The concept of ecosystems and their global distribution

An ecosystem is a dynamic community of living organisms interacting with their non-living environment, including elements like soil, water, and climate. Large-scale ecosystems, also known as biomes, are distributed across the globe in patterns largely determined by climatic conditions.

The type of ecosystem in a region is primarily shaped by its climate, including the specific patterns of temperature and precipitation. Diverse climates around the world result in a variety of ecosystems, from lush rainforests near the equator to barren tundras at high latitudes.

Factors influencing ecosystem distribution

While climate plays the dominant role in determining where ecosystems develop, local factors also significantly impact their formation and characteristics. These factors influence the types of plants and animals that can thrive in a given area.

Key influences on ecosystem distribution

• Climate - Temperature, rainfall, and hours of sunshine are the primary drivers, dictating the overall structure and productivity of an ecosystem.
• Altitude - Higher elevations experience colder temperatures, resulting in fewer plant species, limited animal diversity, reduced organic matter, and thinner soils.
• Soil - The type of soil affects plant growth through:
  • Nutrient content - Nutrient-rich soils support denser vegetation.
  • Acidity levels - Highly acidic soils, like peat, only sustain acid-tolerant species such as conifers.
  • Drainage and texture - Clay soils, which are sticky and retain water, challenge plants needing well-drained conditions, while thin soils lack nutrients for larger plants.

Characteristics of forests

Tropical, temperate, and boreal forests are three major forest ecosystems, each adapted to distinct climatic conditions.

Tropical forests

• Location - Found in low-lying regions close to the equator.
• Climate - Hot and wet throughout the year, with a consistent 12-hour day length.
• Vegetation - Dominated by evergreen trees that grow rapidly and are adapted to capture maximum sunlight.
• Wildlife - Extremely high biodiversity, supported by dense vegetation offering varied food sources and habitats.
• Soils - Continuous leaf fall and decomposition ensure a constant cycle of nutrients, maintaining soil fertility.

Temperate forests

• Location - Situated in mid-latitudes with moderate climates.
• Climate - Features four distinct seasons, with warm summers, cool winters, and high rainfall, often reaching up to 1400 mm annually.
• Vegetation - Comprises broad-leaved deciduous trees that shed leaves in autumn, along with shrubs and undergrowth.
• Wildlife - Supports a diverse range of mammals, birds, and insects, sustained by seasonal plant growth.
• Soils - Thick and nutrient-rich due to the decomposition of autumn leaf litter, enhancing soil fertility.

Boreal forests

• Location - Found in high latitudes with a cold climate.
• Climate - Characterised by short summers and long winters, with temperatures dropping to -20°C in winter and rising to around 10°C in summer; precipitation is low, under 500 mm yearly, mostly as snow.
• Vegetation - Mainly evergreen conifers, alongside mosses and lichens, suited to cold conditions.
• Wildlife - Fewer species compared to other forests, but includes large mammals adapted to the cold.
• Soils - Thin, acidic, and nutrient-poor, with much of the ground frozen for extended periods.

Characteristics of deserts and tundra

Deserts and tundra are uniquely adapted to harsh environmental conditions, including extreme temperatures and very low precipitation.

Deserts

• Location - Positioned between 15° and 25° north and south of the equator, in zones of high pressure and minimal rainfall.
• Climate - Receives less than 250 mm of rain annually, with extreme temperature swings, often reaching 45°C during the day and falling below 0°C at night.
• Vegetation - Sparse, with drought-resistant plants that often have short life cycles to exploit brief periods of moisture.
• Wildlife - Limited to a few specially adapted species, such as reptiles and arthropods, capable of surviving with minimal water.
• Soils - Thin and lacking nutrients due to scarce vegetation and slow decomposition rates.

Tundra

• Location - Situated at high latitudes, above 60°N.
• Climate - Extremely cold, with winter temperatures below -30°C and summer temperatures between 5°C and 10°C; precipitation is low, under 250 mm annually.
• Light conditions - Features continuous daylight in summer and little to no daylight in winter.
• Vegetation - Restricted to mosses, grasses, and low shrubs due to harsh conditions.
• Wildlife - Limited to a few species, including Arctic animals and migratory birds.
• Soils - Thin and nutrient-poor, with a permafrost layer that hinders drainage and root growth.

Characteristics of grasslands

Grassland ecosystems are shaped by specific climatic and geographical conditions, resulting in distinct vegetation and animal life adapted to their environments.

Tropical grasslands

• Location - Near the equator in regions where rainfall is too low to support forests, typically between 800-900 mm per year.
• Climate - Marked by distinct wet and dry seasons, with temperatures varying from 15°C to 35°C; frequent fires occur during the dry season.
• Vegetation - Dominated by grasses, scrub, and occasional drought-resistant trees.
• Wildlife - Rich in insects, large herbivores, and predators, supported by open landscapes.
• Soils - Thin but relatively nutrient-rich, though nutrients are often leached away during wet seasons.

Temperate grasslands

• Location - Found at higher altitudes and latitudes compared to tropical grasslands.
• Climate - Experiences extreme temperature ranges, from 40°C in summer to -40°C in winter, with precipitation between 250-500 mm annually.
• Vegetation - Primarily grasses and small plants, with few trees due to limited rainfall.
• Wildlife - Includes grazing mammals and burrowing rodents adapted to open terrain.
• Soils - Thick and fertile due to rapid decomposition of plant material during warmer months.