Exam 2 Flashcards
In what types of tissue are nutrient concentrations highest?
More metabolically active tissue
Foliage > fine roots > new twigs > old branches > new stem wood > old stem wood
In what species are nutrient concentrations higher?
Deciduous > evergreen
(Also, Temperate > Tropical)
Wet deposition
atmospheric input of nutrients dissolved in precipitation
dry deposition
atmospheric input of nutrients deposited as dryfall from blown dust particles
Where do sodium and chloride deposits come from/occur?
Coastal areas (from the ocean)
What are the two main types of weathering? Explain them briefly
Physical: degradation of rock from climatic factors or biological activity.
Chemical: dissolution of mineral when it reacts with water from rainfall or other liquid
What nutrients come from weathering of SILICATES?
Ca, Na, Mg, Fe
What nutrients come from weathering of CARBONATES? (Limestone, dolomite)
Ca, Mg
What nutrients come from weathering of APATITE?
P
What nutrients come from weathering of GYPSUM?
S
What nutrients come from weathering of SERPENTINE?
High amts of Mg
In what climates does weathering occur most?
Warmer and Wetter climates
What is the Redfield Ratio for decomposers and why is it important?
6-8:1 C:N
Important because things closest to this range are the easiest to decompose.
What factors influence Nitrogen fixation?
DECREASES WHEN: pH < 6.0
Low soil Oxygen
Micronutrient deficiencies
temperature optimum 30-35 C
Soil moisture optimum near field capacity
Why would a forest manager plant red alder in a douglas fir forest?
Red alders fix nitrogen, due to symbiotic bacteria (Actinomycete)
They would raise the soil and plant nutrient content
What are the types of nutrient outputs in an ecosystem?
Leaching (through the soil)
Erosion (along the soil)
Gaseous losses/denitrification (to the atmosphere)
Why are anions lost in the soil during leaching?
Because most forest soils do NOT have an anion exchange capacity!
Where do organic acids come from in forest soils?
Incomplete decomposition due to poor litter quality
What types of forests have poor litter quality?
Temperate and boreal evergreen conifer forests
Needles have lots of acids in them
Where might denitriffication occur and why?
Warm areas with hypoxic soils and high NO3 supply
What three major processes are responsible for nutrient uptake?
ROOT GROWTH to access the nutrients
MASS FLOW
DIFFUSION
What is the most rate limiting step in plants taking up nutrients?
ROOT GROWTH to access the nutrients
Retranslocation
What is it? What factors influence it?
Removal of nutrients from senescing/dying tissue
Influenced by:
Tissue type (foliage > wood)
Which nutrient
Nutrient availability
Leaf habit
What are the ecological advantages of retranslocation?
Greater nutrient use efficiency
Prevents loss of nutrients to forest floor (immobilization)
Decreases litter quality
Independence from soil supply of nutrients
What are some mechanisms to increase availability of limiting nutrients?
Add Nitrogen fixing plants
Tap roots
Plant selection
Add symbionts (rhizobium are acid tolerant, mycorrhizae decay lignin and absorb organic N)
What are the two key players in decomposition?
Aerobic heterotrophic bacteria and fungi
What are the results of decomposition?
Production of HUMUS
MINERALIZATION of nutrients from organic matter
How do we estimate decomposition?
Use the equation:
dx/dt = e-kt
k=-ln(1-fraction of original mass lost)/t
or k=litterfall / FFM
How do you estimate Mean Residence Time (MRT)?
MRT = 1/k
OR ratio of OM conent: OM input
AKA Forest Floor Mass:Litterfall
How can you tell what is immobilized vs mineralized when doing litterbag nutrient measurements?
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
How can you measure decomposition in logs?
WL = (V1* SG1) - (V0* SG0)
WL=weight loss
V=volume
SG=Specific gravity
Why might measuring CO2 evolution as a proxy for decomposition be inaccurate?
It includes ROOT RESPIRATION
May not include ANAEROBIC decomp (no CO2)
What are the three major factors influencing decomposition?
