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University of Minnesota
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Methods for Experiment 107 -

Disturbance method

In August 1991, after seeded plant communities became established, 27 plots were randomly selected (9 control, 9 low variance, 9 high variance) for a factorial experiment with 3 nutrient heterogeneity levels and 3 disturbance levels replicated 3 times. Disturbance treatments were imposed on the inner square meter of each plot by removing vegetation and turning the soil within randomly located 20cm x 20cm areas. Disturbance treatments included 3 levels: no disturbance, disturbance in 3 random locations and disturbance in 9 random locations.

General Design and Site Characteristics

These experiments are located at Cedar Creek Natural History Area, Anoka county Minnesota, on a large glacial outwash sandplain. In May 1990, a bulldozer was used to remove the upper 20cm to 30cm of soil from a 20m x 50m area of a 29 year old field. The exposed subsurface sand contained an average of 267 ppm nitrogen and had a pH of 7. The bulldozed area was divided into 215 1.5m x 1.5m plots with a 0.5m aisle between each plot on all sides. Plots are laid out in 22 rows of 10 plots each and each plot has been randomly assigned an experimental treatment. Every plot is surrounded by aluminum flashing that is driven approximately 20cm into the soil to inhibit movement of roots into neighboring plots. All plots receive an annual fertilizer treatment (20g/m2 of P2O5, K2O, and CaC03; 30g/m2 of MgSO4; 2 tsp/ m2 of trace elements) that is complete for plant macro- and micronutrients with the exception of nitrogen.

To create initially identical plant communities, 59 species of plants (47 forbs and 12 grasses) commonly found on Minnesota tallgrass prairie reserves were planted in each plot (Table 1). Seeds for each plot were mixed with moist dirt in a bucket and then spread evenly over the entire plot. All plots received the same number of seeds of each species (see Table 1 for actual numbers). One monoculture plot for each species was also seeded with these same numbers of seeds to determine germination rates and plant allocation patterns.

These experiments are unfenced. However, gophers are excluded from plots by trapping. Schizachyrium scoparium (little blue stem) is maintained (but mown before flowering) in the aisles between the plots in order to draw down nutrient levels within the aisles to eliminate edge effects.

