3.5 Plant Succession

Question 1

Keychain for sandy coastal environments creating psammoseres

Answer 1

• Marram grass establishes good root networks in bare sand which stabilises the fore dune
• Sand blows towards land, trapped around obstacles to form embryo dunes
• Embryo dunes collect more sand and create conditions for pioneer plants (can tolerate low levels of organic matter and high alkaline pH and high wind speeds)
• Vegetation starts to colonise and hold the sand together

Question 2

Keychain of salty marshland environments creating haloseres

Answer 2

• Long blades of cordgrass in salt marsh traps sediment = muddy substrate builds up = stabilises roots of other plant species + further sediment deposition
• Newly established salt marshes act as buffer zone between sea and land to absorb coastal floods + storm impacts
• Halophytic (salt-tolerant) plants stabilise the dunes (green algea and eel grass), can tolerate being submerged for 11/12 hours of tidal cycle

Question 3

Keychain for sand dune plant succession for psammoseres

Answer 3

• Sand particles collect with obstacles to build an embryo sand dune
• Xerophytic plant species (pioneers) e.g. marram grass colonise embryo dune
• Roots of pioneer species stabilise embryo dune, reduce wind speeds + add organic matter (upon decomposition)
• Harsh environment altered so other species can tolerate it, their growth traps more sand = fore dune
• Sand continues to be deposited and change shape and size - yellow dunes the highest
• Further environmental modifications as soil develops, nutrient and water more available = greater range of plants (e.g. heather, sedges) = grey dunes (high humus content)

Question 4

Keychain for sand dune plant succession for haloseres

Answer 4

• Fine clays + silt deposited (flocculation) in extremely low energy environments (e.g. estuaries) to form mudflats
• Halophytic plant species (pioneers) e.g algae colonise area, trap moving sediment
• Roots of pioneer species stabilise mudflats, trap matter and add to organic material (upon decomposition) = salt marsh
• Harsh environment now altered so other species e.g. cordgrass can grow = further sediment trapped + salt marsh built up above high tide so inundation less frequent
• Further environmental modifications as soil develops, nutrients more available = greater range of plants e.g. Salt grass, Marsh grass, Pickleweed = stable and mature salt marsh with carpet of vegetation

Question 5

What disrupts psammoseres?

Answer 5

• Wind erosion can cause dune slacks

Question 6

What disrupts haloseres?

Answer 6

• Creeks/small channels can dissect salt marshes