Ecology 6e – Biomes, Climate, Freshwater & Marine Ecosystems; Ancient Egypt

Flashcards covering core concepts of biomes, climate patterns, freshwater and marine ecosystems, mountain ecology, and Ancient Egypt as discussed in the lecture notes.

What is the biosphere and where is it located?

The zone of life on Earth; it lies between the lithosphere (Earth’s surface crust and upper mantle) and the troposphere (the lowest layer of the atmosphere).

What are biomes?

Large-scale terrestrial communities shaped by the physical environment; categorized by dominant plant growth forms and leaf traits; taxonomic relationships are not taken into account.

How are terrestrial biomes categorized?

By dominant plant growth forms and characteristics such as leaf deciduousness or succulence.

Why are we vegetation biased in biome concepts?

Because plants don’t move and often have long lifespans, so biome classifications emphasize plant responses to the environment.

Where are tropical rainforests located and what are two key features?

Located between 10°N and 10°S; abundant rainfall and high biomass with high species diversity.

What is a key factor for growth in tropical rainforests and what arrangement helps plants cope with light?

Light is key; plants must grow tall or adjust to low light, with emergent plants rising above the canopy.

What proportion of Earth’s species live in tropical rainforests?

About 50%.

What plant growth form rises above the canopy in tropical rainforests?

Emergent plants.

What plants commonly use trees as support in tropical rainforests?

Vines and epiphytes (e.g., Spanish moss) use trees for support.

Where are tropical seasonal forests and savannas located relative to the wet tropics?

North and south of the wet tropics.

What seasonal patterns characterize tropical seasonal forests and savannas?

Wet and dry seasons.

How do tropical seasonal forests and savannas differ in tree height and leaf behavior during dry seasons?

Shorter trees; deciduous in dry seasons; more grasses and shrubs.

What ecological process fires promote in tropical seasonal forests and savannas?

Establishment of savannas: grasses with intermixed trees and shrubs.

Which large African herbivores influence the grass–tree balance in savannas?

Wildebeests, zebras, elephants, and antelopes.

What percentage of seasonal tropical forests and savannas remain?

Less than half.

What are the key characteristics of deserts and where do they form?

High temperatures, low moisture, sparse vegetation; at high pressure zones around 30°N and 30°S.

Why do cacti and euphorbs show convergent evolution in deserts?

Both have adaptations to store water in arid conditions.

What other plant forms are common in deserts besides succulents?

Shrubs, grasses, and short-lived annuals that take advantage of brief rains.

Where are temperate grasslands located and what maintains them?

Between about 30° and 50° latitude; maintained by frequent fires and large herbivores; high soil fertility.

What threats have converted many temperate grasslands?

Agriculture; grazing can lead to desertification; irrigation can cause soil salinization.

What characterizes temperate shrublands and woodlands?

Between 30° and 40° latitude; evergreen shrubs/trees; Mediterranean climate with cool, wet winters and hot, dry summers; sclerophyllous leaves.

What is the role of fire in temperate shrublands?

Fire is common and helps maintain the biome; without regular fires shrublands may be replaced by forests.

What challenges affect shrublands due to human activity?

Urban development; nutrient-poor soils; invasive grasses; more frequent fires reduce recovery.

What are the defining features of tundra and where is it located?

Above 65° latitude; cold temperatures, low precipitation; short summers; permafrost; sparse human settlements.

What has Arctic warming done to the tundra relative to the global average?

The Arctic has warmed almost double the global average.

What does elevation do to climate in mountains and what zones are identified?

Elevation creates latitudinal-like gradients with zones such as lower montane, montane, subalpine, and Alpine; mean annual temperature decreases with elevation.

Name the four elevational zones listed from lowest to highest.

Lower montane, Montane, Subalpine, Alpine.

What tropical alpine plant example is discussed and what is its leaf form?

Espeletia spp. with rosette leaves that protect developing leaves from frost.

What stream order system describes streams from smallest to largest?

First-order streams are the smallest; they converge to form second-order streams; large rivers are sixth-order or greater.

What is the river continuum concept?

As streams increase in size, detritus becomes less important and fine organic matter, algae, and macrophytes become more important; shredders give way to collectors.

What habitats are found in lentic (still) waters and what determines their nutrient status?

Lakes and ponds; deep lakes are nutrient-poor; shallow lakes with large surface area are nutrient-rich.

What are pelagic, littoral, and benthic zones?

Pelagic: open water dominated by plankton; Littoral: near shore where photic reaches bottom and macrophytes occur; Benthic: bottom-dwelling organisms and detritivores; hyporheic zone lies beneath/near streams.

What factors influence marine organisms?

Salinity, temperature, light, water depth, bottom substrate, and interactions with other organisms.

What influences nearshore marine zones?

Local climate, tides, waves, and influx of fresh water and sediments from rivers.

What is the photic zone depth range in marine environments?

Approximately 0.5 to 200 meters.

What are estuaries and why are they productive?

Where rivers flow into oceans; salinity varies with mixing; rivers bring in sediments and nutrients that boost productivity.

What dominates salt marshes and how do salinity gradients shape them?

Shallow coastal wetlands dominated by grasses and rushes; tides create salinity gradients that determine species distributions.

What role do mangrove forests play in coastal ecosystems?

Salt-tolerant evergreen trees/shrubs; roots trap sediments and provide nutrients and habitat; threatened by human development (e.g., shrimp farming).

What characterizes rocky intertidal zones?

Stable substrates for many organisms; residents cope with wet/dry cycles and varying salinity due to tides.

What ecosystems are common in shallow ocean zones and why are they important?

Coral reefs, seagrass beds, and kelp beds; support high biomass production and diverse communities.

What is notable about deep benthic zones?

Cold temperatures, very high pressure, sparse populations; bioluminescence used by predators.

What factors contributed to the fragility of Ancient Egypt’s food webs according to the slides?

Aridification pulses and human population growth.