Treatment Layout

Experiment numberPlot numberTreatmentSubplot numberAmount (inches) of black dirt mixed with sandNumber of 20cmx20cm squares disturbed per plotStandard deviation of the amount of black dirtNitrogen fertilizer addition (g/m2/yr)
1072b16200
10717b4110.2592.33
10717b4120.2592.33
10717b413292.33
10717b4140.2592.33
10717b415892.33
10717b416292.33
10717b417292.33
10717b418292.33
10717b419292.33
10717b4110292.33
10717b41110.2592.33
10717b4112292.33
10717b4113292.33
10717b41140.2592.33
10717b4115292.33
10717b41160.2592.33
10717b4117892.33
10717b41180.2592.33
10717b4119292.33
10717b41200.2592.33
10717b41210.2592.33
10717b4122292.33
10717b4123892.33
10717b4124292.33
10717b4125292.33
10724b6210.2503.29
10724b6220.2503.29
10724b623803.29
10724b6240.2503.29
10724b6250.2503.29
10724b6260.2503.29
10724b6270.2503.29
10724b628203.29
10724b6290.2503.29
10724b62100.2503.29
10724b6211803.29
10724b62120.2503.29
10724b62130.2503.29
10724b62140.2503.29
10724b6215803.29
10724b62160.2503.29
10724b62170.2503.29
10724b6218803.29
10724b6219803.29
10724b62200.2503.29
10724b62210.2503.29
10724b62220.2503.29
10724b62230.2503.29
10724b62240.2503.29
10724b6225803.29
10725b29200
10726b1230
10738b3310.2503.29
10738b332803.29
10738b3330.2503.29
10738b334803.29
10738b335803.29
10738b3360.2503.29
10738b337203.29
10738b3380.2503.29
10738b3390.2503.29
10738b33100.2503.29
10738b33110.2503.29
10738b33120.2503.29
10738b33130.2503.29
10738b3314803.29
10738b33150.2503.29
10738b3316803.29
10738b33170.2503.29
10738b33180.2503.29
10738b33190.2503.29
10738b33200.2503.29
10738b33210.2503.29
10738b33220.2503.29
10738b33230.2503.29
10738b3324803.29
10738b33250.2503.29
10740b471202.33
10740b472202.33
10740b473202.33
10740b4740.2502.33
10740b475202.33
10740b476802.33
10740b477802.33
10740b4780.2502.33
10740b479202.33
10740b47100.2502.33
10740b47110.2502.33
10740b4712202.33
10740b4713202.33
10740b4714202.33
10740b4715202.33
10740b4716202.33
10740b47170.2502.33
10740b47180.2502.33
10740b4719202.33
10740b47200.2502.33
10740b4721202.33
10740b4722202.33
10740b47230.2502.33
10740b4724802.33
10740b47250.2502.33
10747b561202.33
10747b5620.2502.33
10747b563202.33
10747b564202.33
10747b5650.2502.33
10747b566202.33
10747b567202.33
10747b568202.33
10747b5690.2502.33
10747b5610802.33
10747b5611202.33
10747b5612202.33
10747b56130.2502.33
10747b56140.2502.33
10747b56150.2502.33
10747b56160.2502.33
10747b5617802.33
10747b5618202.33
10747b5619202.33
10747b56200.2502.33
10747b5621202.33
10747b5622202.33
10747b56230.2502.33
10747b5624802.33
10747b5625202.33
10752b7010.2593.29
10752b7020.2593.29
10752b703293.29
10752b7040.2593.29
10752b7050.2593.29
10752b706893.29
10752b707893.29
10752b708893.29
10752b7090.2593.29
10752b70100.2593.29
10752b70110.2593.29
10752b70120.2593.29
10752b7013893.29
10752b70140.2593.29
10752b70150.2593.29
10752b7016893.29
10752b70170.2593.29
10752b70180.2593.29
10752b70190.2593.29
10752b70200.2593.29
10752b70210.2593.29
10752b70220.2593.29
10752b7023893.29
10752b70240.2593.29
10752b70250.2593.29
10753b201202.33
10753b202202.33
10753b2030.2502.33
10753b204202.33
10753b2050.2502.33
10753b2060.2502.33
10753b2070.2502.33
10753b208202.33
10753b2090.2502.33
10753b2010202.33
10753b2011202.33
10753b20120.2502.33
10753b2013202.33
10753b2014802.33
10753b2015202.33
10753b2016202.33
10753b2017202.33
10753b20180.2502.33
10753b2019202.33
10753b2020802.33
10753b20210.2502.33
10753b2022202.33
10753b2023802.33
10753b20240.2502.33
10753b2025202.33
10761b491232.33
10761b492232.33
10761b493232.33
10761b4940.2532.33
10761b4950.2532.33
10761b496832.33
10761b497232.33
10761b498232.33
10761b499232.33
10761b49100.2532.33
10761b4911232.33
10761b49120.2532.33
10761b4913232.33
10761b49140.2532.33
10761b4915832.33
10761b4916232.33
10761b4917232.33
10761b4918232.33
10761b49190.2532.33
10761b4920232.33
10761b49210.2532.33
10761b49220.2532.33
10761b49230.2532.33
10761b4924832.33
10761b4925232.33
10767b30230
10772b611893.29
10772b6120.2593.29
10772b613893.29
10772b614893.29
10772b6150.2593.29
10772b6160.2593.29
10772b6170.2593.29
10772b6180.2593.29
10772b6190.2593.29
10772b61100.2593.29
