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