How a Tree Grows J.G. Mexal H/R 302 Spring 2005

Forestry & Society How a Tree Grows- Trees are the 2nd largest organism- Eucalyptus Sequoia Trees are the oldest organism-bristlecone pine (5,000 yrs) Norway spruce (9,550 yrs) They can grow: as much as 25 ft/yr as little as 25 mm/yr (1”) They can survive: 10 ft of precipitation 10 in of precipitation They can survive: >100 o F temperatures <-50 o F temperatures

Trees live a long time! Alder White birch Sugar maple Oak Douglas-fir Bristlecone pine Norway spruce 25 yrs 50 yrs 300 yrs >500 yrs >700 yrs >2,000 yrs >9,000 yrs

Forestry & Society How a Tree Grows- What does your tree look like? –A 100 ft tree weighs about 4,000 lbs –Has > 200,000 leaves (~120 lbs) Will shed 3,600 lbs of leaves in a lifetime –Produce >5,000 seeds/yr –Have 1,300 lbs of roots –Require 8,000 lbs of CO 2 2,900 lbs of H 2 O for Ps, and 5,000,000 lbs for Ts –Generate over 8,000 lbs O 2

Source: Ed Gilman, IFAS

Trees in the forest grow with one trunk, and codominant stems toward the top of the tree Source: Ed Gilman, IFAS

Forestry & Society Comparison between forest tree and landscape tree Source: Ed Gilman, IFAS

Factors affecting tree growth Genetic Information Environmental Conditions Physiological Processes Tree Growth

Bark Cambium Heartwood Sapwood Latewood Earlywood Forestry & Society How a Tree Grows-Functions Seed- reproduction Leaves- photosynthesis (carbon capture) Roots- water & nutrient uptake Bark- protection Cambium/buds-growth Xylem- water transport (up) [dead] Phloem- carbohydrate transport (down)

How a Tree Grows

Our secondary growth model: A typical hardwood tree in cross section (transverse surface). What can you identify? Source: Ed Gilman, IFAS

The Bark: The bark is everything outside the vascular cambium. As you can see, there is a lot going on in the bark. Source: Ed Gilman, IFAS

The Bark: periderm: Periderms form the outer bark. They are subdivided further. Source: Ed Gilman, IFAS

The Bark: periderm: phellogen (cork cambium) : The phellogen is the region of cell division that forms the periderm tissues. Phellogen development influences bark appearance. Source: Ed Gilman, IFAS

The Bark: periderm: phellem (cork) : Phellem replaces the epidermis as the tree increases in girth. Photosynthesis can take place in some trees both through the phellem and in fissures. Source: Ed Gilman, IFAS

The Bark: periderm: phelloderm: Phelloderm is active parenchyma tissue. Parenchyma cells can be used for storage, photosynthesis, defense, and even cell division! Source: Ed Gilman, IFAS

The Bark: phloem: Phloem tissue makes up the inner bark. However, it is vascular tissue formed from the vascular cambium. Source: Ed Gilman, IFAS

The Bark: phloem: sieve tube elements: Sieve tube elements actively transport photosynthates down the stem. Conifers have sieve cells instead. Source: Ed Gilman, IFAS

The Bark: phloem: companion cells: Companion cells provide sieve tube elements with needed metabolites. Conifers have albuminous cells instead. Source: Ed Gilman, IFAS

The cambium: The cambium is the primary meristem producing radial growth. It forms the phloem & xylem. Source: Ed Gilman, IFAS

The Xylem (wood): The xylem includes everything inside the vascular cambium. Source: Ed Gilman, IFAS

The Xylem: a growth increment (ring): The rings seen in many trees represent one growth increment. Growth rings provide the texture seen in wood. Source: Ed Gilman, IFAS

The Xylem: vessel elements: Hardwood species have vessel elements in addition to trachieds. Notice their location in the growth rings of this tree Source: Ed Gilman, IFAS

The Xylem: fibers: Fibers are cells with heavily lignified walls making them stiff. Many fibers in sapwood are alive at maturity and can be used for storage. Source: Ed Gilman, IFAS

The Xylem: axial parenchyma: Axial parenchyma is living tissue! Remember that parenchyma cells can be used for storage and cell division. Source: Ed Gilman, IFAS

