• Sherri L. Johnson - Principal Investigator
  US Forest Service ;Pacific NW Research Station ;3200 SW Jefferson Way, Corvallis, OR, 97331, USA
  Phone: 541-758-7771
  Email: sherri.johnson2@usda.gov, sherri.johnson@oregonstate.edu
  URL: https://www.fs.fed.us/research/people/profile.php?alias=sherrijohnson
• Julia A. Jones - Principal Investigator
  Oregon State University;Department of Geosciences; Wilkinson Hall 104, Corvallis, OR, 97331-5506, USA
  Phone: (541) 737-1224
  Email: Julia.Jones@oregonstate.edu, geojulia@comcast.net
  URL: http://ceoas.oregonstate.edu/profile/jones/
  ORCID: http://orcid.org/0000-0001-9429-8925
• Matthew G Betts - Principal Investigator
  Department of Forest Ecosystems and Society; 201E Richardson Hall; College of Forestry; Oregon State University, Corvallis, OR, 97331
  Phone: (541) 737-3841
  Email: matt.betts@oregonstate.edu
  URL: http://www.fsl.orst.edu/flel/index.htm
• Michael P. Nelson - Principal Investigator
  Department of Forest Ecosystems and Society; 201K Richarson Hall; College of Forestry; Oregon State University, Corvallis, OR, 97331
  Phone: 541-737-9221
  Email: mpnelson@oregonstate.edu
  URL: http://www.michaelpnelson.com
  ORCID: http://orcid.org/0000-0001-6917-4752
• David Bell - Principal Investigator
  Email: david.bell@usda.gov, david.bell@oregonstate.edu
  URL: https://lemma.forestry.oregonstate.edu/about/david-bell

• The H.J. Andrews Experimental Forest is a living laboratory that provides unparalleled opportunities for the study of forest and stream ecosystems in the central Cascade Range of Oregon. Since 1980, as a part of the National Science Foundation Long Term Ecological Research (NSF-LTER) program, the Andrews Experimental Forest has become a leader in the analysis of forest and stream ecosystem dynamics.
• Long-term field experiments and measurement programs have focused on climate dynamics, streamflow, water quality, and vegetation succession. Currently researchers are working to develop concepts and tools needed to predict effects of natural disturbance, land use, and climate change on ecosystem structure, function, and species composition.
• The Andrews Experimental Forest is administered cooperatively by the USDA Forest Service Pacific Northwest Research Station, Oregon State University and the Willamette National Forest. Funding for the research program comes from the National Science Foundation (NSF), US Forest Service Pacific Northwest Research Station, Oregon State University, and other sources.

Data were provided by the HJ Andrews Experimental Forest research program, funded by the National Science Foundation's Long-Term Ecological Research Program (DEB 2025755), US Forest Service Pacific Northwest Research Station, and Oregon State University. National Science Foundation: DEB1440409

• Long-Term Ecological Research
  The Andrews Forest is situated in the western Cascade Range of Oregon, and covers the entire 15,800-acre (6400-ha) drainage basin of Lookout Creek. Elevation ranges from 1350 to 5340 feet (410 to 1630 m). Broadly representative of the rugged mountainous landscape of the Pacific Northwest, the Andrews Forest contains excellent examples of the region's conifer forests and associated wildlife and stream ecosystems. These forests are among the tallest and most productive in the world, with tree heights of often greater than 250 ft (75 m). Streams are steep, cold and clean, providing habitat for numerous aquatic organisms.

• Mineral soil samples were collected with a trowel to a depth of 10 cm and transported to the laboratory in an ice chest. Soils were stored at 15°C until the initiation of the analyses which was within 16 h of their receipt. All variables except field respiration rates were measured during Aug. 1995.
• Field (forest floor) respiration rates were measured using a non-dispersive, infrared CO analyzer (Li-cor, LI-6200). Measurements were made over a period of 1 min after the chamber gas had reached ambient CO concentration. The instrument was calibrated on-site against a known standard at each of the locations. A Q10 adjustment was made for ambient soil temperature. Soil temperatures were measured by electronic thermometers that had been calibrated at 0°C with ice water. The probes were inserted 10 cm into the mineral soil.
• The occurrence of ectomycorrhizal mats in cores was determined visually in the field by inspecting the relative abundance of mats in 4.5 x 10 cm cores. Two distinctive mat types were scored separately; as mats similar to those of the genus Hysterangium and mats similar to those of the genus Gautieria. This approach has been used successfully in the past to document ectomycorrhizal mat distribution patterns in coniferous forests of the Pacific Northwest (Griffiths et al., 1996)

