What are the levels of organisation in the biosphere?

2.1.6 Define the terms species, population, habitat, niche community and ecosystem with reference to local examples.

QUESTIONS: What is the biosphere, and how is it different to a biome, an ecosystem, and a habitat? What do these terms have to do with ‘scale’? Can you rank these natural systems according to size?

EcoSYSTEM Biosphere (diagram)

In ecology, all living organisms can be studied and organised in different levels or ‘ranked’ at different scales of complexity. The diagram below is a visual representation of key terms in a more-or-less hierarchal order. Do you agree with how it is organised? Is it possible to sort these differently?

QUESTION: What is the difference between a species or population’s habitat and their niche? [refer to ESS glossary for assistance]

Review the lesson notes here: 2.1.6 Definitions+ Terms

Practice terminology here: T2 Terms Review Quiz

TASK: Using a Southeast Asian rainforest species complete the table with information you have researched. T2 TRF Terms & Examples. You should also refer to the following online source for information on the SEA Rainforest (click on the image below)

In class worksheet handouts: Ecosystem look like – handout

As we know, we can study ecosystems at a variety of scales because they come in all shapes and sizes. There are many, varied ecosystems in the world but if we step back and analyse them, we see general system similarities regardless of their type and scale. The general commonalities include structure, function and population dynamics. These allow us to compare and measure different ecosystems.

Let’s first look at the common “design” and “shape” of ecosystems with all their components and interactions in place, i.e. the ecological system’s structure. Each ecosystem is made of food chains, which make up food webs, which in turn can be sorted in to trophic levels and pyramid (x3) structures. They can also be structured by population interactions.

Every ecosystem’s community are be structured in similar ways. One example is a food chain and another is trophic structure. A food chain comprises a sequence of organisms or species, each of which is a source of food for the next. Food chains in ecosystems are organized according to trophic levels: the position an organism occupies in a food chain (hierarchy). Species are assigned to trophic levels on the basis of their feeding ‘rank’ and source of energy.

Trophic

Producers from the first trophic level, 1st order consumers (primary consumers) eat producers (i.e. they are herbivores), 2nd order consumers (secondary consumers eat herbivores (i.e. they are carnivores) etc. Organisms may occupy more than one trophic level depending on their diet. Detrivores and decomposers obtain their energy from all other trophic levels and therefore not assigned a specific trophic level.