Unit 2.3 & 2.4

Question 1

Pathway of radiation

Answer 1

As solar radiation (insolation) enters the Earth’s atmosphere, some energy
becomes unavailable for ecosystems as this energy is absorbed by inorganic
matter or reflected back into the atmosphere.

Reflected and scattered by atmosphere 6%
Reflected and scattered by clouds 20%
Reflected and scattered by earth 4%
Absorbed by the atmosphere 19%
Absorbed at the surface 51%

Question 2

Biomass

Answer 2

The mass of living organisms in a given area expressed as dry weight of mass per unit of area or g m–2.

Question 3

Productivity

Answer 3

the conversion of energy into biomass in a given time expressed as J m-2 yr-1. The rate of growth of plants and animals in the ecosystem. In business it is how much output you get from your input, usually measured annually.

Question 4

Gross

Answer 4

Total amount of product made
Total amount of biomass

Question 5

Net

Answer 5

What is left after losses like respiration and decal loss

Question 6

Primary productivirty

Answer 6

The process of photosytnethis to make organic compounds from CO2 and water.

Question 7

PRIMARY TO DO WITH ANIMALS

Answer 7

SECONDARY TO DO WITH PLANTS

Question 8

GPP - Gross primary productivirt

Answer 8

All biomass produced by primary producers in a given amount of time (before respiration)

Question 9

NPP - net primary productivity and formula

Answer 9

Takes into account respiratory losses (R)
Represents amount of usable biomass that will be used for growth and hervivor consumption

NPPg m-2 yr-1. = GPP - R

Question 10

Where is NPP highest and lowest

Answer 10

Highest - land based ecosystejms around the equator where temperatures, sunlight and precipitation are higher
Lowest - hot dry climates

Question 11

Secondary productivirty (GSP)

Answer 11

Total amount of energy or biomass assimilated by consumers
GSP = food eaten – fecal loss

Question 12

Net Secondary productivity

Answer 12

NSP = GSP – R
what is left at the end of all processes like animal grwoth

Question 13

Sustainable yield

Answer 13

Sustainable yield (SY) is the amount of biomass that can be extracted without reducing natural capital of the ecosystem.

Question 14

Storages and flows in carbon cycle

Answer 14

Storages - organisms and forests (both organic),
atmosphere, soil, fossil fuels, oceans (all inorganic).

Flows - consumption (feeding), death and
decomposition, photosynthesis, respiration, dissolving and fossilization.

Question 15

Storages and flows in nitrogen cycle

Answer 15

Storages organisms (organic), soil, fossil fuels,
atmosphere and water bodies (all inorganic).

Flows nitrogen fixation by bacteria and lightning,
absorption, assimilation, consumption (feeding), excretion, death and decomposition, denitrification by bacteria in waterlogged soils

Question 16

Carbon cycle and human impact

Answer 16

1. Deforestation releases carnon from soil and plant biomass
2. Fewer trees are available to remove CO2

The carbon store has been increasing since 1760 and in 2015 broke the 400ppm mark

Blamed on industrial revolution and reliance on fossil

Question 17

Nitrogen cycle and human impact

Answer 17

1. Fossil fuels burning = acid rain + photochemical smog
2. Draining wetlands = less nitrogen in atmosphere
3. inorganic fertilizrs = ammonia takes N3 from atmosphre and 2) increases denitrification and leahing –> eutrophication
4. Livestock ranching = increasing ammonia entering soil near aquatic ecosystems

Question 18

Biome

Answer 18

Biomes are collections of ecosystems sharing similar climatic conditions that can be grouped into 5 major classes: aquatic, forest, grassland, desert and tundra.

Climatic variation is influenced by many factors including atmospheric circulation and latitude, the tilt of the earth’s axis in its orbit, ocean currents and topography

Question 19

Explain the distribution of biomes with two specic biome locations

Answer 19

Insolation, precipitation, and temperature are the main factors governing.

The distribution of two different biomes like tropical rain forest and desert can be explained using the tricellular model.

The tropical rain forest is located in the hadley cell bwteeen tropic of cancer and capricorn where there is low latitude. This means that because it is closest to the equator,it recives the highest insolation which results in high temperatrues and high precipitation as the air rises and condenses due to low pressure.

Then, as the air decends 30 N and S of the equator, a desert biome can be found in the ferrell cell.

Here, latitude is higher and the pressure is high as well. this creates very high temperatures and insolation but low precipitation.

Climate change is altering the distribution of biomes

Question 20

Discuss what this graph shows

Answer 20

How mean annual temperature and precipitation combine to effect biomes distribution.

Temperatures above 20°C can have a wide range of biomes from hot desert through to tropical rainforest and precipitation levels between 150 and 200 cm can support various types of forest.

The graph shows that in general forests need higher levels of precipitation but can survive at pretty low temperatures.

Deserts on the other hand are found in areas ranging from 30 to -7°C. The reasons for the high temperatures are discussed in Case study: Desert biome.

