Ecosystem: Concept | Zoology Optional Notes for UPSC PDF Download

Comprehending Ecosystems

Ecosystem Definition

• An ecosystem represents a geographical region where plants, animals, various species, weather, and topography converge, creating a living entity.
• Ecosystems can be understood as the foundational structural and functional elements of ecology, where living entities interact among themselves and with their surroundings.
• The term "ecosystem" was first coined by the English botanist A.G. Tansley in 1935.
• Ecosystems encompass the biological and behavioral interplay between living and nonliving components that comprise the ecological system.
• Non-living attributes of the environment include factors like climate, soil, water, sunlight, earth, rocks, atmosphere, temperature, and humidity.

Ecosystem

Ecosystem vs. Biome

Ecosystem

• These interconnected units of living and nonliving elements are present across the Earth's entire surface.
• Ecosystems often have interrelations within broader biomes.
• They represent specific, localized areas like forests, ponds, reefs, and tundra.

Biome

• Biomes denote large expanses of land, sea, or atmosphere.
• They encompass diverse ecosystems based on the resident plants and animals.
• Each biome can further contain a variety of distinct habitats, which can differ substantially within a single biome.

Distinguishing Environment and Ecosystem

Environment

• The environment constitutes the surroundings in which organisms thrive.
• It is primarily comprised of physical components.
• It provides a habitat for elements to reside.
• It offers the necessary conditions for survival.

Ecosystem

• An ecosystem, on the other hand, is the community where biotic and abiotic elements interact.
• Ecosystems consist predominantly of biological components.
• They facilitate interactions among these components.
• Ecosystems establish connections between elements, enabling them to coexist and function together.

Comparing Ecology and Ecosystem

Ecology

• Ecology concentrates on the interaction between the environment and living organisms.
• The study of various places and environments, such as streams, still water, deserts, rivers, grasslands, and woodlands, is fundamental to ecology.
• Ecology encompasses the examination of the natural environment and its diverse ecosystems.
• It does not generally involve broad categorization.

Ecosystem

• Ecosystems are a subset of ecology and represent distinct communities or areas.
• Ecosystems take various forms, including marine ecosystems, forest ecosystems, or pond ecosystems.
• They delve into the complex interactions between living and nonliving organisms within a particular locality or community.
• Unlike ecology, ecosystems focus on these intricate relationships within specific environments.

Key Components of Ecosystem

Ecosystems consist of a variety of components, which can be classified into two main categories: biotic (living) components and abiotic (non-living) components.

Biotic Components

Biotic components encompass all living organisms within an ecosystem. These living elements can further be categorized based on their nutritional roles:

• Producers: Producers, such as plants, are autotrophs capable of generating their food through processes like photosynthesis. They form the foundation of the food chain as other organisms rely on them for sustenance.
• Consumers: Consumers, also known as heterotrophs, are organisms that feed on other living beings. They can be divided into three categories: primary consumers (often herbivores), secondary consumers (predators or omnivores), and tertiary consumers. Some ecosystems may even include quaternary consumers at the highest trophic level, having no natural predators.
• Decomposers: Decomposers, like fungi and bacteria, play a vital role by breaking down dead and decaying organic matter. This process recycles nutrients in the ecosystem, allowing plants to use them again for growth.

Abiotic Components

Abiotic components refer to all non-living elements within an ecosystem. These elements significantly influence the interactions and survival of biotic components. Abiotic factors can include:

• Water: The presence and quality of water have a substantial impact on an ecosystem's dynamics.
• Temperature: Temperature affects the distribution and behavior of living organisms within the ecosystem.
• Air: Air quality, particularly the concentration of gases, is important for respiration and other processes in the ecosystem.
• Soil: Soil properties, including its composition, minerals, organic matter, and moisture, play a key role in supporting plant life.
• Atmosphere: The atmospheric conditions, such as air pressure and gas composition, influence various ecological processes.
• Minerals: The availability of minerals and nutrients in the ecosystem's soil is critical for plant growth.
• Humidity: Humidity levels impact the survival of many organisms, particularly those in terrestrial ecosystems.