10772b61110.2593.29
10772b61120.2593.29
10772b6113293.29
10772b61140.2593.29
10772b6115893.29
10772b61160.2593.29
10772b61170.2593.29
10772b6118893.29
10772b61190.2593.29
10772b61200.2593.29
10772b61210.2593.29
10772b61220.2593.29
10772b61230.2593.29
10772b6124893.29
10772b61250.2593.29
10774b431232.33
10774b432232.33
10774b4330.2532.33
10774b434832.33
10774b4350.2532.33
10774b436232.33
10774b4370.2532.33
10774b438232.33
10774b4390.2532.33
10774b4310232.33
10774b43110.2532.33
10774b4312232.33
10774b4313832.33
10774b4314232.33
10774b4315232.33
10774b43160.2532.33
10774b43170.2532.33
10774b43180.2532.33
10774b4319232.33
10774b4320832.33
10774b43210.2532.33
10774b4322232.33
10774b4323232.33
10774b4324232.33
10774b4325232.33
10776b25290
10785b10230
10787b7230
107110b6200
107114b471202.33
107114b472202.33
107114b473202.33
107114b4740.2502.33
107114b475202.33
107114b476802.33
107114b477802.33
107114b4780.2502.33
107114b479202.33
107114b47100.2502.33
107114b47110.2502.33
107114b4712202.33
107114b4713202.33
107114b4714202.33
107114b4715202.33
107114b4716202.33
107114b47170.2502.33
107114b47180.2502.33
107114b4719202.33
107114b47200.2502.33
107114b4721202.33
107114b4722202.33
107114b47230.2502.33
107114b4724802.33
107114b47250.2502.33
107117b11290
107124b7110.253.29
107124b7120.253.29
107124b7130.253.29
107124b7140.253.29
107124b7150.253.29
107124b71683.29
107124b71783.29
107124b7180.253.29
107124b7190.253.29
107124b711083.29
107124b711183.29
107124b711283.29
107124b71130.253.29
107124b71140.253.29
107124b71150.253.29
107124b711683.29
107124b71170.253.29
107124b711823.29
107124b71190.253.29
107124b71200.253.29
107124b71210.253.29
107124b71220.253.29
107124b71230.253.29
107124b71240.253.29
107124b71250.253.29
107126b3710.2593.29
107126b3720.2593.29
107126b3730.2593.29
107126b374893.29
107126b375893.29
107126b3760.2593.29
107126b3770.2593.29
107126b3780.2593.29
107126b379893.29
107126b37100.2593.29
107126b37110.2593.29
107126b37120.2593.29
107126b37130.2593.29
107126b37140.2593.29
107126b37150.2593.29
107126b3716893.29
107126b37170.2593.29
107126b3718893.29
107126b3719293.29
107126b37200.2593.29
107126b37210.2593.29
107126b3722893.29
107126b37230.2593.29
107126b37240.2593.29
107126b37250.2593.29
107138b191232.3
107138b192232.3
107138b193232.3
107138b1940.2532.3
107138b195232.3
107138b196232.3
107138b197232.3
107138b198232.3
107138b1990.2532.3
107138b1910232.3
107138b19110.2532.3
107138b1912232.3
107138b1913832.3
107138b1914232.3
107138b1915232.3
107138b1916832.3
107138b19170.2532.3
107138b1918232.3
107138b19190.2532.3
107138b19200.2532.3
107138b19210.2532.3
107138b19220.2532.3
107138b1923232.3
107138b1924832.3
107138b1925232.3
107161b7210.2533.29
107161b7220.2533.29
107161b7230.2533.29
107161b7240.2533.29
107161b7250.2533.29
107161b7260.2533.29
107161b727833.29
107161b7280.2533.29
107161b729833.29
107161b7210833.29
107161b72110.2533.29
107161b7212833.29
107161b72130.2533.29
107161b72140.2533.29
107161b72150.2533.29
107161b72160.2533.29
107161b72170.2533.29
107161b72180.2533.29
107161b72190.2533.29
107161b72200.2533.29
107161b7221833.29
107161b7222233.29
107161b7223833.29
107161b72240.2533.29
107161b72250.2533.29
107177b2410.2592.26
107177b2420.2592.26
107177b243292.26
107177b244292.26
107177b245292.26
107177b2460.2592.26
107177b247892.26
107177b2480.2592.26
107177b249292.26
107177b2410292.26
107177b2411892.26
107177b2412292.26
107177b2413292.26
107177b24140.2592.26
107177b2415292.26
107177b2416292.26
107177b24170.2592.26
107177b2418292.26
107177b2419292.26
107177b2420292.26
107177b2421292.26
107177b2422292.26
107177b2423892.26
107177b24240.2592.26
107177b2425292.26
107199b401833.29
107199b4020.2533.29
107199b403833.29
107199b4040.2533.29
107199b4050.2533.29
107199b4060.2533.29
107199b407233.29
107199b4080.2533.29
107199b4090.2533.29
107199b40100.2533.29
107199b40110.2533.29
107199b4012833.29
107199b40130.2533.29
107199b40140.2533.29
107199b40150.2533.29
107199b40160.2533.29
107199b40170.2533.29
107199b40180.2533.29
107199b4019833.29
107199b40200.2533.29
107199b40210.2533.29
107199b40220.2533.29
107199b4023833.29
107199b4024833.29
107199b40250.2533.29