2.4 biomes, zonation, and succession

Question 1

Define the terms biome, productivity, succession, and zonation

Answer 1

• Biome = a collection of ecosystems that are classified according to their predominant vegetation
  Productivity = the conversion of energy into biomass in a given time
• Succession = the process in which an area changes over / through time
• Zonation = the change in a vegetation community along an environment gradient e.g. change as you go up a mountain

Question 2

The five major classes of biomes

Answer 2

1. Aquatic
   - freshwater
   - marine
2. Forest
   - tropical rainforest s
   - temperate forests
   - boreal/taiga
3. Grassland
   - savanna
   - temperate
4. Desert
   - hot
   - cold
5. Tundra
   - arctic
   - alpine

Question 3

Explain how insolation, precipitation, and temperature determine the distribution of the biomes

Answer 3

• Insolation = drives photosynthesis
• Precipitation = allows plant growth and high biodiversity
• Temperature = p/e rate changes biomes, below 1 = deserts, 1 = stable areas (forests), above 1 = waterlogged

Question 4

the tri-cellular model

Answer 4

Hadley cell = centered on the thermal equator
- intense surface heating on the thermal equator –> rising air at the ITCZ which creates high rainfall and regular thunderstorms –> forming the tropical rainforest
- as the air descends over the subtropics it warms –> descending air is stable and dry => desert areas
Polar cell = starting point is mid-latitudes –> warm air in the region rises going towards the poles and cools –>
- the polar cell acts as a heat sink –> balancing the incoming solar radiations at the equator
Ferrel cell = rising air in cooler regions and sinking air in warmer

Question 5

Explain how energy flows, GPP and NPP, diversity, and mineral cycling change during succession

Answer 5

• starts with pioneer community, bare rock, and harsh/unstable env. + no soil –> low productivity due to limited amount of vegetation
• pioneer species grow fast and biomass accumulates quickly –> high NPP
• by the climax community the production/respiration ratio = 1 meaning the gross productivity and respiration are balanced

Question 6

Distinguish the roles of r and k strategists in succession
- Demonstrate how reproductive strategies change between pioneer and climax communities

Answer 6

• k-strategists produce very few offspring but increase their quality by good parenting, more common in the climax community as it’s more stable and complex
• r-strategists focus on increasing quantity at the expense of quality, more common during pioneer stages of succession when conditions are harsh and unstable

Question 7

Explain how succession links to habitat, species, and genetic diversity

Question 8

Explain how complex ecosystems contribute to stability by having a variety of nutrient and energy pathways

Answer 8

• if one pathway is disrupted alternative pathways can compensate for the loss - maintaining essential ecosystem functions and processes
• complex ecosystems have greater adaptive capacity and flexibility to respond to environmental changes
• complex ecosystems lead to improved resilience and withstanding distruptions

Question 9

Explain how climax communities will vary depending on climate, soil, and a range of other local factors

Answer 9

• Climate =
• Soil =
• Temp =
• Insulation =

Question 10

precipitation/evaporation rates

Answer 10

• below 1 = water shortages (deserts)
• 1 = good soil moisture conditions –> fertile soil and water availability
• above 1 = waterlogged or heavily leached soils

Question 11

desert biome and forest biome

Answer 11

Desert = areas with dryness and a lack of precipitation
- p/e rate below 1
- productivity is very low due to a lack of water for plant growth
- low biodiversity due to harsh conditions
Forest (temperate deciduous forest): area covered by woody vegetation
- four seasons
- high biodiversity