Question 21

Need to know about biomes

Answer 21

Location
Climate
Limiting factors
Productivity
Biodiversity
Vegetation structure
Named plants and animals

Question 22

Temperate deciduos Forest biome

Answer 22

Make up 80% of earths biomass
between 40 and 60 noth and south of equator

Ex. Europe, Sherwood forst UK

Rainfall –> HIGH, max at summer
Temperatures –> winter cool above 0 summer 20-25

Productivity –> High NPP due to large layered vegetation

Limiting factors –> Sunlight limied to lower layers

Nutrient cycle –> balanced stores

Plants –> in winter trees shed their leaves to aviod moisture loss and tissue damage on spring leaves are adapted to catch light and photozynthezise quikcly

Biodiversity –> HIGH in plants an mammals , reptiles and aamphibians

Question 23

Desert Biome

Answer 23

Deserts are areas of the world where there is less than 250 mm of precipitation in a year. Caused by
- descending air from hadley to ferrell
- coastal rain shadows
- continentiallyity
- cold ocean currents

Ex, Sahara
Northen third of Africa
Less thann 100mm year
Max tempof 38 bwtween may and JUly
Low productivity - rain even evaoprates befor plants can use it
Limiting factors –> water, soil, food
Diversity is high in animals like fox and pkants with long roots

Question 24

Differences between K and R strategists

Answer 24

K strategies
- few offspring
- good quality
the environment must be stable - climax communities

R strategists
- large quantity
- low quality
beneficial in unstablem un predicatble environmnents like early stages of succession

Question 25

Succesion vs zonation

Answer 25

Succession is a change over time; zonation is a spatial change in response to changing conditions.

Succesion (a temporal phenomenon) zonation (a spatial phenomenon)

Question 26

Zonation

Answer 26

Change in a vegetation community along environmental gradient determined by changes in abiotic factors like latitude, tidal leel, distance from shore

Question 27

Succession and producivity

Answer 27

In early stages of succession, gross productivity is low due to the unfavourable initial conditions and low density of producers. The proportion of energy lost through community respiration is relatively low too, so net productivity is high—that is, the
system is growing and biomass is accumulating.

In later stages of succession, with an increased consumer community, gross productivity may be high in a climax community. However, this is balanced by
respiration, so net productivity approaches 0 and the productivity–respiration (P:R) ratio approaches 1

Question 28

Succession process

Answer 28

Succesion is the process of change over time in an ecosystem involving pioneer, intermediate and climax communities.

During succession, patters of energy flow, gross and net productivity, diversity and mineral cycling change over time.

Colonization:
- pioneer species that adapted to extreme conditions
-R-strategists suited to unstable environment of early succession
-Small organisms with short life cycles that produce offspring
-Soil starts to form as weathering begins ti break down rocks and plants

Establishment
-Ecosystem is getting going as opposed to a collection of constituent parts
-Soil becomes deep enough to provice niches
-Improves waterholding capacity
-Resources increase - food shelter water

Competition
-Pioneers have done their job - made a barren area into an area that can sustain a wider variety of plants
-Abiotic conditions less extreme
-More plants join the area and outcomete the original species for -space, light, nutrients
- K strategy is more successful

Climax community = Steady state of equilibrium and soil

Question 29

Why are Climax communities stable

Answer 29

Climax communities are stable and the stability is due to the complexity of the ecosystem. More complex = more stable. In a complex food web, where there as numerous organisms at eachtrophic level the disappearance of one organism will not cause any great impact. Stability tends to give an ecosystem a higher level of resilience too

Recilience: how well the ecosystem resists damaged caused by a disturbance and how well it recovers

Disturances: may be natural lke floods, insect explosions or human induced like deforestation
Thus, an ecosystemabiliy to return to its previous state is dependent on resilience. A system is more resilient if it has high bioduversty with complex food webs and nutrient and energy path ways.

Features of a climax community
Greater biomass
Higher level of species and habitat biodiversity
More favourable soil conditions (deeper soil)
Better soil structure (greater water retention)
Taller and longer living plant species
Greater community complexity and stability
Steady state equilibrium

Question 30

Biome productivity

Answer 30

NPP is high at the equator due to ideal growing condititions of high temperatures with plentiful sunlight and water supply. (Tropical rainforest)

NPP drops towards the poles as growing conditions are less favorable. Deserts have favorable temperayre but low NPP due to water scarcity.

Question 31

Climate change and biomes

Answer 31

One tenth and a half of the earth will be affected by biome shifts.

Changes in precipitation, temperature and humidity are making some areas less favorable for the vegetation. The result is a move to higher latitudes and higher altitudes

Eg. African Sahel, woodlands are being replaced by grassland

Artic scrublands are moving to tundra areas.

Question 32

Secondary succession

Answer 32

Human activities or natural disasters may arrest succession part way through or they can destroy the climatic climax and send the process of succession back to the beginning. This is often referred to as a secondary succession.

The amount of the impact the distrurbance has depends on the stage of succession and how stable the ecosystem is