The Natural Disturbance Papers -1

Working on it

A review of natural disturbances to inform implementation of ecological forestry in Nova Scotia, Canada
by Anthony R. Taylor, David A. MacLean, Peter D. Neily, Bruce Stewart, Eugene Quigley, Sean P. Basquill, Celia K. Boone, Derek Gilby, Mark Pulsifer’ Published on the web in Environmental Reviews Aug. 18, 2020

Abstract (paragraphing inserted)

Like many jurisdictions across North America, the province of Nova Scotia (NS) is faced with the challenge of restoring its forests to a more natural, presettlement state through implementation of ecological forestry. At the core of ecological forestry is the idea that natural forest structures and processes may be approximated by designing management practices that emulate natural disturbances. Successful natural disturbance emulation depends on fundamental knowledge of disturbance characteristics, including identification of specific disturbance agents, their spatial extent, severity, and return interval. To date, no comprehensive synthesis of existing data has been undertaken to document the natural disturbance regime of NS forests, limiting the application of natural disturbance emulation.

Using over 300 years of documents and available data, we identified the main natural disturbance agents that affect NS forests and characterized their regimes. Overall, fire, wind (predominantly hurricanes), and outbreaks of spruce budworm (Choristoneura fumiferana (Clemens)) are the most important disturbance agents, causing substantial areas of low- (<30% mortality), moderate- (30%–60%), and high- (>60%) severity disturbance.

While characterization of natural historic fire is challenging, due to past human ignitions and suppression, we estimated that the mean annual disturbance rate of moderate- to high-severity fire ranged between 0.17% and 0.4%·year−1 (return interval of 250–600 years), depending on ecosystem type.

Hurricanes make landfall in NS, on average, every 7 years, resulting in wide-scale (>500 ha) forest damage. While hurricane track and damage severity vary widely among storms, the return interval of low- to high-severity damage is 700–1250 years (0.14%–0.08%·year−1).

Conversely, the return interval of host-specific spruce budworm outbreaks is much shorter (<50 years) but more periodic, causing wide-scale, low- to high-severity damage to spruce–fir forests every 30–40 years.

Further disturbance agents such as other insects (e.g., spruce beetle), diseases, ice storms, drought, and mammals can be locally important and (or) detrimental to individual tree species but contribute little to overall disturbance in NS.

Climate change is expected to significantly alter the disturbance regime of NS, affecting current disturbances (e.g., increased fire) and driving the introduction of novel agents (e.g., hemlock wooly adelgid), and continued monitoring is needed to understand these changes.

Timing (from the Ecological Forestry web page)
– June 25, 2019 “Timeline: The assessment will be ready to be submitted for peer review this fall.”
Feb 19, 2020 Update: A scientific paper on natural disturbance agents has been submitted to a journal for peer review and publication. Planning for the next phase of research is underway.
– Aug 18, 2020: As reported in a Aug 30, 2020 post, the paper was posted in pre-publication web form with access to the authors’ manuscript in Environmental Reviews on Aug 18, 2020. There was no update or other announcement of it on the L&F Ecological Forestry website at the time.
– Aug 28, 2020 Timeline: Winter/Spring 2020: Next phase research to advance Natural Disturbance Regimes work


The two senior authors of this paper are A.R.  Taylor and D.R. MacLean, who were the ‘Expert Advisors’ for the Natural Disturbance Regimes project. Taylor is with the Canadian Forest Service/Natural Resources Canada where he heads a very active research unit, the Forest Stand Dynamics Laboratory; he is also an Adjunct Professor at UNB Forestry. MacLean is a Prof & Dean Emeritus  (2018) in Forestry and Environmental Management, his area is cited as Forest Ecology; he is  well recognized as a researcher.

In the meantime,  another very relevant paper has  appeared in Environmental Reviews. See Borealization of the New England – Acadian Forest: a review of the evidence by Joshua Noseworthy & Thomas Beckley (2020).

There is a lot in both of these papers. Taylor et al., do not cite “borealization” as such and there is a need to bring the two perspectives together. (DNR, when asked in 2017  about borealization of the NS forest indicated it does not accept that perspective – see post Nov 3, 2017)

The paper by Taylor et al. 2020 relies heavily on a 39 page report contracted by DNR/L&F:

Reconnaissance study of Forest Disturbance History In Northeastern Nova Scotia
Interim Report (2015-2017)
Prepared for P. Neily, NS DNR
By Dr. E.V. Ponomarenko
Consulting soil scientist, Ecosystem Archaeology Services
Ottawa 2018

I requested the report from L&F and was directed  to the the Natural Sciences Library; it was not available there but they obtained the paper for me and said it would be available subsequently as a PDF to anyone on request (contact Tracy Lenfesty<>). I find it odd that the 2018 paper has not been placed on the L&F website, but then again neither have  the peer-reviewed papers of Keys et al. 2016 and 2018.

EV Ponomarenko is a highly respected soil scientist specializing in “Ecosystem Archaecology” and L&F deserves credit for eliciting her expertise in helping to investigate the history of forest disturbance in NS. Nevertheless, given its significance to the Natural Disturbance Regimes Project and Lahey’s Recommendation 7.  I think Ponomarenko’s results  should also have been submitted  for publication in a recognized, peer-reviewed journal, e.g. in a paper by EV Ponomarenko and P. Neily and others as appropriate.

DNR should
a. transparently acknowledge and address, with peer‐reviewed science, the concerns and  critiques that have been raised with DNR’s mapping of natural disturbance regimes in  Nova Scotia and align its ecosystem‐based management framework for forestry on  Crown lands with its revised and peer‐reviewed mapping of Nova Scotia’s natural  disturbance regimes 

b. align its ecosystem‐ based management framework for forestry on Crown lands with its  revised and peer‐reviewed mapping of Nova Scotia’s natural disturbance regimes  – Lahey Recommendation 7

Regardless, I and likely others with a science or forestry background had/still have many questions/points of discussion related to the and report cited above and to the second paper. It would certainly  have been appropriate and I think consistent with the Lahey recommendations for the half dozen people (I was one of them) who  pushed hard for Prof. Lahey to look at DNR’s science related to Natural Disturbance Regimes to have had an opportunity as a “stakeholder group” to discuss the Taylor et al. review before it was finally submitted for publication.  We were asked to participate in the Workshop on Nova Scotia’s Natural Disturbance Regime and Ecological Forestry Framework special workshop on the topic convened by Lahey on Feb of 2018 (see Independent Review Addendum p.9) which clearly led to that review. However, there was no ‘stakeholder consultation’ for this project, and a request for it  was firmly rejected.

There was some related research ongoing within L&F, not announced or described anywhere on their website but revealed in a Aug 2020  MTRI webinar – Successional Dynamics in Nova Scotia’s Coastal Black Spruce Communities by Emily Woudstra); L&F Forester/landscape ecology specialist Peter Bush was cited as her supervisor. Perhaps there was/is more going on; we don’t know because L&F does not provide such info routinely. The presentation is available on YouTube.

Some further comments to follow.