AP Environmental Science

Ecosystem

A community of living (biotic) organisms interacting with the non-living (abiotic) components of their environment as a system through various nutrients and energy cycles.

Organism

A living thing that can function on its own.

Species

Organisms that resemble each other; are similar in genetic makeup, chemistry, and behavior; and are able to interbreed and produce fertile offspring.

Interspecific

Means between different species.

Population

Organisms of the same species that interact with each other and occupy a specific area.

Community

Population of different species.

Ecological Niche

A particular area within a habitat occupied by an organism, as well as the function of that organism within its ecological community.

Physical environment

It influences how organisms affect and is affected by resources and competitors.

Niche

It reflects the specific adaptations that a species has acquired through evolution.

Symbiosis

A term used to describe any type of close and long-term biological interaction between two different biological organisms of the same or different species.

Amensalism

The interaction between two species whereby one species suffers and the other species is not affected.

Commensalism

The interaction between two species whereby one organism benefits and the other species is not affected.

Competition

It can be either intraspecific and interspecific. It is the driving force of evolution whether it is for food, mating partners, or territory.

Intraspecific

Competition between members of the same species.

Interspecific

Competition between members of different species.

Mutualism

The interaction between two species whereby both species benefit.

Parasitism

The interaction between two species whereby one species is benefited, and the other species is harmed.

Predation

Predators hunt and kill their prey.

Opportunistic predators

Kill and eat almost anything.

Specialist predators

Only prey upon certain organisms.

Saprotrophism

Saprotrophs obtain their nutrients from dead or decaying plants or animals through the absorption of soluble organic compounds.

Law of Tolerance

It states that the existence, abundance, and distribution of species depend on the tolerance level of each species to both physical and chemical factors.

Limiting Factor

Any abiotic factor that limits or prevents the growth of a population.

Predator-prey relationship

Predator-prey cycles are based on a feeding relationship between two species.

Morphological partitioning

It occurs when two species share the same resource but have evolved slightly different structures to utilize the same resource.

Spatial partitioning

It occurs when competing species use the same resource by occupying different areas or habitats within the range of occurrence of the resource.

Temporal partitioning

It occurs when two species eliminate direct competition by utilizing the same resource at different times.

Biomes

These are major regional or global biotic communities characterized by dominant forms of plant life and the prevailing climates.

Determinants of biomes

Temperature and precipitation are the most important determinants of biomes.

Deserts

Defined in terms of the amount of rainfall they receive, not temperature. They cover about 20% of Earth's surface and occur where rainfall is less than 20 inches (50 cm) per year.

Daily extremes in temperature in deserts

Result from exceptionally low humidity as water vapor tends to block solar radiation.

Location of most deserts

Most deserts are located between 15° and 35° north and south latitudes.

Arctic tundra

A cold desert due to the low amount of rainfall it receives yearly.

Succulents

Plants that have fleshy leaves or stems that store water.

Characteristics of succulents

They have deep roots to tap groundwater, open stomata at night, shallow roots to collect and store water after short rainfalls, small surface areas exposed to sunlight, vertical orientation to minimize exposure to the sun, and waxy leaves to minimize transpiration.

Cactus

They have sharp spines that create shade, reduce drying airflow, discourage herbivores, and reflect sunlight.

Wildflowers

They are dependent on water for germination, have short life spans, perform their entire life cycle from seed to flower to seed within a single growing season, and store biomass in seeds.

Desert animals

They are generally small, often nocturnal, have small surface areas, and spend time in underground burrows where it is cold.

Aestivation

A summer hibernation.

Forests

Forests cover about one-third of Earth's land surface, mostly in North America, the Russian Federation, and South America, and account for 75% of gross primary productivity and plant biomass.

Ecozones

Ecozones like boreal forests near the poles and tropical forests near the equator are formed by forests at different latitudes and elevations.

Closed canopy

Tree crowns cover more than 20% of the ground's surface, making up the majority (80%) of the forest biome.

Open canopy

Tree crowns cover less than 20% of the ground surface.

Tropical Rainforests

Animals include numerous birds, bats, small mammals, and insects. Decomposition is rapid and soils are subject to heavy leaching.

Characteristics of tropical rainforests

Distinct seasonality where winter is absent and only two seasons are present, with an annual rainfall exceeding 80 inches (200 cm) that is evenly distributed.

Temperature in tropical rainforests

Temperature is warm to hot and varies little throughout the year.

Temperate Deciduous Forests

Occur in eastern North America, northeastern Asia, and western and central Europe, with a distinct winter, moderate climate, and a 140-200-day growing season during four to six frost-free months.

Temperature range in temperate deciduous forests

Temperature varies from -20°F to 85°F (-30°C to 30°C).

Precipitation in temperate deciduous forests

Precipitation averages 30-60 inches (75-150 cm) per year.

Soil in temperate deciduous forests

Fertile soil is enriched by decaying leaf litter.

Temperate Coniferous Forest

Found in temperate regions with warm summers, cool winters, and enough rainfall to support forests.

