Ecosystems Flashcards
Describe characteristics of desert plants.
- Short lived with a fast lifecycle or long lived with dormant seeds.
- Waxy leaves with few stomata
- Large underground or above ground water storage bodies
- Slow growing to tolerate stress and not to overuse resources
How do desert plants reduce competition for water?
They partition root space so that adjacent plants alternate between wide reaching shallow roots and deep reaching straight roots so that adjacent plants are not competing as much for the available water.
Give one adaptation for each a camel, kangaroo, budgerigar and gemsbok have to be adapted to the desert environment.
- Camel has a hump fat for storage.
- Kangaroo concerts the hydrogen by-product of fermentation into acetate (not methane) which is used to provide further energy
- Gemsbok can withstand high body temperatures
- Budgerigars are nomadic- stay for the good times and leave for the bad
What behavioural adaptations do desert organisms have to survive in their conditions?
- Gular fluttering- flapping wings near gulag (throat) to avoid overheating
- Increasing surface area to radiate as much heat as possible (e.g. large ears to dissipate heat)
- Some birds can carry water in breast feathers after long distance flights to water
- White to reflect the sun which would increase the temperature
- Loosely packed feathers to prevent insulation and air moving between feathers
Describe the trends of grasslands and compare it to savannahs
- 4 seasons
- Monthly average temps go up and down over the course of a year as not inside tropical zone
- Temperate grasslands receive rain every month unlike savannahs which experience annual drought.
- Rainy when its hot and less rainy when its cool
What are granivores and give an example.
Animals that eat seeds and grain. Eg Quelea quelea
Compare the trends for tropical savannah and tropical rainforest.
- Savannah does not receive monthly rain like rain forests
- Seasons are marked by rainy and dry in savannahs
- Savannahs are tropical and subtropical grasslands with scattered trees and shrubs
A typical tree in the savannah is an acacia tree. Describe how it is adapted to the savannah conditions.
- Some have deep tap roots
- Thorns to minimise herbivory
- Leaf form is pre adapted to heat and water stress
What are:
- Obligate grazers
- Bulk grazers
- Selective grazers
Selective grazers – eat fewer species, typically more nutritious species
Obligate grazers- confined by certain parameters
Bulk grazers- eat anything, usually all species of grasses. Zebra are examples of this.
Describe two ecosystem engineers in savannahs.
Elephants- keep the savannah open by moving logs and trees
Termites- main grazer in african savannah. They eat lignin and plant material which does a lot of damage.
How does solar energy drive surface air patterns?
IT heats the air and causes local convection currents
How do elevation and attitude determine distribution of major vegetation zones?
The adiabatic lapse rate determines that every 100m gained in altitude decreases the temperature by 0.6˚C which therefore causes the organisms present to change
Describe how the vegetation changes from the equator to the Arctic.
Arctic circle
Polar ice Tundra Boreal forest Temperate forest Tropical rain forest
Equator
Describe the dominant plants in
- tropical evergreen forest
- tropical deciduous forests
- temperate deciduous forest
- boreal and temperate evergreen forest
-tropical evergreen forest
> trees and vines
-tropical deciduous forests
>deciduous trees
-temperate deciduous forest
> trees and shrubs
-boreal and temperate evergreen forest
>trees, shrubs and perennial herbs
Describe the features of a tropical evergreen forest.
- Major producer of oxygen
- Greatest source of biodiversity (both plants and animals)
- Lots of rainfall each year
- 2˚C temperature range
Describe the features of a tropical deciduous rainforest.
- Rainfall is an important abiotic factor
- Deciduous trees in the dry season
- Little temperature range- 5˚C
- Hot dry winters and hot wet summers.
Describe the features of a temperate deciduous forest.
- Cold snowy winter and warm moist summer
- 31˚C temperature range
- Rich in animas, rich biota
Describe the features of boreal and temperate evergreen forest.
- Tall trees
- 41˚C temp range
- Low species richness but trees preserve biodiversity but low diversity as few trees are able to survive at these temperatures
- Migrant birds move away when cold
- Tree lines common separating forest and tundra
- Most species conical and evergreen so snow falls off
- Leaves are waxy needles
- Mycorrhizae allow trees to obtain limited soil phosphorous
Describe the features of tundra.
-Range of 28˚C
-Short growing season due to low temperatures meaning plants can only grow a few months a year
-Permafrost (permanently frozen ground)
-Perrenial herbs and small shrubs
-
How does topography help plants survive in the tundra?
The cushioned topography of plants allows them to shelter from the wins and allows a microclimate to be created which is more favourable for the plant to survive
why does tundra have a low net primary productivity?
