Global Change Driver, Land-Use Change

Question 1

What are the stages of land-use change as human societies evolve? (as discussed in lecture and in Foley 2005)

Answer 1

it goes from natural ecosystem -> frontier clearings -> subsistence agriculture and small farms ->intensive agriculture ->urban areas -> protected/recreational lands (Foley 2005)

Question 2

Name three mechanisms by which land-use changes can affect climate, and indicate the scales on which these mechanisms operate.

Answer 2

1) alters GHGs (photosynthesis and respiration)
2) affects the energy balance (albedo)
3) affects the water balance (evapotranspiration and runoff)

Question 3

What important general trend in land-use has occurred in temperate zones over the last century? (what has happened to the farms on the marginal farmland in many areas of the northeast US?)

Answer 3

Because of the deforestation that occured in the northeast for agriculture, there is now a large terrestrial carbon sink in north america presumably because of the young forests now reclaiming the land. Farming intensity has since shifted from the northeast to the mid -US, which has allowed for the new growth.

Question 4

What important general trend in land-use has occurred in the last few decades in the tropics?

Answer 4

Major deforestation in the amazon is contributing carbon to the atmosphere. Deforestation is primarily being driven by private interests and for agriculture.

Question 5

What are some possible causes of a northern hemisphere carbon sink? (Remember Thoreau!)

Answer 5

the massive deforestation that occured back when America was colonized put carbon back into the atmosphere, so we are actually making up for that now that the forests are growing back.

Question 6

What are the potential impacts of large scale deforestation on climate (temp and precip) and how might you expect these to differ between high latitudes (boreal forests) and low latitudes (tropical forests)? Why?

Answer 6

Large scale deforestation would result in less precipitation and a decrease in temperature due to the change in albedo. In high latitude forests the change in albedo is even more dramatic than in tropical regions because a loss in trees means more snow is exposed.