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Forest Ecology > Physiography & Soils > Flashcards

Physiography & Soils Flashcards

1
Q

What is physiography?

A

physical geography

the study of the form and substance of the surface features of a region (the abiotic features)
including

what the abiotic features of a terrestrial environment are and how they shape the environment’s biotic communities
and how it shapes ecosystem composition, structure and function

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2
Q

What are the 3 characteristics of physiography?

A

setting (glacial vs. not glaciated, coastal vs. inland)

specific landforms (elevation, size, form, parent material, slope)

position of the landform on the landscape (elevation, proximity)

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3
Q

What other features can shape the biotic community aside from the main 3 physiographic ones?

A

soil type and characteristics
disturbance events (type, frequency, severity)
human modification of landscape or biotic features

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4
Q

How has physiographic setting shaped landscapes in Canada and BC?

A

glaciation has had strong influence on physiography as most of the province was glaciated with some refugia

these glaciations and then subsequent retreating has modified the landscape and caused many gradients of elevation across the province and country (ex. looking at a cross section of the province, there’s huge variation in physiographic regions from the coast to the strait of Georgia, to the coast mountains, to the interior plateaus, to the Cassiar-Columbias, to the Rocky Mtn Trench, to the Rockies, and the Great Plains in Alberta

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5
Q

What are considered major physiogeographic regions in BC?

A

the mountains

ex.
coastline
Insular mountains
Strait of Georgia depression
Coast Mountains
Interior plateaus (Fraser Valley, Okanagan)
Cassiar-Columbia mountains
Rocky Mountain Trench
Rockies

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6
Q

What are some examples across Canada of past glacial activity creating unique landscape features?

A

Champlain Sea - past glaciers suppressed the land and created an inland sea from the Atlantic Ocean in Southern Ontario and Quebec - contains different soils and topography from surrounding area

Oak Ridges Moraine - dense (200m) glacial deposits in Southern Ontario has become a large aquifer and headwaters for a lot of rivers

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7
Q

What are some examples of coastal landforms (physiography)?

A

coastal lagoon
coastal dunes
brackish river estuary
cliffs
sea arches
beaches
sea stacks
sea stumps
mangroves
lagoons

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8
Q

What shapes shorelines?

A

sediment deposits from land and erosion by waves

sea level changes (isostatic rebound)

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9
Q

What is isostatic rebound?

A

when land masses rise that were depressed by glaciers after glacial retreat

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10
Q

What are examples of specific landforms in BC?

A

ranges from continental to regional/local

continental = mountain ranges (ex. coastal mountains) and plains (ex. Central Plateau), river basins (ex. Fraser River)

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11
Q

What major influence do landforms have?

A

they can influence ecosystem characteristics

ex. mountains create rainshadows

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12
Q

What 5 things does the influence of local landforms depend on?

A

elevation
size
form
slope
parent material

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13
Q

Will influences of elevation be more regional or continental?

A

regional

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14
Q

Describe how Interior Fraser-Thompson Plateau is an example of how elevation can create varied landscapes

A

this region has 84 peaks with elevation up to 2334 m

this is a highly varied landscape that includes a variety of forest types

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15
Q

What kind of BEC zones are heavily influenced by elevation?

A

Engelmann Spruce-Subalpine fir
Montane Spruce
Alpine tundra (BAFA, CMA, IMA)

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16
Q

How does elevation effect MAT? MAP?

A

Lower MAT with increasing elevation

higher MAP with increasing elevation and potential leeward rainshadows created

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17
Q

How is growing season effected by elevation?

A

shorter growing season with increasing elevation - soil temperatures decrease = low NPP

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18
Q

How does elevation effect productivity?

A

decreases productivity with increasing elevation

it limits plant establishment, growth and species composition - lower temperatures and higher ppt

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19
Q

How does size of landform effect the landscape?

A

the effects can vary massively depending on the size, incline, aspect, and elevation

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20
Q

What is an example of a BC small mountain range that has different landscapes/ habitat on either side of the range?

A

Strathcona Park - Landslide Lake vs Mt Colonel Foster

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21
Q

Use Mount Doug as an example for how aspect of landform size (even if landform is small) has an effect on the landscape

A

Mount Doug, though small, has 2 unique habitats on it depending on the side of the mountain

the south side is drier, thin soil, with little trees
the north side is wetter and dominated by WRC and Df

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22
Q

T or F: landform size can cause significant changes to climate and growing conditions

A

true

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23
Q

What are some examples of how microtopography can change growing conditions?

A

even minor changes to elevation - ex. forest floor vs the top of a log will support different biota

windthrow create different conditions = opens forest canopy

nurse logs colonized by other organisms in CDF - create habitat

changes soil conditions = change plant community structure

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24
Q

What landforms are considered level terrain?

