The Water Cycle, Essay Example

Water is an important element for the survival of living things.  The hydrologic cycle refers to the precipitation and evaporation of water from the atmosphere and back to the earth. Water on earth is mostly found in the ocean, which covers over 70% of the earth’s surface and is the source for the major reservoir.  In fact, the oceans contain about 97% of the earth’s available water. The hydrologic cycle is driven through solar energy, which causes the water to evaporate into the atmosphere and return to the earth’s surface in the form of precipitation via gravity. Water that falls onto the land can be absorbed through living organisms, such as plants.  Water molecules taken up by plants are returned to the atmosphere in form of evaporation from leaves. Other water molecules are absorbed into the water and undergo photosynthesis through combining with carbon dioxide resulting in high energy molecules referred to as glucose. These glucose molecules are then further broken down during cellular respiration of living organisms into water and carbon dioxide and released back into the atmosphere.

The patterns of both precipitation and evaporation result in the distribution of plants on the earth’s surface.  For instance, this change in hydrologic cycle can be observed in different types of habitats, such as the desert or rain forest.  In deserts, there is a decrease observed in living communities due to the decrease in biological productivity from the lack of water. On the other hand in rain forests, there is an abundance of water resulting in an increased biological productivity.  In these habitats, therefore, different types of plant species and abundance occur. Changes in the hydrologic cycle could results in changes of plant communities in these areas, which thereby effect the distribution of plants on earth.

Living organisms in an ecosystem require both energy and nutrients in order to maintain life activities essential to living organisms, such as growth, development and reproductions. Plants are key to the cycle of energy and nutrients within an ecosystem.  The plants capture sunlight and convert the sunlight into chemical energy through the process of photosynthesis. The energy captured through the plants is transferred through the food chain starting with the herbivores. The herbivores eat plants and obtain energy.  Carnivore animals eat the herbivores to obtain energy. Scavengers obtain energy from left over animal remains.  Finally, decomposers obtain energy through decaying material. Sunlight provides the energy that powers life. Nutrients and C N P H20 enter the ecosystem via the non-living components of the planet, such as the atmosphere, earth, or ocean.  Solar energy continually bombards the earth and provides a limitless source of energy.  This flow of energy is limitless since the energy provided from the sun is limitless.  However, the nutrients essential for living organisms is limited.  For instance, the earth only contains a certain amount of available Carbon, Phosphorus, or Nitrogen. The process of photosynthesis provides 1/7^th of the available carbon. Therefore, if cellular respiration were to discontinue and carbon dioxide was not released into the atmosphere, energy for life would also discontinue, as the availability of Carbon would decrease or end for the uptake of plants.  Therefore, the flow of energy and the cycling of nutrients play major roles in the populations within an ecosystem.

The differences in ecosystems depend of two different types of factors. These are abiotic and biotic factors.  The abiotic factors refer to components such as non-living things such as water and light.  The biotic factors are the living community of organisms. Different habitats are comprised of different abiotic and biotic factors.  In a swamp, the most important abiotic factor is water. The water in a swamp has a huge biotic community for micro biotic organisms, such as animal and plant-like protists, fish, plants, insects, amphibians, and reptiles.  Birds and mammals also utilize the swamps as well. All of the biotic community comprises the biotic factors.

Matter and energy flow through an ecosystem when organisms feed on one another, making up the food chain. Food producers are the first chain, such as plants and algae that capture sunlight and convert chemical energy to food via photosynthesis. After the food producers, are the consumers. Consumers consume food producers; therefore, they eat the plant material. Next are the second order consumers, third order consumers and decomposers.

Pyramids were developed to illustrate the energy flow through an ecosystem with the producers on the bottom, consumers, 2^nd order consumers, and third order consumers at the top. This pyramid showed that 16% of the energy is passed on to the consumers, 11% to the secondary consumers, and only 5% to the third order consumers.

The Carbon cycle moves through ecosystems starting with air, since it contains carbon dioxide.  Plants absorb carbon dioxide and break it down to glucose and oxygen. Carbon dioxide also diffuses into water for aquatic plants.  Some of the Carbon atoms are used to build body tissue and other molecules are returned back to the atmosphere. Carbon is also released back to the environment through the burning of wood or fossil fuels. Decomposers also return Carbon to the atmosphere as well. All of these components affect the carbon cycle.