Characteristics of Ecosystems and Global Biomes

An ecosystem is considered self-supporting due to several intrinsic functional characteristics and interactions between its components: - A continuous flow of energy through the system. - The recycling of inorganic nutrients between the biotic and abiotic components. - The adjustment of biotic population sizes according to the volume of food resources available for each specific population.

Biomes are defined as large natural terrestrial ecosystems.
Biomes are primarily identified and characterized by their vegetation. - Vegetation is the primary identifier because plants constitute the majority of the community's biomass in any given ecosystem. - Examples of vegetation-based identification include: - Forest Biomes: Characterized by densely packed tall trees. - Savanna Biomes: Characterized by grasses and a few scattered shrubs.

The specific type of vegetation that develops in a biome is largely determined by climatic factors.
The two most critical climatic factors are: - Rainfall (Precipitation). - Temperature.
Correlation of Climate and Biome: Regions across the globe that share similar climates will exhibit similar biomes.

Due to climatic gradients, distinct zones of different biomes occur from the equator toward the Arctic in the North and the Antarctic in the South.
Specific regional examples based on latitude and temperature: - Equatorial and Tropical Areas: Regions where temperatures remain high throughout the entire year support tropical forests. - Temperate Regions: Characterized by the presence of coniferous and deciduous forests. - Arctic Regions: Characterized by cold temperatures and treeless plains known as tundra.

Transitions between different types of biomes are often dictated by the amount of annual rainfall received by the region.
Forest transitions: - Forests transition into tropical and temperate grasslands when annual rainfall is relatively low, typically ranging from $300\,\text{mm}$ to $1000\,\text{mm}$ . - Forests and grasslands transition into deserts when rainfall becomes extremely low, specifically falling below the threshold of $300\,\text{mm}$ .

Climate varies not only with latitude but also with height above sea level (altitude).
As a result of these temperature and climate changes, zones of different biomes occur vertically on a mountain side.
This phenomenon is illustrated in the transcript's reference to Figure 5-3, indicating that ascending a mountain mimics the climatic and biological changes seen when moving from the equator toward the poles.