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EP 660 was a conventional silvicultural trial established in 1967 which involved single species plantings of lodgepole pine (Pl), white spruce (Sw), and Douglas-fir (Fd) at different spacings. Three installations were established in the Prince George - Vanderhoof area: Buckhorn Ridge, Bobtail Road, and Chilco Creek.

General details on EP 660 are given by:
Coopersmith, D., M. McLellan, and J. Stork. 1997a. Experimental Project 660 overview of three experimental installations – a 30-year progress report. B.C. Min. For., Prince George For. Reg., Res. Note #PG-12.

Details on the Buckhorn installation are given by:
Coopersmith, D., M. McLellan, and J. Stork. 1997b. Experimental Project 660 30-year progress report: Buckhorn Installation. B.C. Min. For., Prince George For. Reg., Res. Note #PG-12-1.

At the Kenneth Creek installation (Ministry of Forests E.P. 886.13), forest floors and mineral soils were sampled on 3 occasions: 1996 (by Brockley), 1999 (by Sanborn), and 2005 (by Sanborn). In addition, bulk density measurements and geochemical analyses were conducted for selected depths on the "Bowron" pedon previously published in the mineralogical study by Arocena and Sanborn (1999); this pedon was sampled on the southeastern edge of the installation beside the main access trail.

The 1996 sampling (2 years after treatments began) involved forest floors and 0-15 cm depth mineral soils, sampled at 10 random points in each plot; there were no measurements of forest floor mass or mineral soil bulk density.

The 1999 and 2005 sampling was more intensive, and included forest floor mass and mineral soil bulk density measurements, as well as a greater depth of mineral soil sampling (0-20 cm; 20-40 cm). Note that the mineral soil bulk density measurements were not repeated in 2005; 1999 values were used in subsequent analyses.

Results from the 2005 soil sampling were published along with those from the Crow Creek (spruce) installation in:
Brockley, R.P. and P.T. Sanborn. 2009. Effects of repeated fertilization on forest floor and mineral soil properties in young lodgepole pine and spruce forests in central British Columbia. Technical Report 052. B.C. Ministry of Forests., Research Branch, Victoria, B.C. http://www.for.gov.bc.ca/hfd/pubs/Docs/Tr/Tr052.htm [Note that this publication included mineral soil data only for the 0-20 cm depth.]

During Dr. Sanborn's years with the Ministry of Forests research program (1991-2002), he worked on forest fertilization research with silviculturist Rob Brockley (retired; formerly at Kalamalka Research Station, Vernon, BC). Brockley’s work in the 1980s and early 1990s had documented the widespread pattern of sulphur deficiencies across the BC interior, and the superior response of managed stands to fertilization treatments involving sulphur (S) and nitrogen (N) rather than nitrogen alone.

To progress farther, different methods for understanding the fate of sulphur fertilizers in forests and soils were needed. Sanborn contacted the stable isotope group at the University of Calgary which had done important work on the fate of pollutant sulphur emitted by oil and gas extraction and processing in Alberta, using natural abundances of sulphur stable isotopes as a tracer. This was the beginning of a collaboration with Dr. Bernhard Mayer of the University of Calgary, and also with his German soil scientist colleague, Dr. Joerg Prietzel (Munich Technical University).

The research team engaged in the Cluculz retrospective study (E.P. 886.10) for the BC Ministry of Forests.

An ancillary project involved resampling (2002 - foliage, 2003 - soil) of a previously fertilized (1990) installation (E.P. 886.10) south of Cluculz Lake in order to compare the longer-term effects of different fertilizer sulphur forms on soil and foliage chemical properties. Results were published as a journal article and a Ministry of Forests Extension Note:

Sanborn, P.T., J. Prietzel, R.P. Brockley. 2005. Soil and lodgepole pine foliar responses to two fertilizer sulphur forms in the Sub-Boreal Spruce zone, central interior British Columbia. Can. J. For. Res. 35 (10): 2316-2322. https://cdnsciencepub.com/doi/abs/10.1139/x05-138

Sanborn, P. and R. Brockley. 2005. Sulphur deficiencies in lodgepole pine: occurrence, diagnosis, and treatment. Ext. Note 71. B.C. Min. For., Res. Br., Victoria, B.C. https://www.for.gov.bc.ca/hfd/pubs/docs/en/En71.pdf

At the Kenneth Creek installation (Ministry of Forests E.P. 886.13), a 7-year litterbag experiment was installed October 15 1997, following the methods of the Canadian Intersite Decomposition Experiment (Trofymow et al., 1998), as also applied by Sanborn and Brockley (2009) in an experiment connected to E.P. 1185. Litterbags contained two initial materials – pine needle litter collected from the Control and ON2 (highest rate of annual fertilization) treatments – were emplaced in the Control and ON2 plots.

