly passing through organisms and the soil or water
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9
Q

Minerals

A

solid substances with characteristic chemical properties

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10
Q

Rocks

A

collections of different minerals

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11
Q

Weathering

A
  • the process of elements being released from rock minerals
  • one of the processes that result in soil formation
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12
Q

Mechanical Weathering

A
  • The physical breakdown of rocks
  • Exposes minerals to the processes chemical weathering
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13
Q

Chemical Weathering

A
  • chemical reactions release soluble forms of the mineral elements
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14
Q

Soil

A

a mix of mineral particles, organic matter, water, and organisms

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15
Q

The Water

A

contains dissolved organic matter, minerals, and gases

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16
Q

Soil Properties Influence Availibility of Nutrients to Plants

A
  • Texture: determined by particle size
    Influences soil water- holding capacity
  • The Coarest particles: sand
  • Clays: the smallest particles
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17
Q

Cation Exchange Capacity

A

the ability of a soil to hold and exchange cations; it is related to the amount and types of clay particles present

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18
Q

Parent Material

A
  • The rock or mineral material that was broken down by weathering to form a soil
  • May be bedrock, or sediment deposited by glaciers, by wind, or by water
  • Chemistry and structure determines rate of weathering, amount and type of minerals released, and it influences soil characteristics such as fertility
  • exerts an influence on abundance, growth, and diversity of plants in an ecosystem
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19
Q

Climate

A

influences rate of soil development

20
Q

Soil Development

A
  • fastest in warm, wet conditions
  • In terrestrial ecosystems, the proportion of nutrients in the soil is greater
21
Q

Most of the Nutrients in these Ecosystems

A

are in the living tree biomass

22
Q

What Contributes to Organic Matter in Soils?

A
  • organisms such as plants, bacteria, and fungi
23
Q

Organic Matter is a Reservoir of Nutrients

A
  • Such as nitrogen and phosphorus
  • Organisms also affect weathering
24
Q

Atmospheric Sources of Nutrients

A
  1. Nitrogen Fixation
  2. Aerosols/Atmospheric Deposition
25
Q

Nutrient Transformation

A
  • Chemical and biological transformations in ecosystems alter the chemical form and supply of nutrients
26
Q

Decomposition of Organic Matter

A
  • Releases nutrients back into the ecosystem
27
Q

Detritus

A

includes dead plants, animals and microorganisms, and egested waste products

28
Q

Decomposition

A
  • the breakdown of dead organic molecules, that are released as soluble organic or inorganic compounds for other organisms to take up
29
Q

Litter

A

Fresh, undecomposed organic matter on the soil surface

30
Q

Fragmentation

A

increases surface area, which facilitates chemical breakdown

31
Q

Mineralization

A

Chemical conversion of organic matter into inorganic nutrients

32
Q

Heterotrophic Microorganisms

A

release enzymes into the soil that break down organic macromolecules

33
Q

What Determines Nutrient Availibility to Autotrophs

A
  • Abiotic and biotic controls on decomposition and mineralization
  • Decomposition and mineralization rates are faster in warm, moist conditions
34
Q

Soil Moisture

A
  • influences the availability of water and oxygen to microorganisms
  • Wet soils: low oxygen concentrations- which inhibit detritivores
35
Q

Lignin

A
  • strengthens plant cell walls, and is difficult for soil microbes to degrade
  • It decomposes very slowly
  • amount of lignin in cell walls varies with plant species
36
Q

Nitrification

A

NH3 and NH4 + are converted to NO3 – by chemoautotrophic bacteria, in aerobic conditions

37
Q

Denitrification

A

some bacteria use NO3 – as an electron acceptor, converting it into N2 and N2O, in anoxic conditions

38
Q

Soil Fertility

A

estimated from the concentration of inorganic forms of nitrogen

39
Q

Nutrient Cycling

A

influenced by climate, as temperature and moisture affect metabolic rates of the organisms involved in nutrient transformations

40
Q

Mean Residence Time (Turnover Rate)

A
  • amount of time on average that a molecule spends in the pool
  • Total pool of element/rate of input
41
Q

Pools

A

total amount of a nutrient in a component of the ecosystem

42
Q

Catchment or Watershed

A
  • the land area that is drained by a single stream, is often used
  • For terrestrial ecosystems
43
Q

Measuring Nutrient Inputs and Outputs

A
  • Atmospheric deposition includes elements in precipitation or aerosols and fine dust
  • Wet deposition collectors open during precipitation events, then close to prevent evaporation
44
Q

Early Primary Succession

A
  • little organic matter in the soil, and little nitrogen from decomposition
  • Nitrogen availability should limit primary production and community composition
45
Q

Phosphorus (P)

A
  • originates from weathering of the mineral apatite
  • As the supply of P from weathering is exhausted over time, decomposition becomes increasingly important
46
Q

Occlusion

A
  • Soluble P may combine with iron, calcium, or aluminum to form insoluble compounds that are unavailable as nutrients

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