310lect5

Natural Vegetation

I. Introduction

A. Human influences

1. Fire

2. Lumbering

3. Forest management

4. Introduction of non-native species

a. Water hyacinth

i) Chokes bayous

B. Natural Vegetative Regimes

1. Climate

2. Physiography

3. Soil Type

C. Subtropical Evergreen

1. Broadleaf

a. Similar to rainforest

b. Fewer species here

i) Live Oak

ii) Magnolia

iii) Lianas

iv) Epiphites

(a) Ferns

(b) Lichen

(c) Mosses (Spanish Moss esp)

2. Needleleaf

(a) Southern Pine Forest

· Sandy soils

· Prone to fire

· Well adapted to drought

II. Vegetation of the Tertiary and Pleistocene Uplands

A. Shortleaf Pine and Hardwoods

1. Northern hill country

a. Shortleaf

b. Loblolly pine

i) wings

ii) Most common tree in Louisiana

iii) Quick to reestablish itself in clearcut areas

c. Oak

d. Hickory

B. Longleaf Pine

1. Traditionally the dominant species

2. Most economically valuable

a. Pure stands

b. Grow straight and tall

c. Harder wood of the pines

3. Susceptible to wild hogs

4. Slow growing

5. Highly resistant to fire: pyrophytic

6. Climax forest in fire prone areas

C. Flatwoods

a. Hardwoods

b. Long leaf pine on "flat" terraces

2. Florida Parishes

a. More slash pine and

3. Western Sector

a. No slash pine, no undergrowth

D. Prairie

1. Very little of it left

2. Mostly along rail corridors

3. Agricultural conversion

4. Gallery Forests

a. Along stream courses

b. Oak, sweetgum and hickory

5. Why grasslands in humid Louisiana?

a. Claypan

b. Winter grass fires

c. Native Americans

III. Vegetation of the Holocene Plain

A. Upland Hardwoods

1. Oak, hickory, gum, magnolia, holly

2. Blufflands next to the floodplain

B. Bottomland Hardwoods and Cypress

1. Natural levees, splays

a. Prime agricultural land

b. Live Oak

i) Symbolic quality

2. Backswamp Areas

a. Poor drainage

i) Bald Cypress

(a) Heartwood was valuable

(b) Dominate stands

(c) Deciduous needleleaf-not evergreen

(d) Not fire resistant

(e) Swamp climax

(f) Seedling requires dry ground

ii) Tupelo gum

iii) Swamp Oak

iv) Willow

C. Marsh

1. No trees

2. Species distribution determined by salinity

a. Freshwater

b. Brackish

c. Intermediate

d. Saline

3. Ghost Forests

4. Black Mangrove

a. Silt-like roots

b. Saline-to-brackish water

c. Vulnerable to freezes

d. Indicator of climatic zone

e. Nothern limit of the tropics

IV. Conclusion