• In preparation for laboratory analysis, all soils were sieved through a 2-mm sieve. Soil pH was measured in 1:10 (soil: distilled water) slurries of oven-dried (100°C) soil. These slurries were shaken for 1 h prior to reading pH values with Sigma model E4753 electrode. Soil organic matter (SOM) was measured by loss-on-ignition at 550°C for 6 h following oven drying at 100°C.
• Denitrification potential (DENIT) was measured using a method similar to that used by Groffman and Tiedje (1989). Each reaction vessel (25 mL Erlenmeyer flask) contained 5 g of less than 2mm, field-moist soil. The flask was sealed with a rubber serum bottle stopper and purged with Ar to displace O in the headspace. After purging with argon, 2 mL of a 1 mM solution of glucose and NO was added each flask which was subsequently incubated at 25°C for one hr. This preincubation period was used because time series experiments on representative soils showed a lag in NO production during this period. The same experiments have shown linear NO production rates during the following 2-4 hr (data not shown). After the preincubation period, 0.5 mL of headspace gas was removed from the reaction vessel and injected into a gas chromatograph fitted with an electron capture detector (Hewlett Packard model 5890 GC fitted with Hewlett Packard model 3396 integrator). The integrator was calibrated using known gas standards and the external calibration method.
• Another headspace NO analysis was made after an additional two hr incubation at 25°C. The net NO released over this 2 h period was used to estimate NO production rates. Acetylene was not routinely added to the headspace to prevent the conversion of NO to N because randomly selected samples (10% of the total) were also assayed with a 10% acetylene atmosphere. There were no significant differences between NO production rates with and without acetylene.
• Long-term respiration measurements (LTR) were made on field moist sieved soils (4 g dry wt.) which were brought to 75% moisture. Enough sterile deionized water was added to equal 3 g water per flask to give a final soil moisture of 75%. As was the case with denitrification potential measurements, LTR were measured in 25 mL Erlenmeyer flasks. Once the flasks were sealed with serum bottle stoppers, they were incubated for 14 days at 24°C and analyzed for CO concentrations in the headspace by gas chromatography. CO concentrations were measured on the same gas chromatograph and integrator as that used for measuring NO. A flame ionization detector and a methanizer in series was used to measure CO.
• Exchangeable NH (AMMONIUM) concentration was determined by shaking 10 g field-moist soil with 50 mL 2 M KCl for 1 h (Keeney and Nelson, 1982). After adding 0.3 mL 10 M NaOH to the slurry, NH concentration was measured with a Orion model 95-12 ammonium electrode (Orion Research Inc. Boston, Ma, USA). Mineralizable N (MINN) was measured using the waterlogged technique of Keeney and Bremner (1966). Ten g of field-moist soil was added to 53 mL of distilled water in a 20 x 125 mm screw cap test tube and incubating at 40°C. After 7 days, 53 ml of 4 M KCl was added to the slurry and NH concentration was determined with the ammonium electrode. Mineralizable N was calculated from the difference between initial and final NH concentrations.

• Soil samples were collected along 27 transects with one transect taken at each site. These transects were 150 m long running along the same contour from OG forests into harvested stands. The transect extended 75 m either side of the edge with soil samples taken every 5 m. Fifteen m on either side of the edge, the sampling spacing was decreased to 1 m intervals to better define patterns closest to the edge. It also allowed us to test for spatial variability at both 1 and 5 m intervals. This dataset contains all of the 1 meter data to give the finest spatial definition 15 m either side of the edge between the oldgrowth segment of the transect and the harvested stand.
• Stands used in this study had been commercially harvested which means that in each case, OG stands were cut, the slash and debris burned leaving burnt stumps and some old decayed logs. They were typically replanted with Douglas-fir seedlings within 2 years of harvest. The edge was defined as the line formed by the main stems of uncut old-growth trees along the perimeter of the harvested site. In most cases, the edge was well defined.
• The experimental design consisted of 3 stand ages and 3 locations with each replicated 3 times for a total of 27 transects. The three stand ages were those harvested approximately 5, 15, and 40 years prior to the study. Nine transects of each age class were sampled. Of these 9 transects, 3 transects were in low-flat sites (646 to 800 m in elevation, 3 were higher (1000 to 1262 m) south-facing and 3 in higher (800 to 1338 m) north-facing sites.
• The 5 year stands (YS) generally had early successional herbs and shrubs with large gaps between young trees which were usually less than 2 m height. Much of the ground had little vegetation. Stands approximately 15 years still had gaps between trees and contained only small areas that were not covered with trees or shrubs; few herbs are present. Most of the trees were Douglas-firs which were generally less than 5 m in height. The 40 year stands had enclosed Douglas-fir canopies (most greater than 15 m) with relatively little understory vegetation.
• Within OG adjacent to 5 YS, understory vegetation was starting to grow in response to increased solar radiation. The extend of this zone varied with elevation and aspect. This zone of understory growth was generally wider and better established in OG adjacent to 15 YS and persisted in a reduced form in OG stands adjacent to 40 YS.

• Andrews Experimental Forest (HJA)
  W -122.26172200, E -122.10084700, N 44.28196400, S 44.19770400
  Altitude: 1631 to 1631 meter

Object name: SP00701.csv

Records: 1473

Attributes: 23

Temporal coverage: 1995-01-01 to 1995-12-31

File size: 140625 byte

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