Swanson 1988 - Landform effects on ecosystem patterns and processes

Question 1

What is the greatest influence of geomorphic processes operating before, or subtly coexisting w/ vegetation?

Answer 1

• Geo processes may have greatest influence on vegetation through controlling patterns of soil properties

Question 2

Geomorphic processes over the long vs. short-term

Answer 2

• Long: create landforms

- Short: landforms are boundary conditions controlling the spatial arrangement and rates of geo processes

Question 3

Example of a fine-spatial scale interaction of geo processes

Answer 3

Plants may restart soil erosion or may be damaged by earth movement

Question 4

Example of broad-scale interaction of geo processes

Answer 4

• Distribution and height of landmasses control distributions of plans and animals through influences on environmental gradients of temp and moisture and on migration corridors during envr change

Question 5

What does landscape commonly refer to?

Answer 5

• Form of the land surface and associated ecosystems at scales of hectares to many km
• Composed of landforms and ecological units such as patches

Question 6

What does landform commonly refer to?

Answer 6

• ex. like a landform carved out by a landslide or created by sediment deposition forming a gravel bar
• Component of landscape

Question 7

Geomorphic process refers to?

Answer 7

• Mechanical transport of organic and inorganic material

- or Transfer of material/disturbance of biota w/o regard to development of landforms or timescale in which that occurs

Question 8

Effect of landforms on ecosystems: 4 classes

Answer 8

• Landforms and envr gradients
• Landforms and movement of material, organisms, propagules, and energy
• Landforms and nongeomorphically induced disturbances
• Interaction among landform, geomorphic processes and ecosystem

Question 9

Class 1

Answer 9

• Landforms and envr gradients (elev, aspect, parent material, slope steepness) influence temp, moisture, nutrients available at sites w/in landscape
• Both simple and complex landform effects cannot easily be separated from effects of landforms on movement of materials and energy

Question 10

Class 2

Answer 10

• Landforms affect/regulate flow of organisms, propagules, energy, and material through a landscape by defining gradients, influencing paths (wind), and forming barriers/corridors for movement

Question 11

Class 3

Answer 11

• Landforms may influence frequency and spatial pattern of nongeomorphically induced disturbances by agents such as fire, wind, and grazing

Question 12

Class 4

Answer 12

• Landforms constrain the spatial pattern/rate or frequency of geomorphic processes that alter biotic features/processes

Question 13

How does Class 4 differ compared to Classes 1-3

Answer 13

• Classes 1-3 considered static

- Class 4 regards landforms and ecosystems as dynamic

Question 14

Where is precipitation larger?

Answer 14

• Higher elevations from orographic effects

Question 15

How do landforms influence the temporal/spatial patterns of fluxes of material carried across landscapes by surface water?

Answer 15

• Water quality can vary w/ lake position in landscape
• Lakes lower in landscape reflect proportionate increase of surface or groundwater contributed to lower lakes
• Lower lakes have higher conc’n of solutes due to water passing through more veg and soil
• Lakes high in system get more water by precip and more spring melt

Question 16

How does water flow?

Answer 16

• Along gravitational gradients

Question 17

What controls the dominant wind paths or animal migration paths?

Answer 17

• Controlled by landforms at broader scales

Question 18

How do landforms affect some vertebrates?

Answer 18

• Delimit ranges
• Gullies, cliffs, streams may form physical barriers
• Or as convenient, but passable features that can mark home ranges of neighbouring animals

Question 19

What are some examples of landforms affecting vertebrates in semi-arid landscapes?

Answer 19

• Size/abundance of cavities in outcrops and boulder piles control distribution of rodents
• Raptors use air space above cliffs to ride convective wind induced by heating of cliff and talus surfaces
• Birds prey on the rodents using the fine-scale landforms below

Question 20

What is the relationship of grazing on the landscape?

