Question

How do energy and nutrients move through an ecosystem?

Answer 1

The storage and expenditure of the energy is based on two basic laws of thermodynamics.
The behavior of energy in ecosystems is referred to as energy flow as energy transformations are directional, in contrast to the cyclical behavior of nutrients.

Complete answer:
Energy flow is the key function in the ecosystem. The storage and expenditure of the energy is based on two basic laws of thermodynamics. The first law of thermodynamics states that when energy is converted from one form into another, energy is neither gained nor lost. The second law of thermodynamics states that every transformation results in a reduction of the free energy of the system. Energy transformation cannot be 100% efficient.
The behavior of energy in ecosystems is referred to as energy flow because energy transformations are directional, in contrast to the cyclical behavior of nutrients. The conversion of solar radiation to chemical energy by photosynthesis is the starting point of energy flow within the ecosystem.

Solar energy is transformed from the radiant to the chemical form in photosynthesis and from the chemical to mechanical and heat forms in cellular metabolism. These conversions and sequences are fundamental to the energetics of organisms and ecosystems as energy passes into and through producers, to and through consumers and decomposers. Usable energy flows from the external environment to the plants, then to the herbivores, carnivores and top carnivores. Death at each level transfers energy to decomposers. Energy lost as heat is returned to the external environment.Only about 1-5 % energy of incident radiation is actually captured by the photosynthetic process and the remaining portion is dissipated.
Nutrient Cycling: As the earth is essentially a closed system with respect to matter, Every matter that is used by living organisms passes between biotic and abiotic components of the biosphere. Nutrient cycling is the movement of matter through the system.
In general we can subdivide the system into: atmosphere, hydrosphere, lithosphere and biosphere.

General model of nutrient cycling: A general model of nutrient cycling includes the main reservoir of elements and the processes that transfer elements between reservoirs. Each reservoir is defined by two characteristics: whether it contains organic or inorganic materials and whether or not the materials are directly available for use by organisms. The nutrients in living organisms and in detritus are available to other organisms when consumers feed and when detritivores consume nonliving organic matter. Some materials are moved from the living or organic reservoir to the fossilized organic reservoir, when dead organisms were buried by sedimentation over millions of years, becoming coal, peat. The nutrients in these deposits cannot be assimilated directly.

Inorganic materials that are dissolved in water or present in the soil or air are available for use. Organisms assimilate materials from this reservoir directly and return chemicals to it through the relatively rapid processes of cellular respiration, excretion and decomposition. Although organisms cannot directly tap into the inorganic elements tied up in the rocks, these nutrients may slowly become available through weathering and erosion. Similarly unavailable organic materials move into the available reservoir of inorganic nutrients when fossil fuels are burned, releasing exhaust into the atmosphere.

Note: Only about 1-5 % energy of incident radiation is actually captured by the photosynthetic process and the remaining portion is dissipated. Every matter that is used by living organisms passes between biotic and abiotic components of the biosphere. Nutrient cycling is the movement of matter through the system.