Investigation+4


 * Digital Resource - Interactive Ecology Lab (lesson 1) **


 * Focus Question: ** What effect can plant dominance have on an ecosystem and how can the introduction of a herbivore alter the population of species?

**//Step 1://**

//** Method/Procedure **//

1. Use the digital simulator to investigate how two newly forming plants survive in an ecosystem. 2. Run the simulator to 100 steps. 3. Record results of the population of both plants in a table.

__// **P**redict //__// (Hypothesis) //

In lesson 1 (step 1) it was predicted that the starting population would be an even distribution given that the investigation is to observe change of species over a period of time. The ending population was predicted that a plant B would have a greater dominance over plant A.

__// **R**eason //__

The digital simulation did not provide information about plant types therefore it can only be assumed that the newly forming ecosystem began with an even distribution of species as both producers would have been strong species particularly if they were the first colonizers of successive growth in an area after an event such as fire or flood. It can be assumed that over a period of time one of the plants would be more dominant as it would need to compete for survival.

//__**O**bserve__(results)//

As it can be seen from the table below there was a considerable difference in the starting population of both species of plants. Plant A had almost double the population of plant B having grew rapidly to result in dominating 100 % of the ecosystem. This resulted in plant B being completely eradicated by the more dominant plant A.

Step 1 || Plant A (Dark green) || Plant B (Light green) ||
 * DATA TABLE 1: ECOLOGY **
 * Lesson 1:
 * Prediction: starting population || 50 % || 50% ||
 * Prediction: ending population || 30 % || 70% ||
 * Starting population || 6114 || 3427 ||
 * Ending population || 10 000 (100%) || 0 ||

//**Questions (The Annenberg Foundation, 2012):**//


 * What assumptions does this model make about co-dominance as well as the general terrain of the ecosystem?
 * Do you find one producer to be dominant? Why might one producer be dominant over another?

__//**E**xplain//__

From the results it shows that plant A was in fact the more dominant producer and also suggests that it must have been quite a harsh terrain such as low nutrients, sunlight or lacking the availability of water that resulted in the a more dominant producer (plant A) having to compete for its survival (The Annenberg Foundation, 2012).

(Frangenheim, 2010)

**//Step 2://**

**//Method/Procedure//**

1. Use the digital simulator to introduce a herbivore (rabbit) into the environment. 2. Select plant A to be consumed by the herbivore. 3. Run the simulator to 100 steps 4. Record the populations of plants and herbivores in the ecosystem.

__// **P**redict //__

As established in the first step there is always a plant more dominant in an ecosytem therefore it was predicted that plant A had a greater starting population. The ending population was predicted to be the opposite with plant B becoming more prominent upon the introduction of a herbivore. It was difficult to put a figure on the population of an introduced species but it was predicted to be considerably less than the plant species as it would not be as established in the ecosystem.

//__ **R**eason __//

The ending population of plant B was higher than plant A because a herbivore would be more likely to consume the more dominant plant species that would allow more growth for the less dominant plant over a period of time. As the herbivore became established in the ecosystem it would reproduce having a much greater population thn when it introduced.

//__ **O**bserve __ (results) //

As the table below shows the herbivore depletes the more dominant plant A. In figure 2 the herbivore had an initial spike in population but eventually a plateau in numbers can be observed. The results show that plant B did had a substantially greater population compared to plant A over the period of 100 days.

Step 1 || Plant A (Dark green) || Plant B (Light green) || Herbivore A ||
 * DATA TABLE 2: ECOLOGY **
 * Lesson 1:
 * Prediction: starting population || 70 % || 30% || introduced (10%) ||
 * Prediction: ending population || 30% || 70% || 50% ||
 * Starting population || 5200 || 3800 || 1200 ||
 * Ending population || 3100 || 5000 || 2000 ||

figure 1


 * // Questions (The Annenberg Foundation, 2012): //**


 * Does adding the herbivore establish a more equal field? Is one producer still dominant over the other? Why might one producer be dominant over another?
 * If the simulation included decomposers, how would your current results change?
 * How do producer population numbers with the presence of an herbivore compare to the primary colonizer model?

__// **E**xplain //__

Due to the introduction of the herbivore consuming plant A, plant B was given the opportunity to proliferate creating a greater equal field. Through the introduction of further species such as a decomposer it might encourage an even greater distribution of plant and animal species in an ecosystem as it would provide increased nutrient levels through the recycling of decaying matter. Therefore the results of populations would be significantly different again. In comparison to the results of step 1 the introduction of a herbivore into an ecosystem can stabilise the population of plant species through consumption and increased nutrients which provides less competition for survival (The Annenberg Foundation, 2012).

(Frangenheim, 2010)


 * Reflection **

The investigation using the digital resource outlined an important consideration and that is the use of ICT to carry out investigations that can mimic an environment that might not be tangible or would take considerable amounts of time to observe such as a newly forming ecosystems. The simulation provided a lot of interesting data and I was able to learn about the impacts that introduced species can have on an ecosystem sometimes not always negative as my prior knowledge lead me to believe. Through the introductions of species it can cause succession for further species and can essentially transform the ecosystem. It also emphasised the role human beings can have on an ecosystem and how their contributions can see a much rapid transformation or growth that would otherwise occur naturally. Nevertheless such roles might also lead to less favourable outcomes depending on what species are being introduced (The Annenberg Foundation, 2012).

__// Ecology website //__

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