Decomposition of wood stakes in the Pacific Northwest after soil compaction and organic matter removal

• Published in: Forest ecology and management 2021-08, Vol.494, p.119362, Article 119362
• Main Authors: Page-Dumroese, Deborah S., Jurgensen, Martin F., Miller, Chris A., Busse, Matt D., Curran, Michael P., Terry, Thomas A., Tirocke, Joanne M., Archuleta, James G., Murray, Michael
• Format: Article
• Language: English
• Subjects: Decay; Harvest operations; Long-term soil productivity; Soil processes
• ISSN: 0378-1127; 1872-7042
• DOI: 10.1016/j.foreco.2021.119362

•There were no consistent trends of wood stake decomposition in the mineral soil.•Aspen and pine stake water content was correlated to wood stake mass loss (p = 0.0009).•Decomposition was less in adjacent unharvested stands than in LTSP treatments. Forest operations can affect soil productivity by impacting the amount and distribution of surface organic matter (OM) and changing the properties of surface mineral soil. The North American Long-Term Soil Productivity Study (LTSP) was developed to address such long-term changes after pulse disturbances associated with clearcut harvesting, soil compaction, and OM removal across a wide spectrum of forest sites. From 2000 to 2002 we established a study to assess the impact of four soil disturbance treatments on OM decomposition in the mineral soil on seven LTSP study plots from southern British Columbia, Canada to southern Oregon, USA. The soil treatments were combinations of two levels of compaction and organic matter removal: 1) removal of only merchantable logs [OM0] , 2) removal of all the forest floor and woody material [OM2], 3) no soil compaction after harvest [C0], and 4) “severe” soil compaction after harvest [C2]. Aspen (Populus tremuloides Michx.) and pine (Pinus taeda L.) wood stakes were inserted into the mineral soil of each treatment plot and in an adjacent unharvested control stand to a depth of either 20 or 30 cm (depending on soil depth). At the end of three years the soil compaction and the OM removal treatments had relatively little effect on pine or aspen stake decomposition at the British Columbia study sites. In the United States, soil compaction increased decomposition on the two study sites with coarse-texture mineral soil with surface OM intact. Three key findings were: (1) a strong positive relationship (p = 0.0009) between stake water content and stake mass loss, (2) aspen and pine stake decomposition was greater in the clearcut-LTSP treatments than in the unharvested stands, (3) the rehabilitation of the compacted soil treatment on the British Columbia study sites generally increased wood stake decomposition. However, overall, there were no consistent wood stake decay trends across all sites and LTSP treatments.