- Non-destructive evaluation (NDE) of wood fibre attributes in a high quality red pine plantation
- New Scientists at the Great Lakes Forestry Centre (GLFC)
- Great Lakes Forestry Centre officially opens the Insect Production and Quarantine Laboratories and Invasive Species Centre
- GLFC Webinar Report
- Ten-year results from forest harvesting impacts study
- Upcoming 2013 webinars
- Recent GLFC Publications
Ten-year results from forest harvesting impacts study
GLFC scientists recently collaborated on an analysis of tenth year results from the North American Long Term Soil Productivity (LTSP) network of research sites. Data assessed included planted tree and total above-ground biomass across 45 installations, as well as concentrations of nitrogen and phosphorus in foliage. Scientists were interested in determining whether biomass production or foliar nutrition had a tendency to decrease with increased organic matter removal and whether these results were evident at the 10 year mark. They also looked at the relative importance of vegetation control compared to other stand treatments.
The LTSP network includes more than 100 core and affiliated sites, 18 of which are in Ontario. The remainder are in BC and throughout the US and represent a range of climates, soil conditions and species. The network of research sites allows researchers to evaluate short- and long-term effects of forest harvesting and post-harvest treatments and their interactions on site productivity.
Soil productivity represents the capacity of the site to capture carbon and produce biomass. Properties that may be influenced by harvesting and silvicultural activities include soil porosity and site organic matter. Porosity can be reduced by site compaction during harvesting, but effects vary depending on soil type. Intensity of site organic matter removal may have different impacts on seedling establishment than on long term growth. The relative importance of vegetation control was also considered, although impacts may vary, depending on whether productivity is measured for the entire plant community or only the crop trees.
Four broad climatic groups are represented, including Warm Humid, for sites in the southeast US; Mediterranean, for sites in California; Western Montane, for sites in higher elevations in the western interior; and Boreal-Great Lakes, for sites in the northern cool temperate and boreal climates near the Great Lakes. Three different levels of harvesting were tested, including stem-only harvest, full-tree harvest and full-tree harvest with forest floor removal. Soil compaction and vegetation control effects were also investigated.
Ten year results showed no consistent impacts study-wide due to varying amounts of organic matter removal. This was true for both planted tree and total above-ground biomass. It is expected that effects may be seen in the future, as more stands approach canopy closure and demand for soil nutrients increases. On average, greater soil compaction actually resulted in an increase in planted tree biomass on the sites, which were mostly coarse textured soils, particularly when organic matter was not removed. This response appeared to be associated with improving soil physical properties. The use of herbicides generally increased planted tree biomass and the concentration of nitrogen in foliage, but not necessarily total stand biomass.
This network of long term study sites allows researchers to make North American-wide comparisons of the effects of harvest-related site and soil disturbances on site productivity. Increasingly valuable information will be obtained with future measurements as impacts will likely change as the stands develop, reflecting evolving environmental constraints, plant community development and recovery from treatment.
Ponder, F.; Fleming, R.L.; Berch, S.; Busse, M.D.; Elioff, J.D.; Hazlett, P.W.; Kabzems, R.D.; Kranabetter, J.M.; Morris, D.M.; Page-Dumroese, D.; Palik, B.J.; Powers, R.F.; Sanchez, F.G.; Scott, D.A.; Stagg, R.H.; Stone, D.M.; Young, D.H.; Zhang, J.; Ludovici, K.H.; McKenney, D.W.; Mossa, D.S.; Sanborn, P.T.; Voldseth, R.A. 2012. Effects of organic matter removal, soil compaction and vegetation control on 10th year biomass and foliar nutrition: LTSP continent-wide comparisons. Forest Ecology and Management 278:35-54.