Lecture 3 - RH Flashcards
What is the gross level and nett level of photosynthesis?
Gross level is the maximum capacity of photosynthesis for a particular species of plant.
Nett is the gross photosynthesis minus consumption of biomass during respiration.
What are the environmental factors that affect ecosystems?
Light
Temperature
Water
Wind
Nutrients
Slope and aspect
What is a sun plant and a shade plant?
Shade plants have low light compensation points and so can produce carbs from little light. (usually found in the understorey)
Sun plants need lots of sunlight and have high nett photosynthetic rates.
What are leaves like in sun and shade plants?
Sun plants have thick and hard leaves.
Shade plants have thin and soft leaves
What causes leaf cells to be hard in sun plants?
sclerenchyma cells
How can temperature influence an ecosystem?
Limiting temperatures can influence life cycle
Optimum temperature for some plants allow them to produce their greatest biomass
Is the temperature of the environment a good indication of optimum temperature?
Where an organism grows is not necessarily a good indication of its optimum temperature
What is the difference between a photosynthesis vs leaf temperature curve that describes a plant adapted to hot environment (C4 plants) and a plant adapted to cold environments (C3 plants)?
A cool adapted plant has a large optimum range of temperatures which drops off at a certain high temperature.
A hot adapted plant has a small range of optimal temperatures and photosynthesis increases constantly until the temperature is too high
What is the difference between C3 and C4 plants?
Carbon dioxide is stored in C4 plants but not in C3 plants.
C4 plants photosynthesize at night rather than during the day to avoid losing water.
What are the important aspects of water taken into account when thinking about ecosystems?
Rainfall + evapotranspiration
Salinity
Each species has a minimum water demand
Balance between availability in the soil
How do plant species minimise output?
Waxy cuticle and hairy surfaces
What happens to species living in areas with lots of available water?
More species can cope but there is more competition as well
Name forests from most water to least water:
Rainforest -> Closed forest -> Open forest -> Mallee
Name shrubland from most water to least:
Tall -> Low
What are the Australian multi-stemmed eucalypts?
Mallee
Snow Gum
Why is salinity such an issue with water uptake by plants?
It affects the bioavailability of water through a decrease in the osmotic pressure into the roots thus slowing rate of water uptake.
What kind of species dominate salty habitats?
Salt-tolerant species dominate salty habitats
What are the effects of wind on plants?
Affects rate of transpiration
Causes disease
Causes sand to move onto leaves
Windy habitats are also stressful habitats
is sand high in nutrients?
No
How is the ability of soil to store nutrients measured?
Cation Exchange capacity (CEC)
How does soil type affect vegetation?
Plants are adapted to a certain amount of nutrients so there are abrupt changes in vegetation with changes in soil type
What is a mesophytic habitat?
A non-extreme environment with relatively good levels of water etc
What is the biodiversity like in mesophytic habitats?
Very low due to competition resulting in one dominant species
How does slope and aspect affect ecosystems?
Interacts with water via drainage. Less water in the higher areas compared to lower areas
Any slope facing north gets more sun then slops facing west
More wind on top of the slope then on the bottom