Answer 20

• Forage may be better in lowlands due to influence of landforms on spatial patterns of soil moisture and nutrients
• Animals preferentially grazing may then redistribute nutrients on landscape

Question 21

What is a known example of landforms controlling patterns of ecosystem disturbance across landscapes (nongeomorphically induced disturbances)

Answer 21

• Inundation of channels and floodplains by floodwaters

Question 22

How do landforms increase frequency of disturbance?

Answer 22

• Channeling of things like fire and wind into areas

Question 23

What can control patterns of snow distribution

Answer 23

• Topography, subtle ridges/depressions

- Can be redistributed by wind

Question 24

What is the result of persistent snow accumulation? Class 3

Answer 24

• Suppression of vegetation
• Creation of bare soil
• Loose sediment associated with water source (snow bank)
• redistribution of water in form of snow (class 2 effect) leads to disturbances of veg by shortened growing season/establishment
• Disturbance of site/adjacent areas by erosion and sed transport (Class 4 effect) may follow

Question 25

What is the distinction btwn landform effects of classes 3 and 4?

Answer 25

• In both classes, landforms constrain movement of agents that disturb ecosystem (fire, water, wind, animals)
• Class 3 disturbances operate through veg, which leads to secondary disturbance by accelerating geo processes
• Class 4 geo processes are the primary disturbances
• Emphasis on physical dynamics of the landscape in class 4

Question 26

Which class focuses on the physical dynamics of the landscape?

Answer 26

• Class 4

- Geo processes are the primary disturbances

Question 27

What are 2 examples of geomorphic disturbances in Class 4? What is the role of the landforms in this?

Answer 27

• Landslides
• Later shifts of river channels
• Landforms constrain the frequency and magnitude of change

Question 28

What limits the lateral channel change in mountain streams? Class 4

Answer 28

• Steep channels, coarse beds and bank seds, and bedrock outcrops
• Floodplains experience more persistent migration and reconstruction of floodplains in valley floors than mnt streams

Question 29

What dictates the vegetation in valley bottom vs. mountain channel streams? Class 4

Answer 29

• Valley bottom more adjusted to deposition of fine seds
• Mnt streams lack of fine sed restricts floodplain vegetation to species adapted to frequent minor deposition of fine seds
• Controls distribution of substrates available to plants and animals

Question 30

How do landslides work?

Answer 30

• Hollows/ depressions in bedrock collect seds from surrounding hillslopes
• Landslide eventually moves this stored material
• Landslide potential increases w/ moisture, soil depth exceeding root depth (less anchoring), decomposition of veg after fire, logging or other disturbance causing mortality

Question 31

Frequency/magnitude relationships of events

Answer 31

• Catastrophic more imp for some landforms more than others (landslides in bedrock hollows)
• Floodplains experience progressive resetting by frequent small events
• Some landforms and geoprocesses co-evolve and maintain a steady-state dynamic equilibrium along topo sequence

Question 32

Describe the 4 Classes as they relate to a mountain like mount Rainier

Answer 32

• Class 1: Pattern of vegetation zones up elevation
• Class 2: Higher productivity of lakes in valley bottom due to downslope movement of moisture and nutrients
• Class 3: Ridges and valley bottoms are barriers to fire, avalanches move down bedrock defined paths that cut through veg
• Class 4: Valleys experience severe disturbance by mud-flows triggered high on the mountain

Question 33

Landscape Ecology as defined by Risser

Answer 33

• The development and dynamics of spatial heterogeneity
• spatial and temporal interactions and exchanges across heterogeneous landscapes
• influences of spatial heterogeneity on biotic and abiotic processes
• and management of spatial heterogeneity

Question 34

Knowledge of geomorphic underpinnings of ecosystems is essential to…?

Answer 34

• interpreting ecosystems in context of their landscapes

Question 35

What class(es) influence occurs through the effects of landforms on envr gradients?

Answer 35

Class 1 and 2

Question 36

What class(es) influence occurs through regulation by landform of the patterns and frequency of disturbance?

Answer 36

Class 3 and 4