Because if the low nutrients, low temperatures and short growing seasons
Why is the low soil nutrients in tundra?
Low inputs from slowly decomposing plant litter
Why is soil thin in tundra?
Only a thin layer of permafrost melts each year, making soils thin and poorly drained. Also due to slowly decomposing plant litter so not much time for accumulation.
Why are bryophytes abundant in tundra?
They are non vascular plants so survive well due to the permafrost restricting the abundance of tracheophytes.
Why do plants in tundra tend to reproduce by budding an division rather than sexually by flowering
Because its energetically more expensive to produce flowers and pollination is hard due to large distances between plant groups and lack of pollinators.
How are arctic and alpine tundra differentiated?
Alpine tundra has better drained soil as little permafrost so soils are drier
How do cushion plants harbour their own compost heap?
They group together to insulate heat and so no mineral nutrients gets blown away from the cushion’s personal “compost pile”
Describe 3 important properties of water.
- High freezing and boiling point- allowing water to retain heat well and H bonds being in closest association at 4˚C
- Is a universal solvent, important inorganic materials available
- Transport and reaction system, fundamental to cellular life
Describe the turnover rates in fresh and salt water. What is a turnover rate. Why is there a difference between salt and fresh water.
The process of turnover occurs in autumn when the thermally stratified layers of the lake, the epilimnion cools and becomes more dense and sinks, causing “turnover” of the water in the lake.
Fresh water high turnover and salt water has a low turnover.
The difference is due to fresh water mainly occurring in lakes which can become thermally stratified in summer, allowing turnover as water cools in the autumn whereas salt water is usually in the oceans which flows and therefore does not undergo stratification so there is little turnover.
Describe the salt accumulation patterns in salt (ocean) and fresh waters.
Ocean has a concentration of salt due to evaporation. Fresh water has little salt accumulation due to liquid outflow.
Why is there lower biodiversity in fresh water?
In oceans there is less disruption so species can differentiate more easily- longer timescale for species differentiation
In fresh waters there is more (seasonal) disruption (due to turnover) which causes discontinuity and no escape, especially in lakes .
How does the depth of a lake influence habitat stability?
Shallow waters:
-Shallow water dries out so therefore is better suited to generalists to cope with the changing conditions and range of food
Deep waters:
-Never dry out so therefore fish are more specialist and resources are finely partitioned as small niches can be maintained
How did glacial periods affect dispersal and colonisation?
Glaciers caused changes in geomorphology that were important in shaping temperate freshwater communities (shaping their distribution )
Eg after the last glaciation, eastern rivers of England were connected to continental Europe
Describe the diversity in the UK due to the glacial period.
Eastern England most diverse and Ireland least diverse because it separated first (separated from glacier)?
What is a hydrosere?
A plant succession starting from a lake: In time, an area of open freshwater will naturally dry out, ultimately becoming woodland. During this change, a range of different landtypes such as swamp and marsh will succeed each other.
What changes the composition of fresh water
- Water picks up particles
- CO2 from atmosphere dissolves in water and makes it more acidic
- SO2 dissolved strongly reduces pH
Describe the buffering capacities of waters of differing salinities.
Marine and brackish (half way between fresh and marine water) has high buffering capacities and fresh water is influenced by soil and underlying geology
Describe how the rock weathering of igneous and sedentary rocks change the buffering capacity of fresh water.
Igneous rocks= low buffering because it has
- dilute ionic composition
- tight intimate mixtures of mineral crystals which means few soluble ions are released
Sedimentary rocks = high buffering capacity due to
- Abundance of calcium carbonate
- jumbled particles
- often porous
- cement binding is often soluble so soluble ions are often released
- neutralisation of rainwater
Why is calcium a ket inorganic material in fresh water?
-influences the distribution and abundance of organisms, especially molluscs and crustaceans (as they have calciferous shells)
How are Ca, Mg, Na, K, P, N and S mostly incorporated into the freshwater composition?
Ca, Mg, Na, K, P- mainly from weathering
N from fixation
S from rain and snow and dry deposition
In fresh water, which nutrients tend to be the most limiting?
P limiting for plant growth and N limiting.
N abundance depends on cycling, fixation and anthropogenic inputs
How is the abundance of algal crop controlled in freshwater?
P sets a limit for the amount of algal crops and washout/grazers may remove crop as fast as it is produced.
What are the terms to describe lakes of low, intermediate, high and very high nutrients and primary productivity?
