Topic 4: Ecology

The Timeline / Powerpoints / Video’s / Assignments for this Topic are on the class website

4.1 Species, communities and ecosystems

Essential idea: The continued survival of living organisms including humans depends on sustainable communities.

Understandings:

  • Species are groups of organisms that can potentially interbreed to produce fertile offspring.
  • Members of a species may be reproductively isolated in separate populations.
  • Species have either an autotrophic or heterotrophic method of nutrition (a few species have both methods).
  • Consumers are heterotrophs that feed on living organisms by ingestion.
  • Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.
  • Saprotrophs are heterotrophs that obtain organic nutrients from dead organisms by external digestion.
  • A community is formed by populations of different species living together and interacting with each other.
  • A community forms an ecosystem by its interactions with the abiotic environment.
  • Autotrophs obtain inorganic nutrients from the abiotic environment.
  • The supply of inorganic nutrients is maintained by nutrient cycling.
  • Ecosystems have the potential to be sustainable over long periods of time.

Applications and skills:

  • Skill: Classifying species as autotrophs, consumers, detritivores or saprotrophs from a knowledge of their mode of nutrition.
  • Skill: Setting up sealed mesocosms to try to establish sustainability. (Practical 5)Winter Break Project
  • Skill: Testing for association between two species using the chi-squared test with data obtained by quadrat sampling.Bamfield
  • Skill: Recognizing and interpreting statistical significance.Bamfield Labs
Mesocosom Project: Practical #5

Ecosystems describe the interaction between biotic components (i.e. communities) and abiotic components (i.e. habitat). They are largely self-contained and have the capacity to be self-sustaining over long periods of time

There are three main components required for sustainability in an ecosystem:

  • Energy availability– light from the sun provides the initial energy source for almost all communities
  • Nutrient availability– saprotrophic decomposers ensure the constant recycling of inorganic nutrients within an environment
  • Recycling of wastes– certain bacteria can detoxify harmful waste byproducts (e.g. denitrifying bacteria such asNitrosomonas)

Mesocosms are enclosed environments that allow a small part of a natural environment to be observed under controlled conditions. A terrarium is a small transparent container (e.g. glass or plastic) in which selected plants (or animals) are kept and observed

Here is the Assignment Outline Link as well as the Link to the Rubric

Making a Self-Sustaining Terrarium

A terrarium can be created using a glass or plastic bottle with a lid,you can find a guide for how to set this up on BioNinja

  1. Building a verdant foundation
  • Add a bottom layer of pebbles, gravel or sand – this layer exists for drainage (smaller vessels require thinner rock layers)
  • Add a second thin layer of activated charcoal – this will prevent mold and help to aerate the soil
  • Spread a thin cover of sphagnum moss (or use an organic coffee filter) to create a barrier between the lower layers and soil
  • The final layer is the pre-moistened growing medium (i.e. potting mix)
  1. Selecting the right plants
  • Ideally, choose plants that are both slow growing and thrive in a bit of humidity (e.g. most ferns, club moss, etc.)
  • Inspect the plant thoroughly for any signs of disease or insects before introducing to the terrarium
  1. Maintaining appropriate conditions
  • Ensure the terrarium is placed in a location that provides a continuous source of light
  • Locate the terrarium in a place that does not experience fluctuating temperature conditions (i.e. avoid direct sunlight)
  • Do not initially over-water the plants – once the right humidity is established, a terrarium can go months without watering
  • Occasional pruning may be required – however, as level of soil nutrients decrease, plant growth should slow down

Example of a Self-Sustaining Terrarium