Swanson 1988 - Landform effects on ecosystem patterns and processes Flashcards
1
Q
What is the greatest influence of geomorphic processes operating before, or subtly coexisting w/ vegetation?
A
- Geo processes may have greatest influence on vegetation through controlling patterns of soil properties
2
Q
Geomorphic processes over the long vs. short-term
A
- Long: create landforms
- Short: landforms are boundary conditions controlling the spatial arrangement and rates of geo processes
3
Q
Example of a fine-spatial scale interaction of geo processes
A
Plants may restart soil erosion or may be damaged by earth movement
4
Q
Example of broad-scale interaction of geo processes
A
- 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
5
Q
What does landscape commonly refer to?
A
- Form of the land surface and associated ecosystems at scales of hectares to many km
- Composed of landforms and ecological units such as patches
6
Q
What does landform commonly refer to?
A
- ex. like a landform carved out by a landslide or created by sediment deposition forming a gravel bar
- Component of landscape
7
Q
Geomorphic process refers to?
A
- 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
8
Q
Effect of landforms on ecosystems: 4 classes
A
- 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
9
Q
Class 1
A
- 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
10
Q
Class 2
A
- 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
11
Q
Class 3
A
- Landforms may influence frequency and spatial pattern of nongeomorphically induced disturbances by agents such as fire, wind, and grazing
12
Q
Class 4
A
- Landforms constrain the spatial pattern/rate or frequency of geomorphic processes that alter biotic features/processes
13
Q
How does Class 4 differ compared to Classes 1-3
A
- Classes 1-3 considered static
- Class 4 regards landforms and ecosystems as dynamic
14
Q
Where is precipitation larger?
A
- Higher elevations from orographic effects
15
Q
How do landforms influence the temporal/spatial patterns of fluxes of material carried across landscapes by surface water?
A
- 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
16
Q
How does water flow?
A
- Along gravitational gradients
17
Q
What controls the dominant wind paths or animal migration paths?
A
- Controlled by landforms at broader scales
18
Q
How do landforms affect some vertebrates?
A
- Delimit ranges
- Gullies, cliffs, streams may form physical barriers
- Or as convenient, but passable features that can mark home ranges of neighbouring animals
19
Q
What are some examples of landforms affecting vertebrates in semi-arid landscapes?
A
- 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
20
Q
What is the relationship of grazing on the landscape?
A
- 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
21
Q
What is a known example of landforms controlling patterns of ecosystem disturbance across landscapes (nongeomorphically induced disturbances)
A
- Inundation of channels and floodplains by floodwaters
22
Q
How do landforms increase frequency of disturbance?
A
- Channeling of things like fire and wind into areas
23
Q
What can control patterns of snow distribution
A
- Topography, subtle ridges/depressions
- Can be redistributed by wind
24
Q
What is the result of persistent snow accumulation? Class 3
A
- 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
25
What is the distinction btwn landform effects of classes 3 and 4?
- 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
26
Which class focuses on the physical dynamics of the landscape?
- Class 4
| - Geo processes are the primary disturbances
27
What are 2 examples of geomorphic disturbances in Class 4? What is the role of the landforms in this?
- Landslides
- Later shifts of river channels
- Landforms constrain the frequency and magnitude of change
28
What limits the lateral channel change in mountain streams? Class 4
- 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
29
What dictates the vegetation in valley bottom vs. mountain channel streams? Class 4
- 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
30
How do landslides work?
- 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
31
Frequency/magnitude relationships of events
- 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
32
Describe the 4 Classes as they relate to a mountain like mount Rainier
- 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
33
Landscape Ecology as defined by Risser
- 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
34
Knowledge of geomorphic underpinnings of ecosystems is essential to...?
- interpreting ecosystems in context of their landscapes
35
What class(es) influence occurs through the effects of landforms on envr gradients?
Class 1 and 2
36
What class(es) influence occurs through regulation by landform of the patterns and frequency of disturbance?
Class 3 and 4
