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Forest Ecology 550 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

In what types of tissue are nutrient concentrations highest?

A

More metabolically active tissue

Foliage > fine roots > new twigs > old branches > new stem wood > old stem wood

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2
Q

In what species are nutrient concentrations higher?

A

Deciduous > evergreen

(Also, Temperate > Tropical)

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3
Q

Wet deposition

A

atmospheric input of nutrients dissolved in precipitation

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4
Q

dry deposition

A

atmospheric input of nutrients deposited as dryfall from blown dust particles

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5
Q

Where do sodium and chloride deposits come from/occur?

A

Coastal areas (from the ocean)

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6
Q

What are the two main types of weathering? Explain them briefly

A

Physical: degradation of rock from climatic factors or biological activity.

Chemical: dissolution of mineral when it reacts with water from rainfall or other liquid

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7
Q

What nutrients come from weathering of SILICATES?

A

Ca, Na, Mg, Fe

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8
Q

What nutrients come from weathering of CARBONATES? (Limestone, dolomite)

A

Ca, Mg

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9
Q

What nutrients come from weathering of APATITE?

A

P

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10
Q

What nutrients come from weathering of GYPSUM?

A

S

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11
Q

What nutrients come from weathering of SERPENTINE?

A

High amts of Mg

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12
Q

In what climates does weathering occur most?

A

Warmer and Wetter climates

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13
Q

What is the Redfield Ratio for decomposers and why is it important?

A

6-8:1 C:N

Important because things closest to this range are the easiest to decompose.

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14
Q

What factors influence Nitrogen fixation?

A

DECREASES WHEN: pH < 6.0

Low soil Oxygen

Micronutrient deficiencies

temperature optimum 30-35 C

Soil moisture optimum near field capacity

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15
Q

Why would a forest manager plant red alder in a douglas fir forest?

A

Red alders fix nitrogen, due to symbiotic bacteria (Actinomycete)

They would raise the soil and plant nutrient content

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16
Q

What are the types of nutrient outputs in an ecosystem?

A

Leaching (through the soil)

Erosion (along the soil)

Gaseous losses/denitrification (to the atmosphere)

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17
Q

Why are anions lost in the soil during leaching?

A

Because most forest soils do NOT have an anion exchange capacity!

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18
Q

Where do organic acids come from in forest soils?

A

Incomplete decomposition due to poor litter quality

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19
Q

What types of forests have poor litter quality?

A

Temperate and boreal evergreen conifer forests

Needles have lots of acids in them

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20
Q

Where might denitriffication occur and why?

A

Warm areas with hypoxic soils and high NO3 supply

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21
Q

What three major processes are responsible for nutrient uptake?

A

ROOT GROWTH to access the nutrients

MASS FLOW

DIFFUSION

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22
Q

What is the most rate limiting step in plants taking up nutrients?

A

ROOT GROWTH to access the nutrients

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23
Q

Retranslocation

What is it? What factors influence it?

A

Removal of nutrients from senescing/dying tissue

Influenced by:

Tissue type (foliage > wood)

Which nutrient

Nutrient availability

Leaf habit

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24
Q

What are the ecological advantages of retranslocation?

A

Greater nutrient use efficiency

Prevents loss of nutrients to forest floor (immobilization)

Decreases litter quality

Independence from soil supply of nutrients

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25
Q

What are some mechanisms to increase availability of limiting nutrients?

A

Add Nitrogen fixing plants

Tap roots

Plant selection

Add symbionts (rhizobium are acid tolerant, mycorrhizae decay lignin and absorb organic N)

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26
Q

What are the two key players in decomposition?

A

Aerobic heterotrophic bacteria and fungi

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27
Q

What are the results of decomposition?

A

Production of HUMUS

MINERALIZATION of nutrients from organic matter

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28
Q

How do we estimate decomposition?

A

Use the equation:

dx/dt = e-kt

k=-ln(1-fraction of original mass lost)/t

or k=litterfall / FFM

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29
Q

How do you estimate Mean Residence Time (MRT)?

