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Ecosystem science > Lecture 2 > Flashcards

Lecture 2 Flashcards

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Biology 101 flashcards
1
Q

What is vapour

A

A vapour is a gas below it’s ‘critical temperature’ - it can easily be condensed or liquefied by a small change in temperature and pressure

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2
Q

There is a maximum amount of water that the…

A

Air can hold before become saturated - this increases with increasing temperature

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3
Q

Relative humidity (degree of saturation) =

A

Actual vapour pressure / saturation pressure

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4
Q

Dew point

A

Air becomes saturated and condensation may occur

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5
Q

Aerosol particles

A

Smoke, dust, pollen and salt act as condensation nuclei

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6
Q

Cloud formation occurs and their appearance reflects…

A

Air movements

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7
Q

Collision and coalescence of water droplets increases…

A

Droplet size

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8
Q

Precipitation is the main input of

A

Water on earth

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9
Q

When does precipitation occur?

A

When moist air is cooled below its dew point and the air becomes saturated

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10
Q

What variations are there in precipitation?

A

Stochastic variations
Periodic
Secular

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11
Q

Stochastic variations?

A

Arising from probabilistic or random nature of precipitation occurrences

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12
Q

Periodic (cyclic) variations ?

A

Astronomical cycles

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13
Q

Secular (long term) variations ?

A

Due to climate change

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14
Q

Measuring precipitation

A

Recording rain gauge

Automatically registers intensity or rate of accumulation

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15
Q

Rain gauge sources of error

A

Wind turbulence
Siting
Evaporation losses
Extreme rainfall

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16
Q

Density of rain gauge networks depend on

A

Accuracy of data requirements
Spatial variability of rainfall
Temporal nature of dataset required

17
Q

I-rain: mobile app for precipitation data

A

Rain data from network of precipitation sensing satellites

Users enter own rainfall or snowfall observations from raingauges

Display top 50 extreme weather events around the world

18
Q

Human impacts on precipitation

A

Land use / vegetation cover

Fossil fuel burning and global warming

19
Q

Canopy interception

A

Is the precipitation retained by the vegetation as surface storage and subsequently evaporated

20
Q

Interception by different vegetation types

A

Different storage capacity
Different aerodynamic roughness
Rainfall duration and intensity

Generally…
Interception losses will be greater for denser and taller vegetation in wetter climates

21
Q

Coniferous forests v deciduous

A

D - bends more under weight and shaken more by wind

D - higher stem flow in deciduous plants

22
Q

Factors influencing interception

A

Vegetation characteristics
Rainfall intensity and duration
Wind speed and turbulence
Energy balance

23
Q

What is evaporation from open water

A

The process by which a liquid is turned into a gas and it’s transfer away from the surface to the atmosphere

24
Q

Measuring evaporation

A

Evaporation pans and tanks

Easy and cheap to manufacture but prone to error

25
Q

Estimating evaporation

A

Very difficult to measure directly so estimated with mathematical models

26
Q

Modelling potential evaporation

A

Evaporation is often estimated using empirical models based entirely on data observations

This is because of the issues with directly measuring of evaporation

Models:
Predict potential evaporation

27
Q

Modelling potential evaporation

A

Advantages
Modest data requirements so ease of use
Can work well over long time periods

Disadvantages
Does not work well over short time periods
Can severely underestimate evaporation in arid and semi arid regions

28
Q

Evaporation from the soil depends on…

A

The amount of water in the soil

The ability of the sort to transmit water to the surface

29
Q

Evaporation from different soils

A

Open water
size of water surface, water depth and mixing salinity

Bare soils
Size, density, orientation and connectivity of pours in the soil, depth to the water table, local heat budgets, pattern of rainfall

Vegetated
Vegetation high and windspeed, stomatal control, soil factors

30
Q

Soil potential energy

A

Soil water moves so slowly that it’s connected energy is insignificant, and it is its potential energy that is important in determining water movement

Potential energy is defined as the work required to transport a quantity of water from a pool of pure water atmospheric pressure to a given soil water location

31
Q

Soil water availability to plants

A

Build capacity is water retained by a soil once gravitational water has drained out, organic matter enhances field capacity because of its hydrophilic nature, clay soils had four times more water than sandy soils

Permanent melting point is the soil water potential at which most plants will it because they can no longer attend water from the soil

Plant available water is filled capacity minus permanent wilting point

32
Q

Plant rooting depths

A

Plant rooting depth reflects a compromise between water and nutrients availability

Most roots near soil surface where nutrients are most available

Deep roots tap water from depth

33
Q

Water movement through a plant

A

Takes place in soil-plant-atmosphere continuum inter-connected by a continuous thin film of liquid water

Driven entirely by physical process of evaporation from leaf surface

34
Q

Transpiration

A

Evaporation of water that has passed through plants

Occurs at all exposed parts of the plant particularly the stomata

They open and close in response to environmental conditions such as light and temperature

Opening and closing affect the rate of transpiration and control the flow of water from the plant roots

35
Q

What is water loss from leafs controlled by?

A

Evaporative potential of air

Water supply from soil

Regulation of water loss by leaves using stomata

36
Q

Factors controlling transpiration?

A 
Types of vegetation 
Season
Time of day 
Stage of growth
Meteorological factors
Soil properties

Ecosystem science (5 decks)

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