Deserts and Desert Ecosystems - Week 2 Notes

Vocabulary flashcards covering deserts geography, abiotic factors, adaptations, soils, and species patterns.

Global desert coverage

Deserts occupy about 20–30% of Earth's terrestrial surface.

Desert population

About 1 billion people live in deserts, roughly 1/6 of the world population.

Desert rainfall threshold

Deserts are defined by an annual rainfall of about 10 inches (25 cm) or less.

Subtropical desert

Deserts formed by Hadley cell circulation producing dry air and high pressure, leading to low precipitation.

Cold desert

Deserts at higher latitudes with cold conditions and low precipitation.

Coastal desert

Deserts near cold coastal waters; fog and humidity are high but not enough to cause significant precipitation.

Fog Oasis

A moist microhabitat where fog condensation supports plant and animal growth in coastal/desert regions.

Rainshadow desert

Desert on the leeward side of a mountain where moisture is blocked from prevailing winds.

Interior desert

Desert located far from water sources; often with endemic species and variable rainfall.

Boom cycles

Periods of variable, high-volume precipitation that allow rapid plant growth in deserts.

Liebig’s Law of the Minimum

Population growth is limited by the scarcest resource, not by the total amount of resources.

Limiting resource

The resource in shortest supply that constrains growth (e.g., water, nutrients).

Water availability

One of the primary limiting resources for desert organisms.

Soil fertility

Nutrient content of soil that affects plant growth.

Extreme temperatures

Large temperature fluctuations that can limit organism performance in deserts.

Principle of Tolerance Limits

Organisms have an optimal growth range with limits beyond which growth declines.

Stenothermal

Narrow, restricted optimal temperature range for a species.

Eurythermal

Wide tolerance to a range of temperatures.

Net Primary Productivity (NPP)

Biomass and organic matter produced by photosynthesis after accounting for respiration.

Photosynthesis

Process by which plants convert CO2 and H2O into glucose and O2 using light energy.

Xylem water transport

Movement of water up the plant via cohesion and adhesion in the xylem, driven by transpiration.

Crassulacean Acid Metabolism (CAM)

Desert photosynthesis where CO2 is fixed at night as malate and used in the day for the Calvin cycle.

Desert soils horizons

Desert soils typically have horizons such as O, A, E, B, and C reflecting weathering and deposition.

Ardisol

Desert soil order (as listed): an arid soil developed from parent material.

Alfisol

Desert soil order with ill-defined argillic/pale horizons and typically higher fertility than aridisols.

Oxisol

Highly weathered tropical soil order; in deserts may be listed among desert soil types.

Transpiration

Plant cooling via evaporation of water from stomata.

Perspiration

Animal cooling through sweating or evaporative cooling.

Nocturnal behavior

Desert animals active at night to avoid daytime heat.

Aestivation

Drought-time dormancy or hibernation-like state in hot, dry conditions.

Adaptation

Heritable trait that improves an organism's survival and reproductive success.

Escaping

Adaptive strategy of avoiding bad conditions by migrating or relocating.

Evading

Adaptive strategy of avoiding dry conditions through burrowing or deep rooting.

Resiting

Adaptive strategy of living within a stressful zone by tolerance and resource concentration.

Enduring

Traits enabling survival in harsh conditions (e.g., aestivation).

Structural adaptation

Physical changes like leaf coatings, skin, or exoskeleton to reduce water loss.

Physiological adaptation

Internal functional changes to conserve water or optimize metabolism.

Behavioral adaptation

Behavior changes such as timing activities to cooler periods.

Life History Strategies

Evolutionary trade-offs in reproduction and energy use to survive in deserts.

Desert species diversity patterns

Mammal diversity is higher along western coasts; reptiles along the south; birds along coastlines.