Topic 4: THE TERRESTRIAL ENVIRONMENT

Question 1

Compare aquatic and terrestrial environments

Answer 1

• High variability in microclimates in comparison to aquatic environments
• Variability of conditions especially in temperature and moisture

• Open ocean; very little changes in abiotic condiitons across

High variability; tundra, deserts, rainforest; drives higher biodiversity

Question 2

Explain some challenges faced by animals living on land

Answer 2

Water balance and desiccation
• Organisms on the land must deal with significant losses of water due to
evaporation
• Living cells contain up to 95% water and must remain hydrated
• Animals can drink water or eat plants
• Plants and microorganisms can obtain it directly from the soil or environment

Air has low density/viscosity relative to water; animals and plants subjected to large gravitational forces
• Cellulose/lignin reinforcing in plants
• Advanced skeletons in animals

- Organisms that live on land have to develop a rigid structure 
- Adaptations to keep water; thicker leaves, high amount of cellulose and lignin to maintain form and maximize photosynthesis 
- Adv. Of skeleton; allows for movement 
- Skeleton of fish vs chameleon; attachment points and how limbs are supported are much more large and intricate compared to fish

Question 3

Soil defined?

Answer 3

the foundation upon which all terrestrial life depends on

A natural product formed by the weathering of rocks and the actions of living organisms

• Composed of mineral and organic matter capable of supporting plant growth

• More than just an abiotic medium for plant growth…it is a living system of interacting parts (biotic and abiotic); AN ECOSYSTEM

• Controls the fate of water in terrestrial ecosystems, breaks down waste products; bc things exist in limited quantities , releases nutrients and serves as a habitat for a community of animals, fungi and microorganisms

• Maintaining water balance is a major driver of evolution

Question 4

What property of soil varies across landscapes?

Answer 4

Soil depth varies across the landscape

Question 5

What is soil depth determined by?

Answer 5

Determined by degree of weathering, type of parent materials, and vegetation (organic matter additions)

Question 6

Why are deeper soils more beneficial?

Answer 6

Deeper soils also have more capacity for holding water and minerals.
Soil depth influences how deeply roots pene- trate, affecting the stability of vegetation, especially trees

Question 7

What type of soils do grasslands have?

Answer 7

Grasslands tend to have deep soils
• Low decomposition rate and large amounts of organic materials
being added from roots underground

Question 8

What type of soils do forests have?

Answer 8

Forest tend to have thin soils
• High decomposition rate and organic material added on the surface

- Forest; vegetation mostly grows above ground

Question 9

compare soils in slopes vs alluvials

Answer 9

Soils which develop on slopes tend to be shallow while those in alluvial plains tend to be deep

Alluvial- large amount of soil, it’s a flat land

Question 10

Parent material

Answer 10

is the matter from which soil develops

Question 11

Soil Horizons

Answer 11

Initially soil development occurs within the parent material
• Over time the soil changes from the surface down though the accumulation of organic material
• Percolation of water downward moves material along with it

- Organic material on surface dies begins to decompose and mixing of those 2 creates soil profile 
- Percolation- how fast water runs thru, causes mixing of 2 layers 

Results in the formation of layers which are different physically, chemically and
biologically

Question 12

Layers –

Answer 12

termed horizons, collectively called the soil profile

Question 13

Describe the different layers of the soil

Answer 13

• O horizon is the organic layer, it is made up debris, in various stages of decomposition

• A horizon is often called the topsoil and is composed of both mineral and organic materials

• B horizon is often called the subsoil and contains less organic and more mineral components relative to the A

• C horizon is a layer of unconsolidated material and is in general made of the same material from which the soil developed

O- dead and decomposing organic material
A- focus on when determining whether land is suitable for agriculture
C- layer that is parent material

Question 14

How are different soil types generated?

Answer 14

Differences in parent material, climate, topography, biota, site history and time yield different soil types with different minerals, nutrients and chemical properties.

Question 15

• What causes variation in the moisture-holding capacity of soil?

Answer 15

1. Climate
2. Type of parent material
3. Topography
4. Aspect
5. Presence/absence & Type of Vegetation

Question 16

Climate

Answer 16

directly influences the physical & chemical reactions in the soil & water availability Temperature, precipitation, wind currents in exposed areas, etc.

Question 17

Type of Parent Material/Texture

Answer 17

Material from which the soil develops
Physical and chemical characteristics determine the properties of the soil

Some parent material gets broken down in smaller particle size then others which has a very large affect on how fast water can trickle thru

Question 18

Texture

Answer 18

is used to differentiate soil particle sizes. It is partially inherited from the type of parent material and the types of weathering processes

Question 19

Describe the different size of soil particles and their advantages and disadvantages

Answer 19

• Gravel > 2.0 mm
• Sand 0.05 – 2.0 mm
• Silt 0.002 – 0.05 mm
• Clay < 0.002 mm

- Gravel soil doesn’t hold water good, water will run thru very quick 
- Sand; holds water more easily then gravel but not the best 
- Silt; holds water much easier  Clay; very fine particle size holds water very easy

Question 20

A soils texture is

Answer 20

% of its sand, silt and clay components. Typically divided up into texture classes.

Question 21

What does soil texture determine?

Answer 21

• Soil fertility
• The size of soil pore spaces

Question 22

compare large pores vs small pores in soil

Answer 22

• Large pores cause rapid water infiltration, percolation and drainage but have low holding capacity

• Small pores cause slow water infiltration, percolation and drainage but the soil does have high holding capacity.

Question 23

Topography

Answer 23

A sloped surface is less likely to hold moisture than flat ground due to gravitational forces

Question 24

Presence/Absence & Type of Vegetation

Answer 24

– Vegetation alters microclimates:
• Light (via shading)
• Temperature (via shading)
• Moisture (via use)
• Wind movement
• Structure – habitat for animals

- Plants provide shade- protection from abiotic envir.

Trees growing in line- windbreaker (prevent water loss from soil, prescience of tree prevents this)
Plants take water from soil so more plants you have growing they are competing for water more plants= drier soil

Question 25

Microclimate Variability

Answer 25

Vegetation provides a high diversity of microclimates for terrestrial ecosystems

Question 26

What should the soil be made out of to hold as much water as possible?

Answer 26

Be made out of entirely clay
- Drawback of this is its to dense small particle size makes it very dense but makes it difficult for plant to pull water out of it whereas in gravel its easier to pull water

- Want a mixture of particle sizes

Question 27

Aspect

Answer 27

Windward facing slopes receive more precipitation Differences in exposure to solar radiation and wind

- Direction of slope surface can determine how much moisture 
- Rain shadow side will have dry soil b/c less rain 
- North facing slope less direct sunlight so less evaporation and more plants can grow