NREM 301NREM 301Forest Ecology & SoilsForest Ecology & Soils

Nutrient CyclingNutrient Cycling

Field Quiz Today – Be Field Quiz Today – Be Prepared for WetPrepared for Wet

Day 25Day 25November 11, 2008November 11, 2008

Soil DepthSoil Depth

Summit (linear)Summit (linear)Shoulder (convex)Shoulder (convex)

BackslopeBackslope (linear)(linear)

ToeslopeToeslope

(concave)(concave)FootslopeFootslope(linear)(linear)

Ice TransportedIce TransportedGlacial TillGlacial Till

Residual BedrockResidual Bedrock

ColluvialColluvial

Alluvial Alluvial

Soils – Parent Material – Topography in Central Iowa

LesterLesterHaydenHayden

StordenStorden

TerrilTerrilColandColand

SpillvilleSpillville

Slope Position &Shape

Field QuizField Quiz

L – litter (Oi)L – litter (Oi)

H – humus (Oa)H – humus (Oa)

F – fermentation (Oe)F – fermentation (Oe)

MorMor – Oi (L)Oi (L) Oe (F)Oe (F) Oa (H)Oa (H)

Mull – Oi (L)Mull – Oi (L) Oe (F)?Oe (F)?

ModerModer – – Oi (L)Oi (L) Oe (F)Oe (F) Oa (H)?Oa (H)?

Soil & FF horizons, texture, structureSoil & FF horizons, texture, structure

Kinds of FF’sKinds of FF’s

ConiferConiferAcidAcid

Low C/NLow C/NDeciduousDeciduous

BasicBasic

ThalwegThalweg

Bend – deep poolBend – deep pool

Riffle – shallow, Riffle – shallow, turbulent flowturbulent flow

Run – fast smooth flowRun – fast smooth flow

IslandIsland

Riparian ZoneRiparian Zone

Habitat Habitat UnitsUnits (page 13-14) (page 13-14)

River Continuum Concept

Heterotrophic/Allochthonous

Autotrophic/Autochthonous

TermsTerms

EcologyEcology

EcosystemEcosystem

CommunityCommunity

PopulationPopulation

EcotoneEcotone

Vertical & Vertical &

Horizontal StratificationHorizontal Stratification

Landscape EcosystemLandscape Ecosystem

Group Activity - Group Activity - please use this picture to define and please use this picture to define and provide examples of each of the terms.provide examples of each of the terms.

Lake ecosystem – the biotic & abiotic factors that Lake ecosystem – the biotic & abiotic factors that interact to create the functioning lake system.interact to create the functioning lake system.

Fish/invertebrates = animal communityFish/invertebrates = animal communityAquatic plants – plant communityAquatic plants – plant community

All individuals of sunfish = the sunfish populationAll individuals of sunfish = the sunfish population

All individuals of duck weed = duckweed populationAll individuals of duck weed = duckweed population

Floating mat ofFloating mat ofplants – ecotoneplants – ecotonegradation between gradation between aquatic and forest.aquatic and forest.

Vertical Stratification – various canopies in forestVertical Stratification – various canopies in forest

Horizontal StratificationHorizontal Stratification lake, floating plant mat, forestlake, floating plant mat, forest

Landscape Ecosystem = Landscape Ecosystem = northern lake/bog ecosystemnorthern lake/bog ecosystem

Differences between plant typesDifferences between plant types

DecurrentWeak Apical

Control

1 3 years

Many Years

ExcurrentStrong Apical

Control

1 3 YearsMany Years

Bud Activity & Tree Shape

P 5 - HandoutP 5 - Handout

TangentialTangentialWallWall

Xylem Cell WallsXylem Cell Walls

RadialRadialWallWallRaysRays

44

33

33

22

RadialRadialWallWall

TangentialTangentialWallWall

Outside WallOutside WallCallus/CambiumCallus/Cambium

What wall produced the callous?

