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BIOMES AND ECOSYSTEMS

What is a Biome?

A biome is a large ecological area on the Earth's surface, characterized by distinct climates, soil types, and unique communities of plants and animals. Biomes are composed of multiple ecosystems that share similar environmental conditions, including temperature, precipitation, and biodiversity. For instance, various biomes can be found in Korea, ranging from temperate forests to coastal regions, each supporting different forms of life and ecological interactions.

Major Biomes

Biomes are categorized into two main types, with several subcategories:

Land Biomes (4):

1. Deserts:

   • Characterized by low precipitation (less than 25 cm annually).

   • Temperature can vary dramatically between day and night.

   • Flora and fauna have adapted to harsh conditions (e.g., succulents like Saguaro Cactus, nocturnal animals to escape daytime heat).

2. Forests:

   • Classified mainly into tropical, temperate, and boreal (taiga) forests.

   • High biodiversity, with dense vegetation and layers of tree canopy.

3. Grassland:

   • Receives between 25-75 cm of rain, ideal for grasses and few trees.

   • Experiences periodic fires and droughts, which can rejuvenate the ecosystem.

   • Includes savannas, which are grasslands located near the equator supporting large herbivores.

4. Tundra:

   • Cold, dry regions with little precipitation, mostly in the Arctic.

   • Characterized by permafrost and short growing seasons with limited flora and fauna.

Aquatic Biomes (2):

1. Freshwater:

   • Includes ecosystems such as rivers, lakes, and wetlands.

   • Organisms are specially adapted to lower salt concentrations; key examples include various fish species and aquatic plants.

2. Marine:

   • Encompasses oceans, coral reefs, and estuaries.

   • Exhibits high biodiversity with organisms suited for varying ocean depths and salinities, like fish, marine mammals, and coral species.

Factors Influencing Biomes

Climate:

• Encompasses long-term weather patterns, focusing on temperature and precipitation, which directly influence the types of organisms that can thrive in a biome.

Terrain:

• Geography plays a critical role, affecting biomes through physical features like mountains, valleys, and bodies of water, which can create microclimates within a biome.

Latitude and Climate:

• Latitude Zones: Different latitudes receive varying amounts of sunlight, affecting climate conditions and the distribution of biomes:

  • Frigid Arctic Circle (66°19'N): Low sunlight angle leads to cold climates.

  • Temperate Zone (around 30°N): Moderate sunlight and seasonal variations.

  • Tropic of Cancer and Capricorn (23.5°N & 23.5°S): Direct sunlight, leading to tropical conditions.

  • Equator (0°): Receives the most direct sunlight, resulting in warm and humid climates.

Altitude and Climate:

• Altitude (Elevation): Climatic conditions change with elevation. Typically, the temperature decreases by approximately 3°C for every 500 m increase in elevation.

Ocean Currents:

• Ocean currents significantly influence climate and weather patterns, contributing to temperature distributions across global biomes.

Seasonal Changes:

• Earth's axial tilt results in seasonal variations, impacting temperature and precipitation patterns in different regions, with each biome experiencing Spring, Summer, Autumn, and Winter differently.

Biome Climate Determinants

Biomes are primarily determined by:

• Temperature

• Precipitation

Abiotic Factors Affecting Biomes

Key abiotic factors include:

• Insolation (Solar Radiation)

• Precipitation

• Temperature

• Precipitation to Evaporation Ratio:

  • Critical for assessing biome health. For example:

    • Tundra (Norway): Precipitation = 75 cm, Evaporation = 50 cm → P/E ratio = 1.25.

    • Desert (Jordan): Precipitation = 5 cm, Evaporation = 50 cm → P/E ratio = 0.1.

• The P/E ratio influences soil fertility, where salinization can occur when minerals leave behind salts.

Biome Productivity

Productivity indicates the efficiency of biomes in producing organic material:

• High Productivity: Estuaries, swamps, and tropical rainforests, benefiting from abundant sunlight, nutrients, and water.

• Lower Productivity: Deserts, tundras, and extreme environments where harsh conditions limit life.

Climate Change and Biome Shift

Rapid climate change is prompting shifts in biomes:

• Projected temperature increases of 1.5 to 4.5°C by 2100 (per IPCC).

• Increased warming noted in higher latitudes, especially during winter months.

• Shifts may occur towards poles or elevations, impacting the distribution of species and habitats.

Migration Challenges for Species

• Obstacles for Plant Migration: Limited seed dispersal, slow adaptation leads to challenges adapting to climate shifts.

• Animal Migration Challenges: Barriers such as mountains and seas, as well as human-induced obstacles (roads, cities), hinder movement, leading to potential extinction risks due to migration failure.

Biodiversity Hotspots Due to Climate Change

Regions under potential threat due to climate change include:

• Himalayas

• Equatorial Eastern Africa

• Mediterranean Region

• Madagascar

• North American Great Plains

Societal Implications

Approximately one billion people are considered vulnerable to alterations within biomes. Climate change also opens opportunities for resource exploitation (e.g., oil drilling in the Arctic, new trade routes).

Atmospheric Circulation

The Tricellular Model explains atmospheric circulation and biome distribution:

• Hadley Cell: Hot air rising at the equator creates low pressure, leading to rainforests.

• Ferrel Cell: Westerlies at mid-latitudes result in variable weather patterns impacting forests and grasslands.

• Polar Cell: Cold air sinking at the poles generates high pressure, leading to tundra conditions.

Energy Transfer in the Atmosphere

Energy from solar radiation, primarily received at the tropics, influences climate and productivity:

• Insolation is highest at the tropics and lowest at the poles, contributing to declines in productivity as latitude increases.

Rainforest Types

Temperate Rainforest:

• Moderate temperatures and over 300 cm of rain annually, characterized by large trees like Cedars and Redwoods.

Tropical Rainforest:

• Warm and humid climates support a diverse range of vegetation and high precipitation levels.

Desert Biomes

Deserts expose organisms to extreme conditions with less than 25 cm of annual rain, leading to drastic daytime and nighttime temperature shifts. Organisms have adapted uniquely to thrive in these environments.

Grasslands

Grasslands, receiving between 25-75 cm of rain, are defined by periodic fires and droughts. The savanna, located near the equator, receives more rainfall, supporting larger fauna compared to other grassland types.

Deciduous Forest

Characterized by trees that shed their leaves yearly, these forests are sustained by adequate rainfall levels, contributing to high biodiversity.

Boreal Forest (Taiga)

Consists of coniferous trees adapted to severe winters and moderate summers.

Tundra

Found in cold, dry regions with minimal precipitation, tundras feature permafrost and seasonal ponds, with flora and fauna uniquely adapted to harsh climatic conditions.

Freshwater Ecosystems

These ecosystems encompass streams, rivers, ponds, and lakes, hosting a variety of specialized organisms adapted to freshwater environments.

Marine Ecosystems

Marine biomes include estuaries, intertidal zones, neritic zones, and the open ocean, featuring unique life forms adapted to fluctuating conditions such as salinity and pressure.