A Local Ecosystem-Mt Keira

2. The abiotic features of Sites 1 and 2 were measures using different devices. Chemical testing, using universal indicator suited for use in soil was used to measure the pH of the soil at Sites 1 and 2. This process involves the removal of the top organic layer, then taking a small sample of the soil from a few centimetres below the surface and placing it on a white spot plate. To this a few drops of universal indicator are added and then a thin sprinkling of Barium Sulphate powder. After a few minutes the powder will begin to change colour and the pH of the soil can be read by matching up the colour to a pH colour chart. A high pH reading, above 7, (above neutral) will mean the soil is alkaline, while a low pH reading, below 7, (below neutral) will mean the soil is acidic. (Refer to Figure 5: pH levels, below)

Figure 5: pH levels

                1                                 7                                 14

              Acidic                                    Neutral                               Alkaline

Using a Soil Moisture Probe, that when inserted into the ground gives a reading; the moisture of the soil can easily be read. To find the aspect of the area, a compass was used to record the direction on which the slope pointed. By simply feeling and looking at the appearance of the soil it can be determined whether the soil is of a sandy makeup or mainly clay.

3. To measure the distribution and abundance of the plant population of the area, a quadrant was constructed and using a dichotomous key the species of the plants inside the quadrat can be found. Often it is impractical, or impossible, to determine the number of organisms present in an area by counting all the organisms. Rather, a quadrant study is performed, which counts the number of organisms in a small sample and then by extrapolating the number, the estimated number of organisms in a larger area can be determined. A quadrat can be constructed by using a centre pole that has four ten metre ropes extending from it. When these ropes are pulled out at right angles to each other, four points of a 10m by 10m square are formed, creating an area 100m2. Using a dichotomous key, which clearly describes each organism present in the area, the species of a tree can be identified.  

4. Organisms interact with each other in a variety of ways, usually by their feeding pattern etc. In our study, a commensal relationship was observed through the interactions between the Birds nest fern and the tree in which it lives. A parasitic relationship was observed between the leech and human. A mutual relationship was observed, through the interactions between the Moreton Bay Fig and the Agaonid Wasp. When looking at the interactions between these species, often-small hand lenses and microscopes were used, however when looking at other interaction the naked eye is all that is needed.

Results:

Figure 6: Results of the Chemical and Physical Components of Sites 1 and 2:

This table shows the chemical and physical components at each of the two sites. It shows the soil components, such as pH, moisture level and texture type. While aspect shows the direction in which the slop of the area faces. It was not appropriate to measure aspect at Site 1, due to its location at the top of the escarpment. Site 1’s location means that it is exposed generally to sunlight all day, and exposed to wind coming from nearly all directions.  

Figure 7A: Results of Quadrat at Site 2:

Figure 7A shows the abundance of trees in the Narrabeen shale Rainforest within the quadrat area (100m2), this number was then extrapolated to find the number of trees per 10,000m2, and finally extrapolated again to find the number of trees per 250 ha.

Figure 7B: Graph of Quadrat Results for Site 2(from table above):

Figure 7B shows the abundance tree species throughout the Narrabeen Shale Rainforest per 250 ha.  

2. As mentioned above wet forests in Australia (ie Site 2), posses plants and animals with unique adaptations and relations. These relationships can be commensal, parasitic or mutual.

        

Commensalism was observed between the Birds Nest Fern and its host tree. The Birds Nest Fern uses the leaf litter from the tree as nutrients and benefits from the tree’s size by being protected from heavy rainfall and wind etc. The tree is in no way affected; the fern does not feed off the tree or put its roots into the tree. Thus it is a relationship where one species, in this case the fern, benefits while the tree neither benefits nor is harmed.

Parasitism was observed between the leech and the human or other mammals, where the leech is the parasite and the human is the host. The leech feeds of the human’s blood until it is full and then drops off. In this relationship the parasite benefits, in this case the leech, while the host is disadvantages, the mammal or human.

Mutualism was observed between the Moreton Bay Fig and the Agaonid Wasp. In this relationship the fig needs the wasp to pollinate its flowers, while the wasp needs the safety of the fig to lay its eggs and thus reproduce. Thus in this relationship both species, the Fig and the Wasp, benefit and in this case would not be able to survive without the other.

