Week 6 & Week 7 Experimental design: Field Experiment

In this experiment, two pan-trap datasets for invertebrates were collected at approximately 3pm-4pm on October 15th , 2015 and on October 22nd , 2015. This experiment was conducted by Maleeha, Astor, Rachel and Laiba. The objective of this experiment was to determine the affect of location on the abundance of invertebrates. Specifically, the abundance of invertebrates was studied in 3 areas: York University’s Osgood Law School’s parkinglot, mowed grasslands, and unmowed grasslands. The prediction that we made was that the abundance of invertebrates would be highest in the unmowed, undisturbed area. The alternative hypothesis for this experiment was that since there is more shelter and resources available in the tall unmowed grasslands, that would account for the greater number of invertebrates found there. Similarly, it was expected that the the invertebrates in the disturbed area, the parkinglot, would be least abundant due minimal resources and shelter found there. Moreover, 54 pans, out of which 18 were whit, 18 were blue and 18 were yellow, were used for each of the two pan-trap datasets. First, in the parkinglot, 18 pans were positioned in a linear fashion with approximately 1m distance between them. They were positioned towards the edge of the sidewalk in the parkinglot, where there was little interaction of the pans with plants and insects. The distance between the pans was estimated, not precise. The pans were arranged in an alternating pattern of blue, white and yellow. When the pans were set up on October 15th, it was approximately 3:00pm and it was raining, which reduced our chances of capturing many invertebrates. On the second day of collecting the pan-trap dataset, Ocobter 22nd, it was windy, which also affected the abundance of any invertebrates caught. After the pans were positioned, they were filled in half-way with soapy water. The soapy water would allow for invertebrates to be easily caught through the pan-trap method due to the property of surfactant which would reduce surface tension of the water with an invertebrates. Additionally, in the mowed grasslands, 18 more pans were arranged in an alternating pattern of blue, white and yellow pans and they were placed in the center of the mowed grasslands. These pans were also placed approximately 1m apart with respect to eachother. The pans were also filled in half-way with soapy water to trap any invertebrates. Lastly, 18 additional pans were positioned within the unmowed grasslands, in the same pattern of blue, white and yellow pans. These pans also had a distance of 1m between them. These pans were then filled in half-way with soapy water. Moreover, approximately 30min after setting up all the pans, the pans in the parkinglot, mowed grasslands and unmowed grasslands were checked for trapped invertebrates. The number of invertebrates in each pan was counted and the observations were recorded. Furthermore, each invertebrate’s name and taxonomic order were defined using the invertebrate key in the lab manual, under week 4. Once the pans were checked, they were emptied out and collected.