When it rains and snows in a forest, that precipitation must pass through the tree canopy before it reaches the forest floor. The precipitation that passes through the canopy is known as throughfall. If you think of precipitation as the rain above the tree canopy and throughfall as the rain below the canopy, then plotting the two together gives you an idea of how the canopy is altering the chemistry of the rain.
Data Sampling & Compilation
Cary Institute of Ecosystem Studies property in Millbrook, NY. See the metadata files for more detailed sampling location descriptions.
Throughfall: Two sampling sites were established on the Cary Institute property. Ten throughfall collectors were set up on each site. Throughfall collectors consist of a one-gallon plastic jug with a plastic funnel placed in a plastic milk crate, designed to collect rain as it falls from the tree canopy. Sampling was conducted consistently every month from 1993-1999. See the throughfall sampling metadata file (below) for more detailed sampling information.
Precipitation: Precipitation chemistry data is collected on the Cary Institute property using a Yankee Environmental Systems collector, which uses a sensor that causes a cover to open, revealing a clean bucket when precipitation occurs and closes when the precipitation stops. The instrument collects all kinds of precipitation, including snow and ice as well as rain. Samples are collected after every precipitation event and analyzed at the Cary Institute for pH and ion concentrations. See the precipitation sampling metadata file (below) for more detailed sampling information.
Data provided for use:
- throughfall data from 1993-1999 and precipitation data from 1984-2013
- amount of throughfall and precipitation (in centimeters)
- pH of throughfall
- mean concentrations of ions (H, Ca, Mg, K, Na, NH4, NO3, SO4, Cl) in throughfall and precipitation
Data Source: Gary Lovett, Charles Canham, Clive Jones, and Rick Ostfeld (Cary Institute of Ecosystem Studies). Data were posted online.