Yearly Shoot Growth Patterns

Determinate growthDeterminate growth – terminal bud stays active with strong control

Indeterminate growthIndeterminate growth – no true terminal bud – weak control or maybecome a floral bud or abort

Determinate Indeterminate Result of IndeterminateP 5 - HandoutP 5 - Handout

VA MycorrhizaeVA Mycorrhizae

EctomycorrhizaeEctomycorrhizae Special Soil FungiMycorrhizal Fungi

Mycorrhizae = symbiosis between fungi and root.

Fungi receives carbon from plant,plant gets a 10-100X increase in absorbing root surface area.

EctomycorrhizaeBasidiomycetes & Ascomycetes* spores wind & water dispersed* 2,100 species of fungi in NA* most conifers, willow, aspen, oak, hickoryEndomycorrhizae (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?

Short Shoot

Short ShootLong Shoot

Bud Growth Patterns

Fixed Growth – one annual flush

Free Growth – continuous growth

Fixed

Free GrowthMany Riparian Species P 4 - HandoutP 4 - Handout

Recurrent Growth (Southern Pines)

Epicormic Branch

Adventitious bud

What is the name for this kind of branch & what kind of bud gives rise to it?

How do forest stands respond to disturbance?

Stand DevelopmentModel

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

Gap Succession

Forbs/Shrubs/SeedlingsForbs/Shrubs/Seedlings

Even-agedEven-agedSingle SpeciesSingle Species

Older Trees Older Trees DieDie

Create Gaps – Create Gaps – MixedMixed

SpeciesSpecies

Whole Area MixOf Different AgedGaps – Uneven-agedMixed Species

Site changes: moresunlight, some compaction

Any species can seed in if seed can get there

All can germinate & start to grow

Mainly shade intolerant will capture site at the beginning

Rate of change depends on longevity of species

Site changes: loss of OM structure but soil still fertile

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

Site changes: new material, no bio- logical legacies

Only “pioneer” species can get established

Next seral stage depends on rate of modification of site by pioneers

FacilitationTolerance Inhibition

Succession PathwaysSuccession Pathways

Diagram the general nutrient cycle for an ecosystemGroup ActivityGroup 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

Think of nutrients cycling in an ecosystem box

Page 525 Textbook

GeochemicalGeochemical

BiogeochemicalBiogeochemical

BiochemicalBiochemical

General NutrientGeneral NutrientCycleCycle

Ability of fresh OM to be incorporated into the soil helps

dictate rate of cycling

Oi (L)Oi (L)

Oe (F)Oe (F)

Oa (H)Oa (H)

Mineral soilMineral soil

Histisol Organic SoilHistisol Organic Soil

BogsBogs

1. Northern or high elevation climates2. Water source – precip – bowl

with not other in or outputs

3. Anaerobic water

4. Low pH < 5

5. Slows decomposition

6. Sphagnum moss

FensFens

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

Two Concave Depression Sites

Salt FlatSalt Flat FenFen

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?

Group ActivityGroup Activity

pH very basicpH very basic pH very acidpH very acid

Low precipitation, high ET Higher precipitation, lower ET, morePlant growth – conifers dominate

Fall is here and the leaves are falling off of the trees Group ActivityGroup 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 ActivityGroup Activity

B) What % of the aspen leavesare C, H, O and ash?

A) What % of the aspen leavesis water?

Lignins & phenolic compounds

Cellulose

Sugars, starches & simple proteins

Hemicellulose

Fats, waxes, etc.

Crude proteins

C) Rank the compounds from fastest decomposition to slowest.

Sugars, starches & simple proteinsCrude proteinsHemicelluloseCelluloseFats, waxes, etc.Lignins & phenolic compounds

Rapid decomposition

Slow decomposition

Composition of typicalComposition of typicalgreen plant materialgreen plant material

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

C) What are the three major steps of decomposition?

Group ActivityGroup 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?

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

C/N = 30:1

C/N = 120:1

C/N = 300:1

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 microbes take N from NO3 in soil5. So lack of N can slow decomposition