A

MRT = 1/k

OR ratio of OM conent: OM input

AKA Forest Floor Mass:Litterfall

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30
Q

How can you tell what is immobilized vs mineralized when doing litterbag nutrient measurements?

A

The nutrients that retain a % stock ABOVE that of the leaf dry wt are IMMOBILIZED

Ones that are MORE DEPLETED than the leaf dry wt are MINERALIZED

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31
Q

How can you measure decomposition in logs?

A

WL = (V1* SG1) - (V0* SG0)

WL=weight loss

V=volume

SG=Specific gravity

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32
Q

Why might measuring CO2 evolution as a proxy for decomposition be inaccurate?

A

It includes ROOT RESPIRATION

May not include ANAEROBIC decomp (no CO2)

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33
Q

What are the three major factors influencing decomposition?

A

CLIMATIC VARIABLES (temp, moisture/evapotranspiration, oxygen)

LITTER QUALITY (Redfield ratio, Lignin level->resistant)

SA:V RATIO

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34
Q

What are the implications of cultivation on atmospheric CO2 concentrations?

A

The CO2 in the atmosphere gets higher because there are no plants to absorb the broken down organic matter.

This would increase the replenishing time of soil organic matter.

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35
Q

Who first coined the term production ecology?

A

EGLER

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36
Q

How are biomass and production measured?

A

Biomass: quantity of OM per unit area

Production: Rate of increase of OM per unit area per unit time

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37
Q

What are the different levels of study of production ecology?

A

Leaf/cellular

Tree/plant

Ecosystem

Landscape to regional

Global

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38
Q

What are some methods of estimating above ground biomass?

A

Area harvest (difficult)

MEAN TREE APPROACH: BM of area based on DBH of average trees (most accurate for even-aged)

Allometry: plot wet tissue mass against DBH for representative trees, get ratio of wet:dry mass, use to get dry tissue mass

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39
Q

What factors influence aboveground biomass?

A

STAND AGE

CLIMATE

WATER AVAILABILITY

NUTRIENT AVAILABILITY

LEAF HABIT (evergreens have more bc they retain longer)

40
Q

How do we estimate belowground biomass?

A

Allometry of COARSE ROOTS (excavated and weighed)

WATER EXCAVATION and allometry

fine roots

41
Q

What factors influence below ground biomass?

A

STAND AGE

NUTRIENT AVAILABILITY (more fine roots on nutr poor)

WATER AVAILABILITY (more fine roots on dry)

LEAF HABIT (evergreen more FRs)

42
Q

Gross Primary Production (GPP)

A

TOTAL amt of carbon assimilated by plants per unit area and time

43
Q

Net Primary Production (NPP)

A

NET amount of carbon assimilated by plants per unit area and time

NPP=GPP - RA

or NPP=deltaBTT + H

delta BTT=change biomeass for each biomass component

H = herbivory loss

44
Q

Carbon Allocation

A

the priority in which photosynthate is partitioned in the plant

45
Q

Net Ecosystem Productivity (NEP)

A

Change in total organic matter (living and dead) in the ecosystem per unit area and time

NEP=GPP-Ra-Rh

or NEP=NPP-Rh

46
Q

What can NEP values tell you about an ecosystem’s carbon balance?

A

NEP= + : C SINK

NEP= - : C SOURCE

47
Q

What factors influence NPP and carbon allocation?

A

TEMPERATURE

WATER

NUTRIENT AVAILABILITY (FR inversely rel to lim nutr)

LEAF HABIT

48
Q

Production Efficiency

AKA Vigor Index

AKA Growth Efficiency

A

Amt of carbon produced per unit leaf area or foliage mass

PE = Wood NPP/LAI

49
Q

What factors influence Production Efficiency?

