Fire Scars & Old Trees

Fire Scar on base of a white pine by Williams Lake, Apr 11, 2023. Center: Lone White Pine in burnt over barrens on Osprey Trail area ( Apr 29 2023) and fire scar at base (right) The former likely dates to 1964, the latter, to 2009 (see below).
Click on image for a larger version

Distinct fire scars seen at the base of some of the taller, older white pines in the Backlands (pics above) are visual reminders of fires past. They can also occur on red pines and red oak.  These are all “moderately fire-tolerant” tree species whose bark is thick enough when they get older to withstand surface fires.   About their Fire Tolerance the U.S. FEIS (Fire Effects Information System) has this to say:

WHITE PINE – FIRE ECOLOGY OR ADAPTATIONS : Eastern white pine is moderately fire resistant. Mature trees survive most surface fires because they have thick bark, branch-free boles, and a moderately deep rooting habit. Younger trees are not as fire resistant [68]. The needles have relatively low resin content so are not highly flammable [30]. Read more. SUCCESSIONAL STATUS : Eastern white pine is intermediate in shade tolerance [2] and is present in all successional stages. It is a pioneer species on old fields and other disturbed sites, a long-lived successional species, and a physiographic climax species on dry, sandy soils [53,68]. Eastern white pine is sometimes a component of climax forests on certain sites such as steep slopes and ridge tops where windfall provides regeneration opportunities [54]. Read more

RED PINE – FIRE ECOLOGY OR ADAPTATIONS, Fire adaptations: Red pine depends upon fire for regeneration [28,94,127,128,129,130] and has numerous fire adaptations. Peaks in red pine regeneration generally occur in the years following fire [28,89], primarily from on-site seed sources. In forests of the northeastern United States, red pine fire resistance is ranked third in order behind pitch pine and chestnut oak (Quercus prinus) [257,262,263].
Bark: Red pine bark thickness is its most important fire adaptation. At maturity (beginning at age 20-40), red pine’s fire-resistant, thick bark helps protect it from surface fires of low to moderate severity Read more. SUCCESSIONAL STATUS:
Red pine is shade intolerant and occurs in even-aged stands. It often succeeds its less shade-tolerant and shorter-lived associates such as jack pine, paper birch, and aspens and is succeeded by more shade-tolerant species such as eastern white pine, white spruce, and balsam fir [23]. Read more

RED OAK – FIRE ECOLOGY OR ADAPTATIONS: Northern red oak is well adapted to periodic fires [3,70]. Older, larger individuals often survive fire and young, small trees typically resprout vigorously from the stump or root collar [33]. Postfire seedling establishment has also been reported. Fire is integrally associated with oak forests [131]. Many researchers maintain that recurrent fires are the key to oak dominance in some areas. Read more. SUCCESSIONAL STATUS: Northern red oak is intermediate in shade tolerance [101]. It is generally considered a midseral species, but its successional status is poorly known. Read more

White pine, red pine and red oak are pretty well  the only old trees (80 yrs & older) we see in much of the Backlands, and only here and there or in pockets where past fires burned everything else.Only a few have distinct fire scars as in the pic above – there may have been scarring during past fires, but they have been grown over.

There are old yellow birch, which is not fire tolerant, along stream corridors, notably the un-named stream that goes from Colpitt Lake to Williams Lake, and along Lawsons Brook which goes from Williams Lake to The Arm. There are also old eastern hemlock, likewise not fire tolerant, in settled areas in the area of Purcells Cove Road/Williams Lake, a moist area where there has been a long history of no fire because of efficient fire suppression.

