7 - aeolian, fluvial, biotic processes and landforms

Question 1

what is plant succession

Answer 1

• evolution of plant communities from pioneer species to climax vegetation
• related to change in environment brought about by plants themselves
• change then favours new species

Question 2

what is the order of dune succession

Answer 2

ZONE 1 - embryo and fore dunes, species:
orache, saltwort, sandwort, sea rocket, sand couch, lyme grass, marram (on fore only)

ZONE 2 - yellow dunes , species:
marram grass, dune fescue, sand sedge, sea holly, ragwort, thistles

ZONE 3 - grey (fixed) dunes and dune stacks, species:
marram grass, lichens, mosses, herbs, shrubs

ZONE 4 - dune heath/grassland and woodland, species:
heather, gorse, birch, oak pine etc

Question 3

how are sand dunes formed

Answer 3

dune formation begins in back of foreshore in upper beach

formed from sand deposits that have been blown off the beach. Where sufficient sand is deposited and dries in the intertidal zone (foreshore – the area between the high and low tide marks) it is then transported by saltation by the blowing wind. Sand dunes only form where the rate of beach deposition is greater than erosion (positive sediment budget).

• strong offshore winds
• wide foreshore area exposed at low tide, sand dries out and transported beyond mean high tide by offshore winds
• trap on backshore needed to encourage accumulation

Question 4

what are the main phases of dune succession

Answer 4

1. PIONEER SPECIES/EMBRYO DUNES
2. FORE DUNES
3. YELLOW DUNES/MAIN RIDGE
4. GREY DUNES/FIXED DUNES
5. DUNE SLACK
6. DUNE HEATH
7. CLIMATIC CLIMAX

Question 5

what is an estuary and where does its sediment originate from

Answer 5

estuary = location where rivers extend into coastal zone, mixing salt water and fresh water

sediment from:

1) fluvial/glacial land-based sources
2) estuary margin sources
3) sources outside estuary (LSD, cliff erosion down drift of estuary)

Question 6

what are tidal flats

Answer 6

around edges of estuaries, extensive unvegetated depositional areas are found - tidal mudflats

intertidal areas consisting of sand and mud and at low tide intricate patterns of channels and rills exposed

Question 7

what is the energy input within mudflats

Answer 7

outer (seaward) part of estuary receiving tidal/wave energy
inner (landward) part receiving energy from river currents

finer sediments transported through both zones into less energetic central zone
coarser materials deposited in inner and outer parts of estuary

Question 8

what is bioturbation

Answer 8

tidal mudflats = ideal environments for organisms eg lugworms

these creatures churn up tidal mudflats by burrowing

Question 9

where are salt marshes usually formed

Answer 9

usually formed in protected, sheltered environments eg behind spits and bars as well as along estuaries fringe

extremely complex and fragile so quickly eroded by storms, sea levels and human activity

Question 10

what is involved with salt marsh succession

Answer 10

salt marsh succession = halosere

form in low energy tidal environment where pioneer species trap sediment and build up platforms of sediment accretion

Question 11

what are coral reefs composed of

Answer 11

primarily comprised of small invertebrate marine animals called a polyp

POLYP - cyclindrically shaped with exoskeleton giving it hard body and sac like inner body

Question 12

how does the coral reef build up

Answer 12

corals secrete calcium carbonate from bodies which forms exoskeleton, and remains after death building up reef

corals remain immobile and individual polyps group together to form colonies allowing them to secrete calcium carbonate and form coral reefs

Question 13

what is the relationship between coral reefs and algae

Answer 13

coral reef attracts algae aiding coral to produce food and in return algae receive shelter

symbiotic relationship and reef needs algae to survive

Question 14

what is the function of coral reefs

Answer 14

help prevent sediments from washing up and damaging shoreline acting as physical barrier helping create healthier, protected coastline habitat allowing waves to break offshore

also a carbon sink reducing CO2 in the area

coral also have economic benefits (harvested for use in medicines/jewellery, marine plants harvested for aquariums, jobs created in tourist and conservation)

Question 15

what is coral bleaching and what is it caused by

Answer 15

corals expelling tiny bits of algae which give them colour and nutrition

caused by global warming as higher base temperatures of ocean, main indicator of climate change

not dead, but under more stress

Question 16

where do mangroves occur

Answer 16

they occur worldwide in tropics and subtropics

they cover 50000 sq miles of coastline spanning 118 countries

Question 17

what are mangroves and what are some adaptions

Answer 17

mangrove plants include trees, shrubs, ferns and palms

unusually adapted to anaerobic conditions of salt/fresh water

they produce stilt roots projecting above mud and water in order to absorb oxygen
they are salt tolerant (halophytes) and are adapted to life in harsh conditions by having complex salt filtration system and root system to cope with salt water immersion and wave action and low oxygen waterlogged mud

Question 18

what harsh conditions are mangroves subject to

Answer 18

• submergence
• low nutrient levels, soil perpetually waterlogged and little free oxygen available to aid decomposition of organic matter
• high levels of salinity
• high temps at low tide much lower temps when submerged

Question 19

what is the importance of mangroves

Answer 19

• act as natural/cheap form of coastal defence in region with eustatic sea level rise of 3mm per year
• unique habitat for flora/fauna
• carbon sink for removing CO2 from atmosphere

Question 20

what are threats to mangrove forests?

Answer 20

• clearing
• overharvesting
• river changes
• overfishing
• destruction of coral reefs
• pollution
• climate change