Key Concepts
Definitions
Biogeography is the study of the current distribution and patterns of life on earth. Its study therefore is concerned with the natural and human processes that cause these distributions. Biogeography also is concerned with predicting and managing such patterns.
Ecology is the study of where organisms live. Habitats are the homes of individual species, which form part of the biosphere: all of the ecosystems in the world.
An Ecosystem is the interrelationship between biotic factors (plants and animals) and abiotic factors (such as air, water, heat, nutrients, rocks and sediment). Ecosystems are open systems due to the flows of energy across their boundaries. The map below represents the different ecosystems and their rough location globally.
Biogeography is the study of the current distribution and patterns of life on earth. Its study therefore is concerned with the natural and human processes that cause these distributions. Biogeography also is concerned with predicting and managing such patterns.
Ecology is the study of where organisms live. Habitats are the homes of individual species, which form part of the biosphere: all of the ecosystems in the world.
An Ecosystem is the interrelationship between biotic factors (plants and animals) and abiotic factors (such as air, water, heat, nutrients, rocks and sediment). Ecosystems are open systems due to the flows of energy across their boundaries. The map below represents the different ecosystems and their rough location globally.
An Environment as a collective term for all the conditions in which an organism lives and are subject to. These can be split also into biotic (e.g. plants, animals, bacteria and fungi) and abiotic factors (e.g. temperature, pH, water availability, light, wind, nutrients, carbon dioxide, oxygen, humidity and underling geology).
In ecology and biogeography, a population is the total number of a particular species in a habitat. The community is the total number of individual species in a habitat or ecosystem.
Scales of Investigation
Ecologically, there are several scales or units at which biogeography can be investigated:
· Microhabitat/Niche: Small, specific locations that a plant or animal occupies e.g. under rocks on a river bed.
· Habitat: Specific locations that are commonly found e.g. in freshwater ponds.
· Zones: Units in a biome e.g. the horizontal layers in a tropical rainforest.
· Biomes: Environments found on at least two continents (although they may have individual characteristics) e.g. tropical rainforests.
Energy & Trophic Levels
Ecology is studied in relation to the energy transfer through an ecosystem. These are often represented by Food Chains and Food Webs. Food chains are linear sequences that are incredibly uncommon in the natural world, due to the nutritional requirements of consumers that mean that several sources of energy are required. This results in a more complex food web.
In these webs, there are distinct levels, which are referred to as a Trophic Level. The first level is a producer that can also be described as an Autotroph (which can convert sunlight to energy e.g. plants). Secondly, there are herbivores (plant eaters) and finally, carnivores (animal eaters). These subsequent levels are all consumers or Heterotrophs (which gain energy from feeding on other organisms e.g. humans). Detritivores (such as bacteria and fungi) exist at all trophic levels too, and are also heterotrophs.
Energy is passed from one trophic level to another through consumption. However, this is not an efficient process as only 1% of light energy is transferred to food energy. Energy is represented by Biomass which is the total amount of living matter of one species in an ecosystem.
In ecology and biogeography, a population is the total number of a particular species in a habitat. The community is the total number of individual species in a habitat or ecosystem.
Scales of Investigation
Ecologically, there are several scales or units at which biogeography can be investigated:
· Microhabitat/Niche: Small, specific locations that a plant or animal occupies e.g. under rocks on a river bed.
· Habitat: Specific locations that are commonly found e.g. in freshwater ponds.
· Zones: Units in a biome e.g. the horizontal layers in a tropical rainforest.
· Biomes: Environments found on at least two continents (although they may have individual characteristics) e.g. tropical rainforests.
Energy & Trophic Levels
Ecology is studied in relation to the energy transfer through an ecosystem. These are often represented by Food Chains and Food Webs. Food chains are linear sequences that are incredibly uncommon in the natural world, due to the nutritional requirements of consumers that mean that several sources of energy are required. This results in a more complex food web.
In these webs, there are distinct levels, which are referred to as a Trophic Level. The first level is a producer that can also be described as an Autotroph (which can convert sunlight to energy e.g. plants). Secondly, there are herbivores (plant eaters) and finally, carnivores (animal eaters). These subsequent levels are all consumers or Heterotrophs (which gain energy from feeding on other organisms e.g. humans). Detritivores (such as bacteria and fungi) exist at all trophic levels too, and are also heterotrophs.