About the Fire Tolerance of yellow birch and eastern hemlock, the U.S. FEIS has this to say:

YELLOW BIRCH- FIRE ECOLOGY OR ADAPTATIONS : Yellow birch is susceptible to fire injury due to its thin bark [32]; young yellow birch do not usually survive fire. Mature trees may survive because the thin forest floor under large yellow birch does not usually support severe or persistent surface fire [90]. Yellow birch germinates readily on early post-fire sites [91,92,115]. Read More SUCCESSIONAL STATUS : Facultative Seral Species. Yellow birch is intermediate in shade tolerance. Leak [71] assigned yellow birch to the category of persistent successional species. Yellow birch is described as opportunistic due to its habit of producing abundant small seed [40]. Read more

EASTERN HEMLOCK – FIRE ECOLOGY OR ADAPTATIONS : Eastern hemlock is very susceptible to fire because of its thin bark, shallow roots, low-branching habit, and heavy litter deposits [20,51]. It is possibly the most fire-sensitive mesophytic tree species in its range [51]. Eastern hemlock usually escapes fire because it occurs in moist habitats and is often associated with hardwoods which do not readily burn. read more SUCCESSIONAL STATUS : Eastern hemlock is very shade tolerant [5]. Seedlings survive in as little as 5 percent of full light [14]. Individuals are able to survive several hundred years of suppression, and many show numerous growth releases and suppressions [6]. Saplings less than 2 inches (5 cm) in d.b.h. may be more than 100 years old [10]. Read more

Vegetation Types

The  “Jack Pine-Crowberry barrens” are the most prominent vegetation type in the Backlands and their prominence reflects the extreme droughtiness and fire susceptibility of the Backlands at large. But over the whole of Backlands, fire regimes vary spatially and over time, resulting in at least 5 forest vegetation types in which fire plays a significant role:

(i) Jack Pine/Broom Crowberry Barrens (equivalent to NSFVT OW1*– “This nationally unique, range-limited ecosystem is one of the least common VTs”). The most prominant VT in the Backlands area-wise.

(ii) Red Pine-Jack Pine/Broom Crowberry Coniferous* Woodland (equivalent to NSFVT OW4 “Global occurrences of this provincially uncommon ecosystem are limited to Nova Scotia.”). Very restricted occurrence in the Backlands

(iii) Paper Birch–Red Maple–Big-toothed Aspen Early Successional Forest (equivalent to NSFVT IH6)

(iv) Red Oak–Red Maple/Witch-hazel Hardwood Forest (equivalent to NSFVT IH2)

(v) White Pine-Red Pine-Red Oak Mixed Forest (equivalent to NSFVTs SP3 and and SP4)
*Bolded names from Hill & Patriquin 2014; NSFVT: the name of the closest equivalent in the NS Forest Vegetation Types

At least one of fire tolerant or fire resistant species -jack pine, white pine, red pine, red oak –  is prominent in 4 of the 5 types;  in (iii) white pine and/or red oak are usually present as sprouting stumps, i.e. the disturbance was severe enough to kill these trees. These classifications probably apply broadly to most of the Backlands. One area where more documentation is definitely  required: the forests in the lower MacIntosh Run area, some of those forests, quite wet.

What is remarkable really, or very special, in addition to the rarity of two of the VTs is that this suite of fire-affected forest VTs, all occur within the Backlands, a relatively small area (circa 1350 ha), and are the equivalent of the diversity of vegetation types found in much larger pine barrens, e.g., see description of the Northwest Wisconsin Pine Barrens by Radeloff et al., 2001.

The older white and red pines and red oak give us components of Old Growth 

While these are  forest VTs that  in generak not to grow into Old Growth stages,  some of the trees in vegetation types types ii, iv and v do grow old: those  white pines, red pines and red oaks that lived through fires.

So now  landscapes with those old trees have some components of Old Growth (such as large snags and fallen dead trees) and provide habitat for many Mature Forest bird species* observed in the Williams Lake Backlands by Fulton Lavender and Joshua Barss Donham such as Hermit Thrush, Ovenbird, Golden-crowned Kinglet, Hairy Woodpecker.
*See  Betts et al., 2022 

How often do fires occur in the Backlands?

From” Ecological Assessment of the Plant Communities of the Williams Lake Backlands. A REPORT to The Williams Lake Conservation Company by Nick Hill & David Patriquin 2014:

6.2 Recent fires in The Backlands
Fires since the early 1900s have included those listed below, likely amongst others.

2012: Approximately 15 ha on high barrens and associated forest/woodland on the south side of Williams Lake (see fire icons in Fig. 3.4) burned on May 21, 2012 before being doused by fire fighters. It was a stand-replacing fire in which aboveground portions of all trees and shrubs were killed. Our
observations in 2013 indicate the hardwoods (birch, red maple, oak) promptly stump-sprouted, bushes such as Huckleberry and Rhodora grew up from underground rhizomes, while Jack Pines and Black Spruce and Broom Crowberry are regenerating from seed.

