Methods (10 marks)

Tables 1 and 2, below, show an edited data set of some of the components of the 'organizing framework' collected at two sites in Sevilleta. Note that in each of them, 'NA' means that no data are available for that variable in the relevant year. These data are also available in spreadsheet format from the 'Assessment' section of the module website.

Year	Precipitation/mm	Soil moisture/relative water content	Rabbit density/number of individualshectare1	Coyote density/number of individualskm2
1989	106.4	NA	NA	NA
1990	232.4	NA	NA	NA
1991	334.7	NA	NA	NA
1992	240.8	NA	0.060	0.880
1993	207.4	NA	0.272	0.702
1994	288.1	NA	0.125	0.793
1995	138.8	NA	0.246	0.575
1996	301.9	0.112	0.104	0.598
1997	325.3	0.123	0.168	0.703
1998	225.3	0.114	0.170	0.758
1999	235.7	0.094	0.138	1.065
2000	284.4	0.105	0.085	0.898
2001	214.8	0.095	0.058	0.945
2002	228.7	0.096	0.072	0.738
2003	133.2	0.100	NA	0.543
2004	301.4	0.112	NA	0.303
2005	277.4	0.110	NA	NA

Year	Precipitation/mm	NPP/gm2y1	Arthropods/number of individualshectare1	Rodents/number of individualshectare1
1989	NA	NA	NA	268
1990	NA	NA	NA	122
1991	NA	NA	NA	102
1992	NA	NA	1193	439
1993	NA	NA	986	376
1994	NA	NA	1061	195
1995	NA	NA	772	595
1996	NA	NA	756	118
1997	NA	NA	1811	551
1998	NA	NA	795	305
1999	199.9	42.86	747	361
2000	254.1	49.66	323	478
2001	245.8	67.21	2416	148
2002	226.1	83.84	1451	279
2003	140.6	27.51	2158	695
2004	322.6	84.13	1650	255
2005	283.7	72.95	NA	476
2006	345.8	104.46	NA	301
2007	253.1	153.85	NA	997
2008	272.9	138.84	NA	404
2009	245	42.14	NA	654
2010	200.9	72.70	NA	202
2011	152.9	34.56	NA	239
2012	133.5	NA	NA	335
2013	274.1	NA	NA	174

Use the data in these tables to complete the tasks and questions outlined below.

a.Summarise what variables are present in the data for each site, including the number of replicates and the duration of the studies. (Onesentence for each site)

b.Pick two of the variables in Table1 and compose a hypothesis linking them ('Hypothesis1') that you could investigate using the data in that table. Provide an explanation of the scientific basis for your choice.

c.Looking at the data in Table2, and assuming that the majority of arthropods (such as grasshoppers) in this community eat plant material and that the rodents eat seeds and arthropods, suggest another hypothesis ('Hypothesis2') about how two of these variables might be linked to each other. Provide an explanation of the scientific basis for your choice.

d.Provide an example from either table of a link between variables that may operate with a time lag. Suggest a third hypothesis (Hypothesis 3) that describes this link.

Results (15 marks)

• a.Use a spreadsheet program to draw a graph that is suitable for investigating a correlation between the two variables in your Hypothesis 1. Use an appropriate statistical test to test for a correlation between these variables. Comment on whether your result is statistically significant.
• b.Now use a spreadsheet program to draw a graph that is suitable for investigating a correlation between the two variables in your Hypothesis 2. Use an appropriate statistical test to test for a correlation between these variables. Again, comment on whether your result is statistically significant.
• c.Finally, use your spreadsheet software to draw a graph that is suitable for investigating the correlation between the variables in your Hypothesis 3. Use an appropriate statistical test to test for a correlation between these variables. Again, comment on whether your result is statistically significant.