Global Habitats: Cities, Ecosystems, and Population Dynamics
Human Habitats and Settlements
Understanding Human Habitat
Humans live in environments that they adapt and transform to suit their needs. This adapted environment is what we call a habitat.
Factors Facilitating Settlements
Natural Factors
- Moderate climate
- Access to river water
- Easy communications
Human Factors
- Organization into groups
- Ecological development
Phases of Human Settlements
Hunter-Gatherers
Around 8000 BC, early humans were nomadic and unstable. They lived in small, loosely organized groups, inhabiting huts and caves.
Agricultural Settlements
These were the first sedentary villages, formed by farmers. This is what we call rural habitat. Houses served for people, animals, and farm tools.
After 3000 BC, urban settlements began. These were composed of farmers, artisans, and merchants, forming very large and diverse groups of buildings. After the 18th century, industrial production led to the rise of the modern city.
Historical Development of Cities
Early Cities
Examples include Egypt, Mesopotamia, and the Indus Valley. Characterized by a lack of planning, proximity to rivers, use of basic materials, and defensive walls.
Classical Cities
Examples include Greece and Rome. They were planned, featured public areas, and evolved from Greek to Christian influences.
Medieval Cities
Islamic cities had irregular layouts and narrow streets. Christian cities also had irregular layouts, were usually walled, and featured closely built houses.
Modern Cities
Characterized by the addition of new buildings and urban expansion.
Industrial Cities
Evolved due to the Industrial Revolution in the late 18th century, growing significantly. Saw the emergence of class-based districts and industrial estates.
Contemporary Cities
Developed in the 20th century with advanced urban planning, greater development control, and the emergence of commuter towns (bedroom communities).
Urbanization in Spain
Approximately 80% of the Spanish population lives in urban areas. The urbanization process was delayed but began to develop significantly after 1950. The greatest concentration of large cities is located along the coast, with the exception of Madrid. Currently, there are 26 cities with over 200,000 inhabitants.
Ecosystems and Population Dynamics
Understanding Ecosystems
An ecosystem is a system formed by all living beings, the natural environment in which they live, and the relationships established between them and with abiotic factors in a given space.
Major Biomes of Planet Earth
The Tundra
A region with long, extremely cold winters, frozen ground beneath the surface, devoid of trees, and covered with small plants in the cold, short summer.
The Taiga
A type of milder climate region, characterized by large forests of evergreen conifers and richer soils, which allow for a variety of plant and animal life.
Deciduous Forests
Located in temperate areas of the Northern Hemisphere, mainly in regions with marked seasonal climate differences. They support the development of many living species and have been significantly altered throughout history.
Tropical Forests
Located in regions with high temperatures and constant rain throughout the year, containing the greatest diversity of living species. They have historically maintained a balance with nature, but human activity is breaking this down due to deforestation for timber, minerals, and farmland.
Mediterranean Forests
Occur in areas with short winters and warm, dry summers, featuring shrubs and evergreens. These areas are now highly modified by human activities.
Herbaceous Formations
Located in regions with little precipitation and mild temperatures, where extensive temperate grasslands, savannas, and tropical continental steppes are found.
The Deserts
Located in regions with very little rain, which barely allows for sparse vegetation adapted to extreme dryness. Although life is difficult, these spaces are not completely uninhabited.
Population Pyramids
Expansive (Pyramidal) Form
Presents a wide base and a very narrow top. This indicates very high birth and mortality rates. Life expectancy in this population is not very high. It is characteristic of underdeveloped countries, where the population experiences rapid growth.
Constrictive (Globular) Form
Features a relatively narrow base, with the central zone tending to the same width. This indicates a low birth rate and lower mortality, with an aging trend. It is characteristic of developed countries. The narrower the base and wider the central part, the higher the aging trend. This can lead to negative growth.
Stationary (Bell-shaped) Form
Presents a broad central area with a certain proportion, while the top is narrower. This characterizes a population with a stable demographic regime. Growth tends to slow down.
Labor Force and Population Categories
Labor Force
Comprises individuals who are employed in a paid job (working population) or who are in a position to do so (unemployed labor force).
Inactive Population
Does not participate in the working life, including children, students, homemakers, retirees, etc.