CLIMATIC VARIABLES (temp, moisture/evapotranspiration, oxygen)
LITTER QUALITY (Redfield ratio, Lignin level->resistant)
SA:V RATIO
What are the implications of cultivation on atmospheric CO2 concentrations?
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.
Who first coined the term production ecology?
EGLER
How are biomass and production measured?
Biomass: quantity of OM per unit area
Production: Rate of increase of OM per unit area per unit time
What are the different levels of study of production ecology?
Leaf/cellular
Tree/plant
Ecosystem
Landscape to regional
Global
What are some methods of estimating above ground biomass?
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
What factors influence aboveground biomass?
STAND AGE
CLIMATE
WATER AVAILABILITY
NUTRIENT AVAILABILITY
LEAF HABIT (evergreens have more bc they retain longer)
How do we estimate belowground biomass?
Allometry of COARSE ROOTS (excavated and weighed)
WATER EXCAVATION and allometry
fine roots
What factors influence below ground biomass?
STAND AGE
NUTRIENT AVAILABILITY (more fine roots on nutr poor)
WATER AVAILABILITY (more fine roots on dry)
LEAF HABIT (evergreen more FRs)
Gross Primary Production (GPP)
TOTAL amt of carbon assimilated by plants per unit area and time
Net Primary Production (NPP)
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
Carbon Allocation
the priority in which photosynthate is partitioned in the plant
Net Ecosystem Productivity (NEP)
Change in total organic matter (living and dead) in the ecosystem per unit area and time
NEP=GPP-Ra-Rh
or NEP=NPP-Rh
What can NEP values tell you about an ecosystem’s carbon balance?
NEP= + : C SINK
NEP= - : C SOURCE
What factors influence NPP and carbon allocation?
TEMPERATURE
WATER
NUTRIENT AVAILABILITY (FR inversely rel to lim nutr)
LEAF HABIT
Production Efficiency
AKA Vigor Index
AKA Growth Efficiency
Amt of carbon produced per unit leaf area or foliage mass
PE = Wood NPP/LAI
What factors influence Production Efficiency?
Light (positive relationship)
Water (pos. asymptotic)
Nutr Avail (pos asymp)
Site Productivity
The potential of a site to produce one or more natural resources
Should consider sustainability and multiple resources
Site Index
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
What are the pros of site index curves?
- easy, cheap
- Height growth is less sensitive than basal area to stocking density
- very site dependent (soils, topography, aspect)
What are the cons of site index curves?
Very empirical!
site dependent
differs among species
requires trees growing on the site
cant capture dynamic nature of tree growth and global change
What are some indirect ways to measure site productivity?
- Site index curves
- Overstory tree species (each has specific niche)
- Understory species
- Ecological Site Classification/Habitat Typing
- Environmental Relationships/Factors
- Ecosystem Process Models
- Remote Sensing
What are pros and cons to measuring overstory tree species as a proxy for site productivity?
PROS: allows quick assumptions
CONS: Not good for very adaptive spp
very qualitative
What are pros and cons to measuring understory tree species as a proxy for site productivity?
PROS: More sensitive to micro-climate differences, indicator species can be present
CONS: Doesn’t acct for Disturbance, influence of invasives, and is qualitative
How does habitat typing work?
Basically identify distinct understory species and use a flow chart to assess type
What are the pros and cons of habitat typing?
PROS: Easy, generally correlate with numerous variables
CONS: require good knowledge of flora, somewhat sensitive to disturbance, must have vegetation there
Life History
The reproduction, growth, and allocation characteristics of a species
Niche
The physical or temporal space occupied by a species. Often determined by the life history.
r-selected species
High rate of increase
allocate lots of energy to reproduction, but have low competitive ability
K-selected species
Lots of energy towards rearing offspring
fewer offspring, but greater competitive ability
What are the 3 components of Grime’s Life History Model?
