NREM 301 Forest Ecology & Soils Day 24 November 16, 2008 Succession Nutrient Cycling Field Quiz next Tuesday see study guide
Quiz Review What are 2 different terms for buds that give rise to cones? Floral buds Apical buds Lateral buds Axillary buds
Estimate the age of the conifer
Upland Soils Clarion-Webster-Nicollet Association Name 2 soils that Big Bluestem usually grows on: Clarion, Nicollet, Storden, maybe Webster
Decurrent Weak Apical Control Excurrent Strong Apical Control Many Years 1 3 years Bud Activity & Tree Shape P 5 - Handout 1 3 Years Many Years
Leaf Area Index vs Root Area Index & Above & Below Ground Competition Leaf Area Index = 5-7 Root Area Index = 2X LAI With mycorrhizae = 100X
What wall produced the callous? Tangential Wall Xylem Cell Walls Radial Wall Rays 4 Outside Wall Callus/Cambium Radial Wall 3 Tangential 2 Wall 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 Indeterminate Result of P 5 - Handout Indeterminate
Ectomycorrhizae Special Soil Fungi Mycorrhizal Fungi Mycorrhizae = symbiosis between fungi and root. VA Mycorrhizae Fungi receives carbon from plant, plant gets a 10-100X increase in absorbing root surface area. 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)
Bud Activity and Tree Shape Excurrent strong apical control
Fruit on what kind of shoots? Long Shoot Short Shoot Short Shoot
Bud Growth Patterns Fixed Growth one annual flush Fixed 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
# of Years Leaves are Held? 1 2 4 3
Determinate or Indeterminate Magnolia buds?
Fall Leaf Color Major leaf pigments: Chlorophyll - green Carotene orange/yellow Xanthophyll - brown Anthocyanin red (acid), purple/blue (basic) Ideal weather: Sunny warm days Cold crisp (not freezing) nights
Now talk about response (succession) of a forest to disturbance Secondary Succession
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 Whole Area Mix Of Different Aged Gaps Uneven-aged Mixed Species Even-aged Single Species
Tolerance Inhibition Facilitation Site changes: more sunlight, 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 Succession Pathways 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 biological legacies Only pioneer species can get established Next seral stage depends on rate of modification of site by pioneers
What stage of stand development model; shifting mosaic steady- state model is this? What Succession Pathway will this stand take? Understory initiation/transition stages Tolerance pathway Harvested in this year
What killed the trees with needles still on them? Soil/roots hot enough to kill roots What stage of the stand development model & SMSS model is this? Stand initiation & reorganization stages What pathway of succession will this site follow? Tolerance pathway Develop a sere for the site N-fixing forbs/grasses/shrubs Lodgepole pine can inhibit next seral stage if fire occurs
What succession pathway would you expect on this site? Facilitation Pathway primary succession
Succession pathway for the community that people are walking in? If trees are encroaching what stage of the stand development & SMSS model does this represent? Inhibition pathway if fire is involved Stand initiation stage if tree are encroaching without fire
Does this site resist change or is it resilient to change?
A B D Inhibition Which pathway? Maybe Facilitation C blow-down Tolerance/ Inhibition Tolerance/ Inhibition Tolerance
Bulk Density ph Soils change with succession Succession & soils key to organic matter dynamics Organic Matter Total N Organic matter/biomass integral in nutrient cycling in a community
Soils Contain Organic Matter Living plant tissue Soil organisms Plant exudates Litter Coarse debris Humus Soil is dynamic & full of life!
O Horizons Forest Floor L litter (Oi) F fermentation (Oe) H humus (Oa) Kinds of FF s Mor Oi(L) Oe (F) Oa (H) Mull Oi(L) Oe (F)? Conifer Acid Low C/N Deciduous Basic Moder Oi(L) Oe (F) Oa (H)?
Mor Forest Floor Conifer/Acid Slow Decomposition Oi (L) Oe (F) Oa (H) Mineral soil
Mull Forest Floor Deciduous Basic/Low C/N Oi (L) No Oe & Oa Incorporated Into A
What role does OM play in nutrient cycling? Group Activity Diagram the general nutrient cycle for an ecosystem Showing: a) inputs (how do they get into an ecosystem) b) outputs (how are they lost from the ecosystem) c) how they move around within the ecosystem