Low- oligotrophic
Medium- mesotrophic
High- eutrophic
Extremely high- hypertrophic
Where do oligotrophic and eutrophic lakes occur? Which geographical areas, what are the rock types present and in which part of the stream do they occur?
Oligotrophic
- Upland
- Igneous rock
- Upper part of catchment
Eutrophic
- Lowland
- Sedimentary rock, deeper soil
- Increases downstream
How do settlement and industry change fresh water composition?
Settlement-
Human sewage allows bacteria to grow which increase biological oxygen demand, causing severe deoxygenation. Detergents cause big increases in phosphate levels
Industry-
Lots of different chemicals (although now more controlled) and traces of organic pollutants such as hormones and hormone analogues, causing ‘intersex fish’
How does oxygen availability change and how do fish account for this?
Solubility is inversely related to temperature which causes problems for large tropical aquatic animals
Therefore some fish swim near the surface for more O2 and some are facultative air breathers
Why are lotic and lentic systems not absolute?
Lakes have moderate currents and wind flow and rivers have low velocity in backwaters
Describe the current, size, circulation, suspended material and sources of organic matter differ in lotic and lentic systems.
Lotic-
- unidirectional current
- variable size
- Well mixed and isothermal circulation
- High suspended material due to erosion
- Allochthonous sources of organic matter
Lentic-
- Variable but slow current
- Deep and wide size
- thermal stratification in summer causes water to become stagnant as no mixing occurs
- Low suspended material but higher if shallow and exposed
- Autochthonous sources of organic matter
What do allochthonous and autochthonous mean?
Auto-Originating or formed in the place where found
Allo-Originating or formed in the place where found
Organic material produced outside vs inside the system.
What does autochthonous littoral mean?
Material originating in the place where found which is created by aquatic macrophytes an all algal communities other than plankton.
What is a macrophyte
A plant that grows in or near water
Give examples of how lakes can be formed.
Glaciers retreating forming basins
- Cut off of meanders
- Landslides
- Craters of extinct volcanoes
- Shifts in earth’s crust causing valley to sink
Describe what happens in winter in a lake fi there is ice compared to if there is no ice.
Surface water cools.
Ice:
- Water immediately below ice is warmed and increases intensity, causing it to drop to the bottom so causing a high temperature at the bottom: inverse stratification
No ice:
-High mixing due to wind so no stratification occurs
What occurs in spring in a lake?
The ice melts and surface water drops, causing mixing of water. If the surface water is above 4˚C, summer stratification occurs
Give factors that increase the input and output of oxygen in a lake.
In:
- Atmosphere
- Mixing
- Photosynthesis
Out:
- Increased temperature
- Increased respiration
- Aerobic decomposition
In which type of lake would there be little demand for oxygen in the hypolimnion, little O2 depletion and O2 lasting all summer and why?
Oligotrophic lakes because there is little nutrients so few organisms can survive and therefore there is a low biological oxygen demand.
In what instance could there be lots of oxygen in deep waters?
If the light penetrates below the thermocline (metalimnion) therefore photosynthesis can occur and oxygen is produced in deep waters
What are the zones of a lake?
Littoral- in contact wit the bed
Pelagic- not near the shore nor near the bottom
Profundal- zone below euphotic
Benthic- bottom, all depths
What do these phrases mean:
-High pelagic-littoral ratio
-Low pelagic-littoral ratio
In both of these instances, which organisms dominate?
- High pelagic-littoral ratio = deep open lake (dominated by pelagic phytoplankton)
- Low pelagic-littoral ratio = shallow lakes and extensive bays/wetlands (dominated by macrophytes)
Describe the season phytoplankton fluctuations.
Spring- seeing bloom due to mixing which increases access to nutrients
Summer- drop in populations as stratification depletes nutrients
Autumn- may get smaller peak due to mixing
Compare littoral benthos and profundal benthos habitats.
Littoral benthos
- Heterogenous
- warm
- plentiful o2
- intrinsic food
- many microhabitats
- high complexity and spices richness: primary consumers (e.g. insect larvae and molluscs) and carnivores
Profundal benthos:
- Homogenous
- cold and little o2
- no intrinsic food
- few microhabitats
- low species richness
- low complexity of community
What are catchments?
Catchments are dendritic structures, with the smallest, lowest-order channels draining more elevated land and joining to form high-order channels
What factors dictate the velocity of flow of a river/ catchment?
Size of channel Shape of channel Gradient of channel Roughness of bottom Depth Precipitation
Describe how the velocity of flow changes the sediment content of the water.
High- moves bottom stones and scours steam bed, removes all but boulders
Low- water does not carry as much sediment, silt will be deposited
what are the features of upper, middle and lower catchment?
