1a. What is meant by land use? Give an example of a land use class.

1b. What is swidden agriculture?

1c. What is urban sprawl? Can urban areas be distinguished on satellite imagery?


2a. What is meant by ultimate and proximate causes of change?

2b. How do agricultural extensification and intensification differ?


3a. Why did traditional swidden agriculture practices often work in the past?

3b. How do many modern agriculture techniques sustain adequate nutrients for continued planting and harvesting?


4a. Do environmental changes tend to have more of an immediate impact on people living in industrialized or nonindustrialized countries. Why?

4b. What is the role of remote sensing in understanding and mitigating the effects of environmental change?



1a. Land use refers to the human activities for given areas of land. Some random examples of land use are orchard, pasture, industrial, residential, irrigated cropland, and sheep ranching. See Section 1.

1b. Swidden agriculture is a type of agriculture that farms small parcels of land until successive plantings can no longer be sustained. The land is then abandoned and a new area is prepared for planting. This is often called slash-and-burn agriculture since the area is usually burned during the clearing process. See Section 1.1.1 and 2.4.1.

1c. Urban sprawl describes urban expansion spreading out from a metropolitan center. Yes; urban areas and sprawl are visible on satellite imagery, marked by features such as a bright halo effect (urban areas generally have relatively high albedo), circular beltway roads, and radiating highways. See Section 1.1.2.

2a. Proximate causes of change are the direct actions that create change (such as the actual clearing of land by settlers for farming, and the handling of the cleared land for crops or pasture). Ultimate causes of change are the underlying reasons or needs motivating a desire for change (such as economic incentives that drive the migration of settlers to regions where forest clearing is possible). See Section 2.1.

2b. Extensification involves increasing the total area of land under cultivation to meet growing demands. Intensification attempts to meet demand by enhancing the production of preexisting agricultural land using inputs of nutrients and pesticides. See Section 2.2.

3a. In the past, fallow periods were often much longer, which allowed natural systems to replenish the nutrients removed by the cropping process. See Section 2.4.1.

3b. Many modern agriculture practices depend on added fertilizers (nutrients) to sustain yields. See Section 2.4.2.

4a. The effects of environmental change typically have more of an immediate impact on populations in nonindustrialized nations. This is largely because nonindustrialized nations do not have access to or sufficient money for mitigating resources and technical solutions that can offset some negative effects of change. See Section 3.2.

4b. Remote sensing technology provides tools that can acquire objective information about long-term variability of vegetation and land cover dynamics, rates of land surface change, and global biophysical, geophysical, atmospheric and oceanic processes. Such data records contribute to scientific understanding and assessments of environmental health, viability, and sustainability. Greater understanding in turn supports improved accuracy in predicting future environmental dynamics and outcomes. See Section 3.2.3.