The Xylem: rays (multiserrate & uniserrate): Rays are radial parenchyma cells. Parenchyma cells give rise to adventitious tissues. Source: Ed Gilman, IFAS

Forestry & Society How a Tree Grows/ Diffuse vs Ring Porous Silver Maple White Oak 50X Diffuse Porous Ring Porous

Forestry & Society How a Tree Grows-Idealized Annual rings leaves fruit Taproot Lateral root Leaves Fruit A tree can produce 200,000 leaves/yr

Woody Stem Structure

Shoot Growth

3 o lateral = 6 cm 2 o lateral = 10 cm Lateral branch = 14 cm 2 o lateral = 10 cm 2 o lateral = 12 cm Forestry & Society Shoot Growth in Eastern White Pine Terminal growth = 44 cm Lateral branch = 26 cm Lateral branch = 19 cm

Biomass Partitioning/ Nelda Methany 2005 Time (yrs) Percent 100 Leaves/Roots Wood Fine Roots 30% 35% 5% 90%

Forestry & Society How a Tree Grows Growing regions or meristems –Buds- height, flowers, leaves, (roots) –Cambium- diameter –Cork cambium - bark Factors –Temperature –Light –Water Tropics vs Boreal

Where a tree grows!! Tropical forest Desert Dry tropical forest o F 86 20”80”140”

Forestry & Society Urban Forestry CO 2 capture Basic Photosynthetic Reaction CO 2 + H 2 O CH 2 O + O lb 0.60 lb 1.00 lb1.07 lb λ

Forestry & Society How a Tree Grows/ Kozlowski & Pallardy 1999 clear dayovercast day

Forestry & Society How a Tree Grows Most forests are regenerated sexually –seeds are required –exceptions: aspen, oak, eucalyptus Environmental factors: –light (forest gap) –moisture (mineral soil) –temperature (dormancy & germination)

Forestry & Society How a Tree Grows - Piñon Flower primordia (buds) form in fall (yr-1) Flowers develop in spring (yr-2) Pollination occurs Overwinter Fertilization occurs in spring (yr-3) Growth of cone Maturation of cone with seeds in fall Total time elapsed >24 mo. Drought

Pine life cycle

Forestry & Society How a Tree Grows/ Reproductive Cycle of Pinus contorta (Owens & Molder 1984)

Forestry & Society How a Tree Grows-female cones Pinus elliotii (slash pine) 1 mo. 12 mo.24 mo. pollination maturation fertilization

Rachis Viable seed Empty seed Bract Forestry and Society Pinus eldarica cone

Forestry and Society Pine seed size variation Pinus pinea (Italian stone pine) Pinus nigra (Japanese black pine) wing

Forestry & Society How a Tree Grows-Germination Seed is dispersed Overwinters (dormant) Germinates Growth commences 10,000,000/ac 4,000,000/ac 25 yrs 100 yrs Nothofagus in Chile 0.001%

Ponderosa pine seed rain following harvest-CO / WJAF 21(1):19:06 Year Seeds/m 2 Logged ’80-’81 winter Seedlings/m 2 ~48% of seed consumed by animals regardless of year

Dendrochronology

Forestry & Society Xylem production- earlywood vs latewood Phloem 5 = Earlywood cells 3,4 = Latewood cells L = Preceeding year 1,2 = Developing xylem cells

Forestry & Society Silviculture/Response to Thinning Juniper/NM 10 mm False rings Wider rings Competition

Forestry & Society Dendrochronology /Skaptar Jokull Volcano eruption in Iceland causes ‘the summer that wasn’t’ in western Alaska. ( Earlywood Latewood Eruption occurs June 8, 1783 No Latewood, indicating very early onset of winter

Review Questions Define: xylem, conifer, phloem, hardwood, cambium, softwood, cord, evergreen, board foot, deciduous, basal area, MAI, CAI, PAI, closed forest, earlywood (spring wood), latewood (summer wood), dendrochronology, false ring What environmental factors affect seed production germination? Why does piñon have good seed crops every 4-5 years? Describe the basic process of photosynthesis. Why do trees produce so many seed, yet so few germinate?