These abiotic components are divided into two primary categories:

• Edaphic Factors: These encompass the chemical and physical characteristics of the soil, including soil profile, minerals, organic matter, soil moisture, and soil types.
• Climatic Factors: These pertain to the physical and climatic features of the environment, including atmospheric temperature, wind, humidity, and water availability.

The interaction and interplay between biotic and abiotic components are essential for the functioning and structure of ecosystems.

Classification of Ecosystems

Ecosystems can be classified based on various criteria, such as their natural or artificial nature and the presence of terrestrial or aquatic features. Here's a breakdown of ecosystem classification:

Natural vs. Artificial Ecosystems

Ecosystems can be categorized as either natural or artificial.

• Natural Ecosystems: These are ecosystems that exist in their original, unaltered state without significant human intervention. They are shaped by natural processes and are often considered pristine environments. Examples include undisturbed forests, pristine wetlands, and unspoiled coral reefs.

• Artificial Ecosystems: Artificial ecosystems are ecosystems that have been influenced or modified by human activities. Human intervention can range from urban development and agriculture to creating artificial lakes and urban parks. These ecosystems often exhibit features distinct from their natural counterparts due to human influence.

Terrestrial vs. Aquatic Ecosystems

Ecosystems can also be classified based on their primary habitat, distinguishing between terrestrial and aquatic ecosystems.

• Terrestrial Ecosystems: Terrestrial ecosystems thrive on land and are primarily land-based. They include ecosystems such as forests, deserts, grasslands, and mountainous regions. The availability of water is typically limited in terrestrial ecosystems, and water can be a limiting factor for many species within these environments.

  • To learn more about terrestrial ecosystems, you can explore Terrestrial ecosystem.

• Aquatic Ecosystems: Aquatic ecosystems are those that are found in bodies of water, such as lakes, rivers, oceans, and ponds. These ecosystems are strongly influenced by the aquatic nature of their environment. Aquatic ecosystems can further be categorized into marine ecosystems and freshwater ecosystems, each with unique characteristics and species compositions.

  • To learn more about aquatic ecosystems, you can explore Aquatic ecosystem.

Functions of an Ecosystem

Ecosystems perform various functions to maintain their stability and balance. These functions are essential for the survival and well-being of the species within the ecosystem and include:

• The Flow of Energy: Ecosystems facilitate the flow of energy from one organism to another through feeding relationships. Producers capture energy from the sun and convert it into food, which is then transferred through a series of consumers. This energy flow sustains life within the ecosystem.

• Cycling of Nutrients (Biogeochemical Cycles): Ecosystems play a vital role in recycling essential nutrients, such as carbon, nitrogen, and phosphorus. These cycles ensure that nutrients are continuously available to support plant and animal life.

• Homeostasis (or Cybernetic) or Feedback Control Mechanisms: Ecosystems have feedback mechanisms that help maintain balance and equilibrium. When disturbances occur, ecosystems tend to restore themselves to a stable state, a process known as ecological succession or ecosystem development.

Niche and Habitat: Understanding the Differences

In ecology, the terms "niche" and "habitat" are used to describe specific aspects of how organisms interact with their environment. While they are related concepts, they have distinct meanings and serve different purposes:

Niche:

• Definition: A niche refers to the specific role and position of an organism or population within an ecosystem. It encompasses how an organism interacts with its environment, including its interactions with other species, resource utilization, and adaptations.
• Characteristics:
  • Describes how an organism responds to competition and resource distribution.
  • Specifies the organism's place in the ecosystem.
  • Influenced by both biotic (living) and abiotic (non-living) components of the ecosystem.
  • Involves the species' behavior, dietary preferences, habitat selection, reproductive patterns, and interactions with other species.
• Purpose: Understanding an organism's niche helps ecologists comprehend how species coexist in an ecosystem and how they adapt to their surroundings to minimize competition.
  Niche

