Exam 2: Oak-Hickory-Pine Forests (Ohf)

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OHF climate

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• relatively warm and moist with long growing season
  
• rainfall may be high but upland soils are dry due to high temps

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OHF topography

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gently rolling hills and valleys...not flat but no big elevational changes

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OHF disturbance

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fire is not major determinant of vegetation, but in past, humans used fire to change vegetation

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OHF forest vegetation

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• very diverse

• upland species: scarlet oak, SRO, NRO, white oak, pignut hickory, mockernut hickory

• bottomland along rivers: sweetgum, persimmon, river birch,cherrybark oak

• western edge of region grades into prairie:

- green ash and boxelder on wet sites

- post oak, eastern redcedar on drier sites

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tulip-poplar: most important

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• not a true poplar...Europeans mistook it for one since its leaves, shape, and bark are poplar-like
• most common (intolerant) pioneer in OHF
• very rapid growth; dominant in canopy; live up to 300 years
• sensitive to soil compaction so not planted commercially
• heavily browsed by deer

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tulip-poplar: reproduction

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• monoecious
• pollinated by bees
• produces aggregate of samaras that can remain viable in forest floor for years before germinating
• sprouts prolifically from stump
  

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tulip-poplar: uses

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• wood is v good for carpentry

- excellent self-pruner so wood has small knots; splinter-free and easily worked

• pulp, OSB
• popular ornamental, often used for "xeriscaping" since it handles drought
  

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oriented strand board (OSB)

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• an engineered board formed by compressing layers of wood strands(flakes) in specific orientations with an adhesive
• has mechanical properties that make it particularly suitable for load-bearing applications in construction
• the most common uses are as sheathing in walls, flooring, and roof decking
  

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sweetgum: most important

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• another big hardwood...rivals tulip-poplar in size
• intolerant pioneer
• rapid growth up to 200’ on bottomlands where it is part of the climax forest due to great size and longevity
• smaller on upland sites where it is eventually replaced by oaks and hickories
  
• almost no pests/problems

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sweetgum: reproduction

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• monoecious
• wind-pollinated
• fruit is a head of capsules with a large number of winged seeds
• sprouts vigorously from stumps and root suckers
• aggressively invades open spaces
  

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sweetgum: uses

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• wood is hard and heavy, good for OSB, plywood, crates
• density makes it a candidate for biomass energy
• interlocked grain makes it impossible to split for firewood
• sometimes planted as ornamental, but "gumballs"
  

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American sycamore: scientific name

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Platanus occidentalis

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American sycamore: most important

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• third largest OHF hardwood...called planetree in Europe
• riparian habitat
• fast growing up to 200 feet, may live for 500 years
• has been hybridized with planetree (Platanus orientalis) to create London planetree (Platanus x acerifolia), a popular street tree that can be distinguished by its olive-green bark and fruit heads borne in clusters of 2 or 3
  
• pests include anthracnose and xyella fungi

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American sycamore: reproduction

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• small, light achenes in dense heads
• seeds mature in fall but remain on tree and are dispersed in spring by wind and water, germinate on bare mineral soil
• also can vegetatively reproduce from broken branches that land on wet soil and from cut stumps
  

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American sycamore: uses

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• wood fairly hard and heavy, good for veneers, furniture, pulp
• no taste so used for tongue depressors and popsicle sticks
• planted as ornamental
  

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shortleaf pine: most important

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• most wide-spread pine in the OHF
• intolerant pioneer
• fire-maintained on mountain ridges
• hybridizes with loblolly in western part of its range
• wood is used for poles and pulp, but not grown in plantations
  
• highly resistant to fusiform rust...breeding research has been conducted to introduce resistance to loblolly
  

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shortleaf pine: reproduction

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• seeds in cones
• also capable of stump sprouting up to about 10 years of age after fire or cutting
  

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shortleaf pine: pests/problems

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• littleleaf disease caused by Phytophthera cinnamomi, a fungus that infects roots and reduces water supply to leaves
• southern pine beetle
  