Upper- small erosive streams which if steep have bedrock and boulders and if less steep babe shallow riffles with deeper pools, sand and gravel
Middle- intermediate gradient with riffles with smaller particles
Lower- slower current where nearly all particulates are deposited, high flow= resuspension
Describe how fish donation occurs in rivers with gradient and river width.
Narrow and steep= trout
Narrow and less steep= minnow
Wide and steep= salmonids
Wide and less steep= mixed
Low gradient= chub
Very low gradient= bream
What is the river continuum concept?
A model for classifying and describing flowing water, in addition to the classification of individual sections of waters after the occurrence of indicator organisms.[1] The theory is based on the concept of dynamic equilibrium in which streamforms balance between physical parameters, such as width, depth, velocity, and sediment load, also taking into account biological factors:
The proportions of shredders, collectors, grazers, and predators change from upstream to downstream
Describe the 3 axis of river connectivity.
Longitudinal- has primary importance
Vertical- spring water and rain water
Lateral- inundation of flood plains. Important in lowland rivers for nutrients increasing production
What is an estuary?
A semi enclosed coastal body of water which has a free connection wth the open sea, within which sea water is diluted with fresh water deprived from land drainage.
Describe how the salinity varies in salt wedge and vertically mixed estuaries.
- Gentle slope and high river flow= salt wedge forms as salt water is more dense than fresh water so a saltier wedge tongue extends up estuary and to the river channel
- Steep slope and high tidal flow= very mixed, turbulent environment which does not allow the formation of a salt wedge therefore salt water becomes progressively less saline as you get closer to the fresh water
Describe some of the seasonal influences on estuaries.
- Lots of evapotranspiration when hot = water becomes more saline
- Rainy season= very dilute
- Storm surges = large amounts of sea at the start of the estuary causing a mini enclosure which blocks fresh water from the estuary
What is an intermittent estuary?
Intermittent estuaries connect with the sea only during periods of high river flow
Which ions are more abundant in sea water versus river water?
Sea water higher in:
-Na+, Cl-, SO4-
- River water higher in:
- Ca2+, HCO3-, H4SiO4
How do estuarine sediments arise?
Deposition of materials brought down by river when they encounter higher salinities (delta formation)
Transport of mud or sand into the river mouth from offshore sources
Why do estuaries have high productivity?
Due to detritus carried with the segments downriver or from the sea, or from decaying plant material from fringing salt marshes
What are the estuarine gradients affecting surface dwelling and free swimming animals in the water column?
- Temperature- temperature much more stable in oceans with estuaries experiencing 15-30˚C changes through summer and winter as well as daily changes due to the tide
- Salinity changes: lowest salinity at low tide during max river flow (which restricts the upper limit of marine species). Max salinity at high tide during minimum river flow and restricts the lower limit of fresh water species
- Oxygen- saturation occurs at lower concentrations in the sea than in fresh water
What are the conditions affecting benthic species living in mud and sand?
Distribution of sediments in estuary:
Tidal currents distribute sediments
Describe the subtotal and intertidal interstitial oxygen.
Inter tidally- Oxygen is transpitef by water movement between grains (permeable)
Subtidally- diffusion of O2 via interstitial water (porosity). As most sediment deposition is in areas of little water movement e.g. muds, only the top few mm is oxygenated, giving an anoxic layer below.
Describe the relationship between organic matter % and grain size in estuaries.
The larger the grain size the less organic matter. Fine sediments have a large surface area for bacteria (breaking down organic matter) adsorbed onto them.. Therefore causing N content to be also negative correlated to grain size.
What is the term for organisms present at any one moment?
Standing crop
What are the disadvantages of tidal power?
- Reduced mixing and increased stratification leading to reduced salinity and build up of contaminants and possible eutrophication
- Loss of habitats like intertidal mudflats and salt marshes
- Change in benthic habitats, affecting feeding birds
- Damage to migratory fish and mammals
How does pressure increase in relation to the atmospheric pressure as you go deeper into the ocean?
Every 10m down the pressure increase by 1 atm
What is coastal upwelling?
displaced surface waters are replaced by cold, nutrient-rich water that “wells up” from below.
What is el nino southern oscillation
The warming phase is known as El Niño and the cooling phase as La Niña.
Irregularly periodical variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting much of the tropics and subtropics
Describe the temperature profiles for different latitudes.
High- well mixed water so nutrients constantly distributed- virtually no thermocline
Mid latitudes- seasonal thermoclines and weak permanent thermoclines
Low latitudes- strong thermoclines
