Marshes and mangroves - lecture 13

Question 1

What are marshes and mangroves?

Answer 1

Both types of tidal wetland
20M ha
Prominent component of coastal landscapes for 4000 years

Question 2

Why haven’t marshes/mangroves drowned with SLR?

Answer 2

because of interactions between plants and soil that allow wetlands to actively engineer their position within the intertidal zone in ways that enhance ecosystem persistence

Question 3

Components of marsh/mangrove feedbacks

Answer 3

Sea level rise rate
Sedimentation rate
Above ground plant growth rate
Below ground plant growth rate 
Location, slope, land cover etc

Question 4

What does the mineral sedimentation above ground feedback component entail?

Answer 4

Settles onto wetland soils during tidal flooding by shoots slowing water velocities (low elevation)

Question 5

What does the below ground growth and decay feedback entail?

Answer 5

Balance of plant root growth and decay directly adds organic matter to soil profile, raising elevation by sub-surface expansion

Question 6

What does the above-ground plant growth feedback component entail?

Answer 6

Promotes greater standing biomass
slows velocities 
reduces wave height
reduces erosion 
mineral sed deposition