University of Minnesota
University of Minnesota
College of Biological Sciences

All Methods

Log Out

Methods for Experiment 245 -

Above Ground Biomass Sampling

Biomass is collected from a clip strip that is 2m x 10cm. A handheld clipper is used to cut as close to the ground as possible and the above ground biomass is collected. Clip strips are sorted to species, dried and weighed. This is done for every plot.

Below Ground Biomass Sampling

A 2 inch diameter root core is used to collect four 30cm deep root cores from each clip strip after the above ground biomass harvest. The soil is washed away from the roots. The roots are collected, dried and weighed. This is done for every plot.


This experiment is located in Burn Unit 108 which is scheduled to be burned one out of three years. The following table lists the year and month when this experiment was burned.

ExpYear BurnedMonth Burned

Ceptometer Sampling

Ceptometer readings are taken once a month in the Percent Cover area of each plot throughout the growing season. One measurement is taken above the canopy and 3 measurements are taken below the canopy. The machine averages the 3 below readings and gives an estimate of LAI.

Cropscan Radiometry Sampling

Cropscan Radiometry readings are taken once a week above the Percent Cover areas of each plot throughout the growing season. Data are organized into a spreadsheet for analysis.

Nutrient Addition

In 2019, a nutrient addition treatment was added within each plot of E245. Each plot was divided into two subplots (N=96) and a nutrient treatment (nitrogen, phosphorus, potassium and micronutrients) was added to the West subplot. Nutrient addition rates and sources are: 10g N m2/year as timed-release urea [(NH2)2CO], 10g P m2/year as triple-super phosphate [Ca(H2PO4)2], 10g K m2/year as potassium sulphate [K2SO4] and 100g m2/year of a micronutrient mix of Ca (6%), Fe (17%), S (12%), Mg (3%), Mn (2.5%), Cu (1%), Zn (1%), B (0.1%) and Mo (0.05%). Nutrients were applied annually every spring (except micronutrient mix which was only applied in the first year to avoid toxicity.

Percent Cover Sampling

The percent cover area is in the middle of the plot and is 1m x 1m. Percent of the ground that is covered by each individual species that is rooted within the percent cover area for every plot is measured. The total for the vegetation and non-vegetation cannot be more than 100%.

Pesticide Applications

We have 6 different treatments in this experiment: 1. Soil drench fungicide 2. Foliar fungicide 3. Insecticide 4. Large mammal exclusion (fenced) 5. All treatments 6. Control (no treatments) Pesticides are applied once every 2 weeks to the plot throughout the growing season, weather permitting. They are applied by a licensed applicator (Jon Anderson). The foliar fungicide treatment is composed of Quilt (Syngenta Crop Protection, Inc., Greensboro, NC, USA), a combination of Azoxystrobin (7.5%) and Propiconazole (12.5%), applied every two weeks. The soil fungicide treatment is composed of monthly applications of Ridomil Gold SL (Syngenta Crop Protection, Inc., Greensboro, NC, USA), a soil drench fungicide containing Mefenoxam (45.3%). The insecticide treatment is composed of Marathon II (OHP, Inc., Mainland, PA, USA; 21.4% Imidacloprid) applied ever two weeks. One to two times each growing season, Malathion is applied instead of Marathon II to reduce the possibility for insecticide adaptation by the local insect populations.


Photographs are taken from the south edge of every plot. A tripod is used so the picture is consistently taken from the same location every time.

Plot Description

Plots were established in 2007 and are located in BU 108, north of the oak savanna. They are 3m x 3m and are arranged in blocks. There are 8 blocks which each contain 6 plots, and each plot contains 1 of treatment. Each block contains all 6 treatments, randomized within each block. There are 48 total plots.

aeue245 - Multispectral Radiometry percent reflectance


Multispectral Radiometer Cropscanner MSR5, a 5-band LANDSAT Thematic Mapper compatible model (460-1750nm). CROPSCAN, Inc. Rochester, MN

Radiometry Sampling Protocol

The Multispectral Radiometer Cropscanner is a machine used to measure the reflectance of 5 different wavelengths. Before Taking Readings: Be sure Date, Time, GMT (Greenwich Mean Time) Difference and Location (latitude and longitude) are set correctly for sampling Location. Attach sensors and cables and a do real-time VIEW mode readings test in the sunlight to verify the millivolt readings correspond to changes in irradiance intensity. To see if the readings will change, place something over the top of the sensor head. The IRR values should decrease. When you place the sensor head back in full sun, the readings will increase. Checklist in the field: Attach the sensor head to the pole and assemble the equipment. Before taking the first plot scan, change the position of the top of the radiometer relative to the sun to see if the IRR (I) reading changes accordingly. Check that the sensor head is level. Take the readings facing south from the north part of the plot. This is to keep shadows from interfering with the readings. Take 1 reading per plot over the percent cover area. When Taking Readings: The best readings are obtained under clear skies or lightly cloudy days with IRR readings above 400 Watts per square meter. If there are cumulus clouds (large puffy), let them pass out of the way of the sun before taking readings. Wear grays or darker colored clothing to reduce the amount of reflectance from your clothes onto the sample area. Try to position the radiometer front (serial number side) toward the sun when taking readings. This eliminates your shadow from the sampling area and also yields the best cosine response correction of the top or up-facing sensors. After positioning and leveling the radiometer and initiating a scan, you may move to the next plot as soon as the double asterisks appear on the screen or you hear the double beep from the DLC.

aire245 - Instantenous rates of ecosystem carbon fluxes

Ecosystem carbon fluxes instrument

Li-Cor 850 infrared gas analyser (Li-Cor, Lincoln, Nebraska, USA), field implemented via a 'flux puppy set'

Ecosystem carbon fluxes sampling

During the growing season (May - October 2020), we used a Li-Cor 850 infrared gas analyser (IRGA; Li-Cor, Lincoln, Nebraska, USA) to measure changes in CO2 concentration and air temperature in the headspace of a chamber placed over the plots. We placed the IRGA inside a 1m3 cube that was made from a polyvinyl chloride (PVC) frame and transparent 6-mil plastic sheeting (Polar Plastics Inc., Oakdale, MN, USA), with internal fans to ensure adequate mixing of air, sealed to the ground with two 1.27 cm diameter x 3.04 m length steel chains wrapped around the base of the chamber. Each measurement cycle began by low- ering the chamber, sealing it, and once a consistent rate of CO2 exchange was achieved (typically less than a minute), we began logging a 2-minute flux measurement in the light at a sampling frequency of 0.5 Hz. At time of flux measurement, we also measured photosynthetically active radiation (PAR) using a MQ-100 Apogee PAR meter (Apogee Instruments, Logan, UT, USA) that was mounted to the top of the IRGA just below the upper surface of the chamber. Full light mea- surements were recorded in a minimum of 900 ??mol m^-2 s^-1 between the hours of 0930 and 1530. For each full light measurement, we calculated net ecosystem exchange using Eqn 1 to quantify the maximum continu- ous exchange of CO2 between the atmosphere, vegetation and soil.