Soils synoptic sampling grid (REU sites) site locations, Andrews Experimental Forest (UTM projection)

During the last decade, there have been two major objectives for my soils work at the HJA; to determine how (1) climate change and (2) forest disturbance influences soil nitrogen and carbon cycling. This study is designed to do both. Because of the broad geographical representation of these sites, all climate zones as influenced by slope, aspect and elevation, are represented as well as differing vegetation types, and disturbance histories. At the present time, we represent different climate zones primarily by elevation. As the climate models are perfected, soils data can be evaluated in terms of annual mean temperatures and precipitation.

This synoptic sampling grid was established to conduct basin-scale surveys of forest soil properties. In the first survey conducted in July 1993, forest floor respiration rates were measured at 130 sites covering a large portion of the HJA. The measurements made in this (SP05) were in situ field respiration. In addition to field respiration rates measured by the soda-lime method, soil and air temperatures were recorded along with maximum and minimum soil temperatures for the 24 hr CO2 collection period. Only one measurement was made per site. These data and associated metadata can be found in database SP05 under the title of "H.J. Andrews 1993 REU synoptic soil respiration of permanent forest sites". The following summer, a much more comprehensive study was conducted. The number of sites studied was expended to 183 sites located at 0.5 km intervals along all passable roads on the HJA. With the exception of the max-min soil temperature data, all variables measured in 1993 were repeated in 1994. In addition, the following variables were measured: pH, soil moisture, bulk density, soil organic matter, laboratory respiration (both long and short-term; with and without amendments), denitrification potential, extractable ammonium, and mineralizable nitrogen. In addition, we scored for the presence of moss on the surface and mycorrhizal mats found in 4.7 x 10 cm cores. These data and associated metadata are located in database SP06 entitled "H.J. Andrews 1994 REU study of soil chemical and microbiological properties". The main objective of this study was to provide a broad overview of soil chemical and biological properties to guide us in future large-scale HJA soil surveys. In 1998, we conducted another soil survey designed to provide an accurate assessment of soil properties over the entire HJA. The dataset entitled "The effects of topography on H.J. Andrews Experimental Forest soil characteristics" contains those data. After the 1993 and 1994 surveys, we changed the way we measured soil field respiration rates. Initially we used the 24 hr soda-lime CO2 adsorption method in chambers with only one measurement per site. In 1998 we converted to using the Li-Cor® portable respirometer with 5 measurements made per site.

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While substantial efforts are made to ensure the accuracy of data and documentation, complete accuracy of data sets cannot be guaranteed. All data are made available "as is". The Andrews LTER shall not be liable for damages resulting from any use or misinterpretation of data sets.