What is a Terrestrial Ecosystem?

An ecosystem is a collection of interconnected communities. It includes both living and non-living elements of specific strata. The terrestrial ecosystem is solely related to the ecosystem present on the land and covers 25 to 30% of the total earth’s surface area.

Terrestrial ecosystems are critical because they aid in achieving the sustainable goal of development, which is "life on land."

Different components of terrestrial ecosystem

There are two components of terrestrial ecosystems: Biotic and abiotic. The biotic component includes vegetation on land, terrestrial as well as aerial animals, saprophytic, and decomposing microorganisms. The abiotic part consists of the sun, wind, rain erosion, temperature, soil, and climate change.

Trophic levels and food chain

There following are the trophic levels in the terrestrial ecosystem:

• Producers
• Primary consumers or herbivores
• Secondary consumers
• Tertiary consumers
• Predators

1. Producers (autotrophs): These are photosynthetic or autotrophic plants that can synthesize organic materials from inorganic raw materials with the help of solar light. This process is known as photosynthesis. All other organisms depend on autotrophs for their supply of organic food. Major producers are algae, bryophytes, and plants. In the case of the terrestrial ecosystem, producers are generally rooted plants.
2. Consumers (heterotrophs): They feed on other organisms or their parts for their living. Consumers are broadly divided into two types; herbivores and carnivores. Herbivores derive their energy directly from plants, and they are called first-order consumers. Carnivores ingest or prey upon other animals, and those who feed upon herbivores are called primary carnivores or second-order consumers. While those who feed on primary carnivores are the secondary carnivores or third-order consumers.
3.  Decomposers (reducers): These are the saprotrophic organisms that feed on dead bodies of other organisms and organic waste. They are differentiated into two categories, that is, detritivores and parasites. The latter belong to diverse groups, that is, bacteria, fungi, protozoans, and so on. The detritivores are scavengers that feed on dead bodies of other organisms, including termites, and carrion beetles.

Food chains of terrestrial ecosystems can be exemplified by:

1. Grass→ Grasshopper→ Frog→ Snake→ Peacock/Falcon.
2. Vegetation→ Rabbit→ Fox→ Wolf→ Tiger.
3. Vegetation→ Insect→ Predatory Insect→ Insectivorous bird→ Hawk.

Productivity

One of the functional aspects of an ecosystem is productivity. The rate of synthesis of energy-containing organic matter or biomass by any trophic level per unit area in a unit of time is described as its productivity. It is of two types; primary productivity, and secondary productivity.

Primary productivity

Primary productivity refers to the amount of energy stored in green plants as biomass or organic matter per unit area over time as a result of photosynthesis. Primary productivity is further sub-categorized into two: Gross primary productivity and net primary productivity. The storing of energy through the synthesis of organic matter from inorganic carbon compounds is referred to as primary production. Autotrophic organisms are responsible for primary production.

Secondary productivity

Secondary productivity is the rate at which consumers re-synthesize organic materials. It is determined by the amount of energy-containing organic matter lost during the transfer of energy-containing organic matter from the previous trophic level owing to respiration. With each trophic level, net productivity drops.

Biogenetic nutrients and biogeochemical cycles

The term biogeochemical cycles can be better explained as an exchange of biogenetic nutrients between living and nonliving components of the terrestrial biosphere. Biogenetic nutrients are required for an organism's growth and metabolism. These nutrients are provided by the earth and they get back to the earth once the organism dies and decomposes. Microorganisms play an important role in carrying on the nutrient cycles.

The carbon cycle has played an important role in terrestrial ecosystems. So, here is a detailed structure of the carbon cycle.

The carbon cycle

Carbon is an important component of all organic compounds of protoplasm as carbohydrates, fats, nucleic acid, enzymes, and hormones. It constitutes 49% of the mass of the human body and also is next in abundance to water. The source of carbon is from the environment; it is the abiotic component of the biosphere. It exists in four forms:

• Carbon dioxide in air or atmosphere
• Dissolved carbon dioxide or carbonic acid
• Fossil fuels as coal and petroleum
• Carbonates and graphite in rocks

Carbon recycling: The cycling pool consists of 0.4% of free carbon-di-oxide (CO₂) in the atmosphere. Carbon present in the lithosphere isn’t available to organisms till it is burnt or changed chemically. Carbon present in the atmosphere is picked up by the producers in the process of photosynthesis and converted to organic compounds and the oxygen gas is released as a by-product.

During the process of photosynthesis the amount of carbon from the environment starts decreasing and is replenished by the following methods:

• Respiration of organisms
• Decomposition of organic wastes and dead bodies
• Burning of wood and fuels
• The weathering process of carbonate-containing rocks
• Forest fires, volcanic eruptions, and hot springs

The natural interaction between the lithosphere and the hydrosphere or atmosphere takes a long time. The major exchange in the carbon cycle is between organisms and the atmosphere, that is, producers absorb the carbon and producers release it by the process of respiration. This carbon cycling is a self-regulated feedback system but has been upset recently due to deforestation and increased combustion of fuels by humans. The amount of carbon in the atmosphere is rising, which is likely to have an impact on the climate and eventually wash away arctic and alpine ice.

