APS 124 Ecosystems L1-5 Flashcards
When was the devensian cold stage?
From 115,000 to 10,000 years before present
Define the terms interstadial and stadial when referring to the devensian cold stage
Interstadial = embedded warmer period Stadial = cold sections
First devensian interstadial:
Give the date
Name
Summer and winter mean temperatures
60,000Before present
Summer mean of 16 (currently 17) winter mean of -10 (currently 4)
Chelford interstadial
Describe the flora present in the chelford interstadial
Birch, pine and spruce
Looked like current Scandinavian forests
Describe the fauna present in the chelford interstadial (1st interstadial)
Bears, spotted hyena, wolly rhino, horse, elk
When was the second devensian interstadial?
What was its name?
Why were there shurbs but no trees?
42,000Bp - 38,000Bp
Upton Warren interstadial
No trees because of very cold winter temperatures and a rise in herbivores
After the first two devensian interstadials there is a stadial. What is its name? Give a breif description
Dimlington stadial
Very long cold period, with maximum ice expansion and polar conditions
What happened to herbivores during the dimlington stadial? Give two theories and a piece of evidence to suggest why only one theory is correct
Herbivores pushed south since northern vegetation wasn’t productive enough
- some suggest the reason was that they were hunted more in the north
- but lemmings were not hunted and during this period they to moved south
What was the interstadial after the dimlington stadial?
What were the july mean temperatures then?
Windermere interstadial
July mean = 17/18
What was the flora like in the windemere interstadial, and what happens to the ice caps?
Park tundra, few trees scattered among shrub land
- more strings of continuous woodland
- ice caps melt
What is the name of the stadial after the windemere interstadial? Describe its duration and summer mean temperatures. What could it have been caused by?
Loch lomond stadial
1000 year cold stage
July mean is 10-12 degrees
Could have been caused by the gulf stream
Describe the effect the loch lomond stadial had on ice
Ice melts slower, potentially starts to grow again
More permafrost and tundra
What happens to temperatures at the end of the Loch Lomond stadial?
Tempertures increase leading to the Flandrian period = post glacial
Who were the botanists that proposed a climactic subdivision of the post glacial period?
Alex blytt and sernander
What evidence did Blytt and sernander use to subdivide the post glacial period
Stratigraphy of peatlands mapped onto pollen zonation data using goodwin zones
The first three post glacial zones map onto stadials and interstadials of the devensian show this mapping
Zone 1 = pre windemere
Zone 2 = windemere
Zone 3 = loch lomond stadial
Describe zone 4(IV) of the post glacial period
Post glacial birch zone
9,500 bc
Subarctic climate
Dominat flora is birch but willows juniper and pine are also present
Describe zone 5 of the post glacial period
Hazel - pine - birch period
Hazel expands in north
Birch decreases in number but still dominant in north
Pine now dominates in south
Thermophillus tree evidence e.g. Elm and oak
Describe zone VI of the post glacial period
Pine abundant everywhere
More thermophillus trees e.g. Elm hazel oak, later lime and alder
What name is given to zone VII of the post glacial period? Describe the flora
Forest maximum/ Atlantic period 5500-3000bc Rapid alder increae Peak lime Elm decreases halfway through due to drying out
Describe the spatial distribution of flaura in the Atlantic period
Birch restricted to the north of Scotland Pine in a band below this Oak dominates centrally Thermophilous plants dominate south Hazel dominates ireland
Describe the climate in the atlantic period
Warm and wet,
Climate optimum
2.5 degrees warmer than current
Describe the final zone in the post glacial period
Cooler and warmer
Lime declines
Beach and hornbeam appear
Brings us to 500 bc from here humans become a large cause of change
Describe a normal british woodland
Broadleaf deciduous and temperate
Define the terms native, ancient, recent woodland
Native= consists of native trees grown since the last ice age e.g. Birch and elm (40% of UK woodland)
Ancient = continually wooded since 1600AD
Recent = planted or established woodlands since 1600 AD
The terms primary and secondary woodland arent used much any more, what do they mean and why arent they used?