A

Light (positive relationship)

Water (pos. asymptotic)

Nutr Avail (pos asymp)

50
Q

Site Productivity

A

The potential of a site to produce one or more natural resources

Should consider sustainability and multiple resources

51
Q

Site Index

A

Indirect way to estimate site quality

Based on height of the dominant and co-dominant trees based on some standard age, which depends on location and stand type. Typically 50 but can be 25 in SE or 100 in boreal regions

52
Q

What are the pros of site index curves?

A
  • easy, cheap
  • Height growth is less sensitive than basal area to stocking density
  • very site dependent (soils, topography, aspect)
53
Q

What are the cons of site index curves?

A

Very empirical!

site dependent

differs among species

requires trees growing on the site

cant capture dynamic nature of tree growth and global change

54
Q

What are some indirect ways to measure site productivity?

A
  1. Site index curves
  2. Overstory tree species (each has specific niche)
  3. Understory species
  4. Ecological Site Classification/Habitat Typing
  5. Environmental Relationships/Factors
  6. Ecosystem Process Models
  7. Remote Sensing
55
Q

What are pros and cons to measuring overstory tree species as a proxy for site productivity?

A

PROS: allows quick assumptions

CONS: Not good for very adaptive spp

very qualitative

56
Q

What are pros and cons to measuring understory tree species as a proxy for site productivity?

A

PROS: More sensitive to micro-climate differences, indicator species can be present

CONS: Doesn’t acct for Disturbance, influence of invasives, and is qualitative

57
Q

How does habitat typing work?

A

Basically identify distinct understory species and use a flow chart to assess type

58
Q

What are the pros and cons of habitat typing?

A

PROS: Easy, generally correlate with numerous variables

CONS: require good knowledge of flora, somewhat sensitive to disturbance, must have vegetation there

59
Q

Life History

A

The reproduction, growth, and allocation characteristics of a species

60
Q

Niche

A

The physical or temporal space occupied by a species. Often determined by the life history.

61
Q

r-selected species

A

High rate of increase

allocate lots of energy to reproduction, but have low competitive ability

62
Q

K-selected species

A

Lots of energy towards rearing offspring

fewer offspring, but greater competitive ability

63
Q

What are the 3 components of Grime’s Life History Model?

A

Ruderals - HIGH resources , HIGH disturbance

Competitors - HIGH resources, LOW disturbance

Stress tolerators - LOW resources, LOW disturbance

64
Q

Characteristics of Grime’s Life History Groups

A
65
Q

Mutualism (+Example)

A

Symbiosis where both organisms benefit (Mycorrhizae fungi and plants)

66
Q

Commensalism (+Example)

A

Symbiosis where one organism benefits and the other is not affected (vines on trees, cattle egrets with livestock)

67
Q

Antagonistic relationships

A

relationships where at least one organism is adversely affected

MAJOR role in determining forest distribution

68
Q

What are the three types of antagonistic relationships?

A
  1. Physical Exploitation (non-consumptive and consumptive)
  2. Antibiosis or Chemical (toxins)
  3. Competition (intra- and inter-specific)
69
Q

What is the difference between physiological and ecological niche?

A

Physiological is where it can exist in ISOLATION

Ecological is where it can exist in COMPETITION with other species

70
Q

-3/2 Thinning Law

A

Plant size is negatively proportional to number of plants and plots a slope of ~ -3/2, regardless of species!

71
Q

How do early successional speceis compete for resources?

A

They are shade INTOLERANT, so they must grow tall very quickly and maintain a canopy above that of the competition.

They support lower foliage mass and have a difficult time shading out competition.

Ex: Larch

72
Q

What 3 things must a plant be able to do to out-compete other species BELOW ground?

A
  1. FASTER access to limiting resource (temporal dimension) - root growth
  2. Greater EXPLORATION of soil resource (spatial dimension) - More allocation to fine roots and mycorrhizae
  3. Use resources more EFFICIENTLY (physiological dimension) - translocation and greater growth efficiency.
73
Q

What are the crown classes that foresters use to rank competitive status of trees?