Ruderals - HIGH resources , HIGH disturbance
Competitors - HIGH resources, LOW disturbance
Stress tolerators - LOW resources, LOW disturbance
Characteristics of Grime’s Life History Groups
Mutualism (+Example)
Symbiosis where both organisms benefit (Mycorrhizae fungi and plants)
Commensalism (+Example)
Symbiosis where one organism benefits and the other is not affected (vines on trees, cattle egrets with livestock)
Antagonistic relationships
relationships where at least one organism is adversely affected
MAJOR role in determining forest distribution
What are the three types of antagonistic relationships?
- Physical Exploitation (non-consumptive and consumptive)
- Antibiosis or Chemical (toxins)
- Competition (intra- and inter-specific)
What is the difference between physiological and ecological niche?
Physiological is where it can exist in ISOLATION
Ecological is where it can exist in COMPETITION with other species
-3/2 Thinning Law
Plant size is negatively proportional to number of plants and plots a slope of ~ -3/2, regardless of species!
How do early successional speceis compete for resources?
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
What 3 things must a plant be able to do to out-compete other species BELOW ground?
- FASTER access to limiting resource (temporal dimension) - root growth
- Greater EXPLORATION of soil resource (spatial dimension) - More allocation to fine roots and mycorrhizae
- Use resources more EFFICIENTLY (physiological dimension) - translocation and greater growth efficiency.
What are the crown classes that foresters use to rank competitive status of trees?
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
What are competitive characteristics of shade TOLERANT plants?
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
Sere
Stage in succession, usually named after dominant species
Climax
Self-replacing sere that is relatively stable, implies equilibrium
Primary Succession
Occurs on a surface or terrain that was NEVER vegetated, generally lacks soil development
Usually a more intense disturbance
(Glacial retreat, volcanoes, sand dunes)
Secondary Succession
Disturbance where soil was previously vegetated and soil is relatively intact (Harvests, windstorms, fires)
What influences the rate of succession?
Disturbance intensity
Site fertility
Type of succession
Climate
What are the two major causes of succession?
Autogenic: system modifies itself
Allogenic: bigger picture changes
Autogenic cause of succession
Biophys changes in the environment make it a new niche
Species with BETTER LIFE HISTORY TRAITS grow
Allogenic cause of succession
The physical environment changes - Geologic processes
Ex: meandering streams, sedimentation of lakes, erosion of mountains, climate change
Relay Floristics
Succession is many discrete, PREDICTABLE seral communities that modify the habitat to become more advantageous to other spp that become the next sere.
Initial Floristics
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
Linear Succession Direction
Proceeds to climax community and then an EXTERNAL disturbance resets the clock
Cyclical succession direction
Patchwork communities replace themselves in cyclical sequence (Fir Waves)
What are the Stages of Stand Development?
- Stand Re-initiation
- Stem exclusion
- Understory Re–initiation
- Old-Growth
Stand Re-initiation
Establishment of fresh new seedlings
No overstory
Highest resource availabilty
Stem Exclusion
High Competition for resources
Multi-species
Maximum LAI
Self-thinning
Understory Re-Initiation
Gaps form where self-thinned trees have fallen, allowing light for understory
Diversity of niches
Increased coarse woody debris
Old Growth
Steady state
Species replacement
Most complex structurally
Maximum coarse woody debris
Aboveground biomass Accumulation during succession
Woody biomass increases with stand age
Foliage biomass maxes during Stem exclusion then levels/decreases
Belowground biomass accumulation during succession
Coarse root biomass increases with age
fine root biomass peaks around max LAI (Stem Ex)
When does a stand reach Maximum LAI during succession?
Around the Stem Exclusion Phase
How does NPP change during succession?
It declines with stand development
What are the three hypotheses as to why NPP declines with age?
- Imbalance of respiring and Psynthetic biomass (wood continues after max LAI reached) - not rly accepted bc Ra doesnt really increase
- Nutrient immobilization - nutrients become immobilized in CWD, living wood, and forest floor
- Hydraulic Constraint - Taller trees have more water tension and must close stomates (LEADING HYPOTHESIS)
