Transcript Oe (F)

NREM 301
Forest Ecology & Soils
Day 25
November 11, 2008
Nutrient Cycling
Field Quiz Today – Be
Prepared for Wet
Field Quiz
Slope Position &
Shape
Summit (linear)
Shoulder (convex)
Soil Depth
Lester
Hayden
Backslope (linear)
Ice Transported
Glacial Till
Storden
Residual Bedrock
Colluvial
Footslope (concave)
Toeslope (linear)
Terril
Coland
Alluvial Spillville
Soils – Parent Material – Topography
in Central Iowa
Soil & FF horizons, texture, structure
L – litter (Oi)
F – fermentation (Oe)
H – humus (Oa)
Kinds of FF’s
Mor – Oi (L)
Oe (F)
Oa (H)
Conifer
Acid
Low C/N
Mull – Oi (L)
Oe (F)? Deciduous
Basic
Moder – Oi (L)
Oe (F)
Oa (H)?
Riparian Zone
Run – fast smooth flow
Island
Riffle – shallow,
turbulent flow
Bend – deep pool
Thalweg
Habitat Units (page 13-14)
River Continuum Concept
Heterotrophic/Allochthonous
Autotrophic/Autochthonous
Group Activity - please use this picture to define and
provide examples of each of the terms.
Terms
Ecology
Ecosystem
Community
Population
Lake ecosystem – the biotic & abiotic factors that
interact to create the functioning lake system.
Vertical Stratification – various canopies in forest
Fish/invertebrates = animal community
Aquatic plants – plant community Floating mat of
plants – ecotone
All individuals of sunfish = the sunfish
population
gradation
between
Horizontal Stratification
aquatic and forest.
Alllake,
individuals
duckmat,
weed
= duckweed population
floatingof
plant
forest
Landscape Ecosystem =
northern lake/bog ecosystem
Ecotone
Vertical &
Horizontal Stratification
Landscape Ecosystem
Differences between plant types
Decurrent
Weak Apical
Control
Excurrent
Strong Apical
Control
Many Years
1
3 years
Bud Activity & Tree Shape
Many Years
P 5 - Handout
1
3 Years
What wall produced the callous?
Tangential
Wall
Xylem Cell Walls
Radial
Wall
Rays
Radial
Wall
3
Tangential
2 Wall
4
Outside Wall
Callus/Cambium
3
Yearly Shoot Growth Patterns
Determinate growth – terminal bud stays active with strong control
Indeterminate growth – no true terminal bud – weak control or may
become a floral bud or abort
Determinate
P 5 - Handout
Indeterminate
Result of
Indeterminate
Ectomycorrhizae
Special Soil Fungi
Mycorrhizal Fungi
Mycorrhizae = symbiosis between
fungi and root.
Fungi receives carbon from plant,
plant gets a 10-100X increase in
absorbing root surface area.
VA Mycorrhizae
Ectomycorrhizae
Basidiomycetes & Ascomycetes
* spores wind & water dispersed
* 2,100 species of fungi in NA
* most conifers, willow, aspen, oak,
hickory
Endomycorrhizae (VA)
Phycomycetes – spores below ground
* most widespread, associate with
* most plant families including crops
* most deciduous trees
(P 10 – Handout)
Fruit on what kind of shoots?
Long Shoot
Short Shoot
Short Shoot
Bud Growth Patterns
Fixed
Fixed Growth – one annual flush
Free Growth – continuous growth
Recurrent Growth (Southern Pines)
Free Growth
Many Riparian Species
P 4 - Handout
What is the name for
this kind of branch &
what kind of bud
gives rise to it?
Epicormic Branch
Adventitious bud
How do forest stands respond
to disturbance?
Stand Development
Model
Disturbance where
original species still
present on site.
Disturbance where all
species have been
removed.
What kind of species is A?