Primary = survived since before last ice age
Secondary = after the last ice age
Very little woodland has survived since before the ice age (2%) therefore doesnt really narrow it down much
Describe competitive exclusion in terms of plant
One plant out shading another plant
Give the two varieties of coexistence within plants in woodland
Coexistence through tolerance = two in the same niche competing
Coexistence through complementary resources use
Give the two ways community structure can be split up
Vertical - stratification
Horizontal - birds eye view
Describe the four levels of vertical structure in a woodland
1) tree layer - 5 meters
2) shrub layer - 1.5 meters, saplings and small trees 1.5 meters
3) field layer - tall herbs and under shrubs
4) ground layer - mosses and small herbs
Give the three varieties of horizontal structure
Over dispersed regular, looks like covering the whole area
Random - single plants dotted around
Clumped - under dispersed, spotted around
Give four factors that effect the horizontal pattern of a woodland
Morphology and growth characteristics
Seed dispersal mechanisms
Environmental heterogeneity- variation in the floor environment
Species interactions e.g. Overshading
How many types of woodland are their under the national vegetation classification
As well as the number of sub communities
18 main woodland
73 sub communities, each sub community has a different species abundance
What is the DAFOR scale used for?
An abundance estimate
Dominat, abundnat fequent occasional rare
give methods of abundance estimations
DAFOR
density - number of plants per unit area
Frequency chance of finding a particular species in a sample of vegetation
% cover
Describe methods plants use to be shade tolerant
Change leaf morphology - large thin leaves with a single palisade layer, gives a large surface area to weight ratio. This can be plastic the plant changes in response to the light
Being evergreen, lower energy requirements since no new leaves. E.g. Wavy hair grass and yew trees, but leaves must respire through winter, lower respiration rate so grow slowly
What is the light compensation point
The amount of light where photosynthesis overtakes respiration
Shade tolerant plants will have a lower light compensation point, advantage at low light but is a disadvantage at higher light
Define phenology
Study of life cycle events and how they are affected by seasons
Define the following types of plants
Vernal
Aestival
Hiemal species
Vernal - spring
Aestival - summer
Hiemal - grow in winter
Describe the forest of Coed Cymerau in north wales
Upland oak woodland
Sessile oak on acidic soils
Very little regeneration
Describe the effect squirrels are having on the coed cymerau
Squirrels are eating the acorns however there should still be enough acorns
Not the main reason for lack of regeneration
What is the main reason behind the lack of regenration seen in the coed cymerau forest?
Ground layer dominated by wavy grass - deschampsia flexuosa
- these are a poor trap of oak litter
- oak leaves blow away
- removes protection and reduces soil quality preventing rapid growth of oak trees
Describe vera cycles, and give the stages
A natural process by which woodlands form and reform in four stages
1) open grassland for 125 years - unpalatable thorny bushes colonise
2) scrub vegetation for 75 years - provide protection for tree saplings and reduce the amount of herbivores
3) woodland for 250 years - trees grow and hence thorny plants are shaded out herbivores return
4) break up of woodland 75 years - older trees die, herbivores prevent new trees
Give a breif history for UK grasslands
100,000 years ago out of the last glacial period some parts of the southern UK are not frozen
Till 11,650 years ago very wide spread grassland in non frozen areas
Post glacial forests confine helophiles to naturally open habitats
What event caused a large increase in grasslands in the last 11650 years?
Agriculture - forests felled for farmland
During the atlantic period which type of tree had a huge decline?
Elm
What relationship is there between pollen from grasslands and pollen from elm?
Grassland species pollen dominate when elm declines and vice versa suggesting waves of elm and grassland dominance
What were some causes of the great elm decline?
