Lecture 27: Land Transformation

Question 1

What is land use change?

Answer 1

Conversion of existing natural ecosystems to other forms of landscape (for human use)

Question 2

What are some common changes to natural systems to allow agriculture?

Answer 2

• deforestation
• draining wetlands
• modifying grasslands

Question 3

How does deforestation affect the carbon cycle?

Answer 3

Tress are a major source of carbon sequestering –> deforestation releases carbon (CO2 to atmosphere)

Question 4

How does deforestation affect the hydrological cycle?

Answer 4

trees recycle green water (deforestation = less transpiration) and also affect cloud formation

Question 5

What is slash and burn agriculture?

Answer 5

Removal of woodland through use of fire and then using the nutrient-rich ash as fertilizer for agriculture.

In tropical areas, high rain washes away the nutrients so new virgin land needs to be slashed and burned to continue.

Question 6

How does deforestation affect the radiation budget?

Answer 6

Dark tree canopies have low albedos –> crops and pasture have lower albedo and reflect more solar radiation

Question 7

How does deforestation affect biodiversity?

Answer 7

Forests are super biologically diverse -> deforestation removed habitats and cause extinctions

Question 8

Why is land change use of grasslands so bad?

Answer 8

Grasslands are an endangered biome and can actually be a more reliable carbon sink than forests due to so many recent forest fires (store carbon in soils)

Question 9

What are the impacts of land use change of wetlands for agriculture?

Answer 9

• loss of green/blue water reservoir
• changes in GHG cycles due to artificial fertilizers
• soil degradation
• loss of biodiversity

Question 10

What is urban expansion?

Answer 10

Agriculture is usually situated near human habitation –> expanding urban areas overtakes agriculture land

Question 11

How does urban expansion affect radiation budgets?

Answer 11

most man-made surfaces have low albedos (increased temp due to radiation absorption)

Question 12

How does urban expansion affect the hydrological cycle?

Answer 12

covering land surfaces with non porous coatings prevents capturing runoff & slows groundwater infilitration

Question 13

How does surface mining impact landscapes?

Answer 13

• removal of forests, wetlands, or grasslands and dramatically changes the morphology of landscapes

Question 14

How does mountaintop mining impact landscapes?

Answer 14

• mountaintop removal to extract biomass permanently alters the topography

Question 15

How does sub-surface mining impact landscapes?

Answer 15

• chemical contamination alters soil quality

Question 16

What is desertification in iceland?

Answer 16

human settlement caused mass deforestation and cause rapid desertification, where biological productivity of soil is lost (high winds stripped soil and produced sandstorms)

Question 17

Why is reforestation in iceland good?

Answer 17

• reduces soil erosion & sandstorms
• meeting GHG reduction goals
• recreate local timber industry
• support biodiversity

Question 18

What are the reforestation challenges with Iceland?

Answer 18

• poor remaining soil quality
• lack of other plants to support tree growth
• short growing season
• feral sheep eat seedlings