The Critical Zone

Question 1

What is the biosphere?

Answer 1

• The biologically inhabited part of the earth
• Deep oceans to atmosphere
• Interacts with lithosphere (geology), hydrosphere and atmosphere

Question 2

What is biogeography?

Answer 2

Branch of geography which explores patters - why are organisms where they are?

Question 3

What is historical biogeography?

Answer 3

• Looks at reconstructing the origin, dispersal and extinction of species or taxonomic groups

Question 4

What is ecological biogeography?

Answer 4

• Looks at present distributions and geographic variations in diversity, environmental constraints on species distribution and how biotic and abiotic interactions influence species distribution

Question 5

What happens in the critical zone?

Answer 5

• All activities and resources that sustain human life
• Food and fuel production
• Biological gene pool
• Carbon storage
• Clean water and soil

Question 6

What is species distribution a result of?

Answer 6

A result of multiple biotic and abiotic drivers

Question 7

What are the biotic factors which drive species distribution?

Answer 7

• Influence of ecosystem engineers (humans, beavers)
• Interacting among species - competition
• Individual response of species - extinction

Question 8

What are the abiotic factors which drive species distribution?

Answer 8

• Geographic template
• Temporal dynamics of the geographic template - tectonics, sea level change, climate change
• processes occurring on geological timescales results in temporal patterns of species distribution

Question 9

What are the biological drivers of biotic factors?

Answer 9

• Some biota may respond to environmental variation - adaptation, evolution, dispersal or extinction
• Some species act as ecosystem engineers and alter the physical environment

Question 10

What are the four main processes regulating biogeographical patterns and species distribution?

Answer 10

1) Abiotic processes - physical environment that is external to organism
2) Physiological processes - how a species adapts and evolves
3) Biotic interactions - symbiosis, mutualism and parasitism
4) Historic events - how did a species get there - invasive

Question 11

What is the natural world described as?

Answer 11

• A series of biogeographic units

- Allows a collective description of processes and structures

Question 12

What are the different scales of the natural world?

Answer 12

• Biome - global/continental spatial scale

- Ecosystem - a community of organisms and its environment in one unit

Question 13

What is a biome?

Answer 13

• Biological meta communities
• Similar but unconnected regions
• Two master variables - temp and precipitation
• Collections of areas with similar a biotic factors that produce similar ecological communities

Question 14

What are the biome characteristics of a tropical rainforest?

Answer 14

• Dominated by broad-leaved evergreen species
• High biodiversity
• Hot and wet
• Poor, thin soil
• evolution was not disrupted by glaciation
• High productivity - range of resources

Question 15

What are the characteristics of a savannah grassland biome?

Answer 15

• Grasslands with low density trees and shrubs
• Support Hugh number of herbivores, large grazing mammals
• Warm/hot climate
• Rainfall - 6/8 months
• Maintained through droughts and fires
• Shallow soil

Question 16

What are the characteristics of the desert biome?

Answer 16

• Hot and dry
• Covers 1/5 of earths surface
• Specialised flora and fauna
• Less than 50cm/year of rain
• Soils are nutrient rich
• Low plants, small thick leaves

Question 17

What are the characteristics of a temperate deciduous forest biome?

Answer 17

• Broad leaved deciduous trees
• Less dense, shorter forests
• Few dominant species
• High rainfall
• Rich soils

Question 18

What are the characteristics of a temperate grassland biome?

Answer 18

• Mostly grasses
• Steppes and praises
• Some trees
• Grazed by large mammals
• Deep nutrient rich soil

Question 19

What are the characteristics of a tundra biome?

Answer 19

• Low biotic diversity
• Artic shrubs mosses, grasses and lichen
• Alpine dwarf trees, shrubs and grasses
• simple vegetation structure
• Low temp and no rain
• Poor nutrient soils

Question 20

Define ecosystem structure

Answer 20

Biotic and abiotic components or attributes within an ecosystem

Question 21

What are the two most important functions in an ecosystem?

Answer 21

Energy and nutrient cycling

Question 22

What is energy and nutrient cycling controlled by?

Answer 22

• Producers
• Consumers
• Decomposers
• Water cycle

Question 23

What is primary production?

Answer 23

• Generation of biological material by plants – photosynthesis
• Key process -conversion of inorganic carbon dioxide to organic carbon
• Autotrophs – self feeders
• Not often at equilibrium

Question 24

What cause an ecosystem to change?

Answer 24

• Changes in structure
• Relative species abundances
• Species immigration/emigration (local extinction)
• Feedback to changing abiotic conditions such as soil fertility, microclimate
• Does not mean ecosystem is not stable

Question 25

What is succession?

Answer 25

• Disturbances destroy existing habitats and create new ones
• These are then colonised by species, creating new ecosystems
• Colonisation of bare ground is called primary succession
• Secondary succession occurs when existing vegetation is removed