GEOG5839.02. What are tree rings?

September 6What are tree rings?

Source: dylancantwell

MAJOR TOPICSWhat are trees? of basic anatomy The cambium Tour

GEOG5839 WHAT ARE TREES?

Tree at ChancellorsvilleSource: Andy Frasse o

Trees are not limited to a single order or even division of plants. “Tree-ness” is deﬁned by a speciﬁc GROWTH FORM.

Trees are perennial plants, which are plantsthat live for more than two years.

Trees have a single main stem (or trunk).

Shrubs have multiple stems(and are not trees).

Plants are o en required to a ain a minimum height at maturityto qualify as trees (usually between 3 and 6 meters tall).

Trees are woody plants (a category that also includes shrubsand some vines).

Woody plants are capable of secondary thickening,adding new yearly growth layers of cells onto theaccumulated growth of previous years.

Most recent growthOldest wood

Cross-sectional plane

Cross-sectional (or transverse) plane Radial plane Tangential planeSource: Hoadley, Identifying Wood

Photograph: Dave_Gray

GEOG5839TOUR OF BASIC ANATOMY

Heartwood SapwoodCambium Bark

tissue containing plant ‘stem’ cellsThe vascular cambium is a lateral meristemin the vascular tissue of plants.

The vascular cambium is also the source of boththe secondary xylem (inwards, towards the pith)and the secondary phloem (outwards), and islocated between these tissues in the stem and root.

Photograph: easagor

BarkPith Cambium

The pith is the small core of so spongey tissuethat forms the central longitudinal axis of a treestem, branch or twig.

Scots pine Pinus sylvestrisSource: Fritz Schweingruber

Common beech Fagus sylvestrisSource: Fritz Schweingruber

Sapwood

Source: sonykus

Heartwood Ph oto syn the tic wa ste s

GYMNOSPERMS VS.ANGIOSPERMS

Gymnosperms (coniferous)

Gymnosperms like this Douglas-ﬁr have encapsulated seeds.

Red pinePinus resinosa

Earlywood Latewood Total ring-widthEastern hemlockTsuga canadensis

TracheidsScots pinePinus sylvestris

Tracheids are elongated cells that functionin food conduction and structural support.

large cells thin cell walls small cells thick cell walls Scots pine Pinus sylvestrisPhotograph: Fritz Schweingruber

RayScots pinePinus sylvestris

Rays are ﬂa ened bands of tissue that extendhorizontally in a radial plane through the tree stem.

Angiosperms(deciduous)

White oakQuercus alba

Angiosperms like this oak have exposed seeds.

Bur oakQuercus macrocarpa

Earlywood vesselsEnglish oakQuercus robur

Latewood vesselsEnglish oakQuercus robur

Vessel elements are a type of hardwood cellthat has a relatively large diameter, thick cell walland perforate (open) ends.

Fibre English oak Quercus roburPhotograph: Fritz Schweingruber

Fibres are an elongated hardwood cell with thick wallsthat contributes greatly to the material strength of wood.

Ray English oak Quercus roburPhotograph: Fri s Schweingruber

RING POROUS DIFFUSE POROUS

Bur oakQuercus macrocarpa

Sycamore mapleAcer psudoplantanus

European beachFagus sylvatica

A growth-ring boundary in Chamaecyparis lawsoniana (Port-Orford cedar)Source: Bu erﬁeld and Meylan (1980)

GEOG5839 THE CAMBIUM

tissue containing plant ‘stem’ cellsThe vascular cambium is a lateral meristemin the vascular tissue of plants.

ca m bi um phloem xylem

CHARACTERISTICS OF THE CAMBIUM1Self-sustainingThe cambium is a self-sustaining system, and retains itsfunctions for a long time (sometimes for centuries or millennia).

Bristlecone pine Pinus longaevaPhotograph: mlhradio

CHARACTERISTICS OF THE CAMBIUM2 Resource-intensive As the cambium grows, it consumes scare resources that cannot be used for growth by the rest of the tree.

Limber pinePinus ﬂexilis

CHARACTERISTICS OF THE CAMBIUM3 Flexible Cells produced by the cambium (called ‘cambial derivatives) can be diﬀerentiated into the range of cells found in the xylem and phloem.

Pinus spp.

Source: Marchand, P. J. 1996. Life in the Cold: AnIntroduction to Winter Ecology, 3rd ed. UniversityPress of New England. Hanover, NH. 304 pp.

DORMANT CAMBIUM 1 - 10 cells viscous protoplasm sharp cell walls

Source: Ben Cooper

ca m bi um phloem xylem

DORMANT CAMBIUM ACTIVE CAMBIUM 1 - 10 cells 8 - 20 cells viscous protoplasm ﬂuid protoplasm sharp cell walls semi-transparent walls

CAMBIAL GROWTH

Radi al ﬁle Scots pine Pinus sylvestrisPhotograph: Fritz Schweingruber

Latewood (prior year) phloemEarly season Immature earlywood

Latewood (prior year) Immature earlywoodMid-season phloem Mature earlywood

Mature earlywood Immature latewoodLate season phloem

A growth-ring boundary in Chamaecyparis lawsoniana (Port-Orford cedar)Source: Bu erﬁeld and Meylan (1980)

September 6What are tree rings?

GEOG5839 XT C L AS SNE

GEOG5839.02. What are tree rings?

by Scott St. George on Sep 07, 2012

Accessibility

Categories

Upload Details

Usage Rights

1 Embed 279

Statistics

GEOG5839.02. What are tree rings? Presentation Transcript