Shifting Mosaic Steady State Model
Forbs/Shrubs/Seedlings
Gap Succession
Older Trees
Die
Create Gaps –
Mixed
Species
Even-aged
Single Species
Whole Area Mix
Of Different Aged
Gaps – Uneven-aged
Mixed Species
Tolerance
Inhibition
Facilitation
Succession Pathways
Site changes: more
sunlight, some
compaction
Site changes: loss of OM
structure but soil still
fertile
Site changes: new
material, no biological legacies
Any species can seed
in if seed can get there
Any species can seed
in if seed can get there
light seeded grasses &
forbs
If well established &
if fire occurred then
could keep woody
plants out
Length of grass stage
depends on fire
Only “pioneer”
species can get
established
All can germinate &
start to grow
Mainly shade intolerant
will capture site at the
beginning
Rate of change depends
on longevity of species
Next seral stage
depends on rate of
modification of
site by pioneers
Diagram the general nutrient cycle for an ecosystem
Think of nutrients cycling in an
ecosystem box
Group Activity
Show:
a) Inputs (how do nutrients get
into an ecosystem)
b) Outputs (how are nutrients
lost from the ecosystem)
c) Internal Cycling (how do
nutrients move around in the
ecosystem
Biochemical
General Nutrient
Cycle
Geochemical
Biogeochemical
Page 525 Textbook
Ability of fresh OM
to be incorporated
into the soil helps
dictate rate of
cycling
Oi (L)
Oe (F)
Oa (H)
Mineral soil
Bogs
1. Northern or high elevation
climates
2. Water source – precip – bowl
with not other in or outputs
3. Anaerobic water
4. Low pH < 5
5. Slows decomposition
6. Sphagnum moss
Histisol Organic Soil
Fens
1. Similar locations
2. Water source is
groundwater or stream –
moving into & out of fen
3. Higher pH
4. More nutrients
5. More plant diversity
Group Activity
Two Concave Depression Sites
Both within about 10 miles of each other – one
is at about 6,000 ft the other at 9,000 ft elevation
What reasons cause the difference you see?
Salt Flat pH very basic
Low precipitation, high ET
Fen pH very acid
Higher precipitation, lower ET, more
Plant growth – conifers dominate
Fall is here and the leaves are falling off of the trees
Group Activity
These leaves play an important role in maintaining the organic matter
in the soil. How do you think they become part of the OM?
Please use this figure to expand your answer
Group Activity
A) What % of the aspen leaves
is water?
B) What % of the aspen leaves
are C, H, O and ash?
Lignins & phenolic compounds
C) Rank the compounds from Cellulose
fastest decomposition to Sugars, starches & simple proteins
slowest.
Hemicellulose
Fats, waxes, etc.
Crude proteins
Composition of typical
green plant material
Sugars, starches & simple proteins
Crude proteins
Hemicellulose
Cellulose
Fats, waxes, etc.
Lignins & phenolic compounds
Rapid decomposition
Slow decomposition
Soil Meso & Microfauna
Over 1000 species in a single m2 of
forest soil
Many of the world’s terrestrial insect
species are soil dwellers for at
least some stage of their life-cycle
A single gram of soil may contain
millions of individuals and several
thousand species of bacteria
A typical, healthy soil might contain:
a) several species of vertebrate
animals – moles, shrews, etc.
b)
several species of earthworms,
c)
20-30 species of mites,
d)
50-100 species of insects,
e)
tens of species of nematodes,
f)
hundreds of species of fungi
g)
thousands of species of bacteria
and actinomycetes.
Soil – a very complex ecosystem – 1,000’s of organisms that are critical to global
cycles. The most densely packed ecosystem on the planet.
Macrofauna - > 2 mm – termites, ants, earthworms, beetles, etc. – can dig through soil
& create structures for their movement and habitat (burrows, galleries, nests, etc.)
Mesofauna – 0.2-2mm – collembolas, acarids – live in air-filled pores
Microfauna - <0.2mm – protozoa, nematodes, rotifers – live in water-filled pores
Group Activity
A) What is meant by the term
detrital food web?
B) How is this food web
similar, different from the
traditional terrestrial food
web?
C) What are the three major
steps of decomposition?
Soil (Detrital) Food Web
Decomposition
1. OM is oxidized to
water & CO2
2. Heat energy released
3. Nutrients released
(mineralized)
4. Resistant compounds
produced by
organisms
C/N
Dry Plant OM
42% = C
1-2% = N
1. Microbes need
8 C for 1N to
build cells
2. Need 16 C for Rs
3. Need C/N = 24/1
4. If OM > 24:1
C/N = 30:1
microbes take
N from NO3
C/N = 120:1
in soil
5. So lack of N can
slow
C/N = 300:1
decomposition