Diseases Climate change Pollarded trees Diseased trees easier to clear Landnam clearances
Define landnam clearances
Humans deforest land
Grow crops
Soil quality diminished
Farmers move on
When elm declined one specific species of grassland herb flourished, what was it?
Plantago Lancelota
How many Plantago pollen peaks have there been inbetween the great elm decline and the iron age?
5
Between 5000 and 4100 years ago more permanent areas of deforestation appeared, where, and why these areas?
East anglia
Wiltshire
Dartmoor
Sw cumbria
Because the light dry soils easy to farm
Flint mines present which were centres of neolithic activity
Describe events in the iron age (2700-1900 years ago) that caused the formation of grasslands
Climactic deterioration- more rain
Celts arrive = better farming
Larger settlements
Permanent grassland farmed
What four types of species live in grassland?
Brushes
Sedges
Grasses
Some herbs
Name and describe five methods used by graminoids to be adapted to partial defoliation
Intercalary meristem - meristem present at base allows regrowth, regrow from basal meristem e.g. Horsetails
Rhizomes
Rootstalks provide new nodes for growth
Grazed plants an spread without flowers
Adpressed growth
- negativity phototropism in rosettes
- presses leaves tightly to the ground
Low palitabilty
- spines, woody tissues, distatesfullness and toxicity
Ephermeral
- exploit bare rock patches of soil
- during limited periods of grazing
Give a name of a plant that can grow in a large range of soils
Festuca ovina
Define and give an example of calcifuge plant
A plant that grows in acidic soils e.g. Nardus sticta
Define and give an example of a calcicole plant
Grows in calcareous soils (alkaline) e.g. Scabisoa columbaria (only on limestone)
Describe the layers of a standard soil structure
Organic Surface Subsoil Substrate Bedrock
Describe the standard layers of a rendzina soil structure
Organic Surface Substrate Bedrock (Different to standard by not having a subsoil layer)
Why does rendzina soil give a low fertility?
No subsoil layer Therefore very shallow Allows limestone from bedrock to seep into the substrate High pH above 7 Low fertility
Why does limestone lack in a subsoil layer?
Pure limestone leaves very little insoluble residue on dissolution hence there is very little material to contribute to a subsoil nor deep soil level.
What little ks produced is very suceptible to weathering
Name the three parts of a limestone toposequence
Plateau
Slope
Valley bottom
In a limestone valley where are grasslands found?
On the slopes
Describe the soil on a plateau of a limestone valley
Exposed and soil accumulates
Deep soil
Gets slightly acidic pH<5 podzol soils
Very low fertility
Describe the soils on the slope of a limestone valley
Low fertility (higher than plateau) Rendzina soil
Describe the soil in the valley bottoms of a limestone valley
River brings material
Very high soil quality
Low diversity
Valley bottoms have the highest soil quality in a limestone valley, why then do they have lower biodiversity than on the slopes?
Humpback curve
Where soil quality is high there is very high productivity so one species will dominate
In very low quality the productivity is to low for anything
In relatively low quality productivty is still low enough to provide stress but not high enough to allow dominace hence most species are present on the slopes
Which type of soil has the highest alpha diversity?
Calcareous
Why despite being common in the UK do heaths and moors have such high conservation status?
Very rare globally
Describe heath land
Dominated by ericoid plants
- most dominat = calluna vulgaris
Then bell heather = erica cinerea
And cross leaved heather = erica tetralix
What are the latin names for bell heather and cross leaved heather
Bell heather = erica cinerea
Cross leaved = erica telralix
Why do heathlands have low floristic diversity?
Low nutrient status
Acidic soil
When is a heathland a moor? How much of this in the UK and what percentage of the goobal amount is this?
Upland heathland, above 300-400 meters above sea level
2-3 mil hectares = 75% of global moorland
How much lowland heathland is there in the Uk and what proportion of the worlds lowland heath is this?
58,000 ha
20% of worlds total
What type of soils are present on moors and heathlands?
