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Factors affecting the role that the relationships between biotic and abiotic factors contribute to the relationship between foliage and ground coverBy Effie LucasIntroduction:A functioning ecosystem is totally reliant on the way in which factors such as biotic and abiotic interrelate and create a balance of living and non-living. Biotic factors are those features of the environments of organisms arising from the activities of the other living organisms, relating to, produced by, or caused by living organisms (M. Thain/ M. Hickman 2003:16). Abiotic factors are non-living chemical and physical factors in the environment which include light, temperature, water, atmospheric gases, and wind as well as soil. The six major abiotic factors are water, sunlight, oxygen, temperature, soil and climate (http://el.erdc.usace.army.mil/pmis/biocontro l/html /abio tic .html). Biotic and abiotic factors combine to create a system or more precisely, an ecosystem which is a community of living and nonliving things considered as a unit. Biotic and abiotic factors are interrelated (Groiler 1997:106).
If one factor is changed or removed, it impacts the availability of other resources within the system (http://library.thinkquest.org). If an abiotic factor is changed, such as soil nutrient levels, this may affect the growth of a biotic factor such as grass and trees, in turn making the plants decrease in population. This subtle change in turn affects biotic factors such as large organisms that need the plants to survive. This decreases the number of large organisms and affects the balance of the ecosystem. Ground cover is those herbaceous plants, small shrubs and non-vascular plants growing beneath the tree and shrub canopy (museum.gov.ns.ca/mnh/nature/ nhns2/glossary.htm.) Ground cover is used for two main purposes; to hide the ground beneath, or to protect it from erosion or drought.
Foliage cover is the percentage of a fixed area covered by crowns of plants surrounded by a vertical projection of the outermost perimeter of the spread of the foliage (www.fs.fed.us/r6/ fremont/sycan/text/ APPENDI X_C.htm). Ground cover and foliage cover are along with biotic and abiotic factors interrelated. The quantity of vegetation that lives in a particular area is totally dependent on the percent canopy cover that is above. If the role of photosynthesis; the process by which plants convert water and carbon dioxide into carbohydrates, using sunlight as the source of energy and the aid of chlorophyll (www.psrd.hawa ii.edu /PSRD glossary.html) is relied upon, ground areas with a high percentage of canopy cover will have a decreased amount of living vegetation underneath, as the process of photosynthesis cannot be efficiently accomplished. The relationship between biotic and abiotic factors affects the relationship between ground cover and foliage cover as the two factors interrelate and assist or hinder the others actions.
Aim: To determine the possible relationships between biotic factors, which include the varying organisms which surround an area, and abiotic factors, such as the temperature of an allocated area, humidity, Ph levels and nutrient availability to see how they play a role in the relationship between ground cover and foliage cover.
Hypothesis: If there is more overhead foliage cover than there will be less ground cover (in comparison to an area with no overhead foliage cover) because less sunlight and rain will reach the ground, the temperature will decrease and more animals will stand on and eat the ground cover that is there (due to the reduced temperature).
Materials:1x 50m measuring tape4x small stakes1x Clinometer1x hammer1x permanent marker1x roll of marking tape32m of good quality string1x manometer1x canopy densitometer1x sheet of graph paper1x thermometer2x empty 2L drink bottles1x 30cm ruler with millimeters marked outProcedure:1.The 30x1m transect was marked out by measuring out 32m of string. The stakes were then placed into the ground at the appropriate measurements and the string was wrapped around as shown in Figure 1.
2.The length of the string was marked at 1m intervals with marking tape and the numbers were written on with permanent marker as shown in Figure 2.
Figure 2 :Placement of the marking tape along the 30m string.
3.The gradual slope of the gradient was then taken to determine how steep the selected land area was.
4.This was done with the manometer at zero to half meter by placing each end of the manometer at both beginning and end of each half meter and taking a measurement.
5. This was then continued for thirty meters and was then graphed. See Figure 3.
Figure 3 :Placement of the manometer at every half meter point.
6.The percentage foliage cover was then taken to determine how much light got though the tree leaves onto the ground below. This was done using the canopy densitometer at zero to one half metres.
7.The densitometer was held directly upwards and looked through. The percent coverage was noted. This was continued for thirty meters. See Figure 48.The percentage ground cover was then taken at every half meter by determining how covered the ground was by grass and plants etc. This number was recorded and this was continued for thirty meters.
9.A description of every meter was taken to investigate was lived there and also how it lived there. Animal excretions and flowers etc. Were taken into account, as well as leaf litter. These results were put into table form.
