http://cfs.nrcan.gc.ca/authors/read/20175 Publications by J.J. Roberts en-ca 2006-03-29 00:00:00 MST 2006-03-29 00:00:00 MST webmaster@nofc.cfs.nrcan.gc.ca http://cfs.nrcan.gc.ca/publications?id=26110 Tree growth was measured before, and 9 years after draining a boreal fen that supported a 50- to 60-year-old stand of tamarack (Larix laricina (Du Roi) K. Koch) and black spruce (Picea mariana (Mill.) B.S.P.). Treatments consisted of a series of ditches spaced 30, 40 or 50 m apart, and an undrained control. Nine years after drainage, the diameter, height, basal area, and volume growth of tamarack had increased by 2–5 times that on the control site. Black spruce growth on the drained site was 1.6–5 times that on the control. Tamarack average volume growth (1.20 m3 ha-1 year-1) on the drained site was superior to that of black spruce (0.21 m3 ha-1 year-1). In general for both species, there were no significant differences in growth between trees on the different ditch spacings. This result was attributed to the water table being low enough that adequate aeration zones existed across the strips between ditches on all spacings. Regeneration after treatment was greater on the drained than on the control plots, particularly in the disturbed areas near the ditches where new tamarack seedlings reached densities between 9400 and 12,000 stems ha-1. There was no relationship between increased tree growth and tree distance from the ditches for both species, probably because the water table had been lowered sufficiently so that inadequate substrate aeration was no longer a limiting factor. Wed, 29 Mar 2006 http://cfs.nrcan.gc.ca/publications?id=26110 http://cfs.nrcan.gc.ca/publications?id=26037 The growth of black spruce (Picea mariana (Mill.) BSP) and tamarack (Larix laricina (Du Roi) K. Koch) on two drained peatlands, at McLennan and Wolf Creek in central Alberta, was greater than on undrained control areas 9–10 years after drainage. On the drained plots, diameter growth was 1.6–2.3 times, height growth 2.7–3.5 times, and volume growth 4.4–9.7 times that on the undrained control plots. There were no clear differences in growth among various ditch spacings (30, 40, 50, and 60 m), and correlation between tree growth and distance of trees from the nearest ditch was poor. These results suggest that drawdown of the water table was sufficient to create unsaturated zones that facilitated equitable tree growth across the strips between ditches. Tree ring analyses revealed that increases in growth could begin as early as 3–4 years after drainage. The successful regeneration of black spruce on the control plots at McLennan and the reasonable size of black spruce and tamarack ingrowth on control plots suggest that both species are able to germinate and survive on wet sites initially, but high water tables inhibit their further development. Additional periodic measurements of both species are necessary to determine long-term growth patterns after drainage and to assess the financial feasibility of peatland drainage as a practical option in forest management. Fri, 03 Mar 2006 http://cfs.nrcan.gc.ca/publications?id=26037