Lecture 3 - Landscape Ecology & Watershed Management Flashcards
How does the surrounding landscape influence an ecosystem?
Through:
- erosion
- eutrophication
- habitat
- water quality
- water temperature
ex. the characteristics of a stream in forest very different than that of a stream in agricultural land
What is an example of how organisms can influence their landscapes just as much as landscapes can influence organisms?
Beavers! They are a keystone species as they build dams that can completely change a landscape
Who are 3 people that influenced the creation of landscape ecology?
- Carl Troll: studied aerial photographs for changes
- Aldo Leopold: looked at patterns and animal pops
- Alexander Watt: studied plant communities
What are the main factors that effect landscapes?
- topography
- surface geology
- geomorphology
- natural disturbances
How does topography affect landscapes?
It is the basic cause of landscape patterns.
Ex. alpine tundras only occur in high elevations while riparian vegetation only occurs along streams.
How does geology affect landscapes?
It affects the soil type and vegetation distribution.
Ex. glaciation plays large role
How does geomorphology affect landscapes?
It shapes a landscape through:
- landslides
- erosion
- sand dunes
- permafrost
- fluvial dynamics (creating meandering rivers that are always changing)
How do natural disturbances affect landscapes?
It abruptly alters vegetation.
ex. fire, wind, insects, animals
How does fire affect landscapes?
It is natural part of taiga and certain vegetation depends on it - it creates a characteristic landscape.
It is also necessary for regeneration and creates patchy mosaic forest habitat
How does wind affect landscapes?
Different patterns are created depending on wind type (wind can blow down all or only portion of trees).
Also, hurricanes are wide, so they can take down more than tornadoes can (thin).
How do insects affect landscapes?
The outbreak of tree defoliating insects is very damaging and can affect thousands of hectares at once (ex. gypsy moth and spruce budworm). This also changes tree species composition as well as leaves dead wood behind as forest fire fuel
How do animals affect landscapes?
- Beavers: when they abandon a dam, it breaks down and leaves nutrient-rich sediment behind (excrements) and allows succession to occur again
- Blue jays: carry acorns over large distances and bury them, but won’t retrieve them all so some will be able to germinate. They are known as effective dispersers b/c carry “heavy seeds” farther, allowing range of oak trees to expand
How do humans influence forests?
Human activities intensely influence forests over short periods of time. Settlements create distinct patterns in forested areas.
What do cities do to forests?
They cause forest fragmentation b/c the majority of forest is lost, so they only exist in small and isolated patches. This is universal wherever humans have settled. :(
How does the impacts of forest management of timber harvesting vary?
The size of clear cuts and rotation lengths vary b/w countries, but cutting trees down in SA still affects in NA through climate change (C source).
How does patch size of clear cuts influence ecological processes?
It influences:
- tree seed dispersal
- wildlife dispersal
- plant and animal habitat
- amt of edge habitat
ex. Small patches will have more edge than interior - circles are best b/c least amt of perimeter with max amt of interior.