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Desert Flashcards

(104 cards)

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1
Q

How much of the world’s total land do deserts cover

A

1/3

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2
Q

what time are most animals active in hot deserts

A

nighttime (to avoid the hot temperature)

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3
Q

Hot & dry desert temperature

A

little rain but varies
mean temps 20-25C; often over 40C; can drop into -C
plants w/ thick cuticle and sometimes CAM; small animals (lizards mostly)
include major N amer deserts of mojave-chihuahua-sonoran-great basin, sahara, australia

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4
Q

Soil characteristics

A

Soils are course-textured, shallow, rocky or gravely with good drainage and have no subsurface water. They are coarse because there is less chemical weathering. The finer dust and sand particles are blown elsewhere, leaving heavier pieces behind.

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5
Q

leaf characteristics

A

small, thick and covered with a thick cuticle

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6
Q

common flora

A

ground-hugging shrubs and short woody trees

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7
Q

replete

A

fully supported with nutrients

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8
Q

plant adaptation to conserve water

A

waxy cuticles

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9
Q

C3 Photosynthesis

A

The most prevalent pathway, found in the majority of plants.
Carbon dioxide is initially fixed into a 3-carbon molecule (3-phosphoglycerate).
Best adapted to cool, wet environments.

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10
Q

C4 Photosynthesis

A

An adaptation to hot, dry environments. Carbon dioxide is initially fixed into a 4-carbon molecule (oxaloacetate) in mesophyll cells, then transported to bundle sheath cells for the Calvin cycle. This mechanism helps to minimize photorespiration (a process that reduces photosynthetic efficiency) in hot, dry conditions.

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11
Q

CAM Photosynthesis

A

An adaptation to extremely arid environments.
Carbon dioxide is taken in at night and stored as a 4-carbon molecule, then released during the day for the Calvin cycle. This allows plants to keep their stomata (pores) closed during the day to conserve water, while still being able to photosynthesize.

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12
Q

photorespiration

A

This wasteful metabolic pathway begins when rubisco, the carbon-fixing enzyme of the Calvin cycle, grabs O2 rather than CO2 It uses up fixed carbon, wastes energy, and tends to happens when plants close their stomata (leaf pores) to reduce water loss. High temperatures make it even worse.

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13
Q

xerocole

A

animals that are adapted to dry conditions

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14
Q

xerophyte

A

plants that are adapted to dry conditions

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15
Q

nurse plant

A

plant that allows seedlings to establish themselves, promoting growth of other plant species

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16
Q

erg

A

large sand dune region

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17
Q

largest desert

A

antartica 5.5m m^2

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18
Q

desert definition

A

less than 10in (25cm) of precipitation

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19
Q

aridity index

A

A = P/PET = average annual precip/potential evapotranspiration
<0.05 = hyperarid
0.05-0.20 = arid
0.20-0.50 = semiarid
Dry sub-humid: 0.50 < AI ≤ 0.65
Humid: AI > 0.65

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20
Q

desert soils

A

aridisols (parent material with buildups of minerals that would usually be leached like calcium carbonate)
SW and great basin; 8% of US, 12% world
some entisols (indistinguishable from parent material in W)
very little hummus but high in nutrients

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21
Q

desert fires

A

uncommon, most of the time there isn’t enough vegetation

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22
Q

flash flooding mechs

A

earth is hard baked so all the water just runs off immediately after it falls

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23
Q

desert types

A

hot and dry
cold
coastal
semiarid

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24
Q

semiarid desert

A

cooler (20-25 in summer, 10C at night, cooler winters); precip varies but more dew and condensation
gravelly in hills with hardpan bottoms
plants are larger shrubs like creosote; brickelbrush; somewhat more animals (small mammals)
cent asia, great basin, montana

