ISA Int Society Arboriculture Certification Workshop TREE BIOLOGY
ISA Int. Society Arboriculture Certification Workshop TREE BIOLOGY
What is Tree Biology? n n The Study of Structure and Function of Trees Relationships between the two
Tree Anatomy The studies of the component parts of the tree (inside & out) n Tree Physiology Study of the biological and chemical processes within the tree n
What is a Tree? n n Long lived perennial Woody plant Usually single stemmed Compartmentalizing organism
Types of Trees n n Deciduous oaks, maples, poplars, ash, beech, magnolia, locust, sycamore, sweet gum, willow, etc. Conifers (Evergreens) cypress, pines, spruces, firs, larches, junipers,
Evergreen: n n Strong central trunks (leaders) Conifers Grows one “layer” each year Tamarack? ? Graphic: Urban Tree Foundation
Deciduous trees: n n Lateral shoots outgrow original terminal shoot Oaks, elms, many others Photo: Duke University Winged elm Graphic: Urban Tree Foundation
Leaves n Deciduous – shed leaves every year n n Leaves lost are result of cell changes and growth regulators Abscission zone at stem: Enable leaf drop in fall n Protect leaf area against desiccation & pathogen entry n Graphic: University of California Davis
Trees n Main functions Grow n Reproduce n Maintain/ protect themselves n Photo: North Carolina State University
n Heartwood (darker) n n Water conduction Living xylem Cambium=change= growth n n Non-water conduction Non-living xylem Sapwood n n Tree Anatomy Thin layer of active Xylem & Phloem Bark - Protection Graphic: Colorado State University Extension
Build a Tree Photo: Goshen College
n Cell growth: A. Mitosis - cell division B. Cell differentiation 1. Cells change structure to specific function 2. Arranged tissues organized into organs (leaves, stems, roots, flowers and fruit) 3. Organs organized to function as an organism -tree! Plant Growth Photo: University of Wisconsin
Tree Anatomy Vocabulary Cells & Tissues (GROWTH) n n n Meristems – Cells that produce other cells Differentiation – Change in the cells structure to assume a needed function Apical meristems – Meristems located at the ends of shoots/buds and roots (primary growth) Cambium – Lateral Meristems that produce the tree’s vascular system (secondary growth) Cork Cambium – lateral meristem that produces bark
Tree Growth Meristem is the tree growth zone 1. Primary meristem– Responsible for elongation of roots and stems n Located in the tips of roots and stems (buds) n Graphic: Michigan State University Extension
Tree Growth 2. Secondary or lateral meristem – increase in diameter n n Vascular cambium – produces xylem or phloem Cork cambium - produces bark *Palms lack secondary or lateral growth (no increase in diameter size) Photo: UF Herbarium
Tree Anatomy Vocabulary Cells & Tissues (GROWTH) n n n Cambium produces Xylem and Phloem Xylem – Is produced on the inside of the Cambium, it is the ‘wood’ of the tree. Moves water and minerals up to the leaves. Supports the tree. Stores sugars for future use. Made up of vessels (soda straws) Phloem – Is produced to the outside of the Cambium (next to the bark). It moves sugars down from the leaves
Growth Tissue: Cambium Where growth occurs (Growth rings – seasonal cambium) Cambium produces: n Phloem (outside) n Xylem (inside) Graphic: UF Horticulture
Vascular Tissue - Xylem=Wood of trees n Functions: n n Conduction of water & dissolved minerals Support weight of tree Storage of carbohydrate reserves Defense against spread of disease & decay
Vascular Tissue Xylem n n n Transportation of water and minerals Transpiration is the loss of water through leaves Water molecules are pulled in long, hydrogen-bonded chains from root to leaf Graphic: University of Washington
Vascular Tissue - Xylem n n Water conduction occurs in sapwood Conifers – 2 -12 rings may conduct water Hardwoods – outermost 1 or 2 rings especially elm trees Non-water conduction – heartwood (darker in color than sapwood) Graphic: University of Minnesota Extension
Build a Tree
n n Translocation: conduction of sugars produced in the leaves to other parts of the plant Vascular Tissue Phloem Rays – cells that extend across (radial) xylem and phloem n Transport sugars n Store starch n Restrict decay Graphic: UF Horticulture
Tree Bark Photo: East Tennessee State University Outer, protective covering Function: n Moderates interior temperature n Reduces water loss n Protects against injury Composition: n n Nonfunctional phloem & corky tissues Contain wax and oil to minimize water loss Lenticels – small openings that permit gas exchange Photo: Colorado State Extension
Tree Physiology n n Compartmentalization is a system of defense CODIT: Compartmentalization Of Decay In Trees Graphic: USDA Forest Service
Tree Physiology n Shigo’s model is 4 barrier “walls” n n Wall 1 resists vertical spread, plugs up xylem Wall 2 resists inward spread, plugs latewood cells Wall 3 inhibits lateral spread, activates rays cells to resist decay These 3 walls form reaction zone
Tree Physiology n n Shigo’s model Wall 4 is the next layer of wood to form after injury n n n Strongest of all 4 walls Protects from outward decay Barrier zone Photo: Colorado State Extension
Tree Organs n n n Leaves Stems Roots Flowers Fruits -dry or fleshy
Shoot Terminal Bud Flower Lateral Bud Leaf Axil Leaf Blade Node Internode Petiole Vascular System Primary Root Lateral Root Hair Root Cap
Leaf Anatomy Cuticle Vascular bundles Parenchmya cells -chloroplasts -chlorophyll Stomata Guard Cells Petiole Graphic: Butler University Herbarium
Leaves Primary Purpose: Photosynthesis n n n Carbon dioxide Water Light Yields: ® Carbohydrates/sugar (Photosynthates) ® oxygen Graphic: Butler University Herbarium