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loblolly pine: most important

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• most important commercial tree in SE
  
• originally river bottoms and moist depressions, but following the decline of cotton farming it quickly invaded on the exposed clay soils
  
• intolerant pioneer
• gets taller on bottomland sites than on upland sites
• what is a "loblolly"...British colonists called a mudhole a loblolly which is where loblolly was originally found growing
• natural form is crooked, but breeding programs have selected for straightness
  

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loblolly pine: reproduction

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• very prolific seeder and colonizer
• very amenable to nursery culture
• millions of seeds are produced annually in grafted seed orchards where 􏰂trees have been selected for straight, rapid growth and disease resistance
  

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loblolly pine: pests/problems

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• fusiform rust weakens stems
• southern pine beetle can kill entire stands
• root rot
• snow and ice damage in extended northern range
• a lot of money is spent controlling competing hardwoods, usually with chemicals
  

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loblolly pine: uses

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most important commercial tree in SE, with vast acreages planted annually

• #1 use is kraft paper (paper bags, boxes)
• sawtimber, plywood
• also grown in China, Brazil, South Africa

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the oaks: genus Quercus

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• most important commercial hardwood genus in the world

- wood for furniture and flooring

in Med. area, cork production from cork oak is huge industry

wildlife habitat: mast is critical to many species (mast = fruit of forest trees)

• a taxonomist's nightmare...hybrids

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two subgenera of North American Quercus

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• white oaks vs. red oaks
• differ in leaf, wood, and acorn characteristics
• third subgenus, Cyclobalanus, is found only in Asia

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white oak subgenus

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Leucobalanus (e.g. Quercus alba)

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red oak subgenus

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Erythrobalanus (e.g. Quercus rubra)

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white oaks vs. red oaks: leaf differences

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• white: rounded lobes with no bristles
• red: angular lobes with bristle tips

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white oaks vs. red oaks: wood differences

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white oaks vs. red oaks: tylosis

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white oaks have them while red oaks do not

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tylosis

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• a clogged xylem vessel...no water can move through
• technical definition: an outgrowth of a xylem parenchyma cell that "leaks" into lumen of an adjoining vessel via pits

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white oaks vs. red oaks: fruit differences

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some white oaks of OHF

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• white oak
• Oglethorpe oak
• post oak
• overcup oak
• swamp chestnut oak (Coastal Evergreen region)

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white oak: most important

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• most important member of Leucobalanus and most abundant oak in eastern U.S.
• best oak wood for furniture and flooring, mast for wildlife
  
• habitat is normally upland but growth is best in floodplains
  
• reproduction: acorns germinate in fall soon after hitting ground
• acorns were used for food by Native Americans

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Oglethorpe oak: most important

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• Wilbur Duncan of UGA Department of Plant Sci. discovered the species along a creek in Oglethorpe County and described and named it in 1940
• rare, scattered tree, protected in GA
• found in 3 counties in GA, also populations in SC, LA, MS
  
• pests: chestnut blight

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red oaks of the OHF loosely follow a site gradient from _______ to ______ to ________

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wet (hydric) to medium (mesic) to dry (xeric)

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red oaks of the OHF

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1. cherrybark oak
2. water oak
3. northern red oak
4. black oak
5. southern red oak
6. scarlet oak
7. blackjack oak

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cherrybark oak: scientific name

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Quercus pagoda (Q. falcata var. pagodaefolia)

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cherrybark oak: most important

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• wood quality is the best of southern red oaks
• it's an allelopathic species

- allelopathy: the chemical inhibition of one plant by another

- leaves of this species concentrate salicylic acid and when they fall, the chemical leaches into the soil and inhibits growth of competing plants

• best on well-drained bottomlands

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water oak: most important

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• reproduces aggressively...fast-growing but short-lived
• brittle wood, so not a commercial species for wood products
• popular ornamental and street tree in the south
• bottomland to moist upland