Types of terrestrial ecosystems

 There are several types of terrestrial habitats:

• Forests: Forests affect climate, and climate change affects forests, with carbon linking the two. Forests hold three-quarters of the world's plant biomass, with nearly half of it being carbon. As a result, forests play an important role in carbon storage around the world.
• Tropical rainforests: These are characterized by dense jungles, thick vegetation, no or little sunlight, evergreen, and temperature that favors decomposition. The forest area of South and Central America are tropical rainforests.
• Deciduous rainforests: Trees lose their leaves during autumn such as maple, oak, chestnut. Forests of Northeastern United States are temperate deciduous forests.
• Taiga: Conifer trees that produce cones are dominant, which includes fir, spruce, pine, and hemlock. Lichens and moss are very common here. Taiga ecosystems can be exemplified by British Columbia, Canada, and Alaska.
• Tundra: The temperature in the tundra region is very low, plant growth is less. Lichen, grass, and annual plants grow during the short period of summer. Northern Canada and northern Russia are the tundra ecosystems.
• Deserts: Deserts receive less than ten inches (25 cm) annual rainfall. Deserts have many plants that lie dormant until it rains. It is also home to the plants that are capable of storing their water, such as cactus. Many animals are nocturnal, meaning that they stay underground for the day and wander for food during the night.
• Grasslands: Due to environmental conditions, trees are scarce but temperature favors the growth of grasses. Different types of grasslands are tropical grasslands or savannas, temperate grasslands, and polar grasslands. Around the world, the Midwestern United States and central Africa are grassland ecosystems.

Natural resources management

Natural resource management (NRM) is the regulation of natural resources such as land, water, soil, plants, and animals, with a focus on how it affects current and future generations' quality of life.

The interplay of people and natural landscapes is the subject of natural resource management. It integrates natural heritage management, land use planning, water management, biodiversity conservation, and, as a result, the future viability of sectors such as agriculture, mining, tourism, fisheries, and forestry. Natural resource management focuses on a scientific and technological understanding of resources and ecology, as well as the ability of these resources to support life. Environmental management is related to natural resource management.

How do ecologists get to know about the ecosystem?

• Field research
• Remote sensing
• Geographic information systems (GIS)
• Laboratory research
• System analysis

To study and map the earth's future events, a tool known as the geographic data system is used. Through mapping, GIS technology and remote sensing collect important database functions such as statistical analysis and query. Recent advances in remote sensing technology have resulted in new data collecting capabilities as well as the ability to generate and analyze digital images with high spatial resolution.

Context and Applications

This topic holds relevance to many undergraduates as well as postgraduate courses. It is especially included in courses such as

• Bachelors of Science in Zoology
• Masters of Science in Environmental Science
• Masters of Science in Geology
• Masters of Science in Ecology

Practice Problems

Question 1) Which of the following occurred first on the land, that is, bare rocks?

1. Mosses
2. Lichens
3. Algae
4. Fungi

Answer- Option b

Explanation- The pioneers of the land were the lichens as they could tolerate desiccation, heating, and excessive cooling.

Question 2) In the food chain, which of the following has the largest population?

1. Producers
2. Primary consumers
3. Secondary consumers
4. Decomposers/reducers

Answer- Option a

Explanation- The largest population is of producers as all the other components of the food chain primarily depend on producers or plants for their nutrition.

Question 3) Of which ecosystem are conifer trees the characteristic?

1. Taiga
2. Tundra
3. Deciduous rainforest
4. Tropical rainforest

Answer- Option a

Explanation- Conifer trees or cone-shaped trees such as fir and pine are dominant in the Taiga ecosystem.

Question 4) Where is the savanna ecosystem located?

1. Australia
2. North America
3. Canada
4. Africa

Answer- Option d

Explanation- The savanna ecosystem or grasslands are found in the acacia plains of east Africa.

Question 5) Where is the major reservoir of carbon on earth?

1. Hydrosphere
2. Atmosphere
3. Lithosphere
4. Biosphere

Answer: Option c

Explanation- The lithosphere is the major reservoir of carbon, it also contains carbonate rocks.

Common Mistakes

Students frequently mix up the terms "terrestrial ecosystem" and "anthropogenic ecosystem." A biome is a huge ecosystem that is made up of several smaller ecosystems of the same kind. A man-made ecosystem or artificial form of the terrestrial biosphere is known as an anthropogenic ecosystem. Agriculture, aquariums, and gardens are examples of this.

Related Concepts

• Ecosystem
• Environmental issues
• Biodiversity and conservation
• Ecological relationships between organisms
• Environmental biology