Leaves n Stomata – openings n n n Control loss of water vapor (transpiration) Control gas exchange Guard cells – open and close stomata in response to: Light, temperature, wind and humidity Open-day Close-night n Photo: University of Hawaii at Manoa
Antitranspirant Sprays Artificially close stomata cells to prevent water loss during drought or dormant times n Reduces photosynthesis, cooling of leaves, and carbon dioxide uptake
Modified Leaves n Arid regions: n n Thick cuticle, leathery leaves and few stomata Succulent, water retaining leaves or dense hairy coverings Photo: Texas A&M
Modified Leaves n n Tendrils Spines – reduce water loss and protect Photo: FL Exotic Plant Pest Council
Branches Buds=Stems=Branches n strongly attached underneath but weakly attached above n Branch collar – layers of tissue, bulge around branch base n Autonomous-function on own Photo: University of Florida (Horticulture)
Stem Anatomy Node-gives rise to leaves & buds Internode-distance between nodes Terminal bud-primary growth Terminal bud scale scar- start of new growth of current year
1. Terminal or apical buds - located at the end of a shoot 2. Lateral or axillary buds - located on the sides of the stems. *often dormant – because of apical dominance Buds
3. Adventitious buds arise from loss of primary bud Stems 4. Epicormic shoots. When dormant buds sprout and grow n Environmental stress can trigger response n Can grow from: n n n Internode of the stem Edge of a leaf At the cut on a stem or root Photo by Joseph O’Brien, USDA Forest Service
n n Spur – a compressed stem with short internodes, usually bearing leaves, flowers and/or fruit. Many fruit trees such as apples, pears, cherries and ginkgo Thorn – pyracantha, locust Modified Stems
Roots 4 Main Functions: n Anchorage n Storage n Absorption (sm roots) n Conduction Roots need water & air for optimal growth Photo: Louisiana State University
n n n Absorbing roots: n Small, fibrous n Grow at ends of roots n Found in top foot of soil Lateral or horizontal roots near surface Sinker roots: n Grow vertically downward off lateral roots n Found w/in few feet of trunk Roots Photo: University of Texas
Roots n n Most roots found in upper 1 -12” of soil Taproot is a downward growing root in young trees Roots may extend 2 -3 times the tree crown/canopy Root extent and directional growth is the result of the tree’s environment rather than genetics Wrong Correct
n n n Mycorrhizae (fungus roots) - the symbiotic relationship of roots with certain fungi Symbiosis – both organisms benefit from the living arrangement Fungi get food & in turn aid roots in absorption of water and minerals Roots Photo: Iowa State University Extension
Roots Water enters young roots or mycorrhizal roots by osmosis n Osmosis requires fluid transport from higher concentration to lower concentration n Reverse Osmosis: water movement from out of roots into soil Example: de-icing roads with salt increases (higher concentration in soil) n Photo: Forestry Department South Australia
n n n Production and release of chemical substances by one species that inhibit the growth of other species of plants Reduced seed germination and seedling growth Examples: Walnut, red maple, swamp chestnut oak, sweet bay, red cedar Allelopathy Photo: Texas A&M
Flowers & Fruit Flower is reproductive structure of plant n Once pollinated give rise to the fruit or seed n Most seeds are protected with an ovary or capsule
Tree Physiology n Plant growth limited by n n n Genetics Environment Plant hormones n Auxin: Produced in shoots n Alters crown growth n Involved in tropisms n n Cytokinin – Produced in roots n Shoot initiation and growth n Photo: University of Nottingham, UK
Plant Hormones regulate Growth Hormones signal: n Cell Division n Cell Elongation n Flowering n Fruit Ripening n Leaf Drop n Dormancy n Root Development
Plant Response to Environment Tropisms: n n n Geotropism-gravity response Phototropism-light response Hydrotropism-water response Photo: University of Wisconsin
Photosynthesis Converting light into sugar food n Chlorophyll is the green/leaf pigment that absorbs sunlight n Chlorophyll is stored in chloroplast cells of leaves (Chloroplasts is where Photosynthesis takes place) ENERGY IS STORED
Respiration Energy made from photosynthesis is used (Sugar or carbohydrates /starch) n Oxygen is needed n Carbon dioxide and water are given off Tree able to survive in these situations? 1. Flooded roots (tree roots cannot respire=death) 2. Defoliated leaves by caterpillars (reserved food=lives) ENERGY IS RELEASED
Plant Growth and Development Photosynthesis Respiration Produces Food Stores energy Uses food for plant energy Releases energy Cells containing chloroplasts Releases oxygen Uses water Uses carbon dioxide Occurs in sunlight All cells Uses oxygen Produces water Produces carbon dioxide Occurs all the time
Transpiration Loss of water through stomata (openings) of leaves -similar to perspiration in people n Helps cool leaf during hot times and aids water uptake in xylem (Dependent on water, temperature, & humidity) n 90% water absorbed from roots are lost in leaves
Palms n n Monocots Have no cambium layer Have no growth ring of xylem Have vascular bundles of xylem & phloem Photo: Smithsonian Marine Station, Ft. Pierce
Helpful Websites for Tree ID ISA Tree List & Exam Study Guide n http: //www. isa-arbor. com/certification/exams. aspx n http: //wp. nres. uiuc. edu n http: //urbanext. uiuc. edu/treeselector n http: //utgardens. tennessee. edu/ohld 220/ n http: //www. noble. org/webapps/plantimagegallery/Pl ant. List. aspx? Plant. Type. ID=3&Index. Type=Common. N ame n http: //www. hort. uconn. edu/Plants/
Illinois Chapter ISA Certification Workshop Series Jennifer Hitchcock jenflwr@gmail. com 847 -826 -8763 Photo: University California Berkeley
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