Podzol soils
- no mixing of nutrients or organic matter - very little nutrient cycling
- rainfall removes nutrients
Soil becomes acidic
Why don’t the layers of podzol soils mix?
Because they dont have any inverts
What factor increase how water logged the soil is ?
Iron ore layer - impermable layer
Give facts about peatlands as carbon stores
3 billion tonnes of C stored
Largest carbon reserve in the UK
How do we know that podzol soils are not natural?
At the bottom of ancient graces we find brown forest soil, suggesting everywhere used to have brown foresr soil
- podzol occured after deforestation
- tree roots ordinarily mix soil and introduce inverts (no podzol near trees)
When does heather become the dominat species and hence allow heath formation?
Farming usually prevents heather growth, at 400AD some land is no longer used for grazing hence heather dominates
What is the economic benefit to the Uk per year from red grouse shooting?
100 million pounds
Grouse only eat the young shoots of heather, so moorland needs to be managed how is this done and what are the effects?
Burn the top layer allow shoots to grow through
Makes a mozaic landscape and prevents organic materials from returning to the soil - keeps it podzol
Describe prescribed burning
Only the top layer
Done in winter
Controlled areas
Avoid burning the peat underneath
What are the advantages of burning moorland?
Manages it
Returns nutrients
Increase in insect in long term and plant diversity in short term
What are the disadvantages of burning moorland?
Careful burning can still lose peat
Increase in soil temperatures for 7 years
Reduces insect populations initially
Reduces the water table
Nitrogen is lost in large quanitites due to moorland burning, what is a method to stop this?
Retaining ash
Efforts are being made to re-establish deciduous woodlands on moorland as a method to conserve peat. This has been done in broxa and tulchan, describe both and explain why only one succeded
Broxa - introduced birch - but unsuccessful no increase in biodiversity
Tulchan - birch planting successful
- more earthworms
Podzol soil - brown forest soil
pH increases more Ca and P
Didnt work in broxa since there was lower pH low calcium and acid rain
What are the two main types of wetland?
Aquatic - shallower water ecosystems
Telematic- less standing water and terrestrial
Wetlands can be permanent or seasonal, what are the three types of permanent wetland?
Bog - acidic and fed by rainfall
Swamp - flooded
Fens - alkaline fed by groundwater
Why do swamps, fens and marshes have peat?
Waterlogged environment have fewer inverts and microorganisms hence the ground cant decompose as quickly
Marshes are _______ wetlands
Seasonal
Define allogenic succsession
Driven by environmental change
Define autogenic change
Where succession occurs because vegetation has induced environmental change
What is terrestrialisation?
The in filling of lakes and ponds with mud and peat
What are the three types of terrestrialistion ?
Rooting
Rafting
Paludification
Describe the process of rooting (terrestrialisation)
Water becomes shallower due to mud and peat and allows progressive colonisation - sphagnum often first colonises
- muds are then formed in situ - autochthonous or are washed in - allochthonous
- can form a raised bog 5 meters high which can support trees and shrubs
Describe the process of rafting
Open water becomes overgrown by a matt of peat, a raft of vegetation sits on top - occurs faster than rooting
- found in sheltered basins and can form quaking bogs
Describe the process of paludification
Dry land becomes wetter
Occurs with a blanket bog and no aquatic phase
High humidity
Often found with neolithic artefscts so could be to do with deforestation
Oxygen diffusion is ______ times slower in water than in air and ________ reactions occur dofferently enabling more ___________ to enter the plant
20,000
Redox
Heavy metals
What are the three main adaptations of plants to the lack of oxygen?
1) anaerobic respiration in roots. Accumulates malic acid which is less toxic than alochol
2) high root porosity (more pores) 60% opposed to 5 ish in normal plants. Achieved by aerenchyma - cavities and channels
3) release of oxygen into the rhizosphere can occur by diffusion or enzymatic oxidation in the root surface
