Boreal Forest Structure & Disturbance

Question 1

Communities change due to many different reasons. Is it predictable? Explain 2 hypotheses

Answer 1

According to Clements or Elger: yes
- succession is predictable
- mosses/ lichens colonize first after glacier
- then trees
- conifers drop needles –> acidify soils –> hard for other trees to survive

According to Gleason: it’s sometimes random
- wind
- who arrives first to colonize

Question 2

succession=
primary-
secondary-

Answer 2

= changes in communities over time (at one place)

Primary= absence of soil –> creation of soil after glaciation

Secondary= still soil present (eg after a fire)- seed banks= vegetation comes back

Question 3

3 steps of primary succession:

Answer 3

1. rock weathering
2. soil formation- lichens and moss die
3. successional stages- grasses, shrubs, trees

Question 4

What are autogenic and allogenic influences of succession?

Answer 4

Autogenic= inside influence= enviro change is a result of species in the community
eg. light changes in a forest as a result of changing forest canopy

Allogenic= outside influence= enviro change is a result of the physical enviro
eg changing temps with increase in elevation/ flooding/ drought

Question 5

What are the 3 major subdivisions of north American boreal forests?

Answer 5

1. Open lichen woodland (northern-most)
2. Northern coniferous forest
3. Mixed forest (southern-most)

Question 6

3 forms of open lichen woodland

Answer 6

A. typical lichen-spruce woodland
B. spruce-moss woodland
C. Open tamarack wetlands

Question 7

lichen-spruce woodlands have __ canopies. Why?

Answer 7

open

lots of lichen= spruce germination inhibited
caribou disturb lichen= allows some spruce to colonize

Question 8

spruce-moss woodlands have near ___ soils (___ order0 resulting from a high water table

Answer 8

saturated

gleysolic

Question 9

Open tamarack wetlands are ___ and dominated by ___ bogs and tamarack ___

Answer 9

saturated

sphagnum bog
tamarack fen

Question 10

northern coniferous forests have a ___ canopy and includes ___, pine, and ___ ___

Answer 10

closed

spruce
balsam fir

Question 11

Floodplain succession order (over time):
1
2
3
4
5
6

Answer 11

1. silt
2. willow
3. balsam poplar
4. white spruce
5. black spruce
6. bog

Question 12

Mixed forests include both ___ and broadleaf ___ trees (which are very good at ___).
This is __-most

Answer 12

conifers
deciduous
southern