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25
precip in deserts
under 25cm; most in cool winter; precip varies but always low
26
coastal deserts
cool (15-20C in summers) summers and moderate winters; very little precip, often years between atacama and namib very dry adapted animals and plants
27
cold deserts
cold (below freezing winter, 20C in summer); higher precip (15-25cm) mostly as snow in winter; moister higher elev great basin, antarctica/arctic silty soil
28
the sun and deserts
lack of moisture means 90% of solar radiation hits ground vs. 40% in humid/tropical
29
alluvial fan
a fan-shaped area where silt, sand, gravel, boulders, and woody debris are deposited by rivers and streams over a long period of time
30
bajada
alluvial fans merge into a gradual slope from mountains in desert to base
31
Rain Shadow Deserts
Deserts formed by mountains blocking rain.
32
Interior Deserts
Deserts located far from oceanic moisture.
33
Polar Deserts
Cold deserts found in polar regions.
34
Desert Location
Found between 15° and 35° latitude globally.
35
Argids
Aridisols with clay horizon in desert regions.
36
Orthids
Aridisols without distinct soil horizons.
37
Mollisols
Cracking clay soils found in some desert areas.
38
Desert Wildlife
Includes fennec fox, camels, snakes, and meerkats.
39
Desert Plant Life
Includes yuccas, cacti, and short grasses.
40
Indicator Species
Plants indicating desert conditions, like creosote bush.
41
Desertification
Expansion of deserts, affecting 20% of Earth's land.
42
Sahara Desert
Largest hot desert, over 300 million square miles.
43
Plant Adaptations
Features like small leaves and tap roots conserve water.
44
Succulents
Plants storing water in stems, leaves, or roots.
45
Threats to Deserts
Include climate change, environmental degradation, and human development.
46
Drought Deciduousness
Leaves shed during drought to conserve water.
47
Cacti
Plants that store water in their stems.
48
Dust Storms
Winds gather dust, can travel over 1,000 miles.
49
Köppen Climate Zones
Classification system for climate types.
50
Arid Deserts
Receive less than 10 inches of rain annually.
51
Semi-arid Deserts
Receive 10-20 inches of rain annually.
52
Cold Deserts location
Located at 30° latitude up to the poles.
53
Summer Temperature cold desert
Ranges from 21-26° C in cold deserts.
54
Winter Temperature
Ranges from -2 to 4° C in cold deserts.
55
Annual Precipitation
Cold deserts receive 15-25 cm of rain.
56
Indicator Species
Sagebrush indicates desert ecosystem health.
57
Plant Adaptations
Grow close to ground to resist cold.
58
Animal Adaptations
Fur coats help mammals survive freezing winters.
59
Fat Storage
Animals store fat to preserve body weight.
60
Great Basin Desert
Cold desert in North America.
61
Atacama Desert
One of the driest areas on Earth.
62
Camel Thorn Tree
Acacia erioloba, adapted to arid conditions.
63
Welwitschia mirabilis
Unique plant found in desert ecosystems.
64
Great Basin
Region in Western United States with salt flats.
65
Great Salt Lake
Largest saltwater lake in the Western US.
66
Bactrian Camel
Two-humped camel adapted to cold deserts.
67
Namib Desert
Desert known for its gemstone sources.
68
Takla Makan
Desert in Western China, known for sand dunes.
69
Turkestan
Region crossed by ancient caravans.
70
Heat distribution
Uneven land distribution between North and South causes uneven heat distribution.
71
Biomass
Living matter minus water. Low amount produced in desert, which means low net primary productivity.
72
Rain shadow effect
Warm moist air hits mountain and is forced up. It cools and dumps it's precipitation, then cold and dry aid descends to other side. It warms up and begins to suck up water and not deliver any.
73
Vegetation progression
Defines Biomes,changes with water added or lost. Desert scrub --> grassland --> woodland --> forest
74
Sonoran Desert
Hot. Sea level to minor mountains. South of Mojave. Bimodal rainfall. Succulents, cacti. Leguminous trees, and winter and summer diverse annuals.
75
Mojave Desert
Below Great Basin Desert. Variable temperatures. Elevation low around Colorado river, very hot. Also has high elevations, so cold there. On average, hot. Gets winter precipitation. Joshua Tree above 3000 feet. Yucca, cacti, and shrubs. Has a few annuals with increase precipitation.
76
Chihuahuan Desert
Covers high elevation mountains. Hot desert. Most precipitation in summer. Mesquite trees.
77
Bajada Gradient
On slope, large particles at the top and small ones at the bottom. Bottom has low available soil moisture and top has high. Paloverde at top, Sojaro in middle, and Creosote bush at the bottom.
78
Soil Moisture and Particle Size
Tiny particles have much higher surface area/volume ratio. Water attached to particles, and it is hard for plants to pull it away. Only a few, like creosote bush, can.
79
Winter Rains
Large and long lasting. Large winter storms from Pacific. Makes it over mountains in Great Basin, and it snows. Mojave also gets snow, Sonoran gets some.
