E9

Question 1

What do all biological entities require?

Answer 1

Matter for their construction and energy for their activities

Question 2

What do fluxes of energy and matter strongly link communities with?

Answer 2

Abiotic environments

Question 3

What makes up an ecosystem?

Answer 3

Biological community + abiotic environment

Question 4

What do ecosystems include?

Answer 4

Primary producers, decomposers, detritivores, a pool of dead organic matter, herbivores, carnivores and parasites. Plus the physiochemical environment that provides living conditions and acts as a source and sink for energy and matter

Question 5

What did lindemann do when laying the foundations of ecological energetics?

Answer 5

Attempted to quantify webs by considering the efficiency of energy transfer between trophic levels. Early calculations of productivity in terrestrial ecosystem involved measurements of plant biomass and estimates of energy transfer. In aquatic ecosystems changes of O2 or CO2 were measured in experimental enclosures. Today - in situ chlorophyll concentrations and photosynthetic gases, plus satellite imagery are used

Question 6

What is the definition of standing crop of biomass?

Answer 6

The bodies of the living organisms within an area.

Question 7

What is the definition of biomass?

Answer 7

Mass of organisms per unit area of ground or volume of water ; usually expressed in units of
Energy - J m-2
Dry organic matter - t ha-1
Carbon - C m-2
The great bulk of biomass in communities is typically plants or algae

Question 8

What is the definition of primary productivity?

Answer 8

The rate at which biomass is produced by photosynthetic organisms. Usually expressed in units of
Energy - J m-2 day-1
Dry organic matter - kg ha-1 year-1
Carbon C m-2 year-1

Question 9

What is the definition of gross primary productivity?

Answer 9

Total energy fixation

Question 10

What is the definition of net primary productivity?

Answer 10

GPP - autotrophic respiration

Question 11

What is NPP of the planet and how much is produced by what different ecosystems?

Answer 11

105 petragrams of C per year. Of this, 56.4 Pg C y-1 is produced in terrestrial ecosystems and 48.3 Pg C y-1 in aquatic ecosystems. Oceans cover 2/3 of the planets surface but account for less than 1/2 of its production. On land, tropical rainforests and savannah together are responsible for 60% of terrestrial NPP - reflecting the large areas and high productivity of these biomes

Question 12

In what conditions can incident solar radiation contribute to primary productivity?

Answer 12

If there are sufficient temps, water and nutrients available.

Question 13

What is the pattern shown in productivity of environments?

Answer 13

Productivity of forests, grasslands, and lakes follows a latitudinal trend, increasing from boreal, through temperate to tropical. Patterns are not so clear in oceans, where productivity is often limited by a shortage of nutrients. High productivity is observed in marine communities where there are upwellings of nutrients rich waters. Also pattern according to seasons

Question 14

What are some limiting factors in terrestrial communities?

Answer 14

Sunlight, CO2, water, soil nutrients are required for primary production. Temp has a strong influence on photosynthetic rates. CO2 is unlikely to be limiting. Quality and quantity of light, availability of water and nutrients and temperature all vary dramatically from place to place

Question 15

How can light be a limiting factor in terrestrial communities for photosynthesis?

Answer 15

Only 44% occurs at wavelength suitable for photosynthesis. Not all this radiation is used efficiently as it depends on availability of other resources. Shortage of water is a critical factor. Temperature and precipitation interact ; high temperatures associated with high evapotranspiration.

Question 16

How can drainage and soil texture modify water availability?

Answer 16

Coarse soils are associated with lower nutrient retention. Sandy soils are lower in N. Geological conditions are important - nitrogen and phosphorus are limiting factors.

Question 17

How can length of growing season be a limiting factor in terrestrial communities?

Answer 17

Deciduous trees drop their leaves, conifers can photosynthesise all year round. Conifers, however, are limited by temp and associate with nutrient poor conditions. Tropical evergreen rainforests are most productive

Question 18

What factors can be limiting factors in aquatic communities?

Answer 18

Primary productivity is most frequently limited by light and nutrient availability. Most commonly nitrate and phosphate, but iron can be limiting in open ocean environments. In small forest streams, light and nutrients interact to determine productivity. Nutrients are the most limiting in lakes. In oceans, locally high levels of PP are associate with high nutrient inputs from estuaries and upwelling.

Question 19

How do nutrients flow into coastal shelf regions from estuaries?

Answer 19

Continuously, in the euphotic zone, productivity is hit because a use of high nutrient input and waters are clear, allowing light to penetrate. Closer to land, water is nutrient rich, but highly turbid thus less productive. Outer shelf and open ocean have low productivity due to low nutrients

Question 20

What are the second source of high nutrient concentrations?

Answer 20

Ocean upwellings, occur on continental shelves, where wind is consistently parallel to the coast. Water is moved offshore and is replaced with cooler nutrient rich water originating from the bottom. Consequently, there is a phytoplankton bloom that supports a chain of heterotrophic organism. The great fisheries of the world are located in these areas of high productivity

Question 21

How is iron a limiting factor in the marine environment?

Answer 21

Affects a third of the open ocean, iron is insoluble, ultimately derived from wind blown particulate matter. Experimental seeding of iron can induce phytoplankton blooms. Suggested as a method to reduced atmospheric CO2.

Question 22

How does productivity vary with depth?

Answer 22

As light is attenuated

Question 23

What is the definition of secondary productivity?

Answer 23

Rate of production of new biomass by heterotrophic organisms. Heterotrophic animals, fungi, and bacteria cannot manufacture energy rich compounds from simple molecules. Derive matter and energy by consumption. Primary producers comprise the first trophic level, primary consumers the second, carnivores the third.