Lecture 7- Peatland Disturbances

Question 1

What is a disturbance?

Answer 1

Discrete event that alters ecosystem composition, structure, function or physical environment

Question 2

What is a disturbance regime?

Answer 2

Temporal and spatial patterns of disturbances, characterized by frequency, extent and severity of disturbances

Question 3

What is resistance?

Answer 3

Ability of an ecosystem to withstand a disturbance (stays in the cup even with disturbances)

Question 4

What is resilience?

Answer 4

Ability of an ecosystem to recover structure and function after disturbances (hydrology could have been completely changed, loses resistance and turns into a different ecosystem)

Question 5

What are some natural disturbances in peatlands?

Answer 5

-Fire (lightning strikes)
-Insect outbreaks and pathogens
-Weather
-Permafrost

Question 6

What are some anthropogenic disturbances in peatlands?

Answer 6

-Fire (human ignited)
-Drainage
-Forestry
-Oil and gas development

Question 7

What influences the fire severity of peatlands?

Answer 7

-Tree mortality
-Peat consumption
-Carbon release

Question 8

What influences resistance and resilience of peatlands?

Answer 8

-Species composition (fuel type)
-Microtopography
-Sphagnum dominance
-Surface wetness
-Peat moisture
-Time since last disturbance

Question 9

What are the three fire severities in increasing order?

Answer 9

1.Surface fires
2.Stand-replacing fires
3.Peat fires

Question 10

What are surface fires?

Answer 10

-Lower severity and intensity
-Annual to decadal frequencies
-Promote microtopography and sphagnum development (sometimes can regenerate really well with sphagnum)

Question 11

What are stand-replacing fires?

Answer 11

-Fundamental process in northern peatlands
-All or majority of forest canopy burns (burn so fast that it doesn’t burn the peat)
-Decadal to centennial frequency

Question 12

What are peat fires?

Answer 12

-Highest severity and intensity
-Can burn for months underground (zombie fires)
-Burn 40cm to 1m below
-Most detrimental
-How high is the fire or how fast

Question 13

What do roads do to peatlands?

Answer 13

Changes flow of ground water and surface to and from peatlands which leads to modification of species composition and cover especially in road ditches

Question 14

Describe metal and mineral mining

Answer 14

-Removal of peat and soil to access resources
-Increases water table when peat and soil are removed
-Leach contaminants during and after extraction
-Contaminants can persist for centuries

Question 15

Describe peat harvesting

Answer 15

-Vegetation removed, peatlands drained, dried, then peat is harvested
-Peat exported and sold for horticultural purposes
-Completely destroy environment when you do that
-100s to 1000s of years to restore accumulated peat

Question 16

What is the most common trees harvested in peatlands?

Answer 16

-Tamarack
-Black spruce

Question 17

What happens to the water table when the trees are cut down?

Answer 17

The water table rises

Question 18

What are implications of forestry in peatlands?

Answer 18

-Low tree productivity
-Results in higher water table
-Modify hydrology in adjacent peatlands and wetlands
-Increased soil compaction minimized by harvesting when ground in frozen
-Can regenerate in 10-20 years

Question 19

What are some direct and indirect disturbances of oil and gas development?

Answer 19

-Removal of vegetation
-Removal and compaction of soil
-Altered hydrology
-Contamination
-Emissions
-Reduced resistance and resilience

Question 20

What is open surface mining?

Answer 20

-Bitumen is close enough to surface can remove all vegetation and soil to mine
-Removal of entire peatland ecosystem and function

Question 21

What happens to the peatland in open surface mining?

Answer 21

Increases salinity, gets into soil, salt water kills the plants

Question 22

What is in situ mining?

Answer 22

Force deep underground bitumen deposits to surface

Question 23

What does in situ mining do to the peatlands?

Answer 23

-Fragmentation and loss of contiguous peatlands
-Simplify microtopography
-Soil and hydrological changes
-Removal of overstory trees
-Loss of bryophyte species with shifts to graminoids and shrubs

Question 24

What is reclamation?

Answer 24

Process of making severely degraded land suitable for another use (plant whatever as long as it fills ecological niche)

Question 25

Describe the process of reclamation of oil sites

Answer 25

-Remove contaminated mineral soil
-Restore hydrology
-Transfer new mineral soil or transplant peat
-Mounding and planting in areas where peat loss not significant
-Plant typical species or introduce salt tolerant species

Question 26

What is restoration?

Answer 26

Process of assisting recovery in degraded, damaged or destroyed ecosystem

Question 27

Restoration prioritizes _______

Answer 27

Composition and structure (microtopography, hydrology, overstory understory and ground layer)

Question 28

Describe the process of reclamation for seismic lines

Answer 28

-Access degree of natural regeneration on seismic lines, if naturally regenerating do not treat
-Create microtopography to support tree survival and growth
-Tree planting
-Minimize impacts to soil and grounds layer by completing in winter

Question 29

What is recovery?

Answer 29

Compositional, structural and functional return to reference ecosystems

Question 30

True or False? Restoration leads to recovery?

Answer 30

False, doesn’t always lead to recovery

Question 31

Disturbance interactions coupled with climate change causes _____ rather than _______

Answer 31

-Shifts
-Recovery

Question 32

How long does it take peatlands to recover?

Answer 32

Decades to 1000+ years