80
Summer precipitation
precipitation Monsoons. Intense, local, short duration convection storm. Sonoran and Chihuahuan.
81
Compound Leaf Advantage
Lower dead air space so less insulation and can cool down more.
82
Winter Annuals
Needs moisture enough to wash out germination inhibitor. Low temps also needed. Have long growing season, not arid adapted.
83
Summer Annuals
Growing cue is moisture and high temperature. Short growing season, and has arid tolerance.
84
Sonoran Vegetation
Winter and summer annuals. COlumnar and non-columnar cacti. Legume trees with compound leaves or leaflets. Sojuaro and Cardone cacti.
85
Pack-Rats Middens
Pile stuff up above underground burrow to make it hard for predators to get in. Urine glues stuff together. Take things from 100 m radius zone. If protected from weather, you can see climate and vegetation based on layers. Gets older as you go down. Can be checked with pollen records in lakes.
86
Sky Island Formation
Mesic plants move up in elevation as basin dries up, and desert scrub moves into hot and arid areas. GB had sage brush isolate, and others had creasote bush. Mesic organisms now have less geographic extent, can differentiate ino new species because no gene flow.
87
Nurse Plants2
Have detritus at base that is hydrophilic, increases moisture content, good for seeds to germinate in. Covers baby plants from frost, acts as insulator and reradiaor of some of the heat. Hard for granivores to find seeds with crap in the way.
88
Water Savers
Not succulents, adaptions to prevent water loss. Small leaf size, sunken stomates. Need CO2, holes bring in, goes out by diffusion. Pubescence, fuz on it to make lighter color and reflect more lift. Deciduous leves, falls off if can't afford them.
89
Water Collectors
Succulents. Have CAM photosynthesis. Shallow root system, salt secretion, dew absorption. Hold water inside.
90
Water Spenders
At bottom of arroyos, have very deep tap root so hits water table. Mesquite.
91
arroyos
a steep-sided gully formed by the action of fast-flowing water in an arid or semi-arid region, found chiefly in the southwestern US.
92
Drought Escapers
Desert Annuals. Hang out as seed until moisture so don't need extreme stress adaptions.
93
Dehydration tolerance
Incompletely understood protoplasmic properties. Creosotebush. Ex: Salt bush, removes salt from really salty water and extrudes it so reflects more light.
94
Reduce Water Loss Plant adaptions
No leaves or drought deciduous leaves, photosynthesis in stem, spines, tiny leaves.
95
Reduce Heat Load Plant adaptions
Small leaves, so decrease boundary layer so a cooler leaf. Increase albedo with white color from salt glands or shiny leaves or white fuzz or irregular wax surface. Vertical leaves, so less sun radiation and leaves shade each other.
96
C3 Photosynthesis
Fixing CO2 from atmosphere into biosphere. Rubisco grabs CO2 and reacts with 5C molecule RuBP to form an unstable 6C molecule that splits into 2 3C PGA. At the end, have 6C molecule to store in starch. Evolved 2.8 bya, when there was a huge amount of CO2 in the atmosphere.
97
Rubisco
Has a high affinity for CO2 but has a higher affinity for O2, especially when temperatures are high. C3 using rubisco doesn't work in deserts, respiration happens instead. Works well in shade and in mesic conditions.
98
C4 Photosynthesis
PEP Carboxylase only has affinity for CO2, creates a 4C molecule. Much better at high temperatures, but costly. Worse than C3 at low temperatures. PEP Carboxylase part take place in mesophyll, then 4C goes to bundle sheath cells where Rubisco fixes using C3. Bundle sheath cells are insulated from atmosphere. Not light saturated, needs heat to drive it.
99
Stomata in heat
If hot and dry, plant gets desiccated, so the stomates close. Stops water from leaving but can't get CO2. Concentration of O2 goes up, which Rubisco binds with.
100
CAM Photosynthesis
Water collectors. Close Stomates in daytime to prevent water from leaving. At night, takes in CO2, turns into malic acid, which in day turns into 2C and CO2 and CO2 undergoes C3. Huge vacuoles with water to dilute because malic acid makes it very acidic.
101
Semelparous
Long periods of growth with no reproduction, then one huge reproductive episode. Cost: If you die early, can't reproduce att all. Unpredictable climate or predators may kill all offspring. Benefit: Can put lots of energy into producing seeds. So many that someone's gotta live. Satiate seed predators.
102
Iteroperous
Long life with several small reproductive events. Costs: Spending lots of energy. Benefits: Possible for all to die, oh well try again next year. If die young, put something out there.
103
Brown Fat
Clustered around organs and generate heat. Has some fat but lots of cytoplasm with tightly packed mitochondria. No ATP Synthase, so energy generates heat.
104
Torpor
Overnight temporary body temperature reduction. Micro hibernation.

Ecology (3 decks)

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