b - Biomes Summary

Biomes

Characteristic communities of plants and animals in similar climate regions are called biomes.

Terrestrial Biomes

Driven by regional climate and characterized by vegetation patterns:

• Tropical Rainforest: Warm temperatures, heavy rainfall, high tree diversity.

• Deserts: Found in dry regions; plants like cacti store water.

• Deciduous Forests: Hardwood deciduous trees.

• Savannahs: Tall perennial grasses in warm, dry regions.

• Taiga: Cool, moist, low-lying forests, the world's largest land biome.

The dominant plants in similar biomes on different continents may look similar but are often not closely related, an example of evolutionary convergence.

Evapotranspiration from plants links to the global water cycle, influencing biome distribution. Water moves between reservoirs like the atmosphere, oceans, and groundwater.

Potential evapotranspiration compared to global precipitation patterns determines vegetation types. Deserts have high evapotranspiration ratios, while rainforests have low ratios.

Aquatic Biomes

Split into freshwater, estuary, and saltwater categories. Nutrient and oxygen availability, along with sunlight penetration, are key factors.

Freshwater Biomes

Lakes and rivers/streams. Turbulent waters in rivers/streams are oxygen-rich, while lakes can stratify, leading to anoxic conditions at lower depths.

Estuaries

Ecotones between freshwater and saltwater, with varying salinity levels. They serve as hatchery areas for commercial fish.

Saltwater Biomes

Oceans cover 70% of Earth's surface. Habitats are divided by depth and proximity to the shore.

• Neritic System: Shallow, nearshore, includes intertidal and coral reef habitats.

• Intertidal Biome: Between high and low tide marks.

• Coral Reefs: Diverse, found in shallow, tropical environments; also occur in deep sea.

• Oceanic System: Divided into photic (sunlit) and nonphotic (dark) zones. Deep sea relies on detritus or chemoautotrophs for energy.