rates of coastal recession and stability (2.B3)

Question 1

stabilising coastlines through sand dunes

Answer 1

sand dune ecosystem= Psammosere
PLANT SUCCESSION: vegetation can be used to help stabilise dunes
- bare grounds is gradually colonised by plants, the first colonising plants= the PIONEER species.
- these species begin the process of succession where other species invade and take over until a balance is reached.
- these plants stablise the dunes: pioneer species bind sand together with their roots and add nutrients when they die/ decay, creeping plants allow the dunes to retain moisture allowing other species to colonise and therefore improve the soil.

over time…. will become stable and the final community will be adjusted to the conditions of the area (climatic climax community)

Question 2

sand dunes (the process)

Answer 2

• (1)embryo dune (first to develop)
• develop into (2)foredunes which are initially (3)yellow but darken to (4)grey as decaying plants add humus
• depressions between dunes can develop into (5)dune slacks: damper areas where the water table is closer to, or at, the surface.
• eventually dune reaches (6)mature dune where humus content is over 40% and stable vegetation and woodland has developed

Question 3

stabilising coastlines through salt marshes

Answer 3

salt marsh ecosystem= halosere

• found in mouth of estuary where energy is low: area of flat silty sediment.
• they develop: in sheltered areas where depostion occurs (spits can help form marshes), where salt and freshwater meet and where there are no strong tides or currents to prevent sediment deposition and accumulation.

how they’re stabilised: algae= pioneer species followed by halophyte grass such as glasswort. the grasses slow down water further. mud accumulates and environment changes from a bog into a drier area as soil is formed