Habitat:

• Definition: A habitat refers to the physical environment where an organism or a biological population usually lives, resides, or is adapted to survive. It refers to the specific location where an organism can be found.
• Characteristics:
  • Describes the actual place or physical environment.
  • Is a specific geographic location, such as a forest, river, mountain, or desert.
  • Provides the essential conditions and resources required for an organism's survival.
  • Primarily influenced by abiotic factors like temperature, precipitation, and physical structures.
• Purpose: Identifying an organism's habitat helps ecologists understand where a species is most likely to be found and what environmental conditions it requires to survive.

Key Differences:

• Scope: Niche pertains to how an organism functions within its environment, considering its interactions, adaptations, and role in the ecosystem. Habitat is concerned with the physical location or environment where the organism lives.
• Specificity: Niche is species-specific and involves a wide range of biological and ecological characteristics. Habitat is generally a broader and more generic concept, describing the environment itself.
• Interactions: Niche considers both biotic and abiotic interactions. Habitat primarily focuses on abiotic environmental factors.
• Multiple Niches: In a habitat, there can be multiple niches, as different species may occupy different ecological roles, allowing various species to coexist.

Threats to Ecosystems: Understanding Environmental Challenges

Ecosystems, critical for maintaining biodiversity and environmental balance, face several significant threats due to human activities and natural processes. These threats can have far-reaching consequences on the health and stability of ecosystems. Here are some of the key threats to ecosystems:

1. Environmental Pollution:
   • Definition: Pollution of the air, land, water, and soil by toxic compounds and damaging chemicals, resulting from natural or human-induced causes.
   • Impacts: Directly harms ecosystems by endangering living organisms and degrading the environment.
   • Examples: Air pollution, water pollution, soil contamination.
   • Consequences: Disrupts ecosystem balance, interferes with natural cycles (e.g., oxygen, nitrogen, water), and damages food chains.
2. Over-exploitation of Natural Resources:
   • Definition: Excessive harvesting or utilization of natural resources, such as overhunting, overfishing, overmining, and overlogging.
   • Impacts: Leads to depletion of resources, disrupts community structures, affects species distribution, and results in population declines.
   • Examples: Overfishing leading to the decline of fish species.
   • Consequences: Can lead to the extinction of species, reduced biodiversity, and ecosystem imbalances.
3. Invasive Species:
   • Definition: Introduction of foreign species into an ecosystem through human or natural means, causing harm to native species.
   • Impacts: Competes with native species for resources, alters habitat, and can lead to the decline or extinction of native species.
   • Examples: Introduction of Nile Tilapia into Lake Victoria.
   • Consequences: Loss of native biodiversity, disruption of ecological processes.
4. Eutrophication:
   • Definition: Overabundance of chemical nutrients in water bodies, leading to excessive plant growth and algal blooms.
   • Impacts: Depletes oxygen levels, deteriorates water quality, poisons aquatic life, and hampers recreational activities.
   • Examples: Algal blooms in bodies of water.
   • Consequences: Impacts the survival of aquatic organisms and affects water ecosystems.
5. Climate Change and Global Warming:
   • Definition: Long-term alterations in temperature and weather patterns due to greenhouse gas emissions.
   • Impacts: Affects abiotic factors (e.g., temperature, precipitation) essential for the survival of biotic elements.
   • Examples: Rising temperatures, changing rainfall patterns.
   • Consequences: Shifts in ecosystems, loss of habitat, and potential extinction of species.

These threats are interrelated and often exacerbate one another, making it crucial to address them collectively. Ecosystem conservation and sustainable practices are essential to mitigate these challenges and ensure the continued health and functioning of ecosystems. Such efforts are not only vital for preserving biodiversity but also for supporting global food production and maintaining environmental stability.