10. Forest Strategy

Question 1

What is the CSR straregy theory, also known as Grime’s triangle? 3

Answer 1

Question 2

What are stress tolerators and what are some of the strategies they use? 11

Answer 2

1. on the forest floor- resource limited
2. low in light
3. may be low in nutrients/water as trees prevent water from falling to ground
4. must tolerate strees and optimise investment of resouces to match environment
5. shade liight enriched in green and far red wavelengths
6. partial shade also rich in blue
7. plants can absorb wavelengthss above that aren’t filtered out by forest canopy
8. rate of photosynthesis same as others
9. do not respond to photoreceptor phytochrome telling them to grow in far red
10. shade plants have more chlorophyll b per cholophyll a, allowing capture of light that reaches them, as b absorbs different wavelengths
11. plants arrange leaves to optomise light capture

Question 3

Describe sun plants and how they capture light. 3

Answer 3

1. sense far red light and respond by growing stems to get out of shade
2. far red sensed by photoreceptor phytochrome
3. minimise self shading with leaf arrangements eg. longer internodes between leaves

Question 4

Describe how sun and shade plants are best optomised for photosynthesis in their own ways. 6

Answer 4

1. shade lants don’t waste resources making equipment for light it won’t get
2. plants in dark areas can survive with less photsynthesis
3. shade species ignore light signals and don’t attempt to change based on light capture
4. shade plants have thinner leaves - don’t absorb enough light to be worth energy input
5. pallisae layer much thinner in shade leaf
6. shade plants have single layer of non-overlapping leaves, and fewer roots in relation to shoots/higher root/shoot ratio

Question 5

Describe how some plants avoid the light in order to survive. 6

Answer 5

1. Mercuralis perenne/dog’s mercury lies between c and c
2. can’t survive outside of woods - few, poor surviving seeds
3. oxalis acetosella/wood sorrel between stress and weeds, doesn’t elongate stem
4. folds leaves to avoid high light - controlled by blue light receptors
5. both of the above become bleached and damaged if explosed to high light
6. urtica diocia/stinging nettle between r and c - tolerates high light - opportunist in it

Question 6

What is urtica diocia and what strategy does it use for survival? 9

Answer 6

1. semi-shade competitor
2. nigh n requirement
3. high protein content
4. capable of high photosynthetic rates
5. good acclimation potential
6. good competitor - fast-growing, dense and high shoot thrusts
7. grows in woodland margins, hedgerows and open
8. hates alkaline soil
9. grows in chalky, neolithic areas eg. south downs

Question 7

how do plants use light foraging to survive? 9

Answer 7

1. eg. between c and s, rubus fruticosus/blackberry
2. grows in tangles and can grow in dense shade
3. urtica diocia takes adventage of gaps for light
4. horizontal foraging via stolons eg. strawberries and raspberries
5. grow outwards, find sunlight, put down roots
6. can go over or underground, low cost investment
7. vertical foraging eg. ivy - good photosynthesis at high and low levels
8. long-wined with leathery leaves
9. open out in light - sun morphology

Question 8

How do plants use seasonal shade avoidance to survive? 4

Answer 8

1. eg. Ranunculus ficaria/lesser celandine and Hythacinthoides non-scripta/bluebell
2. deciduous understory plants that leaf/flower in spring or autumn to avoid competition
3. produce underground bulbs, capture resources and store them there
4. can come back very quickly