plant adaptations steve blake aldo leopold high school tropical ecology

PLANT ADAPTATIONS

Steve BlakeAldo Leopold High School

Tropical Ecology

RAINFOREST PLANT ADAPTATIONS

Limiting Factors Adaptations

Sunlight Tall trunks, Epiphytes. 70-90%

Nutrients Efficient usage, Effective capture

Water in Canopy Reduce loss, Effective capture

Strong scent and bright colours of flowers attract insects which assist in pollination

Strong scent of fruits attracts animals, which feed on the fruit and assist in dispersal of the seeds Thick, waxy surface of leaves protects against hot sun, heavy rain, and strong winds Aerial roots of

epiphytes absorb moisture from the air

Tall straight trunks no side branches

Thin, smooth bark

Buttress roots Shallow spreading root system

A Emergent tree canopy

B Large trees of Middle layer

C Lower tree layer

D Shrub/small tree layer

E Ground vegetation

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Epiphyte adaptations

• Advantages of being an Epiphyte in the rainforest:– access to more direct sunlight– a greater number of canopy animal

pollinators,– the possibility of dispersing their seeds

via wind.

Bromeliads• The pineapple family. • Thick, waxy leaves form a bowl shape in the center for catching

rainwater. • Some bromeliads can hold several gallons of water and are

miniature ecosystems in themselves providing homes for several creatures including – frogs and their tadpoles– Salamanders– Snails– Beetles– mosquito larvae.

• Those that die decompose and furnish the plant with nutrients.

• One bromeliad was found to contain several small beetles, crane flies, earwigs, a frog, a cockroach, spiders, fly larvae, a millipede, a scorpion, woodlice and an earthworm!

Tree adaptations

• Height –50-85 m– Light competition

• Biologically diverse (100-300 species/hectare)

–Reduce disease transmission• Smooth bark– Reduce epiphytic growth

• Some rainforest trees have smooth, thin exfoliating bark

• By frequently exfoliating patches of thin, papery bark, the tree can shed epiphytes

• Here an liana is about to lose its grip on the tree trunk

Tree adaptations (continued)

• Leaf shape to shed water – discourage epiphytes, send water to

roots

• Leaf stalks rotate to follow sunlight

• Buttress Roots – Compensate for shallow roots• Because nutrients are shallow

– Support– grow out from the base of the trunk up

to 15 ft above the ground. Extended roots increase area over which nutrients can be absorbed.

Prop or Stilt Roots• Stabilize trees in flood areas like

mangrove trees

Mangrove with prop roots

Stilt roots of “Walking palm tree”

move toward light by adding prop roots to light side and losing them on dark side.

Matapalos(Strangler Fig)

• Hemiepiphytes:– Start as epiphytes and grow very slowly

to ground—then accelerate growth rapidly. Why?

– Eventually kill and replace tree and becomes hollow inside—home to animals that deposit nutrients.

• David Attenborough video of Strangler Fig!!

An adaptation rare in the Neotropics…

• Carnivorous plants!– Trap and consume

animals for their nutrients

Pitcher plant - a carnivorous plant.

slippery rim

tendril

Insects falling into the pitcher are digested, and nutrients which are released are absorbed by the plant.

• Drosera capillaris, (pink sundew)• At the end of each tentacle is a gland that secretes droplets of sticky fluid. • Insects attracted to odor become stuck. • Tentacles slowly enclose the victim and secretes digestive enzymes and acids that dissolve the body.

• Utricularia, bladderworts• Utricularia foliosa• Utricularia gibba

•D

rosera

cap

illa

ris

(sundew

)

• Utricularia gibba: trap showing trigger hairs

• Utricularia foliosa

Lianas and vines

• Thick, woody stems• up to 3,000 ft long• Begin life on forest floor but

use trees for support to climb upwards towards sunlight• 90% of species in rain forests.

Lianas (continued)• Attach to trees with sucker roots or tendrils

and grow with the sapling, or climb by winding themselves around the trunk.

• When they reach top of canopy they spread to other trees or wrap themselves around other lianas.

• Gives support against winds to the shallow-rooted, top-heavy trees. However, when one tree falls several others may be pulled down.

Seed Dispersal

• Seed dispersal processes dominated by vertebrate dispersers – involve individuals belonging to

hundreds of species

Dispersal Types

• Gravity (‘Gravichory’)• Wind (Anemochory)• Water (Hydrochory)• Ballistic (Autochory)• Animal (Zoochory)– Epizoochory (transported externally)– Inadvertent (cached)– Myrmechory (ant-dispersed)– Endozoochory (through the digestive tract)

images: http://www.cas.vanderbilt.edu/bioimages/pages/fruit-seed-dispersal.htm

Fruits

• Nutritive fleshy pericarp or pulp;

• Chemical attractant; • Colors• Fruit size varies from 0.01g to 40g • In Neotropical forests, 50 - 90 % of the

canopy trees bear fruits adapted for animal dispersal, while close to 100 % of the shrubs and sub-canopy trees produce fleshy fruits

Frugivores• High variety of tropical bird, bat, ant,

mammal dispersers• Frugivore size ranges from ~10g tyrannid

flycatchers to African Elephant• Enormous differences in fruit and frugivore

scales imply an enormous potential range of phenomena

http://sites.ac-mayotte.fr/http://www.fsd2010.org/news/65.htm

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