RNR 1001 : RNR Exam 4 Notes
Factors Influencing Forest Development
Tolerance of soil characteristics
Different layers of soil are called soil horizons.
- Nutrients
- Silt – most productive- hold organic material
- Sand – water percolates though too quickly.
- Clay: not as productive, hold too much water.
- Permeability
- Porosity- the total amount of air space in a given soil.
- Organic Content
- Soil Microorganisms
- PH
Most trees cannot have their roots in water.
Fire
- Used to think that it was a negative impact on forests
- Fire is actually a good thing and is a key component of the ecology of forests
on the planet
- Trees have adapted a think, fire-resistant bark. The trees will get charred, but
unless the fire is extremely hot, the trees can live.
- Rapid regeneration after fire.
- Fire climax community
- Part of tree life history- sequoias need to be exposed to fire to reproduce.
2 kinds of fire
- Surface fires are “cool” low-level fires
o Burns undergrowth and litter
o Removes competing plants
o Releases nutrients into the soil
o Kills Fungi
o Improves Wildlife Forage
o Prescribed burning is an important forest management tool.
- Crown Fire – extremely destructive
o Burns the entire forest
o More common in fire-suppressed areas due to litter accumulation
o Forest, wildlife, erosion impacts.
Diseases and parasites
- Parasitic Fungi most destructive
- Viruses, bacteria, nematodes, mistletoe
- Most destructive on tree farms
- Exotics are problematic – chestnut blight, Dutch elm disease.
Document Summary
Different layers of soil are called soil horizons. Silt most productive- hold organic material. Sand water percolates though too quickly. Clay: not as productive, hold too much water. Porosity- the total amount of air space in a given soil. Most trees cannot have their roots in water. Used to think that it was a negative impact on forests. Fire is actually a good thing and is a key component of the ecology of forests on the planet. Trees have adapted a think, fire-resistant bark. The trees will get charred, but unless the fire is extremely hot, the trees can live. Part of tree life history- sequoias need to be exposed to fire to reproduce. Exotics are problematic chestnut blight, dutch elm disease. Primary avenue for secondary mortality: they also weaken trees and make them vulnerable to a second attack. Acid deposition, ozone, and spm (suspended particulate matter: dust, soot, asbestos, heavy metals) Leaf and bark damage, increased susceptibility to pathogens.
