APS124 Pheonix Flashcards
What is the period between 115,000 and 10,000 BP known as?
“The Devensian cold stage”
The Devensian cold stage comprised…
- interstadials - embedded periods of temporarily ‘warm’ condutions
- stadials - embedded periods of ‘cold’ conditions
generally ‘cold’ but considerable temperature fluctuation
What are the cold, arctic tundra-like conditions south of glaciers called?
Periglacial conditions
After the first period of cold in the Devensian cold stage, where there is likely to have been permafrost soils, what is the first interstadial period known as?
Chelford interstadial (~60,000 BP)
- birch, pine and spruce
- rich vertebrate fauna, inc. temperate and boreal species
- February mean of -10C
- July mean of 16C (now 17C)
What was the warm period before the Devensian cold stage called?
Ipswichian interglacial
What is the second interstadial period in the devensian cold stage?
Upton Warren Interstadial complex (42,000-38,000 BP)
- July mean of 16C
- Possible cold winters (-15C Jan?)
- Species-rich flora - thermophilous species
- dward willows and birch but no trees - possibly due to cold winter temps or herbivores (pressure from them)
- rich vertebrate fauna
The Upton Warren interstadial complex was followed by…
the Dimlington stadial - long period of cold
- maximum expansion of Devensian ice (~21,000 BP)
- periglacial fringe south of extensive ice sheets
- large herbivores probably forced south (lemming evidence too)
The Dimlington stadial was followed by…
the Windermere interstadial
- rapid climatic warming after ~13,000 BP
- July mean temps 17-18C
- Park-tundra vegetation
- more continuous woodland
- Pine woods in the south and east
- strong reduction of the ice caps
The Windermere interstadial was followed by…
the Loch Lomond stadial
- return to cold conditions for about 1000 years
- july mean temps 10-12C
- caused by disruption of the gulf stream?
- ended with very rapid temperature rise, leading to the post-glacial (Flandrian period)
So what is the order of everything then?
Ipswichian interglacial –> loooong cold period –> Chelford interstadial –> cold period –> Upton Warren interstadial complex –> Dimlington stadial –> Windermere interstadial –> Loch Lomond stadial –> Flandrian (~10,000 BP)
From 10,000 BP, there is large expansion of…
forests
What is the forest maximum?
The period where the most of the UK is covered by forest
Godwin zonation looks at…
pollen taken from peatland in Hockham Mere (in East Anglia) - deeper peat core = further back in time, so can see dominance of different species
Zones I-III equate to…
I. pre-windermere
II. Windermere interstadial
III. Loch Lomond stadial
Zone IV equates to…
the post-glacial birch zone
- 9500 BC
- sub-arctic climate
- Birch dominant
- willows, juniper
- some pine (probably restricted to south)
Zone V equates to…
the hazel-pine-birch period
- 7600-5500 BC
- Hazel expansion (esp. north and west)
- Birch still dominant despite warming
- In south, pine begins to dominate
- start to see pollen evidence for warm-loving (thermophilous) trees
Zone VI equates to…
Hazel-pine period
- Pine abundant more or less everywhere
- hazel still important
- Appearances of thermophilous trees in some quantity
- expansion of elm and hazel, then oak, then lime and alder
Zone VII equates to…
the forest maximum (alder/mixed oak)
- 5,500 - 3,000 BC
- rapid increase in alder (at expense of pine and birch)
- oak still relatively abundant
- lime reaches peak
- elm declines half way through
What was the climate like during the forest maximum?
- warm and wet (climatic optimum)
- implies high temperatures and pronounced oceanicity
- biological evidence supports that temperatures were up to 2.5C higher than today - trees reached highest altitudes and latitudes
Zone VIII equates to…
alder-birch-oak-beech period
- cooler and wetter
- lime declines
- appearance of beech and hornbeam
- brings us to about 500BC
We can describe species distributions on…
local, national and global scales
Daisies are found everywhere in the uk, so is known as…
cosmopolitan. - well-adapted to the UK
Sea sandwort has a distribution determined by…
maritime conditions
- “salt-loving” halophyte
- grows well in sands and shingle
Often species which favour differing climatic conditions have … distributions
complementary
- e.g. crowberry (northwest) and dogwood (southeast)
Plant distributions can be explained in terms of three groups of factors:
- climatic factors
- physiographic factors
- edaphic factors
Climatic factors include… and are responsible for main global and regional patterns of plant distribution.
temperature, rainfall, light, wind, humidity
In the uk it is warmer in the … and wetter in the …, and windspeeds are higher at higher …
south, west, altitudes
Physiographic factors are determined by… and include…
the landforms (physiography) of the landscape,
- altitude: lapse rate ~-6.5C for each 1000m increase in altitude
- aspect (= direction of slope) influences irradiance received - south-facing slopes tend to be warmer
Edaphic factors are associated with..
the soil
for plants, the main functional features of the soils are that they provide a…
- rooting medium (anchorage)
- source of water
- source of nutrients
The soil (and other parts of the environment) tehrefore provides both conditions and resources
Resources are…
- commodities which are ‘consumed’ by plants
- essential for growth (e.g. CO2, O2, H2O, nutrients)
- Different species have different capacities to use a particularly level of resource supply
- insufficient resources give poor growth (sub-optimal)
- excess resources do not necessarily result in an increase in growth, and are sometimes detrimental (supra-optimal)
Conditions are..
- environmental variables to which plants respond
- not consumed
- some may help to regulate the availability of resources, e.g. pH
Light can be both a…
condition and a resource
Look at interactions pic on phone
go on do it
Competition occurs when…
the growth or development of an individual is adversely affected by the presence of another individual
- may be direct or indirect
Indirect competition is when individuals…
attempt to obtain the same, shared resource (e.g. light, water, nutrients or growing space)
- requires some resource to be of limited availability
- is dependent on the density of individuals
competition increases with higher…
densities
allocation of resources to … is often the first to decline
reproduction
Direct competition is…
a form of antagonism between different plant species - less common than indirect competition between plants
e.g. strangulation (e.g. strangler fig), allelopathy (chemical warfare), parasitism (e.g. mistletoe)
There are over … species of parasitic plants in 17 families. 80% are …, meaning…. 20% are holoparasitic, meaning…
3000,
hemiparasitic - have chlorophyll but obtain some carbon, nutrients and water from their host
holoparasitic - no chlorophyll, obtain all their carbon from their host (e.g. Cuscuta/Dodder)
Facilitation occurs when..
a plant benefits from having a neighbour (opposite of competition)
- especially important in extreme environments (e.g. arctic, alpine, desert ecosystems) - relative neighbour effect more often positive at high elevations
What is dry nitrogen deposition? Wet?
in gas or aerosols
in rain
Oxidised forms of N (NOx) include…
wet: NO3- (nitrate)
dry: NO2 (nitrous oxide)
Reduced forms of N (NHy) include…
wet: NH4+ (ammonium)
dry: NH3 (ammonia)
What is the main source of NOx?
fossil fuel combustion (e.g. power stations, cars)
What is the main source of NHy?
Agriculture (especially ammonia, NH3, from livestock manure)
How much nitrogen does the UK emit every year? How much falls back down?
around 720 kilotonnes
around 400 kilotonnes
Nitrogen deposition velocities are faster to … …
rougher surfaces
Some upland areas have high rates of N deposition due to…
rain and seeder-feeder effect