Deserts Quiz 1

5. Why are plants better indicators of local climate than animals?

Animals are not good indicator for local climate because they can migrate, hibernate, or adapt. Plants are better because it shows the characteristics needed to survive the local climate. There are many different species of plants that helps indicate the type of climate it is living in and also plants do not migrate so only those who survive is able to stay at a certain climate.

*Why do biomes along an elevation gradient mimic similar changes in vegetation along a latitudinal gradient?

As one travels up in elevation, the air becomes colder and, as a result, drier. This mimics the temperature gradient that occurs as one travels from the equator to the poles. Biomes are defined by annual precipitation and average temperature - this means that two locations with similar temperatures and precipitation are part of the same biome. So just as there is a temperature gradient where temperature drops as one moves away from the equator, so too is there a temperature gradient where temperature drops as one moves up in elevation, creating similar biome spreads. The drop in temperature as one increases elevation is due to a decrease in pressure, causing air to expand and average temperature to drop.

*Why are there deserts at 30 degrees N and S latitudes? Describe the process(es) that produce them.

At equator, cooler air pushes warmer, moist air up. As it ascend to atmosphere, the air expands and loses moisture, causing it to become more cold and dry. At 30 degrees N and S this air coming from equator meets with air from 60 degrees N and S high altitude, causing the colder dry air to descend because of rotation of earth and conservation of momentum. As air descends, it gains heat from the ground, thus allowing it to gain moisture from the ground. Ground becomes dry and air is hotter, causing deserts.

State which desert you would be in if you observed the following: a) majority of precipitation in summer, no columnar cacti, lots of leaf succulents such as agave

Chihuahua

*List and describe (in brief) the remaining physical causes of deserts.

Descending cold dry air at 30° N and S. b. Center/Middle of continents (farther from the ocean). Intense storms in the middle of the contentment. The ground is hot. Makes the air hot. Heated expanding air. So the cool air rushes in. The land heats faster than the atmosphere so the air then rises rapidly and sucks electron with it causing storms, tornados, and thunder. c. Mountain: the leeside of the mountains are desert land because the mountains area physical obstacle to the wind. The wind has to go up and as it elevates, it becomes cold and loses moisture holding properties. Then as it descends it heats (at a much faster pace) and boom: hot dry winds. d. Cold Ocean Currents. The cold air from the ocean sucks up moisture as it gets to the shore so it creates a dry environment.

List two fire climax biomes. For each, what trait in morphology or growth habit allows them to survive fire or perhaps even thrive with frequent fires?

Grasslands --> grass grows from the bottom to top and as it grows it needs to be trimmed for the bottom to have access to sunlight as well (hence mowing the lawn). Fires move quickly through the grassland and destroy the dead tops, letting the bottom have access to sunlight to grow. Woodlands --> Ponderosa pines have thick bark and cones that can thrive in hot temperatures. As the fire moves through the area, the pine can sustain the hot temperatures if the fire moves quickly. Chaparral Biome: The plants in the climate regrow from their roots, so fires do not harm their ability to survive. Fires actually help by clearing space and letting sunlight in for the smaller, younger plants. Ponderosa Pines: These pines have very thick bark that allows them to survive the fast, sporadic fires that commonly occur in their biome. Ponderose Pine-->has thick bark, which allows it to withstand frequent fires that move through the area. As long as meristem is not damaged, it can regrow. 2. Chaparral: can resprout from the roots. Frequent, quick fires typically do not significantly damage the roots, so it can continue to live.

*State which desert you would be in if you observed the following: e) Mostly shrubs, few succulents, few annuals

Great Basin/Intermountain

*State which desert you would be in if you observed the following: c) arborescent yucca (Joshua Tree)

Mojave

* How do packrat middens contribute evidence of climate change in the Southwest?

Packrat middens contribute evidence of climate change in the Southwest because these middens are multigenerational and last for up to 50,000 years. When a midden is created, the packrat goes and collects debris from a 50 meter radius of the midden. This debris is then put on top of the midden and peed on so it crystallizes and sticks. When a packrat dies, another packrat will come and take the midden and continue the process. As you go deeper into the midden you can see the types of vegetation that was alive at the time the midden was being built. The vegetation in the midden is then an indicator of what the climate was at the time as the types of plants at that time adapted to survive at that climate at that time. Also the poop of the packrats also provides some evidence as the larger the poop, the colder it was since the packrats were cold and hibernating.

Describe two factors that plants must contend with to successfully establish and persist in cold desert temperatures.

Plants must adapt to have a lower SA/V ratio to retain heat and moisture and exist in lower elevations because it is warmer. 1. Frost 2. Cold Temps 3. Lack of moisture

Some deserts recieve more winter rainfall, while others receive more in summer. Why?

Some of the more Western Deserts receive rainfall in the winter as Cold Deserts that are more affected by Pacific Westerlies that bring stronger winds and Pacific Storms in the winter. Others receive rain in the summer due to the humid/hot summer airs that lead to accumulations of heat that rise and expand and then cool due to low air pressure with increasing elevation, releasing its moisture & precipitation The Chihuahuan desert also receives more moisture in the summer due to stronger Atlantic Trade Winds that bring moisture in the summer.

*State which desert you would be in if you observed the following: b) columnar cacti, leguminous trees

Sonoran

*State which desert you would be in if you observed the following: d) bimodal rainfall, gentle winter rains, local thunderstorms in summer

Sonoran

*In mountains of the SW, bands of vegetation (Merriam's Life Zones or Biomes) extend higher on one side of the mountain than on the other. What side? Why? Explain the pattern.

Southside of mountains allow bands of vegetation to extend higher than on the north side. Typically, the south side of mountains receive more sunlight, thus allowing for warmer temperature and higher evaporation compared to the north side. As a result, the biomes are extended higher. Northside receives less sunlight, and thus is lower in temperature. For example, frost intolerant vegetation goes higher on south side than on the north side of a mountain

Why is there a temperature gradient on Earth from the equatorial regions to the poles?

Sunlight hits the equator directly, producing hot conditions, but because the earth is spherical, the rays of light hit other regions of the earth at an angle. At the poles in particular, the angle is biggest, so the sunlight's heat is spread out over more area, producing cold conditions. In addition, the further away from the equator, the more atmosphere the light must pass through, leading to more scattering and heat absorption.

*What essential element of packrat middens allows them to provide evidence for such a long period of time?

The packrats pee all over their maddens which helps the materials stick together and form cohesive layers and can be analyzed to see what types of plants were in the area in what year. The packrats also only gathered materials to build their middens from their immediate surroundings so the midden can give analysts a very clear picture of the vegetation that in that specific area or region, this, combined with the packrat pee creates huge middens that can survive over thousands of years provided they were not to exposed to the elements or extreme weather conditions. They are really old. The packrats don't start making new middens. Rather they pass down their middens and keep building on top of the old one for centuries.