Results of this experiment have not been published, but data have been shared with collaborator Bjorn Berg (Uppsala).

The Archie Creek site is the informal name used for a research installation established in 1971 east of Prince George by the Canadian Forest Service, and subsequently abandoned by the end of that decade. Dr. Paul Sanborn revisited the site in 1995, and sampled forest floors and mineral soils across a range of conifer-broadleaf mixtures established by natural establishment of broadleaf trees among planted lodgepole pines.

Details of the site conditions, sampling methods, and results were published in:
Sanborn, P. 2001. Influence of broadleaf trees on soil chemical properties: A retrospective study in the Sub-Boreal Spruce Zone, British Columbia, Canada. Plant and Soil 236: 75–82. https://doi.org/10.1023/A:1011973402414

Litterfall was collected at the Kenneth Creek installation for 4 years (May 1995-May 1999), using the litter trap design of Hughes et al. (1987). Initially, 10 traps were installed at random locations in each of the 18 plots (all 6 treatments), but an analysis of litterfall data for the first collection period and consultation with a statistician resulted in relocation of traps so that greater sampling intensity would be gained for a smaller number of treatments (4 treatments, with 15 traps per plot).

During a year away from studies in 1987-88, Dr. Paul Sanborn developed a successful grant proposal to the Science Council of BC (SCBC) to pursue a postdoctoral project with Dr. Tim Ballard in relation to sulphur-deficient soils in BC and prescribed fire. This project built on an existing broadcast burning study conducted by Macmillan Bloedel Ltd. near Port Alberni on Vancouver Island, led by Bill Beese (later at Vancouver Island University). Dr. Sanborn's work addressed sulphur forms and amounts in the soils at these sites, and the chemical processes influencing sulphur availability in relation to prescribed fire.

Only one part of this work was eventually published:
Sanborn, P.T. and T.M. Ballard. 1991. Combustion losses of sulphur from conifer foliage: Implications of chemical form and soil nitrogen status. Biogeochemistry 12: 129–134. https://doi.org/10.1007/BF00001810

The remainder of the work was documented in the Project Completion Report to SCBC, dated February 28, 1990.

Thirty-four of the accompanying project data files were selected for archival retention.

The Sulphur stable isotope tracer study (E.P. 886.15) field experiment was installed in young lodgepole pine stands at two sites in the Prince George Forest Region in 2001, with fertilizer treatments applied in late 2002. These sites are designated as Kenneth Creek (east of Prince George) and Holy Cross (south of Fraser Lake). (The Kenneth Creek installation was established near plots of the older E.P. 886.13 in the same stand.) Full experimental details, including pretreatment soil and foliar date, were given in:

Sanborn, P., R.P. Brockley, B. Mayer, M. Yun, J. Prietzel. 2005. Sulphur fertilization of lodgepole pine: a stable isotope tracer study (E.P. 886.15): Establishment report. Tech. Rep. 020. B.C. Min. For., Res. Br., Victoria, BC. http://www.for.gov.bc.ca/hfd/pubs/Docs/Tr/Tr020.htm

The Kenneth Creek site was attacked by mountain pine beetle in 2006, resulting in at least 80% tree mortality. In 2013, the stand was levelled in order to enable replanting, and due to poor communications within the Ministry of Forests, the opportunity to salvage this installation was lost. The Holy Cross site was hit by a wildfire in 2010, and most of the research plots were destroyed.

Preliminary results from foliar analysis, sufficient to demonstrate that our stable isotope tracer approach could detect fertilizer uptake, were published in:

Sanborn, P.T., R.P. Brockley, and B. Mayer. 2011. Stable isotope tracing of fertilizer uptake by lodgepole pine: foliar responses. Can. J. For. Res. 41: 493-500. https://cdnsciencepub.com/doi/full/10.1139/X10-222