Transcript Temperate Hardwood Hammocks

Temperate Hardwood Hammocks
Chapter 6
Hardwoods
Hardwoods – 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
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
Hardwoods
• Thick shade
• Dense ground cover
captures much sun
• Dense tree canopy captures
most of the sun; not much
ground cover
• Decay recycles nutrients
• Fire 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-drained
Bottom: 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 Hammocks
Beech 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 Hammocks
Spanish 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