temperate hardwood hammocks chapter 6. hardwoods hardwoods – broad-leafed flowering trees, usually...

Temperate Hardwood Hammocks

Chapter 6

HardwoodsHardwoods – broad-leafed flowering trees, usually deciduous

Softwoods – cone-bearing trees; have needles, usually not deciduous

Hardwoods

Hardwoods are more common in the southeast now than in the past

- fire exclusion- wetland drainage

Examples of hardwoods:-oaks, beech, magnolia, bays, cherries- cabbage palm may be found in hardwood forests, although it is not a hardwood

Live oak

Southern magnolia

American beech

Red bay

Carolina laurel cherry

Hardwoods

Hardwood forests may be xeric, mesic, or hydric- different conditions mean different species

Other conditions that affect the species types:• climate• flooding frequency• steepness of terrain• direction slope faces• soil texture and chemistry• age of forest

Beech-Magnolia Forests

Found in northern Florida

Beech and magnolia are the dominant species, but there may be 25+ types of trees

Trees are much more tightly packed than in a pine grassland – dense shade means not much ground-level growth

Beech-Magnolia Forests

Heavy shade is a problem for germinating seeds- new trees can only spring up where an

old tree has died – this is called gap succession

Any gap is quickly used by a succession of seedlings, only some of which will survive.

Always ongoing – the forest therefore has many differently-aged trees

Beech-Magnolia Forests

Not fire-adapted – resists burning

Moisture is held in by the thick canopy and dense leaf litter

Trees are not particularly flammable

Beech-Magnolia Forests

Adaptations to a shady life:• if you need lots of light, grow fast; or else, grow

more slowly but get by on less light• smaller trees and shrubs can capture the more

bluish light that gets through the canopy• smaller trees can also leaf out earlier, or hold

onto their leaves longer

Beech-Magnolia Forests

Beeches and magnolias rule:• both can handle shade• as they get older, they create shade• magnolia leaves also shade out the ground• decaying beech leaves inhibit growth of other

species

Beech-Magnolia Forests

Importance of fallen trees:- they leave tip-up mounds and pits where

the roots are pulled up- this micro-topography allows different

plants and fungi to colonize the area

Hardwood Forests vs. Pinelands

Pinelands• Open, sunny

• Dense ground cover captures much sun

• Fire recycles nutrients

Hardwoods• Thick shade

• Dense tree canopy captures most of the sun; not much ground cover

• Decay recycles nutrients

Beech-Magnolia Forests

Animals

- most can fly or climb- diverse tree species mean many different

types of flowers and fruit for food- decaying matter on forest floor gives lots of opportunities for insects and other

invertebrates

Florida Forests

Forests in Florida are going to vary from north to south – southern Florida is going to have a completely different array of tropical species.

Topography and local climate will also make a difference.

Apalachicola Steephead Ravines

The Apalachicola river flows from the Blue Ridge mountains in northern Georgia.

The deep ravines of its tributaries harbor ancient plant species from before Florida emerged from the ocean.

Apalachicola Steephead Ravines

The steep ravines of the river’s tributaries show a range of conditions from top to bottom, so diversity is very high.

Top: dry, windy, sunny, well-drainedBottom: cool, moist, still, shaded

A steam or tributary will flow out the ravine towards the river.

Apalachicola Steephead Ravines

Since the ravines run east/west, there is a shaded north-facing slope and a sunny south-facing slope.

- the north-facing slope can harbor plants that are generally found much farther north

The bottom of each ravine is like a moist island isolated from all the others – species may differ from ravine to ravine.

Apalachicola Steephead Ravines

Huge diversity of rare species:

• a 35-mile stretch on the east side of the river has more total animal species than any other comparably-sized parcel on the coastal plain

• home to over 100 rare and endangered species

• still not well-surveyed – more to be discovered

Florida torreya, or gopherwood

Florida yew

Apalachicola rosemary

Xeric Oak HammocksBeech and white oak don’t occur as south as central Florida

Central Florida hammocks are typically other oaks and hickories, sometimes with cabbage palms.

Xeric Oak HammocksSpanish moss (Tillandsia)

- an epiphyte (lives on other species) - not a parasite – depends

on trees for structure and shelter, but still photosynthesizes

- shady oak canopies keep it from drying out

Some animals (birds, bats) nest or roost in it.

Xeric Oak Hammocks

Oaks (Quercus species)- live oak, laurel oak, turkey oak, Chapman’s

oak- live oak and laurel oak can get quite large

(100 feet in crown diameter) and may be over 100 years old

Oaks and hickories produce mast (nut-type fruits)

Xeric Oak Hammocks

Some years are “mast years” – a greater than normal abundance of fruit is produced

These are bonanzas for a wide array of animals:

Xeric Oak Hammocks

Other animals that depend on oak forests:

Mesic Oak Hammocks

More trees besides oaks and hickories: bays, magnolia, sweetgum, and many more

Diverse tree types mean that different fruits are ripe at different times – especially important for migrating birds

- many birds fly through Florida on their seasonal migrations

Mesic Oak Hammocks

How birds help the forest:

• spread seeds (with a fertilizer bonus)• control insect pests

Hardwood Hammocks

How the forests help us:• regulate climate, release moisture back into air• control runoff and purify water• allow for decay of organic material into soil• aesthetically pleasing and shady• diverse microhabitats for numerous species• absorb sound, provide privacy