Simon Eco1 Flashcards
What is ecosystem engineering
Aan organism that creates or maintains its habitat
How can animals impact river factors
Sediment deposition, bank strength
How does willow engineer its environment
Roots protect and strengthen banks allowing islands to form
How can vegetation effect bank erosion
Roots retain soil
How does salmon change the river bed
By creating reds in the river bed
Why is willow unique in ecosystem engineering
Can sprout from fallen branches and limbs
What makes it easy for willow to become established in the centre of braided rivers
Quick sprouting from limbs
What carrys willows across the braid plane
Large floods
How long does it take three fragments to establish roots
Less than a year
What can be found behind a willow riparian engineer
Fine sediment
Where is coarse sediment found in relation to an pioneer island
On the sides of the island
What happens when a pioneer island becomes venerated
More resistant to erosion
What can addition of a root network lead to
Increase in sediment trapping and thus aggregation
How can willow riparian engineering affect braided rivers
Can decrease brading and channel sinuosity
What did tal and paola find out about Vegetation in channels
Vegetation progressively focused flow into larger more stable channel than smaller ones
What did vegetation of a braided river lead to in in terms of its moving characteristics
Become more meander like in shape
Why do channels widen in meander systems
Rates of bank erosion are high due to shear stress and are often not matched by depositions leading to erosion
What were rivers like 541-485 mya
Highly unstable river systems due to unconsolidated banks of sediment
What does devopment of plants in the paleozoic coincide with
The devopment of sand bed rivers
What can the addition of a large tree trunk do to a river system
Dissipate energy leading to lower shear stress and therefore erosion
How can CWD reduce flood damage
Can dissipate flood waves stopping a single flood impact, spreading it over time
What happens when many logs come together in a river system
Can form a log jam
While logs can reduce erosion in terms of the whole stream what can happen at the small scale
Erosion is high around log jams due to diversion of water energy
What can larger woody debris lead to in channel depth
Creation of pools that form upstream of the channel, 60-90% of pools in forested river caused by wood
Ecologically how can CWD impact habitats
Provide food and habitat for a variety of biota
How can CWD cause channel belt change
Can cause the belt to avulse due to overflowing pools
Why do crayfish move sediment around
As part of their natural foraging behaviour
What can crayfish movement break up
Rock armour layer, this mobilised fine sediment
How can cray fish burrowing affect river banks
Can reduce bank cohesion and increase erosion
What do caddis spin to catch food
Small under water webs
What did caddis webs lead to in terms of entertainment
10% more velocity needed to move sediment, rising to 30% for higher densities
How does the hippo impact the okavango delta
Acts as a catalyst for geomorophalogical change
What do the hippos create between channels
Pathways between water and land
What do the hippos create between channels
Pathways between water and land, connect lagoons which make them more sedimentated, maintain non vegetation channels linking channels and pools
