Matter and Energy Flow in the Biosphere: Understanding Trophic Levels and Biogeochemical Cycles
Item 4: Matter and Energy Flow in the Biosphere
Key Terms
Biosphere: The set of all living things that inhabit the Earth.
Ecosystem: A natural system consisting of living and nonliving components that interact with each other.
Ecosphere: The set of all ecosystems constituting Earth. In other words, the ecosphere is the grand ecosystem.
Biomes: The different ecosystems on Earth.
Trophic Relationships
Trophic relationships represent the energetic mechanisms of energy transfer within an ecosystem. They are usually represented by food chains that connect different trophic levels with arrows.
Trophic Levels
Producers: Autotrophic organisms that constitute the first trophic level. They synthesize organic matter. Examples include photosynthetic plants and algae, which capture light energy and convert it into chemical energy, and chemosynthetic organisms, which obtain energy for organic matter synthesis from the oxidation of inorganic molecules.
Consumers: Heterotrophic organisms that use organic matter to carry out their vital functions through respiration. They can be classified as:
- Primary consumers (herbivores): Feed on producers.
- Secondary consumers (carnivores): Feed on herbivores.
- Tertiary consumers (top carnivores): Feed on other carnivores.
Decomposers: Detritivorous organisms that break down dead organic matter into its constituent minerals, thus closing the matter cycle.
Trophic Parameters
Trophic parameters are measures used to assess the efficiency of each trophic level and the ecosystem as a whole.
Biomass: The amount of living or dead organic matter at any trophic level of an ecosystem.
Production: The amount of energy flowing through each trophic level. Primary production is the energy fixed by autotrophs, while secondary production refers to the energy flow in the remaining trophic levels. There are two types of production:
- Production area: The amount of energy fixed per unit of time.
- Net production: The energy stored in each level per unit of time.
Productivity: The relationship between net production and biomass.
Renewal time: The time it takes for the renewal of a trophic level in a system.
Efficiency: The performance of a trophic level or system.
Ecological Pyramids
Ecological pyramids illustrate the flow of energy and matter through trophic levels. The fact that only about 10% of energy is transferred from one trophic level to the next gives the pyramid its characteristic shape.
Pyramid of energy: Represents the energy content of each trophic level.
Pyramid of biomass: Represents the accumulated biomass at each level.
Pyramid of numbers: Represents the total number of individuals at each level.
Biogeochemical Cycles
Biogeochemical cycles describe the pathways of matter through the biosphere and other Earth systems. The time spent in each system varies, and the reservoir is the location where the matter resides for the longest duration.
The Carbon Cycle
: This cycle is divided into two phases:
a) life cycle in which the biosphere itself controls the exchange of this element in the atmosphere.
b) biogeochemical cycle itself, which controls the transfers of CO2 between the biosphere and the other subsystems.
carbon in the atmosphere is forming three types of compestos: CO2, CO and CH4
the atmosphere and hydrosphere directly exchanged for CO2 diffusion.
in the lithosphere we can find three different ways to form carbonate rocks, or calcium silicate in the form of fossil fuels.
THE CYCLE OF PHOSPHORUS: Phosphorus is mostly tied up in ocean sediments, litosfera.su part of the process is very slow release for relying geological cycle, and therefore constitutes the main limiting factor, so a resource considerandise not renewable.
is an important Costituyentes of biomolecules, which also part of rigid structures such as shells and bones.
the PO3-4 are released from the phosphate rocks and volcanic ash to form insoluble and transported by water to lakes or streams to the sea, where they precipitate to form sedimentary those stores
The time spent in ecosystems of 10.2-10.4 years vaira a function of efficiency of storage or recycling.
THE CYCLE OF NITROGEN: Nitrogen is necessary for ssvv since it is a constituent of amino acids that form the proteinas.sin But their presence there is minimal.
on the contrary, in the atmosphere is the fact mayoritario.de component as the backup of mismo.la most atmospheric nitrogen is present as inert, making it inaccessible to ssvv PRACTICES.
SULFUR CYCLE: This element is mainly stored in enuentra as sulfato.el hydrosphere cycle Transferred land-ocean is very slow.
during the evaporation of lakes and shallow seas, sulfur dposita forming casts.
in the biosphere are essential for the synthesis of certain moelculas organicas.los ssvv, dying, H2S release to the atmosphere and terrestrial systems.
H2S thus formed can follow two paths:
-one up, combined with iron and precipitate in the form of pyrites.
-a top-down, to reach places oxygenates.