3. Throughout the fieldwork investigation, it was clear that both Sites 1 and 2 and their surrounding areas, although to different extents, were affected by human interactions. The human impacts observed included:

• Extensive land clearing
• The use of the area for housing, industry, commercial uses etc.
• Spread of weeds and exotic plants throughout the rainforest and escarpment areas
• Evidence of domestic and ferrel animals in the area
• Roadside waste, dumping of rubbish
• Water pollution from fertilizers etc.
• Use of area as a tourist and camping facility

4. As seen in the Figure 7A, the abundance of tree species in the Narrabeen Shale Rainforest can be seen. Figure 7B shows the abundance of tree species per 250 hectares. As shown in both the table and graph the Sassafras tree was the most common, it is estimated that there are around 100,000 trees per 250 hectares. The next most common trees were the Brown Beech and Featherwood, with around 40,000 trees per 250 hectares. 25,000 Coachwood trees were estimated to be present in 250 hectares, while only 10,000 Moreton Bay Fig, Sweet Pittosporum, Jackwood, Red Cedar, Brush Cherry, Native Tamarind, Churnwood and Flame Tree were estimated to be present per 250 hectares.

Discussion:

1. Two different ecosystems were examined through the fieldwork; the Hawkesbury Sandstone Open Forest and the Narrabeen Shale Forest. Within these two ecosystems the physical and chemical components were measures. This included the soil moisture, soil pH, soil texture and the aspect of the area. Site 1, the Hawkesbury Sandstone Open Forest, was drier and had a lower pH, while Site 2, the Narrabeen Shale Rainforest had much moister soil with a much higher pH. The soils textures at these sites were considerable different, Site 1 was courser and predominantly contained sand, while Site 2 was a lot finer, mainly of clay content. The aspect of these sites also changed considerably. The aspect at Site 1 was not appropriate to be measured but was exposed to nearly all day sun and winds from almost all directions. Site 2, faced 110o ESE, and was less exposed to wind and received sunlight only part of the day. These results can all be seen in Figure 6 in the Results section.

The abundance and distribution of tree species in the Rainforest at Site 2 was measured using a quadrat study of a small part of the area. These numbers found were extrapolated to find the approximate number of trees per 250 hectares. As seen in Figures 5A and 5B the most common tree species was the Sassafras, followed by the Brown Beech and Featherwood, while the least common was the Red Cedar, Moreton Bay Fig, Churnwood and Flame Tree. The low number of Red Cedar trees can be linked to the early logging that occurred in the early 1800’s in the Illawarra. This area was extensively cleared at that time for farming and now the land is predominantly used for housing.    

The Moreton Bay Fig is an example of a producer organism that has adapted to its living and non-living surroundings. The Moreton Bay Fig has adapted to the area in which it lives by having large leaves with increased surface area to absorb sunlight (Refer to Figure 8, below). The waxy cuticle of the leaf is used to minimise water loss through transpiration and also reflect excess sunlight on hot days. The large, bright fruit that the tree produces is used to attract birds, which disperse seeds so that the tree can reproduce. The leaves of the Moreton Bay Fig are also situated at the top of the tree, so they are easily seen by birds and also in this way can photosynthesis more efficiently and effectively. These features can be seen in Figure 6, on the following page.

Figure 8: Moreton Bay Fig-leaf and fruit 

The unique relationships that occur in this part of the environment were observed the through the interactions occurring between different organisms. These include a commensal relationship between the Birds Nest fern and the tree, a parasitic relationship between the leech and mammals and a mutual relationship between the Moreton Bay Fig and the wasp. The studies of these relationships demonstrate the importance of the existence of some organisms in the environments; some organisms even depend on each other for their survival, including the leech and mammal or Birds Nest Fern and the tree. (Refer to Figure 9: Birds Nest Fern, on following page)

Figure 9: Birds Nest Fern

Through this study we have also acknowledged the effects of human impacts on the   environment. Human impacts such as pollution, the introduction of weeds and the problem of ferrel and domestic animals have all had detrimental effects on the environment. All of these impacts lead to the damage or destruction of native plants and animals in the area. However there are some that although do not repair the damage that has been done to the environment, do raise awareness to these issues, this being the use of Mt Keira as a tourist area. Through this visitors can grasp an understanding of the issues affecting the environment and hopefully will be deterred from creating some of these issues themselves.

2. Throughout the fieldwork investigation there were a number of difficulties that were encountered. Primarily, the time limitation was the greatest. With more time observations could have been made in greater detail or more information could have been gathered. Further, accuracy was also a problem with the quadrat study. Small inaccuracies in the counting of species could have led to very large inaccuracies when the number was extrapolated to find the number of trees per 250 ha.

3. To improve this task, a deeper study of the interactions between plants and animals etc. would give a better understanding to the processes occurring at Mt Keira. Further study of the physical features at both sites may also provide reasons for some of the findings that were found. While repeating some of the chemical testing and retaking the measurements would also improve accuracy and remove any discrepancies that occurred between the five groups.  

Bibliography:

Reference Books:

• Spotlight Biology Preliminary.(2002) Australia: Science Press

Websites:

• No author, (2002) Mount Keira - Local area information. Available at http://www.wollongong.nsw.gov.au/library/localinfo/mtkeira/ Accessed: 29th May 2004