Howland Forest Soil Respiration Date

The Woods Hole Research Center
E.Davdison, H. Hikel, K.Savage

This file contains measurements of soil respiration, and soil temperature measured at the Howland Forest, MA., study site.  There are 6 locations at the Howland forest, ranging in drainage characteristics from very poorly to well drained and all lie within the footprint of a tower measuring NEE by eddy correlation methods.   There are 2 swamps sites, 3 moderately well drained and 1 well drained site.  Sampling began at 2 swamp and 2 moderately well drained sites in the summer of 1996.  Sampling at the well drained site (Howland Mountain) did not begin until May, 1997 and sampling at 1 moderately well drained site (West Tower) did not begin until May of 1999.   The moderately well drained (Tower site) is  ~15 meters W of the tower.  The very poorly drained (Swamp site) site is  ~70 meters SW of the tower.  The moderately well drained (Nutrient Cycling site) is ~100 meters NNE of the tower.  The very poorly drained  (Town Line Swamp site) is  ~120 meters NW of the tower.  The well drained  (Howland Mountain site) is  ~270 meters WNW and the moderately well drained  (West Tower site) is  ~1000 meters NW of the tower.  
	Soil respiration is measured using a dynamic chamber and a portable infrared gas analyzer.  Fluxes were measured weekly during the summer, bi-weekly during the fall and spring and monthly during the winter	Soil CO2 flux (mg C m-2 hr-1) is measured by placing a chamber over collars (that are left in place) in the soil.  CO2 is recorded every 12s for 4.5 min..  A linear regression on the straightest increasing portion of CO2 concentration was preformed to determine a flux rate for each collar.   There are 8 collars per site and values presented are the mean followed by the standard error of the measurements per site for each sampling date.  During the winter fluxes were measured when a collar was exposed or when there was sufficient snow cover to insert the chamber top 1-2 cm into the snow. 
Soil temperature (oC) is taken using a 10 cm probe inserted vertically from the surface.  A soil temperature was measured adjacent to each collar.  Soil temperature values presented are the mean of all soil temperatures per site for each sampling date.