Energy is passed from one trophic level to another through consumption. However, this is not an efficient process as only 1% of light energy is transferred to food energy. Energy is represented by Biomass which is the total amount of living matter of one species in an ecosystem.
Environmental Factors
As with any earth system (such as the atmosphere or hydrosphere), the biosphere is inherently linked with its counterparts. Therefore, any study of biogeography (or ecology) needs to consider these linkages carefully. Of course, this includes human impact too. In the study of different ecosystems and biomes, there are many potential process and functions that can be examined.
Climate:
· Temperature Regime: linked to seasonality (or a lack of), length of the growing season. Actual temperature also has effect on whether animals hibernate, or if high temperature exacerbate the effects of limited rainfall.
· Precipitation: amount of rainfall received providing moisture. However, counteracted by evaporation. May lead to dry seasons, which are influenced by other factors such as geology, soil type, slope and altitude
Soils:
· Outermost layer of the earth’s surface, comprised of weathered bedrock, organic matter, air and water
· Described through a two-dimensional cross section, divided into layers called Horizons:
O – Organic Horizon: (un)decomposed organic litter
A – Mineral-Organic Horizon: mixing of the bedrock minerals and dark organic matter from the surface
E – Eluvial or Leached Horizon: Lighter-coloured horizon where material is leached by water movement
B – Illuvial or Deposited Horizon: Darker in colour where material has been displaced too from the E Horizon
C – Parent/Bedrock
As with any earth system (such as the atmosphere or hydrosphere), the biosphere is inherently linked with its counterparts. Therefore, any study of biogeography (or ecology) needs to consider these linkages carefully. Of course, this includes human impact too. In the study of different ecosystems and biomes, there are many potential process and functions that can be examined.
Climate:
· Temperature Regime: linked to seasonality (or a lack of), length of the growing season. Actual temperature also has effect on whether animals hibernate, or if high temperature exacerbate the effects of limited rainfall.
· Precipitation: amount of rainfall received providing moisture. However, counteracted by evaporation. May lead to dry seasons, which are influenced by other factors such as geology, soil type, slope and altitude
Soils:
· Outermost layer of the earth’s surface, comprised of weathered bedrock, organic matter, air and water
· Described through a two-dimensional cross section, divided into layers called Horizons:
O – Organic Horizon: (un)decomposed organic litter
A – Mineral-Organic Horizon: mixing of the bedrock minerals and dark organic matter from the surface
E – Eluvial or Leached Horizon: Lighter-coloured horizon where material is leached by water movement
B – Illuvial or Deposited Horizon: Darker in colour where material has been displaced too from the E Horizon
C – Parent/Bedrock
Nutrients:
· Circulated and re-used in an environment
· Carbon, Oxygen, Hydrogen and Nitrogen needed in large quantities – known as Macronutrients
· Micronutrients such as Magnesium and Phosphorus are needed in smaller quantities
· Nutrients are used by producers in growth. The nutrients pass up the food chain through consumption. In turn they are returned to soil through excretion and decomposition after death
· Nutrient can be derived from the bedrock (termed sedimentary) or from the atmosphere (e.g. the nitrogen cycle) – sedimentary cycles are more easily disturbed by human activity
· Nutrient cycles often shown by the way of a Gersmehl’s Nutrient Cycles which show the stores (represented by circles) and transfers (represented by arrows) of nutrients
· Circulated and re-used in an environment
· Carbon, Oxygen, Hydrogen and Nitrogen needed in large quantities – known as Macronutrients
· Micronutrients such as Magnesium and Phosphorus are needed in smaller quantities
· Nutrients are used by producers in growth. The nutrients pass up the food chain through consumption. In turn they are returned to soil through excretion and decomposition after death
· Nutrient can be derived from the bedrock (termed sedimentary) or from the atmosphere (e.g. the nitrogen cycle) – sedimentary cycles are more easily disturbed by human activity
· Nutrient cycles often shown by the way of a Gersmehl’s Nutrient Cycles which show the stores (represented by circles) and transfers (represented by arrows) of nutrients