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.

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            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.