Overstory

The uppermost trees in a forest.

Understory

Layer made up of young trees, short species of trees, shrubs, and soft-stemmed plants.

Shrub Layer

Some forests have a shrub layer.

Grassy Understories

Grassy understories in pine forests often burn in ecologically important wildfires.

Conical Trees

Conical trees shed snow and protect branches.

Dark Green Needles

Dark green needles absorb more light for photosynthesis.

Needles

Needles have thick waxy coatings, waterproof cuticles, and sunken stomates.

Transpiration

Needles reduce transpiration by reducing surface area.

Hibernation

In winter, when food is scarce, many animals hibernate to conserve energy and build fat in summer.

Migration

Some animals migrate to warmer climates during the winter months.

Taiga

Largest terrestrial biome; found in northern Eurasia, North America, Scandinavia, and two-thirds of Siberia.

Southern Taiga

Also known as boreal forest, consists primarily of cold-tolerant evergreen conifers with needle-like leaves, such as pines, spruces, and larches.

Northern Taiga

It is more barren as it approaches the tree line and the tundra biome.

Taiga Climate

Cold temperatures, wet soil during the growing season, and needle and moss acids slow organic matter decay.

Taiga Seasons

Seasons are divided into short, moist, moderately warm summers and long, dry, freezing winters.

Grasslands

Grasslands are characterized as lands dominated by grasses rather than by large shrubs or trees.

Savannas

These are grasslands with scattered individual trees and cover almost half the surface of Africa and large areas of Australia, South America, and India.

Savanna Climate

Savannas are found in warm or hot climates with an annual rainfall of 20 to 50 inches (50-130 cm) concentrated in six to eight months, followed by a long drought.

Savanna Soil

Savanna soil drains quickly and has a thin layer of humus to nourish vegetation.

Temperate Grassland

Here grasses are the dominant vegetation, while trees and large shrubs are absent.

Examples of Temperate Grasslands

Examples include the veldts of South Africa, the pampas of Argentina, the steppes of Russia, and the plains and prairies of central North America.

Temperate Grassland Climate

Climate is characterized by hot summers and cold winters, and rainfall is moderate.

Biodiversity in Savanna

Seasonal fires help savannas' biodiversity during dry and rainy seasons.

Tundra

It has extremely low temperatures, large repetitive population changes, limited soil nutrients, little precipitation, low biotic diversity, poor drainage, short growing and reproductive seasons, and simple vegetation structure.

Arctic Tundra

It circles the North Pole and extends south to the taiga, is cold, dry, and desert-like.

Growing Season in Arctic Tundra

The very short growing season averages around 50 days per year.

Summer Temperatures in Arctic Tundra

Summer temperatures range from 37°F to 54°F (3°C to 12°C).

Winter Temperatures in Arctic Tundra

Winter temperatures average -30°F (-34°C).

Yearly Precipitation in Arctic Tundra

Yearly precipitation, including melting snow, is 6 to 10 inches (15 to 25 cm).

Permafrost

A layer of permanently frozen subsoil.

Bogs and Ponds in Arctic Tundra

Bogs and ponds form when water saturates the upper surface, providing moisture for cold-resistant plants.

Plant Adaptations in Arctic Tundra

All plants are adapted to sweeping winds and disturbances of the soil.

Animal Adaptations in Arctic Tundra

Animals are highly specialized for long, cold winters and quick breeding and raising young in summer.

Herbivorous Mammals in Arctic Tundra

Herbivorous mammals include lemmings, caribou, Arctic hares, and squirrels.

Carnivorous Animals in Arctic Tundra

Carnivorous animals include Arctic foxes, wolves, and polar bears.

Migratory Birds in Arctic Tundra

Migratory birds include ravens, falcons, terns, snowbirds, and various species of gull.

Alpine Tundra

It is located on mountains throughout the world at high altitudes where trees cannot grow.

Growing Season in Alpine Tundra

The growing season is approximately 180 days, with nighttime temperatures usually falling below freezing.

Aquatic Biomes

Antarctic, marine, lakes, wetlands, and rivers and streams comprise aquatic biomes.

Nutrient Source for Aquatic Organisms

Aquatic organisms get nutrients from water.

Thermal Capacity of Water

Water's thermal capacity is high, most aquatic organisms don't need to regulate temperature.

Antarctica

Antarctica has the coldest climate on Earth.

Average Temperature in Antarctica

The interior averages −70°F (−57°C), while the coast averages 14°F (−10°C).

Antarctica's Total Precipitation

Antarctica's total precipitation (mostly snow) averages ~6.5 inches (166 mm) per year.

Krill

These are key food sources in this ecosystem and serve as food for many predators.

Marine Biomes

Oceans cover approximately 75% of Earth's surface and have a salt concentration of about 3%.

Primary Source of Rainfall

Evaporation of seawater is the primary source of most of the world's rainfall.

Net Primary Productivity in Oceans

Oceans have the highest net primary productivity per unit area of Earth.

Net primary productivity

Oceans have the highest net primary productivity per unit area of Earth.