Lecture 3- Rainforest Plants

Question 1

How are rainforest divided in Australia?

Answer 1

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Question 2

What are the 4 reasons for rainforest’s importance?

Answer 2

1. Surviving remnants of Gondwanan flora and flora 2. Provide a glimpse back in time to vegetation of Gondwana 3. High conservation value, NE Queensland Wet Tropics World heritage area 4. More species per unit area so more species at risk

Question 3

Why is Castenospermum australe important?

Answer 3

-will make you sick, but could help treat HIV -so lot of things of potential benefit to us in the rainforest

Question 4

What are four more reasons for rainforests’ importance?

Answer 4

1. Species rich- 50% Australian ferns in rainforests 2. 13 of the most primitive flowering plant families 3. Austrobaileya- pollen similar to oldest angiosperms 4. Primitive animals that can provide evolutionary perspective (e.g. musky rat kangaroo: simple rounded teeth, simple gut, fruit-eater)

Question 5

What are the characteristics of Australobaileya?

Answer 5

-genus of 1 species -usually places in its own family - has pollen similar to oldest angiosperms fossils (120 million years old) -no close living relatives known

Question 6

What are the two types of rainforests?

Answer 6

1. tropical rainforests 2. temperate rainforests

Question 7

What are the characteristics of tropical rainforests? (7)

Answer 7

1. lowland- most species rich (diversity decline with altitude) 2. 100-200 tree species per hectare 3. 1000 beetle species per tree 4. Many ferns and palms (in the understory) 5. Trees with large leaves-mesophylls (larger than 12.5 cm) 6. Higher altitude= fewer species 7. Drier monsoonal forests in tip end

Question 8

What are the characteritics of temperate rainforests? (6)

Answer 8

1. fewer species, south, few vines 2. fewer layers, simpler structure (usually dominant layer, medium and shrubs) 3. microphyll leaves (2.5-7.5 cm) 4. warm temperate NSW- east Vic 5. cool temperate Vic-Tas 6. in Victoria single species often dominant: Myrtle beech

Question 9

What are the lowland tropical rainforests? (5)

Answer 9

1. climate uniformly warm wet
2. rainfall above 1800mm, altitude below 1000m
3. rapid nutrient cycling
4. regional differences in composition
5. occur in 23N to 23S

Question 10

What are the characteristics of SE Asian tropical rainforests?

Answer 10

-2 faunal regions separated by Wallace’s line 1. Borneo-Malaya: orangutan, tiger, woodpecker 2. Australian-New Guinea: lorikeets, cockatoos, kangaroos

Question 11

Where is the Wallace line?

Answer 11

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Question 12

What characterises lowland tropical rainforest?

Answer 12

1. Evergreen woody plants 2. No single species dominant (10-15%) 3. Dense overhead canopy cover (90%), low light, high humidity

Question 13

What is the structure of a lowland tropical forest?

Answer 13

-canopy 30-50m above ground -emergents 75m, trunks 3m -structurally complex- 4 strata (layers)

Question 14

What is the leaves’ adaptation in lowland tropical rainforest?

Answer 14

-large leaves= can collect more light -smooth surface and drip tip prevent moisture accumulating and fungal growth -guttation: pores on leaf edge drip water-root pressure forces water and mineral nutrients up plant

Question 15

How is water transported in a plant and what are the implications of that in tropical rainforests?

Answer 15

-plants take up water from soil to roots, then from high concentration to low concentration via semi-permeable membrane -into leaves, into -the whole process driven by evaporation from the leaves, provides tension, sucks up the water -water movement is important, brings nutrients, hydrates -evaporation is slow, that has implication for movement of nutrients - if lot of water in soil= root pressure when water pressured into plant, if no evaporation then use pores to get rid of excess water -when humidity high, little evaporation and transpiration stream

Question 16

What are the buttresses and prop roots (tropical rainforest)?

Answer 16

-structural support as have shallow root system (feeding roots near surface) -competing for light, the buttress provides stability so can grow -having roots laterally extending rather than deep is good as more material in the top layer of soil

Question 17

What is an epiphyte?

Answer 17

-a plant growing on another -advantages: get water and dissolved nutrients as run-off; reach the light (not parasites -e.g. orchids, ferns, lichens, often xerophytic, mycorrhizal -symbiosis: commensalism

Question 18

What is special about elk and staghorn ferns?

Answer 18

-2 leaf types -nest leaves collect litter for nutrients

Question 19

What is special about the strangling fig?

Answer 19

-starts life in the upper canopy light as an epiphyte then crushes the host -seeds dispersed by birds -germinates on another tree, kills the host when has enough stability on the ground

Question 20

Are there many woody vines species in rainforests?

Answer 20

-many species are woody vines -climb to light -climbing palms with spines and whip like extensions of leaf mid-rib

Question 21

What is the stinging tree?

Answer 21

-related to nettles -much stronger -like hypodermic syrringes -takes months to heal

Question 22

What are the characteristics of parasitic plants and one example?

Answer 22

-overcome need for light -e.g. Balanophora: root parasite, no leaves or stem -it is a flowering plant, no chlorophylls, lives undergound, on the roots of trees -emerge when flowering -symbiosis: parasitism

Question 23

What is Rafflesia?

Answer 23

-in Malaysia -no leaves or stem, parasitic plant -odour attracts flies for pollination (rotting meet) -grows as a parasite in vines, threads of tissue in the vine stems -flowers are huge, more than a meter, they sting, attracts flies,