A

plains, plateaus, river terraces, old lake beds, prairies

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25
Q

What usually forms / shapes level landforms?

A

water, but sometimes glacial activity like till deposits

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26
Q

How does water influence the effects on the landscape of level landforms?

A

1 - if there is little lateral movement of water, then water may rapidly drain into subsoil if there’s coarse parent material

2 - if soil drainage is poor (too compact, fine textured, bedrock) water will accumulate - can create bogs, lakes, marshes

both rapid drainage and slow drainage will change the plant community

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27
Q

What is an example of a level terrain with large water influence?

A

Tow Hill Ecological Reserve in Haida Gwaii has a peat bog adjacent to a beach/shore habitat
- the peat bog is a flat landform with poor drainage

Boreal forest wetlands and peat bogs

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28
Q

How does sloping terrain effect the landscape?

A

because it allows the lateral movement of water on the surface (or below), depending on the steepness of slope and shape of the slope, it can have dramatic impact on plant community

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29
Q

What are the 3 shapes of a slope? How do they influence how water moves across a landscape?

A

planar - no curves /\
- water will run right down slopes and pool at bottom = dry at top, wet at bottom and erosion higher

convex - ()
- the higher elevation parts are less steep
- more water might pool here
- water will run quickly down the rest of the slope - but maybe less water (less erosion)

concave - )(
- water will run quickly down the slope and pool at the bottom
- probably high erosion at the top

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30
Q

What features change the level of effect slopes have on the landscape?

A

slope form (planar, convex, concave)
slope aspect (North vs. South)
slope inclination (steepness)
slope length

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31
Q

What is slope aspect?

A

the direction of a slope face (N, E, S, W)

32
Q

How does slope aspect change the landscape?

A

depending on its direction, a slope face will recieve different levels of sun exposure = affects temperature and precipitation

ex. south-facing typically receive more direct sunlight = drier, warmer

33
Q

T or F: the effects of slope aspect are the same regardless of latitude

A

false, latitudes further from the equator experience slope aspect differences more greatly

because the sun hits the earth’s surface at increasingly different angles moving away from the equator (consider tropical vs. boreal)

34
Q

Use the boreal forest to describe the effects of slope aspect at increasing latitudes

A

boreal slopes (high latitude) facing north are less productive and usually covered in permafrost because they receive so little direct sunlight = low activity in soils

soil has deeper active layers and warmer temperatures on south facing slopes = higher diversity of plants

35
Q

How does east-west aspect affect plant community?

A

air temperature

east-facing slopes receive early morning sunlight when temperature is still cool and moisture is higher

west facing slopes receive hotter afternoon sun - temperature higher and drier

36
Q

Give an example of a latitude and a forest that have more productive north-east facing slopes?

A

Appalachian mountains (mid-latitude east coast)

37
Q

What is a site index?

A

the measure of potential site productivity (higher index = better growth)

38
Q

How does slope inclination effect landscape?

A

the steepness of a slope will influence the amount of water available, the drainage, and accumulation of OM and nutrients

steeper = more water and nutrient run-off

39
Q

How does slope length effect landscape?

A

the relationship to inclination will change the gradient of conditions

ex. short and steep will be very different from long and gentle

40
Q

Describe the conditions on higher positions on slopes

A

drier = more drainage + sun + winds

usually less soil, OM and soil nutrients

41
Q

Describe the conditions on lower positions on slopes

A

less windy and less sunny usually due to more shelter = wetter and cooler

usually more OM, soil and soil nutrients than at the top of a slopei

42
Q

in what latitudes does slope position become more important?

A

higher latitudes where there’s shorter growing periods

43
Q

What influences soil development and quality?

A

physiographic conditions + soil biota

44
Q

Why are soils so important to forest ecosystems?

A

they are the foundation of terrestrial ecosystems and they contain complex abiotic and biotic components

45
Q

Describe soil

A

material that develops naturally and is composed of loose mineral components and organic matter component

exists in all terrestrial ecosystems in varying quantities

supports microbiota and macrobiota that help develop soil composition, nutrient levels and complexity

a growth medium that responds to abiotic and biotic components

46
Q

What does it mean that soil is a growth medium?

A
  • habitat for microbes
  • substrate for plants
  • source of water and nutrients for plants
  • both direct and indirect food source for animals
  • resource bank for forest biota
  • influences local microclimate
47
Q

what 5 factors contribute to soil formation?

A

parent material - mineral contribution

topography/relief - shape of landscape

climate - temperature, ppt, wind

biota - micro and macro

time (geological)

48
Q

How are parent material classified?

