Forests

Importance

• • • • • • Wildlife habitat Soil Erosion Wind block Aesthetics Fuel Climate moderation

Plants

• • Primary source of energy – Sun -> grass -> deer -> humans Carbon cycle – Take in carbon dioxide, produce glucose and oxygen

Bit of History

• Tall grass prairies and forests – Resources for homes & agriculture – Mid – 1800s approx 6.7 million forested acres ( 1 / 5 ) – By 1900s only 1.5 million acres remained • Breadbasket of the world – Forest cover has increased to 2.1 – 2.5 million acres • • Result from less livestock grazing State & Federal cost – sharing reforestation programs

Parts of a Forest

Succession

Parts of a Plant

Parts of a Plant

• Four basic parts – Leaves – Stems – Roots – Flowers (fruit/seeds)

Leaves

• • • “Food Factory” through photosynthesis Leaf is made of specialized cells Vary in shape, size, and arrangement – Help identify plants – Simple, compound – Toothed, pointed, smooth – – Lobed, ovate, lanceolate Whorled, alternate, opposite

Parts of a leaf

• • Food manufactured in leaf moves down through the stem to the roots – Used or stored in stem or root Sometimes cells in roots, stems, and leaves – Respiration • • Oxygen used to produce energy for cells Too much water can affect efficiency

• • • Support leaves Transport materials Provide storage

Stems

Types of Stems

• • • • • Woody or nonwoody (herbaceous) Stolons – Grow along soil surface – Produce new plants Tuber – Store energy Cacti – Green fleshy stems – Store water and photosynthesis Modified for protection

Stem Structures

• Did you know that a sign nailed 2m (7ft) high on a tree will remain at that height, even though the tree may grow much taller?

Stem Structure

• • • Grow in length only at tip Apical meristems – Primary tissues Lateral meristems – Secondary growth (diameter)

Stem Features

• • • Node – Leaf attaches to stem Internode – Space between nodes – Lateral bud Bud – Stem or leaf – Apical meristem enclosed by bud scales

Winter Identification of Trees

Primary Growth in Stems

• Apical meristem – Dermal, protect plant – Ground, cortex and pith • Pith located at center of stem – Vascular tissue, occurs in bundles • Xylem (inside) and phloem (outside)

Secondary Growth in Stems

• Stems increase in thickness – Cell division in vascular cambium (xylem/phloem) – Dicot and gymnosperms (Monocot Trees may differ) • Stem forms b/w xylem and phloem in vascular bundle – Vascular cambium • produces 2 0 – xylem (inside) and phloem (outside) 2 0 xylem represents the wood of the plant • New cambium cells increases stems diameter

Cross Section of Woody Stem

• • Older xylem stop producing water – Darken wood called heartwood • Will increase in diameter – Lighter – colored wood called sapwood • Stays about the same Phloem near outside of stem – Bark • Cork, cork cambium, and phloem – Protective layer – Cork cells die at maturity • Cannot elongate and will rupture as stem increases in diameter • Bark pattern (maples and oaks)

Annual Rings

• • • • Springwood – Water plentiful – Vas. Cambium form new xylem cells – Wide and thin cell walls Summerwood – Water scarce – Vas. Cambium forms smaller thicker cells Difference causes a change in appearance One ring each year used to determine age

Transport of Water

• • Water and mineral nutrients occur in xylem Water is constantly evaporating from plant – Stomata – Transpiration

Roots

• • • Anchor the plant in the soil Absorb and transport water and mineral nutrients Storage for water and organic compounds

Types of Roots

• • • Taproot – Primary root – Rarely more than one – two meters Fibrous root system – Numerous small roots Adventitious roots – Specialized roots grow from other places – Leaves and stems – corn and epiphytic orchid (aerial roots)

Root Structures

• • • • Root cap – Covers apical meristem – Produces oil Root hairs – Extensions of epidermal cells – Increase surface area Dependent on stems and leaves for energy Store starch

Reproduction of Plants

Propagation

Sexual and Asexual

• • Asexual – No seeds – Leaf, stem, or root Sexual – Union of pollen and egg – Pollination – Fertilization • Pollen tube, male gametes unite with egg cell to form zygote

Pollination

• • • • • Transfer of pollen Pollen grains – Pores where pollen tubes grow Self – pollination Cross – pollination Wind or animal