Tree Biology PDF

Tree Biology Grant Jones [email protected] 630.797.8581 Tree Biology In order to grow trees, we need to understand how trees grow Image from Internet Two Trees Image from The Body Language of Trees ...

Tree Biology Grant Jones [email protected] 630.797.8581 Tree Biology In order to grow trees, we need to understand how trees grow Image from Internet Two Trees Image from The Body Language of Trees Ratio of Whole Tree Structures 5% Leaves 15% Stems 60% Trunk 15% Woody Roots 5% Absorbing Roots Image from Internet Tree Biology Anatomy (cellular structures) Morphology (organs) Physiology (chemical/biochemical) Plant Cell (ISA Diagram) Cell Wall Cellulose – (a complex sugar) Image from Internet Growth How does a tree go from 1 cell to a 300 foot redwood? Images from Internet Differentiation Not all cells are identical. Specialization of each individual cell occurs after cell division, this is call differentiation. A cell may become the bark, flower, wood, root, etc. Meristem Types Apical/Primary Meristem – meristem located at tips of shoot and roots Lateral/Secondary Meristem – residual meristem responsible for secondary growth and ultimate size trees obtain. – Vascular Cambium – produces xylem (sapwood & heartwood) & phloem – Cork Cambium – produces bark Apical Meristem Image from Internet Growth – Lateral Meristem Image from Physiology of Woody Plants by Kozlowski and Pallardy Factors Affecting Growth Image from Internet Environmental Factors Moisture Air Nutrients Temperature Light Growth Cycle Image from ISA Trunks, Stems, and Branches Support for the tree Store carbohydrates Movement of water and nutrients Stem Structure (young stem) Image from ISA Vascular Cambium Thin layer of cells that produce xylem to the interior and phloem to the exterior. Phloem – Sieve Tube Cells Image from Internet Cork Cambium Cork Cambium Initiation Cork Cambium & Cork Images from Internet Xylem Structures Tracheids – elongated dead cells with pointed ends and thick walls containing pits Vessels – Stacks of dead, hollow cells that form long tubes stacked above each other Fibers – Provide mechanical strength Vessels (Angiosperm Wood) Images from Plant Physiology by Taiz and Zeiger Tracheids (Conifers) Image (left) from Plant Physiology by Taiz and Zeiger Wood Types Softwood – wood composed of only tracheids (pines, other conifers & gymnosperms). Hardwood – wood composed of tracheids & vessels (angiosperms) Images from Internet Mature Stem Image from ISA Xylem (Wood) Sapwood- living wood that conducts water. – Conifers often have 8-12 living rings. – Angiosperms (e.g. elms, oaks) often have 1-2 living rings, while maples may have 4-6 living rings. Heartwood- dead xylem that does not conduct water. Sometimes darker in color than sapwood. Will form boundaries when wounded. Functions of Sapwood Transport from roots to shoots Stored energy Mechanical support cells with strong walls of cellulose and lignin Produce chemicals to resist decay Wood Types - Hardwoods – Ring Porous- large vessel produced in spring and smaller vessels in summer. – Diffuse Porous – vessel roughly the same size in spring and summer. Hardwood Ring Porous (Oak) Few annual rings (1-2) Springwood/Latewood Images from Internet Ring Porous Tree-of-Heaven Coffetree Hickory Osage-Orange Chestnut Mulberry Hackberry Red/White Oak Groups Ash* Black Locust Honeylocust Elm Hardwood Diffuse Porous (Maple) Sapwood is many annual rings (4+) Image from Internet Diffuse Porous Maple Yellow-Poplar (Tulip Tree) Buckeye Magnolia Alder Black Gum/Tupelo Birch Hophornbeam Hornbeam Sourwood Dogwood Sycamore Hazelnut/Filbert Poplar/Aspen/Cottonwood Beech Buckthorn Holly Willow Sweetgum Linden/Basswood Cherry (Prunus) Growth Rings Formation of larger conducting cells in spring and then smaller cells in the summer and no (or little) growth in winter create rings. Rays Thin lines of cell that extend from the phloem toward the pith. Rays transport water, sugar, and other compounds. Image from Internet Lenticels Small openings in the bark that allow for gas exchange Lenticel (microscopic) Image from Internet Symplast Living cells linked together by plasmodesmata Radial and axial transport of nutrients, carbohydrates, water and other solutes Solutes can move in the symplast, but cells usually take up compounds they need and export those available in excess. Image from Internet Apoplast Apoplast consists of the vessels, fibers, cell walls and open spaces of the sapwood Water and solutes can move freely in the apoplast (transpirational pull) Image from Internet  Branch Attachment Image from ISA Branch Anatomy Image from Up by the Roots Twig Morphology Internode & Node Image from ISA Function of Leaves Photosynthesis – Sugar production Transpiration – Water regulation and gas exchange Leaf Structure Image from ISA Chloroplasts Nitrogen, magnesium, iron, and sulfur make up the chloroplasts and chlorophyll Image from Internet Leaf Showing Cuticle (red) Image from Internet  Deciduous- trees that lose their leaves in Fall Petiole – stalk that attaches leaf to stem Evergreen – trees that hold their leaves for more than 1 year Fall Color Cool Days (not freezing) Shorter Days Bright Sunny Days These three factors increase sugar accumulation, which decreases chlorophyll production and allows other pigments to become visible (anthocyanins & carotenoids). Abscission Zone Cellular changes that allow leaf drop Protects region on stem from desiccation, insect invasion, and disease infection. Abscission Zone Images from Internet Needle Drop Roots Anchor & Support Absorb Water & Nutrients Store Water & Energy Rich Compound and Conduct Them to the Trunk Produce Organic Compounds Healthy Roots = Healthy Plants Available Water Proper Drainage (no flooded soils) Available Oxygen (no compaction) Available Nutrients Soils roots can penetrate Avoid Mechanical Injury Image from Internet What Does a Root System Look Like? Image from The Influence of Soils and Species on Tree Root Depth by Peter Crow Roots Image from ISA Root Crown Root Types Image from Up from the Roots Root Types Absorbing Roots – fine non-woody roots responsible for water & nutrient absorption typically in top 1-foot of soil Root Tip Anatomy Image from Internet Root Types Lateral Roots – Woody horizontal roots important for supporting the tree. Typically in upper soil surface. Root Types Sinker Roots – Woody vertically downward growing roots helping to anchor tree and exploit soil depth. Root Systems True Tap (Hickory, Pine, Walnut, Coffeetree Heart Roots (Red Oak) Plate Roots (Maples, Most Trees, etc) Image from Principles and Practice of Planting Trees and Shrubs by Watson and Himelick Tap Root Tap Root Initial root developed during seedling growth. This root is typically choked out or diverted. Mature trees lack tap roots. Heart Root Images from Internet Plate Roots Image (top left) from Internet. Images (bottom right and left) from Len Burkhart, PhD. Mycorrhizae “fungus root” 1. Symbiotic (beneficial) relationship between fungus and roots of a plant. 2. Benefits: 1. Absorption of water & nutrients 2. Physical protection-barrier to pathogenic fungi 3. Secret fungistatic substances that inhibit pathogenic fungi Types of Mycorrhizae Ectomycorrhizae Endomycorrhizae Image from Plant Physiology by Taiz and Zeiger Products From Photosynthesis Image from ISA Respiration Sugar + Oxygen ↓ Energy + Carbon Dioxide + Water Respiration The process where sugars are broken down in the presence of oxygen to release carbon dioxide, water, & energy. All Living Cells Respire Trees under anaerobic conditions (lacking oxygen) cannot respire. Living root tissue lacking oxygen (flooded soils, compacted soils) have limited respiration and can die as a result (essentially suffocation). Respiration Images from Internet All Living Cells Respire Image from the University of Minnesota Transpiration Loss of water through the foliage in the form of water vapor Image from Internet Transpiration Water vapor leaves the leaf through openings called stomata Guard cells regulate the amount of water vapor that can exit the leaf Image from ISA Transpiration 90% through open stomata Stomata open during day & closed at night Transpiration cools leaf surface Transpiration increases when: – Temps are high – Humidity is low – Wind speed increases – Adequate soil moisture Image from ISA Osmosis What has more (salt), gets more (water)! Image from Internet Transport Axial Transport – Movement of water, nutrients, sugars and other solutes up and down in the tree Radial Transport – movement of sugars across the xylem and phloem through rays Image from Modern Arboriculture Phloem Loading Leaves pump sugars into the phloem (sieve tubes) Sugars are squeezed through the phloem which requires energy Most energy stays nearby Image from Modern Arboriculture Source/Sink Source – Plant structures that produce energy Sink – Plant structures that consumer energy Sinks - Stress Heavy seed production can be a large sink and consume a lot of energy Heavy seed production can be a sign of stress in landscape trees Apical Dominance Inhibition of the growth of lateral buds (under hormonal control) Removal of terminal bud can release lateral buds leading to new shoot development Image from ISA Single Stem-Excurrent Multi-Stemmed - Decurrent Decurrent Epicormic Shoots Suckers emerge below the graft union or from the root system. Shoot produced from stems or roots where meristems are not normally found. Watersprouts form above the graft union and are typically produced from meristematic points that are carried along in the cambium (residual lateral bud). These are sometime called latent buds. Watersprouts Latent Bud Suckers (rarely adventitious) Plant Hormones Auxin – root initiation, cell division, apical dominance Cytokinin – cell division Gibberellin – cell elongation Abscissic Acid – leaf abscission Ethylene (gas) – fruit ripening Auxin IAA – Indole Acetic Acid (naturally occuring in the plant. Synthetic Auxins – IBA, NAA, 2,4-D : used as rooting compounds and herbicides. Tropism Orientation of growth in response to an external stimuli (auxins involved in this mechanism). Geotropism – response of plant to gravity (reason shoots grow upward and roots grow downward). Phototropism – plant growth towards light Geotropism / Gravitropism Image from Up by the Roots Phototropism Image from Internet CODIT Compartmentalization Of Decay In Trees Wall 1- resists vertical spread Wall 2- resists inward spread Wall 3- resists lateral spread Wall 4- resists spread to newly forming wood (diagram from Shigo, 1986) Aerial Roots Palm Crown and Fronds 1 bud (apical meristem) producing new leaves If bud is killed the palm dies Fronds produced slowly (1 month per leaf) Damage to leaves while in the bud may take 1 year to visibly appear Palm Trunk Can’t compartmentalize decay Trunk won’t increase in width over time Chronic environmental stress can cause “pencilling” of the trunk Palm Roots Cabbage Palms regenerate from root initiation zone (RIZ) Coconut Palms will regenerate from root tip or RIZ Queen and Royal Palms regenerate more new root tips Image (top) from Principles and Practice of Planting Trees and Shrubs by Watson and Himelick  Palm Trunks Image from A.D. Ali Palm Trunks Images (left and top right) from the Internet. Image (bottom right) from A.D. Ali Inflorescence  Grant Jones [email protected] 630.797.8581