ECEC - 3 Flashcards
why was the environment mainly grassland in the devensian period?
the climate couldnt support forests - warming up led to the development of forests
how could we know there was an ‘elm decline’?
pollen in bog showed a distinctive decline in elm pollen - reasons for decline are unclear
what are landnam clearances when did they take place and what was their affect?
temporary forest clearances for crops and grazing- similar time as elm decline (3500 BC) - initial decline in tree pollen and increase in grasses but only temporary
what were clearances like in the bronze age(2100 - 700 BC) ?
landnam clearances continued with increasing intensity - continued deforestation in well populated areas - centre of the microlithic industry
what was deforestation like in the iron age (500 BC)?
climatic deterioration and increased precipitation with increasing deforestation continuing on from the bronze age
what are 4 adaptations of grassland species to help survive grazing?
1) intercalary meristem - growth from mertistem at the base of the leaves so they aren’t destroyed when grazed - graminoid species
2) adpressed growth - leaves close to the ground (negatively phototrophic)
3) low palatability
4) ephemeral life history - grow during times of limited grazing and exploit bare patches of soil
what types of soils do calcifuge and calcicole plants grow in and examples of species?
calcifuge = acidic soils - Nardus stricta
calcicole = calcareous soils - Scabiosa
columbaria
why is PH a major influence on plant distribution?
because it influences the availability of ions
why is species diversity much higher in the south?
because most limestone grasslands are there and this bedrock produces the most species rich grassland
3 features of rendzina soils
1) high PH - low fertility
2) thin soil - shallow A horizon
3) immature soils
describe the soils in the plateau, slope and valley of a limestone top sequence
Plateau = accumulation of acidic soils less affected by bedrock Slope = shallow soils with high levels of erosion valley = influenced by rivers bringing in organic matter increasing depth and nutrients
what does crop litter mean?
the productivity of an area
calcareous grasslands have intermediately low nutrient status but what is there alpha diversity like?
they have very high alpha diversity
are low PH soils species rich or poor?
species poor
what are helophile species and what effect did the development of post glacial forests have on them ?
sun loving - Development of the post-glacial forests
confined heliophiles to naturally open habitats- heliophiles eradicated from large areas of
shaded habitat
when did the elm decline take place and what was happening during this time?
Boundary between the pollen sub-zones VIIa and VIIb ≈ Atlantic / Sub boreal boundary - Establishment of Neolithic farming in parts of Britain
the reasons for the elm decline but what are 3 possible reasons?
- disease
- selective cropping
- trees pollarded to provide leaves for winter
feed for livestock
what are the reasons behind landnam clearances and how long did they occur for?
- For pasture or first cultivated and then grazed
- 50 years
how many landnam clearance phases are there evidence for?
- 5 peaks of Plantago pollen between the Elm Decline and the Iron Age
- suggests 5 clearance phases, progressively larger and longer
describe extensive neolithic clearances
- More extensive and ‘permanent’ deforestation in some parts of Britain
- starting after elm-decline & becoming progressively more important
- Associated with well-populated areas
describe breckland soils?
- light, dry soils: quite easily cleared
- Centre of the microlithic industry
what species grow over a wide range of PHs?
Festuca ovina - sheeps fescue
which ion has low availability at high and low PHs?
phosphorous
why are rendzina soils thin?
due to the purity of the bedrock - pure limestone provides very little insoluble residue on dissolution – little material to contribute to the development of a deep soil profile
describe Grimes hump back curve for species richness and crop mass?
between crop-mass 300 - 900 g m-2 =corridor of high potential species richness however within the corridor of
300 - 900 g m-2 both species-rich and species poor vegetation can occur
what is the reservoir effect?
fewer species are adapted to grow on acidic soils than
calcareous soils
