Urban Tree Biology Developed by Sheldon Hammond Northwest

Urban Tree Biology Developed by: Sheldon Hammond, Northwest District ANR Program Development Coordinator In Cooperation with The University of Georgia Cooperative Extension Service Urban Forestry Issue Team

Tree Biology n Tree Anatomy - study of component parts of the tree n Tree Physiology - study of the biological and chemical processes within these structures, providing the basis of function

Tree Anatomy Basic Structures - Cells and Tissues n Trees made up of cells, tissues and organs n Cells come from meristems Meristems - undifferentiated tissue where cell division takes place n Cells then undergo differentiation (development of cells in which they become specialized for various reasons) n n Cells similar are arranged into tissues n Tissues are organized into organs (leaves, stems, roots, flowers and fruits

Tree Anatomy Meristems n Two Types n Primary or Apical meristems- produce the cells that result in elongation of shoots and roots n Secondary or lateral meristems - which produce cells that result in increase in diameter

Tree Anatomy Apical Meristems

Tree Anatomy Lateral Meristems Two Types n Cambium xylem to the inside n Phloem to the outside n n Cork Cambium n Bark to outside

Tree Anatomy n n Xylem Conduction of water & mineral elements Support of the weight of the tree Storage of carbohydrate reserves Defense against the spread of disease and decay

Tree Anatomy Xylem n Terms n Growth Rings n Earlywood n Latewood n Sapwood n Heartwood

Tree Anatomy n n n Phloem Responsible for the movement of sugars, produced in the leaves Process is slow Requires energy Composed of sieve tubes Incorporated into bark

Tree Anatomy Rays n Transport sugars and other compounds throughout the trunk n Store starch n Aid in restricting decay in wood tissue

Tree Anatomy Bark n Protective tissue n Moderates temperatures n Offers defense n Reduces water loss n Composed of non- functional phloem and corky tissues n Contains lenticels

Tree Anatomy Structure n Basic tree structure n Stems n Leaves n Roots

Tree Anatomy Stems n Twigs, braches, trunk n Twigs n Terminal bud or apical bud n Lateral or axillary bud n Adventitious buds (epicormic) n Node n Internode

Tree Anatomy Stems n Branches & Trunk n similar in structure and function but autonomous n Each branch self sustaining n Attachment terms n Branch collar n Branch bark ridge n Included bark

Tree Anatomy Leaves n Function n photosynthesis n Transpiration n Structure n n n Chloroplasts Cuticle Stomata Guard Cells Abscission zone

Tree Anatomy Roots n Primary functions n Anchorage n Absorption n Storage n Conduction n Structural Roots n Absorbing roots n Lateral roots n Sinker roots

Tree Physiology Photosynthesis n Photosynthesis - the process by which green plants use light energy to build sugar molecules. Takes place within cells that contain chloroplasts n Produces sugars or photosynthate or carbohydrate n Proteins, starch, fat, vitamins, amino acids and others are produced from photosynthate when combined with N, P, K, Ca, Fe. n Much of the photosynthate stored by tree in from of sugar or starch for later use n

Tree Physiology Respiration n Respiration- the process by which the chemical energy generated by photosynthesis, and stored as starch or sugar, is used by the tree. Energy produced by breaking the chain of molecules n Constant process n Plants are only organisms that produce own food n Oxygen is required n

Tree Physiology Transpiration n Transpiration - loss of water in the form of water vapor from leaf surfaces n Water movement in xylem from root to leaf n Factors affecting transpiration n Light, temperature, humidity, available water, cuticle thickness, #of stomata, antitranspirants

Tree Physiology Absorption, Translocation, and the Vascular System n Terms n Osmosis movement of water from higher concentration to lower concentration n Phloem transport n Source and sink n Longitudinal and axial transport

Tree Physiology Other terms and functions n Hormones Auxins, gibberellins, cytokinins, ethylene and abscissic acid n Control such things as cell division, cell elongation, fruit ripening, leaf drop and root development n n

Credits n Pictures and diagrams n Introduction to Arboriculture – Tree Biology CD-ROM; International Society of Arboriculture, 2003.

Acknowledgements n This publication/training was funded in full or in part by the USDA Forest Service Urban and Community Forestry Program as recommended by the National Urban and Community Forestry Advisory Council (NUCFAC).