Evaluating Biodiversity in Leaf Litter

Evaluating Biodiversity in Leaf Litter of Pines and

Oaks using Berlese Funnel Technique

Rachel Perry

 

Introduction:

Berlese funnels are used for extracting arthropods from soil and litter samples. They work on the principle that insects and other arthropods that normally live in soil and litter will respond negatively to light or the loss of moisture due to the heat caused by light. Therefore, a light source is used to force the arthropods to move downward, where they will fall into a funnel and then into a container of ethanol. Soil and litter samples are first collected in a natural habitat, usually in a forested area. The samples may be sifted first so as to maximize the amount collected.

Method:

Leaf litter samples will be taken weekly from several species of trees. Samples will then be processed using a Berlese Funnel in order to quantify the insects found within the leaf litter. Samples will be placed in a funnel over a mesh net with a 90 watt bulb overhead overnight. The insects will be caught in a preserving fluid, and examined the following day.

The soil underneath the leaf litter sample collected will be tested to determine its Ph level.

Average amount and type of insects will be calculated within tree species.

Chi squared will be used to find differences in categorical values of insects amongst tree species.

A GIS graph will be made to show placement of trees on a map of New College main campus as well as indicating the trees that had the highest number of arthropods and the highest diversity of arthropods.

Oak and Pine trees are currently the focus of this study, however if a suitable Brazillian Pepper or Australian Pine tree were located, taking samples from the bases of these trees would allow the effects invasive species have on arthropods to be seen.  

A final report will explore the correlation between acidity of trees and concentration of insect species and number.

Factors to Account For:

Weather
Location
Species of tree

Tools needed:

GPS system for lat/long
Berlese Funnel system
    Light bulbs
    Mesh
    Alcohol
    Funnel
    Container
Bags to collect samples

Purpose:

To determine if acidity of trees affects insect concentration in leaf litter.

Hypothesis:

The higher the acidity of the surrounding soil the fewer arthropods there will be in the samples collected.

_______________

            The leaf litter from Live oaks and Slash pines were taken in this experiment to monitor the difference in organism numbers and species numbers. The idea was that the soil with the pH closer to 7 (Live oak) would harbor more insects as the leaf litter would be more accommodating to their natural needs. There were three collection days in which three samples were taken from oaks and three samples were taken from pines. These samples were placed in the berlese funnel over night and the insects in the collection fluid were counted the next morning.

            A pH test was run to make sure the pH of the trees was different: the oaks had a pH of 6.5 and the pines had a pH of 5. The oaks consistently had a much greater number of both organisms and species than the pines. This data was highly consistent except for one outlier pine, which had a mixed leaf litter and high shade and moisture. This tree had a total of 16 insects (4 times more than the highest number of organisms for any other pine) and 38 amphipods. Needless to say, this outlier was removed when calculating the statistics as enough other data was collected to keep this tree out of the final results.

            Significant data was found concurring with our hypothesis. However, some concerns were raised while collecting the data. What if the organisms sought shade and moisture and did not care about pH? The oaks always had more moisture and shade than the pines, except for the outlier pine, where many animals were found. This raised a large concern, and if the experiment were to be repeated testing for pH it is recommended that trees have leaf litter and soil of similar moisture and shade.

Works Cited

Kingsolver, Robert W. "Biodiversity." Ecology on Campus. San Francisco: Pearson/BenjaminCummings, 2006. 299-317. Print.

Stork, Nigel E., and Paul Eggleton. "Invertebrates as Determinates and Indicators of Soil Quality."American Journal of Alternative Agriculture 7.1 and 2 (1992): 38-47. Print.

Microbial Communities using Hay Infusion Lab 9C

Microbial communities on a salt concentration gradient were measured over a period of 4 weeks. This is what was found:

1st measurement

Fresh-none

trace-1 moved

brackish- none

saline- 2 types everything moved-too many to count

high saline-2 types everything moved-too many to count

sea water- 1 type 3 cells

2nd measurement

fresh- 1 type of cell no movement

trace- 0 cells

brackish- 1 type 5 cells

saline- 1 type 4 cells

high saline- 0 cells

sea-  0 cells

3rd measurement-

Fresh-none

Trace-none

Brackish-none

Saline- 2 types,

High saline- 3 types

Sea- 3 kinds

4th measurement

Fresh-none

trace-none

brackish- none

saline- 1 type, lots of them

high saline- 3 types, lots of them

sea- 2 types, lots of them

Like Whittaker's study of trees, there is an ideal level where growth is most sustained. This is true for this experiment as well, high saline was most sustainable for growth, and anything less than saline was not good for growth. Although there may have been some incorrect measurements due to using the microscope wrong, the final result follows this hypothesis. 

