Grassland ecosystem and Energy flow through an ecosystem

Grassland Ecosystem

The grassland is an open terrestrial community covered with grasses. It has varieties of organisms that are interacting together as well as they interact with their physical environment. The grassland occupies about 20% of earth surface whereas about 13% of the total land area is occupied by grassland in Nepal. The major grasslands in the world are developed in the temperate region. The Suklaphanta wildlife reserve is one of the examples of grassland in Nepal which is located at far- western part of Nepal. It has also both structure and function. The structure of grassland ecosystem includes its abiotic and biotic components.

Abiotic components

These are non-living components associated with grassland and affect the life of organisms. These includes:

• Light
• Temperature
• Humidity
• Rainfall
• Wind
• Soil

Biotic components

These are the living organisms associated with grassland which include producers, consumers, and decomposers.

Producers

Producers are able to capture the sun’s energy through photosynthesis and absorb nutrients from the soil, storing them for future use by themselves and by other organisms. Grasses, shrubs, trees, mosses, lichens, and cyanobacteria are some of the many producers found in a grassland ecosystem. When these plants die they provide energy for a host of insects, fungi, and bacteria that live in and on the soil and feed on plant debris. Grasses are an important source of food for large grazing animals such as California Bighorn Sheep, Mule Deer, and Elk, and for much smaller animals such as marmots, Pocket Gophers, and mice.

Consumers

Consumers are organisms that do not have the ability to capture the energy produced by the sun but consume plant and/or animal material to gain their energy for growth and activity. Consumers are further divided into three types based on their ability to digest plant and animal material: Herbivores eat only plants, such as the elk that graze the grasslands of the Columbia valley, or an insect nibbling on the leaf of a sticky geranium. Omnivores eat both plants and animals, such as the black bear. Carnivores eat only animals, such as the red-tailed hawk or western rattlesnake.

Decomposers

Decomposers include the insects, fungi, algae, and bacteria both on the ground and in the soil that help to break down the organic layer to provide nutrients for growing plants. There are many millions of these organisms in each square meter of grassland.

Functional Aspect of Grassland Ecosystem

Interaction: Interaction in biotic communities are food chains and food web. Food chains are of two types which are given below:

1. Predatory food chain: Here, the sun is the source of energy of green plants (autotrophs or producers) which act as a source of energy for primary consumer or herbivorous. Primary consumers are also the source of energy for the secondary consumer that serves as the energy source for tertiary consumers.
2. Detritus food chain: It starts with decomposed organic matter that is consumed by the detrivores like beetles, Collembolas, etc.

Food web

All food chains in grassland ecosystem are interconnected to each other making a food web.

Ecological pyramid

Three kinds of ecological pyramids are found in grassland ecosystems which are the pyramid of number, pyramid of biomass and pyramid of energy. In the predatory food chain, there is always gradual decrease in number, biomass, and energy starting from autotrophs to the secondary carnivorous tertiary consumers. Pyramid of number and pyramid of biomass is inverted in the parasitic food chain.

Energy flows in an ecosystem

(Chart)

Ecosystems maintain themselves by cycling energy and nutrients obtained from external sources. At the first trophic level, primary producers (plants, algae, and some bacteria) use solar energy to produce organic plant material through photosynthesis.

Herbivores, those animals that feed solely on plants, make up the second trophic level. Predators that eat herbivores comprise the third trophic level; if larger predators are present, they represent still higher trophic levels.

Organisms that feed at several trophic levels (for example, grizzly bears that eat berries and salmon) are classified at the highest of the trophic levels at which they feed. Decomposers, which include bacteria, fungi, molds, worms, and insects, break down wastes and dead organisms and return nutrients to the soil.

On average about 10 percent of net energy production at one trophic level is passed on to the next level. Processes that reduce the energy transferred between trophic levels include respiration, growth and reproduction, defecation, and non-predatory death (organisms that die but are not eaten by consumers).

The nutritional quality of material that is consumed also influences how efficiently energy is transferred because consumers can convert high-quality food sources into new living tissue more efficiently than low-quality food sources.

The low rate of energy transfer between trophic levels makes decomposers generally more important than producers in terms of energy flow. Decomposers process large amounts of organic material and return nutrients to the ecosystem in inorganic form, which is then taken up again by primary producers. Energy is not recycled during decomposition but rather is released, mostly as heat.