10.The temperature for the selected area was taken both in the shade; by placing the thermometer under a tree, and in the sun; by placing the thermometer in the open at approximately 12 o’clock. It was made sure that there was no human interference when the temperatures were taken.
11.Thermometers were placed out standing upright at five minute intervals and the temperature was recorded. This was repeated over a period of 10 days.
12.The rain fall had to be measured so a rain gauge was made. A 2L soft drink bottle was cut in half, and then the upper half was inverted to create a funnel.
13. Two gauges were made for under the tree canopy, and out in the open. The measurements were recorded over a period of ten days. The results were then put into table form.
14. A pitfall trap was then constructed to determine what species of animals lived there. A fifteen centimetre square hole was dug in both the undercover and open sections of the belt transect.
15. Two small rocks were placed at either side of the hole. The hole was then covered by a large rock resting on the two smaller rocks. See Figure 6.
16.The traps were then left over night, and the findings recorded. This was repeated over a five day period.
17. pH levels for both the shade and open areas were taken. Soil was taken from both areas and placed into jars.
18.The jars were filled ¼ full and were shaken. A pH strip was placed in, left for one minute and the pH balance was recorded.
19.The height of the trees and shrubs on the belt transect were taken by using clinometers, then by using basic trigonometry.
20. All of the data was then tabled and graphed for analysis.
DayRainfall Under Tree (mm)Rainfall In Open (mm)10026 ½ 8391040052 ½ 46192271011 ½8009791000Table 3: The temperature in the belt transect over a period of ten days, both under a tree and in the open.
LocationpH LevelUnder TreeNeutralOut In OpenNeutralTable 6: Descriptions of every meter along the 30m belt transect.
The results also showed that the relationship between biotic and abiotic also played a major role in what lived in the area and also how it lived these. It can be seen that large organisms, such as wallabies and rats prefer to live and eat in the cooler areas of the belt transect, this was clearly seen when wallaby and rat droppings were found where temperatures were recorded to be lower (See table 6). It was also seen that funguses and smaller organisms such as insects, also preferred to live and eat in cooler environments which had larger amounts of rainfall (see table 6).
The relationship seen in this experiment between biotic and abiotic factors, largely relates to the real world, as species of animals that live in the south American jungle face endangerment as the plant species grown their aren’t able to reproduce at a sufficient rate due to factors such as an increase in the amount of animals living there, a lack of rain and severe climate change (http://news.mongabay.com/2006/0116-pollination.html).If time permitted to create a unbalanced ecosystem in the belt transect, these results could have proved and validated the results found in this experiment.
The results of this experiment have clearly shown that there is a significant relationship between the ground cover and canopy cover of any given area.
Discussion and EvaluationOverall this experiment was successful in proving the hypothesis that, if there is more overhead foliage cover than there will be less ground cover (in comparison to an area with no overhead foliage cover) because less sunlight and rain will reach the ground, the temperature will decrease and more animals will stand on and eat the ground cover that is there (due to the reduced temperature). This confirms that there is a distinct relationship between the ground cover and foliage cover.
There were many factors which could have made this experiment more accurate in proving the statement. Temperatures were taken every day for ten days, though a more precise way in which this could have been done is by going out at the exact same time every day example 12 o’clock. This would have made results more accurate as temperatures vary depending on what time of day. Temperatures could also have been taken at three different intervals of the day to have made an average.
The pitfall traps could have also been checked more frequently as no organisms were found.
This experiment has clearly shown that the proper functioning of an ecosystem is reliant on the way in which certain factors of the environment interrelate and accommodate for the organisms that live in it. The experiment has shown that areas of ground that have a high percentage of foliage cover tend to have less living vegetation and organisms living in it. This was due to many factors including animal eating habits, rail loss and ineffective photosynthesis (Groiler 1997:163).
This experiment has proved an ecosystem (the belt transect) cannot properly function if the relationships between biotic and abiotic factors and ground cover and foliage covers were not balanced and in perfect harmony.
ConclusionThe results of this experiment did prove the hypothesis that if there is more overhead foliage cover than there will be less ground cover (in comparison to an area with no overhead foliage cover) because less sunlight and rain will reach the ground, the temperature will decrease and more animals will stand on and eat the ground cover that is there (due to the reduced temperature). This could be predominantly seen in Tables 6, 7 and 8 where it was shown that less canopy cover produced less undercover foliage in comparison to open areas.
Books:M. Thain/ M. Hickman (2003) Dictionary of biology Australia, Penguin BooksMorran, Jillian (1997) Book of Knowledge. Philippenes: GroilerURL:Biotic and Abiotic Factors, Available