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scarlet oak: most important

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• sprouts after cutting or fire, often undergoes several cycles of natural dieback and re-sprouting
• very popular ornamental due to deep scarlet fall color
• dry soils
  

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blackjack oak: most important

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• grows on driest, most sterile sites (i.e. granite outcrops, sandy soils)...VERY drought tolerant
• no commercial value, but provides acorns for wildlife

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hickories of the OHF

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• like oaks, there are many hybrids
• like oaks, not a stable genus
• wood is heavy, strong, hard, dense, but NOT durable (i.e. not decay resistant)
• valued for tool handles, meat smoking
• heavy seeds fall and are dispersed by animals

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hickories of the OHF are divided into two subgenera...

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1. Eucarya: true hickories (e.g. Carya tomentosa)
2. Apocarya: pecan hickories (e.g. Carya illinoensis)

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differences between Eucarya and Apocarya

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Eucarya species of OHF

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1. mockernut hickory
2. red hickory
3. pignut hickory
4. shagbark hickory
5. shellbark hickory

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mockernut hickory: most important

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• grows best on fertile, moist uplands

• can be part of climax forest

• seeds dispersed by animals and stump sprouts

• uses: tool handles, firewood, meat smoking

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shagbark hickory: sci. name

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Carya ovata

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shagbark hickory: most important

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• can be part of climax forest
• slow-growing but faster than most hickories
• lives to 300 y/o
• reproduction: root suckers are common and stump sprouts when cut
• uses: tool handles
• nuts eaten by rodents

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Apocarya species of OHF

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1. bitternut hickory
2. pecan

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bitternut hickory: sci. name

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Carya cordiformis

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bitternut hickory: most important

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• most abundant and uniformly distributed of the hickories
• only member of Apocarya that grows in the NE
• can be part of climax forests
• no commercial value

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blackgum: most important

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• habitat: cosmopolitan...uplands to bottomlands
• reproduction: drupe fruits are favorite of many birds; root suckers
• uses: wood is heavy and hard

- some plywood, furniture, veneers, but not highly desirable

- some pulp

- interlocked grain makes it difficult to split for firewood

- ornamental due to deep scarlet fall color

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common persimmon: most important

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• habitat: cosmopolitan...uplands to well-drained bottomlands
• reproduction: dioecious and insect pollinated; fruit is berry eaten and dispersed by animals/birds; root suckers
• uses: wood is hard and durable, highly valued, used for golf club heads and pool cues; most of the best trees have already been cut
• fruit is important source of food for wildlife

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sourwood: most important

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• habitat: scattered tree on moist slopes and long ridges
• poor form
• uses: a preferred source for honey; has ornamental potential with deep scarlet leaves in early fall

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sourwood: reproduction

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• clusters of small, white, bell-shaped flowers in mid-summer, pollinated by bees
• fruit hangs on thru winter
• prolific stump sprouter
  

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river birch: most important

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• habitat: riparian
• intolerant pioneer
• highly phototrophic...trees often arch out over water so much they eventually fall in
• short-lived and soon replaced by other bottomland species
• seldom cut but can be used for pulp
• ornamental
• once established, can be grown on drier sites

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river birch: reproduction

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• small seeds dispersed in spring to take advantage of receding flood waters
• must land on flood-deposited silt to germinate

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honeylocust: most important

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• a legume but NOT a nitrogen fixer (no mutualistic relationship with Rhizobium bacteria)
  
• not originally native to GA but naturalized here so can be found in woods
• fast-growing, intolerant pioneer

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honeylocust: reproduction

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• dioecious
• pods have seeds embedded in a gelatinous substance that tastes good...attractive to animals
  

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honeylocust: uses

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• wood is strong and durable but not widely used due to scarcity
• cattle feed on the pods
• clones of a thornless variety, inermis, are widely planted as an ornamental street tree to replace American elms lost to Dutch elm disease
• also planted as windbreak...when wild variety is trimmed into hedge its thorns make it impenetrable