Soils, Fish and Forests
David P. argues that clearcutting is especially damaging to forest health, wildlife and fish in Nova Scotia watersheds already severely affected by acid rain due to their inherently poor buffering capacity. “The broad outlines of this story have been known since the 1980s, when precipitous declines of salmon in many of our Atlantic river systems were traced to increased acidification of surface waters associated with acid rain. That should have raised alarm bells about forests. Declining salmon and increased water acidity are the equivalent of bad blood tests for watersheds. Something was wrong in the forested uplands that fed those rivers.” There still is.
What’s good for salmon is good for trees in Nova Scotia…and v. versa!
Post on this website, Dec 13, 2016. Cites liming experiments.
Water chemistry and dissolved organic carbon trends in lakes from Canada’s Atlantic Provinces: no recovery from acidification measured after 25 years of lake monitoring
T.A. Clair et al. 2011. Canadian Journal of Fisheries and Aquatic Sciences 68(4):663-674
A mass balance, biogeochemical framework for assessing forest biomass harvest sustainability
Joshua Noseworthy. 2009. MSc thesis, Univ of New Brunswick, available on a UNB website. “A computational framework was developed to calculate and map long-term forest biomass harvest sustainability across Nova Scotia, Canada, based on forest mensurational, biochemical and mass-balance principles…” For stem only-clearcuts, Noseworthy’s results indicate an average 52% increase in Base Cation Depletion over the background acid rain effect averaged for all of Nova Scotia. Until late Sept., 2016 (see below) this was the only information publicly available on the Forest Nutrient Budget Model for Nova Scotia (NBM-NS). Promised for mid-2010, NSDNR began to talk about the model in public only earlier in 2016.
A Simple Geospatial Nutrient Budget Model for Assessing Forest Harvest Sustainability across Nova Scotia, Canada
by Kevin Keys, Joshua D. Noseworthy, Jae Ogilvie, David L. Burton, Paul A. Arp. Open Journal of Forestry, 2016, Vol 6, pages 420-444.
This peer reviewed paper describing the Nutrient Budget Model for Nova Scotia (NBM-NS) was published in an open-access journal on Sep. 29, 2016. Of particular note are data showing large declines in %BS (% Base Saturation) compared to earlier soil surveys (for 25 sites, the declines ranged from −37% to −82%). Very low %BS values (5-10%) are seen over a large part of the landscape, notably over most of SW Nova Scotia where new harvesting operations are focussed. See Fig 3. They reference critical values for %BS cited in the literature: “Cronan and Grigal (1995) suggest 15% BS as a threshold below which “aluminum stress” occurs in forest soils, and Driscoll et al. (2001) suggest 20% BS as a general value for assessing soil recovery from already incurred acid deposition impacts.” So these are already highly stressed systems and the intensive harvesting now getting underway will simply increase the stress to forests and aquatic systems.
At least to this reader, other results are likewise not supportive of intensive (clearcut) harvesting, especially in SW Nova Scotia. For example, they tested the model with site specific data for 25 plantations and found that “Based on comparisons with NBM-NS output, approximately 1/4 to 1/2 of the assessed plantation sites have non-sustainable MMAI yield expectations…Plantations with non-sustainable MMAI values are mainly associated with low soil weathering classes (especially Class 1) and/or tree species with high nutrient demands (e.g., Norway spruce).” Class 1 Gibralter soils cover much of SW Nova Scotia. Keys et al. identify calcium and nitrogen as the most common limiting nutrients and note that “Ca has long been considered a nutrient of concern in eastern North America…”, also concluding that “Nutrient assessments are even more important in areas that have been impacted by long-term acid deposition since harvest removals can exacerbate declines in base cation levels (especially Ca) in affected soils.” I am certainly glad to see that last statement, perhaps the first formal acknowledgment from DNR that forest harvests can worsen the effects of acid rain.
Page posted 10 Aug 2016 | Updated 25 Oct 2016