Lecture 24- Plant Adaptations III

Question 1

Arctic plant productivity is ____ because of _____

Answer 1

• Low
• Poor nutrients, short season, frozen soil

Question 2

Daily productivity can be as high as in _____

Answer 2

Temperate and boreal regions

Question 3

What is generally limiting in the north?

Answer 3

Nitrogen and phosphorus

Question 4

In the Arctic, the optimal photosynthesis rates are at ____ than ordinary plants

Answer 4

Lower temperatures

Question 5

Describe the tolerance of Alpine azalea (kalmia procumbens)

Answer 5

• Can tolerate air temperatures to -60C
• Soil temperature to -30C
• Utilizes microtopography (found in areas where snow cover will protect the plant)

Question 6

Describe the tolerance of White Mountain Avens (Dryas intergrifolia)

Answer 6

• Seeds can tolerate -4C
• Main roots die at -6C (Can grow new roots)
• Adaptations = evergreen leaves, clonal growth forms, heliotropism

Question 7

List some aspects of Arctic plant phenology

Answer 7

• Breaking of dormancy (mean temperatures at or above 0C)
• Very rapid growth even at low positive temperatures
• Flowering (preformed the year before)
• Pollination (wind pollination more important with increasing lattitude)
• Flies more important than bees
• Seed production (oppertunistic)
• Onset of dormancy (triggered by photoperiod, low temperature)
• Warmer temperatures at onset of dormancy = delayed dormancy (buds become sensitive to warming later)

Question 8

What are some phenological triggers?

Answer 8

• Early season phenophases triggered by snowmelt (later snowmelt = delayed phenology)
• Later season phenophases = occur at given time since snowmelt
• Once early season phenology starts, all phases happen at the same time regardless of the time of the year
• Adaptation for short growing season (arctic plants dont benefit from longer growing seasons

Question 9

What are the effects of warming on phenological mismatch?

Answer 9

• Increase in above and below ground biomass
• Increase in number of inflorescence

Question 10

What is the effect of early season grazing on plant phenology?

Answer 10

Reduction in overall biomass

Question 11

What are the effects of late season grazing on plant phenology?

Answer 11

• Increase in number of inflorescences
• Increase in dead biomass

Question 12

What is altered with plant phenology mismatch?

Answer 12

• Flowering reliant on snowmelt
• Bumbblebees emerge when soil is consistently warmer than 6C
• If snow melts but soil is not warmed = mismatch
• Can rely on asexual reproduction

Question 13

Describe Phenological Mismatch

Answer 13

Question 14

Describe the shrubification of the tundra

Answer 14

Question 15

What are the two pathways for the shrubification of the tundra?

Answer 15

1. Increase in deciduous shrubs
2. Increase in dwarf evergreen shrubs

Question 16

Shrubification has a ____ on warming

Answer 16

Positive feedback

Question 17

Shrubification alters?

Answer 17

Soil nutrient cycling and soil moisture

Question 18

What are the effects of warming on plants in tundras?

Answer 18

• Increased height and cover of gramminoids and shrubs (reduced albedo)
• Shifts in plant community (reduction in small herbaceous plants, lichens and mosses)
• Decreased species evenness (shift to dominance of one species)
• Increase in sexual reproduction (earlier flowering, heavier seeds)
• Potential for higher genetic diversity
• Response varies by species (graminoids and shrubs respond better)