Lecture 11- Intro to Tundra and Permafrost

Question 1

What is the temperature for continuous, discontinuous and isolated permafrost zones?

Answer 1

-Continuous <-6.7
-Discontinuous -3.9 to -6.7
-Isolated -1.1 to -3.9

Question 2

Permafrost reduces ______

Answer 2

Microbial activity

Question 3

What are the three characteristic of frozen soils?

Answer 3

1. Meltwater pools (cant absorb melted water)
2. Cold soil temperature (minimal microbial activity, reduced decomposition, restricted nutrient cycling)
3. Storage of carbon (trapped in frozen soils)

Question 4

What are some implications of permafrost thaw?

Answer 4

-Soil slump (cannot support weight of forests so trees slump)
-Increased microbial activity (release of carbon and methane)
-Unstable soil causes infrastructure collapse
-Release of pathogens previously frozen
-Discovery of new species

Question 5

What causes a thermokarst lake to form?

Answer 5

-Formed by meltwater from thawing permafrost
-Depression often produced by collapse of ground levels associated with permafrost thaw

Question 6

Describe the feedback loop created by thermokarst lakes

Answer 6

More water = thawing more permafrost = more lakes and general warming = more decomposition in the lakes = more release of methane = more warming potential

Question 7

What is ebullition?

Answer 7

Methane bubbles forming from decomposition

Question 8

How does coastal erosion occur in tundras?

Answer 8

-Loss of summer sea ice
-Rises in sea levels reduce costal tundra and increases the rate of erosion

Question 9

What does the loss of shoreline ice do to the coasts in tundras?

Answer 9

-No protection on shorelines from waves
-Increased wave action undercuts permafrost banks
-Salt water kills tundra plants through salinization

Question 10

In tundra ecosystem, tree growth is hindered by _______

Answer 10

Temperature

Question 11

What are the three types of tundra regions?

Answer 11

1.Arctic
2.Alpine
3.Antarctic

Question 12

What are some characteristics of tundras?

Answer 12

-Dominated by cold, dry polar winds
-Summer temperature < 10
-Short growing season
-Long cold winters
-Continuous permafrost
-Trees stunted or absent
-Low biodiversity

Question 13

What are some limitations to tundra life?

Answer 13

-Trees stunted or absent
-Poorly developed soils, low decomposition
-Very shallow rooting depths
-Low nitrogen availability, low microbial activity
-High proportion of bare rock
-Short growing season
-Long cold winter

Question 14

Why are trees stunted or absent in tundras?

Answer 14

-Cold short growing season, not enough time for growth
-Frozen soils, not stable soil
-High winds

Question 15

What type of soils are present in tundras?

Answer 15

Cryosolic soils

Question 16

What is cryoturbation?

Answer 16

-Mixing of soil materials via repeated thawing and freezing
-Bringing permafrost closer to the surface it will thaw and melt throughout the year and this thaw will start to mix up the soil, horizon bands start to intermingle

Question 17

What are some adaptations to the short growing seasons in tundras?

Answer 17

-Evergreen plants
-Early flowering
-High proportion of asexual reproduction

Question 18

What are some adaptations in the tundras for the long cold winters?

Answer 18

-Hibernation
-Specialized hair and coats
-Body shape reduces heat loss
-Use snow as insulator because is has lots of air in it and can be heated by body heat under the snow

Question 19

Describe what polar desserts are like

Answer 19

-Low annual temperature and evapotranspiration
-Most covered by snow or ice
-Exposed soils generally barren (exposed rocks that dont develop anything)
-No water to support growth
-Can have some primary producers like algae and cyanobacteria

Question 20

Where do you find polar desserts?

Answer 20

At the poles