Clements model for this experiment would say that certain species have a sharp cutoff on the level of salt tolerance in which habitat they can live in. This experiment seems to be more suited to the Gleason model, however, because some species were seen over several gradients of salt, although it was very obvious that their numbers declined in different salt habitats. 

The dried grass was collected from a salt marsh near the sea, but I would expect a different result from grass collected no where near the salt water, because the protozoas would not be adjusted to living in a salty environment. 

The collections smelled terrible:

Smell-

Fresh- bad breath

trace-horrible

brackish-better than trace

saline- same as brackish

highly saline- worse than fresh

sea- barely smell anything

The worst smelling sample had the most bacteria, however, the 2nd worst smelling one had no bacteria. Thus, we could not tell bacteria culture from the smell. However, it can be expected that many bacteria types grew in different hay cultures because of the different and unique smells, not to mention that we looked under the microscope at them. 

Dissolved Oxygen and Temperature Lab 16 A

 

The shape of the standard curve is nearly linear. If the average is taken and a standard fit line is placed, it would be linear. The line, however, is linear in the wrong fashion. Based on previous knowledge, the dissolved oxygen levels should decline as temperature increases, as shown in the following graph found at : http://users.vcnet.com/rrenshaw/do.html.

Our DO meter may not have been calibrated correctly, although we followed the instructions in the manual. No Lab assistants were around to help at the time.

If oxygen is dissolved in cold water, as the water heats up the oxygen will escape in little air bubbles. This can be observed in common phenomenons such as boiling water for your morning tea.

In the field site measurement, the data compared right on with the standard curve. The water at the site was saturated a normal amount compared to the data curve. The DO could change however, depending on the number of organisms living in the water and if the temperature changes throughout the day. This water was taken from an aquarium, which is heavily monitored to prevent the fish from asphyxiation and also oxygen poisoning.

The relationship between temperature and DO explains the adaptive significance of symbiotic algae within bodies of coral polyps on tropical reefs because they are located in fairly warm (35C +) water. The algae releases oxygen which the organisms living in the coral can then use to survive in the low oxygen level waters.

Trapping of infrared radiation by carbon dioxide in the atmosphere can warm the atmosphere a few degrees over the next century. This can greatly affect aquatic habitats because the surface water will be warmed more easily, releasing more oxygen and eventually having the possibility to create a hypoxic surface area on the water.

Allometric Tree Relationships Lab 2C

This graph was created by placing the trunk diameters in cm on the x axis and the tree heights in cm on the y axis. The tree heights were placed in order from least to greatest.


From the graph, the height of the tree shows a curvilinear relationship. This can be interpreted as the tree grows taller, the trunk of the tree must grow wider.

In animals, the strength of a supporting bone is related to the cross-sectional area of the bone. This results in different proportions for legs of heavy animals. A similar trend occurs for heavier trees, as the weight increases the diameter of the tree increases where the height of the tree begins to level off.

If the strength of a tree trunk is proportional to it's cross sectional area, and the weight of a tree is related to it's volume, then the tree heights between 1000 and 3000 cm should yield a straight line on the graph for corresponding diameters.

Using the tangent to find the height of the tree was necessary for this project because we had measured or found the two other necessary components for the equation, the opposite and adjacent were already in hand. Sine would be used to find the distance to the tree base, which was known, and Cosine could be used to find the angle to the top of the tree.

On my campus, other factors than the age of the tree affecting the height and diameter are the number of other trees in the location, if canopies of trees have already grown above the new tree, it's growth will be stunted. The diameter will be affected by nutrients in the soil as well as closeness to other trees. The most affecting factor noticed was the tree canopies overlapping smaller trees. Although some of the shorter trees were more thick, if the canopy had already reached a greater height the shorter tree would have stunted height growth.

Niches of Birds at a Feeding Station

Research Question: Do birds at a feeder exhibit different feeding niches?

A bird feeder was place outside and observed. No birds were observed feeding at this location, so other various apparatuses were set up in different locations on campus. No birds were observed feeding at these other 4 locations either, except for 2 ducks feeding from spilled seeds on the ground under one feeder. Birds were observed flying around the feeder, and feeding from external sources near the feeder, however, no birds were observed directly feeding at the feeder.

Grackles, mockingbirds, blue jays, and woodpeckers were seen flying in abundance near all areas of the feeder.

Possible reasons birds would not feed at the feeder are because of the large lovebug bloom right in that week of observation. It is also a good season this year for feeding, as there is an abundance in plants and insects. Grackles were seen feeding in the air, blue jays on the ground, and woodpeckers and mocking birds feeding in the trees.