A

Dominant (D) - crowns extend above general level of canopy, receive FULL sunlight from top and sides

Codominant (CD) - crowns are AT the general canopy or below, tops receive direct sunlight from top, indirect from sides.

Intermediate (I) - Shorter than above two, crown extends up to the general canopy, PARTIAL direct sunlight

Suppressed (S) - Crown below canopy level, NO direct sunlight

74
Q

What are competitive characteristics of shade TOLERANT plants?

A

1) dense crowns, less foliage
2) slower growth rate
3) do not self-prune branches (conifers)
4) Slower natural thinning
5) Longer needle longevity
6) Slow response to thinning/can have more dense stands

75
Q

Sere

A

Stage in succession, usually named after dominant species

76
Q

Climax

A

Self-replacing sere that is relatively stable, implies equilibrium

77
Q

Primary Succession

A

Occurs on a surface or terrain that was NEVER vegetated, generally lacks soil development

Usually a more intense disturbance

(Glacial retreat, volcanoes, sand dunes)

78
Q

Secondary Succession

A

Disturbance where soil was previously vegetated and soil is relatively intact (Harvests, windstorms, fires)

79
Q

What influences the rate of succession?

A

Disturbance intensity

Site fertility

Type of succession

Climate

80
Q

What are the two major causes of succession?

A

Autogenic: system modifies itself

Allogenic: bigger picture changes

81
Q

Autogenic cause of succession

A

Biophys changes in the environment make it a new niche

Species with BETTER LIFE HISTORY TRAITS grow

82
Q

Allogenic cause of succession

A

The physical environment changes - Geologic processes

Ex: meandering streams, sedimentation of lakes, erosion of mountains, climate change

83
Q

Relay Floristics

A

Succession is many discrete, PREDICTABLE seral communities that modify the habitat to become more advantageous to other spp that become the next sere.

84
Q

Initial Floristics

A

Succession is NOT predictable and is driven by chance (init. seed composition, disturbance regimes, species longevity)

There is a sorting out of species as the environment is changed by chance events

All spp are initially present

85
Q

Linear Succession Direction

A

Proceeds to climax community and then an EXTERNAL disturbance resets the clock

86
Q

Cyclical succession direction

A

Patchwork communities replace themselves in cyclical sequence (Fir Waves)

87
Q

What are the Stages of Stand Development?

A
  1. Stand Re-initiation
  2. Stem exclusion
  3. Understory Re–initiation
  4. Old-Growth
88
Q

Stand Re-initiation

A

Establishment of fresh new seedlings

No overstory

Highest resource availabilty

89
Q

Stem Exclusion

A

High Competition for resources

Multi-species

Maximum LAI

Self-thinning

90
Q

Understory Re-Initiation

A

Gaps form where self-thinned trees have fallen, allowing light for understory

Diversity of niches

Increased coarse woody debris

91
Q

Old Growth

A

Steady state

Species replacement

Most complex structurally

Maximum coarse woody debris

92
Q

Aboveground biomass Accumulation during succession

A

Woody biomass increases with stand age

Foliage biomass maxes during Stem exclusion then levels/decreases

93
Q

Belowground biomass accumulation during succession

A

Coarse root biomass increases with age

fine root biomass peaks around max LAI (Stem Ex)

94
Q

When does a stand reach Maximum LAI during succession?

A

Around the Stem Exclusion Phase

95
Q

How does NPP change during succession?

A

It declines with stand development

96
Q

What are the three hypotheses as to why NPP declines with age?

A
  1. Imbalance of respiring and Psynthetic biomass (wood continues after max LAI reached) - not rly accepted bc Ra doesnt really increase
  2. Nutrient immobilization - nutrients become immobilized in CWD, living wood, and forest floor
  3. Hydraulic Constraint - Taller trees have more water tension and must close stomates (LEADING HYPOTHESIS)

Forest Ecology 550 (2 decks)

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