A

on how they were formed or scattered

49
Q

What are the 7 classifications of parent material?

describe them and what their soils are like

A
  1. residual - bedrock that was weathered in place (non-glaciated) = soil resembles PM
  2. fluvial - sediments deposited from flowing water = soils often well-sorted (of similar size) sand and gravel
  3. glacial till - sediments deposited beneath, within, on top of glacial ice = soils poorly sorted mix of gravel, sand, silt, clay
  4. eolian: sediments moved and deposited by wind = soils usually well-sorted sand and silt (loess)
  5. colluvial - sediments moved by unchannelized flow on slope (gravity/not rivers) = soils resemble sediments from origin
  6. marine - sediments deposited on ocean floor are exposed from isostatic rebound
  7. lacustrine - PM sediment deposited in lakes = soils usually well sorted sand, silt, clay
50
Q

What is another soil ‘parent material’ that is not mineral based?

A

organic matter - not derived from actual parent material but from plant and animal activity and matter

51
Q

What is/are the parent materials for Canada’s soils? explain

A

most are of glacial origin because most of Canada’s land mass was exposed after the last glacial episode

52
Q

t or f: Canada’s soils are old (geologically)

A

false, they are geologically young - most of the land was only exposed after the last Ice Age

53
Q

How does the topography/relief of the land surface influence soil? (ie., what factors influence soil development?)

A

shape of landscape influences flow and distribution of water - erosion or accumulation

slope, aspect and elevation will influence plant growth and soil development

latitude and temperature during growing season will influence soil develppment

54
Q

Will low lying sites have soils developing faster or slower? why?

A

quicker because they will have more moisture (less lateral movement of water) and less erosion (less sloping)

55
Q

How does climate influence soil development?

A

climate influences the amount and type of ppt

the intensity of which may affect erosion in a site as well as the freeze-thaw processes

soil dispersal by wind or water is influenced by climate

56
Q

How do soil micro- and macrobiomes influence soil?

A

plants hold parent material in place with their roots = contribute to water holding capacity of soil

plant roots are associated with microbiota that influence weathering of PM and release of minerals (P and N) to soil (usually a root symbiosis)

plant growth becomes OM in the soil = OM increases soil moisture and nutrient content, improving tolerance to variable abiotic conditions - also moderates microclimate

57
Q

Rank sand, silt, clay in order of largest to smallest particle size (including units)

A

diameters

sand: 2-0.05 (from very coarse-very fine)

silt: 0.05-0.002

clay: =< 0.002 mm

58
Q

What determines soil texture classes?

A

the relative proportions of different-sized particles (sand, silt, clay)

59
Q

Define soil aggregates

A

the arrangement of small/individual soil particles of sand, silt, or clay to form larger particles

(chunks)

60
Q

What helps stabilize and bind soil aggregates?

A

organic matter

61
Q

What key soil conditions does soil structure influence?

A

water movement ability - water holding capacity

aeration

resistance to erosion

62
Q

Which soil particle type/size are best at holding water? why?

A

clay because they have hydrostatic attraction (their negative anions attract and hold positive water cations tightly)

63
Q

Describe flocculation

A

the process by which individual clay particles aggregate into larger chunks - usually associated with water

64
Q

What are the classes of soil macro-aggregates?

A

granular
blocky
prismatic
columnar
platy
single grained

all of which are found in different soil horizon areas

65
Q

Describe soil porosity

A

the distribution of aerated space in soils

66
Q

How does soil porosity influence soil?

A

the amount of available space in soil influences the movement of water and gases (O2)

different soil macro-aggregates have different porosity

67
Q

What % of pore space does a well-structured soil have?

A

65% pore space

68
Q

Which macro-aggregate type would be the most porous? the least?

A

most would be single-grained or granular (mostly sand)

then blocky and prismatic

least would be platy and massive (layered like sediments basically - mostly clay)

69
Q

Define soil consistency and explain the concept relating to its function

A

the physical resilience of soil

the stickiness of soil relates to its ability to resist deformation under stress

70
Q

What factors does soil consistency influence?

A

soil stability and erodibility (resilience to stress) and resistance to compaction

71
Q

What is the bulk density of soil? why is this measurement important?

A

the oven-dry weight of soil/unit of volume (g/cm^3)

this measurement reveals information about structure, texture, porosity, and OM content

72
Q

What does a high bulk density indicate for soil?

A

more soil compaction

73
Q

Define aeration in soil - what influences it?

A

gas exchange in soil

influenced by soil porosity and the distribution of pore space v. water spaces

74
Q

What is the range of ideal bulk density for plant growth across all soil textures?

A

from < 1.10 g/cm^3 for clays to < 1.60 for sands and loamy sands

75
Q

What abiotic and biotic factors determine soil temperature?

A

abiotic:

latitude
aspect
elevation
continentality
soil water content
soil texture
soil porosity

biotic:
vegetation cover

76
Q

What does soil temperature effect?

A

many biological functions in the soil such as

root growth of plants
soil organism metabolism
decomposition rates
nutrient and water uptake

77
Q
A

Forest Ecology (12 decks)

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