Carrying Capacity- 4B

4B
Comparing Exponential and Logistic growth
Research question: How to projections of the exponentially and logistic growth models compare?

Population over time as compared to exponential and logistic models

Expected Population up to the year 2020

Darwin’s projection for his Addo elephants can be plotted as a J curve. This is not nearly as conservative as he thought and claimed, although the curve starts out slower, over the finite period of time the population grows at a much faster rate than projected in these exponential curves shown above.

If the Addo elephants do reach carrying capacity, some factors that may limit the further growth of the population would be amount of nutrition available for consumption, availability of drinking water, and space for inhabitation. In order to maintain biodiversity, however, it is much better to keep the population below carrying capacity. An example of this could be compared to practices in Myakka State Park. Invasive wild boars are harmful to the ecosystem health, so a common way to control this population is to catch the boars in traps to be sent elsewhere. While elephants are a much larger size than boars, a similar method could be devised to maintain the humane aspect of controlling the population. Killing the elephants may be a complicated and publicly opposed process. As another important point, it may be very difficult to dispose of the dead elephants other than in natural means.

The carrying capacity for the exercise was presumed at 500 K, however, in order to calculate a more accurate number the space and resources available should be taken into account. This could effectively raise or lower the K for specific areas. Populations of other animals consuming the same resources will also affect this number, as the resources will be limited.

Humans at one time were assumed to follow a similar problem, our growth would continue until we eventually outgrew our food supply. However, we now have scientific advances that allow us to genetically modify food supplies and effectively lower the cost of food, and the problems that come from harvesting it from the wild. Because we do have more access to necessary supplies to keep us alive, there is no longer really an r-selection applicable. Humans live in a fairly stable environment in terms of resources. Thus, K- selection is increased. This stabilizes the population for now, until living spaces no longer are available and the population must decrease.

Thus, for humans, carrying capacity depends on living space available, as we are able to determine effectively the food supply. At this time it is neither effective or possible to determine a human carrying capacity, as we are not sure of the technological advances yet to come.

Experiment K4A on population growth

4A

Research Question:

How rapidly did populations of the Egyptian goose grow in the Netherlands?

Year	Population Size	ln Population Size
1985	259	5.557
1986	277	5.624
1987	501	6.217
1988	626	6.439
1989	897	6.799
1990	1324	7.188
1991	2475	7.814
1992	2955	7.991
1993	5849	8.674
1994	7259	8.890

Time in Years (x axis) vs. ln N(y axis) / with red “fit” line

The slope of the fit line was found to be 0.382 ln N/year. This indicates that each year, the population of the Egyptian goose in the Netherlands grew exponentially by 0.382. In other words, the population flourished.

Questions:

1.     In the exponential population growth equation, Nt = N0 (e^rt), identify what each of the symbols stand for, and explain whether it is a variable or a constant for a given growing population.

A quantity Nt depends exponentially on time t, where the constant N0 is the original population, and the constant r is a positive growth factor.

2.     In 1985, the number of Egyptian geese observed was 259. Starting with this as an initial population size, N0=259, and using the value of r that you calculated in Method A, use the exponential growth equation to project numbers of geese in year 1994. Since that date is nine years later, use t=9 in the equation. Does the calculated number approximate the number actually observed in 1994?

Nt= 259(e^0.382*9)

Nt= 8061.28

The actual value for this year is actually 7259, giving an 11% error for the calculated value. This is a fairly good representation of the population, although the calculated value was higher than the actual value.

3.     To calculate r, ln was plotted as a function of years, and the best straight line was drawn through the points. Two points were used from that line to determine a slope. Why is this method more reliable than simply choosing two points from the data table to determine the slope?

Date from certain years could be considered outliers on a fitted line graph, thus should be excluded from finding the r value (slope). The values used to find r should be the beginning and end points to the fitted line in order to find the best and most accurate r value.

4.     Why do you think Egyptian goose populations are increasing exponentially in the Netherlands, but not in Africa where they originated?

The geese most likely do not have a natural predator in the Netherlands to control their population. In Africa, however, natural predators do exist, controlling the population from growing exponentially.

5.     When species are introduced to a new continent, they often grow so quickly that they out-compete native species. It may be too soon to tell if this is the case for the Egyptian goose, but there are North American examples of introduced species that have become an ecological problem. Name an example and explain why this species is an ecological threat.

Brazilian red pepper is a common plant to Florida. It was introduced from frost-free south American regions, and is now spreading rapidly and replacing native plants such as mangroves. It is suited to grow in nearly any environment, and grows with a vine like quality choking out many plants nearby and absorbing nutrients in the soil.