Biodiversity, Ecosystems, and Environmental Challenges

Posted on Dec 17, 2024 in Geology

Factors Influencing Geographic Distribution of Biodiversity

Geographic distribution: Among the factors affecting this distribution are:

  • Latitude: Species richness increases from the poles to the Equator. The latitudinal climatic conditions are vital elements for living organisms, such as temperature, precipitation, lighting, etc.
  • Altitude: Biodiversity decreases with altitude.
  • Water availability: Biodiversity increases from extremely arid areas to areas with abundant moisture, evenly distributed throughout the year.
  • The heterogeneity of habitats: Places with more variety in terms of lithology, soil types, microclimates, etc., have greater biodiversity.
  • Islands: Species richness on islands is lower than on the mainland, due to the presence of endemic species (a term used in biology to indicate that the distribution of a taxon is restricted to a small geographical area, not naturally found anywhere else in the world).
  • Size: The larger the region, the more species it contains.

Environmental stability: Extreme environments limit the diversity of organisms. In the tropics, the average annual temperature varies very little, which could explain the great diversity of the humid equatorial forests.

Understanding Ecosystems, Biomes, and the Ecosphere

An ecosystem is defined as all living creatures that inhabit a particular environment, together with the physical-chemical factors of the environment and the many relationships established between them.

    • Biotope: This includes all of the abiotic factors that make up the ecosystem, i.e., all the chemical components (water, salinity, pH, nutrients, types of rock, etc.) and physical factors (temperature, light, altitude, winds, etc.) that characterize the ecosystem.

Biocenosis: It consists of the biotic part of the ecosystem, i.e., all living creatures in the ecosystem, and the relations established between them. The community is also known as biocenosis.

A biome is a particular part of the planet that shares climate, vegetation, and fauna. It is the set of characteristic ecosystems, and a biogeographic zone is defined from the vegetation and animal species that dominate it.

The ecosphere is the global ecosystem of planet Earth, which is formed by those organisms that form the biosphere and the relations established between them and with their environment.

Trophic Levels in Ecosystems

Taking into account the trophic relationships, we can group the different living things in an ecosystem following trophic levels, which are the place living on a chain or food web according to their method of production of organic matter.

Producers: Autotrophs are usually photosynthetic, which provide material and energy that flows through the food chains of the ecosystem.

Consumers: They are creatures that feed on others. They include herbivores that feed on producers, and carnivores. Detritivores are also consumers that feed on dead remains or droppings. Among consumers, we find different levels, depending on the length of chains:

The last level is hardly consumed by another animal: the super-predator, or tertiary consumers/super-carnivores.

Decomposers: Although not usually represented in chains and food webs, they are present in all ecosystems where they play an important role: They feed on organic matter wasted by consumers, transforming it into inorganic materials, completing the cycle of matter in ecosystems.

The representation of these relationships is called a trophic food web, which is the set of all interconnected food chains in an ecosystem.

The Phenomenon of Acid Rain

The phenomenon of acid rain starts when sulfur and nitrogen present in fossil fuels are released into the atmosphere by combustion processes (in power plants, industries, cars, etc.). The S and N are emitted as SO2, SO3, and NOx in said combustion.

The S and N oxides react in the atmosphere with moisture and/or oxygen through the air and sunlight, and are oxidized, resulting in acids (sulfuric, nitric, etc.). These acids can travel in air masses away from their point of release (what is known as transboundary pollution) until they precipitate and are deposited on the surface of the Earth.

Dry deposition: In a gas or aerosol, it can occur near emission sources.

Wet deposition: The primary pollutants (SO2 and NOx) that remain in the atmosphere are oxidized, forming sulfuric and nitric acid (secondary pollutants), which dissolve in water droplets that form clouds and are transported by wind away from the emitting source, returning to the ground by rainfall.

Impacts of Acid Rain

Acid rain occurs on:

  • Aquatic ecosystems (such as rivers and lakes), where acidification causes a decrease or disappearance of living species sensitive to changes in pH.
  • Soil: where acidification causes changes in its composition, resulting in a worse quality: acidification facilitates the dissolution of minerals and nutrients from the soil and produces dragging their cations to deeper zones (leachate), reducing the nutrients available to plants and transforming it into an unproductive soil.
  • The vegetation, especially forests, altering and causing loss of color in the leaves and dropping them, deteriorating the cuticle, which is a decrease in photosynthetic capacity, death of the cups, and alterations in the cortex.

Water Pollution: Types and Sources

  • Water Pollution: Physical contaminants (or energy) are essentially heat radiation. Thermal discharges (causing thermal pollution) tend to come from water used as coolant in power stations. They generate changes in water quality (e.g., reduced dissolved oxygen concentration in water), and living communities (affected, the cycles of growth and reproduction of organisms, causing the disappearance of species) and generally favor processes related to eutrophication.

Radioactive discharges cause serious problems in living organisms (such as burns, cancer, or mutations in the DNA). They often come from leaks in the cooling circuits of nuclear or medical waste or industrial research.

  • Biological contaminants: Pathogenic organisms or parasites (fungi, protozoa) can cause disease directly, producing toxic substances or simply reducing water quality. Most outbreaks are related to the water. These pollutants can come from ranching and urban wastewater.
  • Chemical pollutants: Chemicals in solid, liquid, or gas that come mostly from industrial, agricultural, and urban areas:
    • Strong acids and bases – cause changes in pH that affect water quality and living things. May come from industrial waste, acid rain, etc.
    • Gas – compounds such as CH4 or H2S may be in aqueous solution but end up spreading to the atmosphere. Usually generated by fermentation.
    • Heavy metals (Pb, Zn, etc.) – are highly toxic substances that pass without degrading food chains (bioaccumulation). Mainly from mining and industrial activities and combustion of fossil fuels.
    • Organic matter – carbohydrates, protein, fat, etc. from living organisms that produce organic pollution and loss of water quality (through the consumption of O2 dissolved, eutrophication, etc.).
    • Nitrates, nitrites, and phosphates – are pollutants from organic wastes and fertilizers, detergents, and sewage. Contribute to eutrophication. In addition, high nitrate concentrations are toxic.