Look at the Data


Summary Data Sets

A note about experimentation in nature: because the warming meadow experiment is conducted outside in the open system of the natural world instead of in a closed laboratory setting, abiotic factors such as temperature and precipitation vary within each growing season and from year to year.

Aboveground Carbon (Vegetation and Litter)

Aboveground biomass is a combination of two measures. First, the amount of vegetation is measured by visually estimating how much of the plot is covered by shrubs, forbs, and grasses. This measure is combined with the amount of plant litter in the plot, measured by collecting and weighing (oven-dried) litter. (See Saleska et al., 2002 for details.)

Why do you think the plant litter is dried before weighing?

Aboveground Biomass (Shrubs & Forbs) in Heated Vs Control Plots

Soil Carbon

Four soil cores are taken from each plot, twice each growing season (June and August) in the same area as aboveground carbon measurements. Soil organic carbon is estimated by measuring soil mass before and after “burning” the sample in an oven – the mass lost as a result of combustion is the soil carbon (find Saleska et al., 2002 in the Publications database for details).

Soil Carbon In Heated Vs Control Plots

Soil Temperature and Soil Moisture

Soil temperature and moisture are monitored at 5 cm, 12 cm, and 25 cm depths in the center of zones L, M, U in each of the ten plots. Soil data are automatically collected year-round using data loggers. Soil temperature and moisture data from the warming meadow experiment are not currently available.

Snowmelt Date

The snow melt date for each plot is estimated from soil temperature and soil moisture data. Direct observations of snow melt date are not necessary – snow-free conditions are usually marked by a sharp increase in soil temperature at 5 cm.

Exploring RMBL Data – The Warming Meadow Experiment

In exploring the summary data from the Warming Meadow Experiment, a few patterns emerge. The heated plots have earlier snow melt dates than the control plots. Soil carbon is lower in the heated plots than the control plots, with the exception of the very beginning of the experiment. In general, the heated plots have less forb and more shrub biomass – the control plots show the opposite relationship, with more forb and less shrub biomass.

To evaluate these patterns, a scientist might start by generating some basic statistics from each data set, such as average, maximum and minimum values, which together provide the range of values in the data set. To download the data in the charts above, click here for the Excel file.

But before downloading or using RMBL data, please read the RMBL Data Use Agreement.

Next Step – go to Extend the Findings.