2009: The 2009 Spryfield fire burned an area reported to be approximately 800 ha in the Purcell’s Cove Backlands. The northwestern extremity reached Jack Pine barrens just southeast of Colpitt Lake (Fig. 3.4), as revealed in a survey
of that area on Nov. 6, 2013. 

2006/2007: During a survey on Sept 12, 2013, we noted charcoaled debris on the ground and partially burnt white pines in an open area on top of the drumlin just to the east of Williams Lake. For the location, see Fig. 3.4. Inspection of historical imagery in Google Earth suggest the fire occurred between June of 2006 and July of 2000, most likely in the spring of 2007 which is a peak time for fires in Nova Scotia. The limited burn of the sparsely distributed trees suggest this was essentially a surface fire, and the Google imagery suggest it was limited to about 5 ha (Fig. 6.1).

1964: Residents in the Williams Lake area cite 1964 as the year of a fire in the backlands that extended into the forest on the eastern side of Williams Lake, sparing only the large red and white pines that today bear prominent fire scars at their bases.

Circa 1959: A local resident David P. met in 2009 while monitoring recovery of vegetation in the vicinity of Lower Mud Pond after the 2009 Spryfield fire told him that the last big fire in the Lower Mud Pond Area occurred 45 years prior to the 2009 fire, i.e. in 1959. (He recalled the fire from his childhood.)

1917: At a talk David P. gave to the Halifax Field Naturalists in 2010 about regeneration of forest and barrens after the Spryfield Fire of April 30, 2009, the late Jill Alexander, daughter of Captain Arnell, said the last big fire on the Captain Arnell property was in 1917. (The Capt Arnell property is one of two adjacent properties contributed to the Nova Scotia Nature Trust to form The Purcell’s Cove Conservation Lands.)

Residents in the Williams Lake area commented that they report sightings of smoke in the backlands to fire department officials at least once a year. Often they are campfires that don’t escape, sometimes they have required fire fighters to put
them out.

The above  is very likely only a partial list of fires that occurred in the Backlands 1917 to present.

Some Related Links

A Wildfire Story: Decoding the Past with Tree Scars
Post on Landscapes in Motion, Apr 9, 2019

Fire frequency models, methods and interpretations
EA Johnson, SL Gutsell, 1994. Advances in Ecological Research, 25: 239–287.

The most often used evidence of past fire is fire scars. Although fire scars may seem easy to recognize, they can be confused with scars resulting from other causes (e.g. Mitchell et al., 1983) such as those shown in Table 2. If the origin of a scar is in question, it should not be used. Fire scars always form at the base of the tree, usually in a triangular shape. They often form near the boundaries of a burn in active crown fires, but this is not always the case in ground fires or passive crown fires. Active crown fires have a fire front which is a wall of flame extending into the crowns, whereas passive crown fires occur when a ground fire extends into the crown and burns a single tree (Van Wagner, 1977). Trees with multiple fire scars often, but not always, have charring on the older scar faces and consequently could provide evidence that the most recent scar was caused by fire. Several investigations (e.g. McBride, 1983; McClaran, 1988) have found some evidence that a tree once scarred is more easily scarred subsequently. Consequently, unscarred and scarred trees may have different potential for scarring and hence have different fire records. Also, the speed at which healing allows closure of the scar and the time between fires interact with the potential for scarring. Clearly a good understanding of the physical processes involved in fire scar formation would be useful. Unfortunately, at the present time this understanding is incomplete (Spalt and Reifsnyder, 1962; Hare, 1965a,b; Gill and Ashton, 1968; Vines, 1968; Gill, 1974; Tunstall et al., 1976).

Human Demographic Trends and Landscape Level Forest Management in the Northwest Wisconsin Pine Barrens
Radeloff et al., 2001 in Forest Science. “. The effects of landscape pattern on forest ecosystems have been a recent focus in forestscience. Forest managers are increasingly considering landscape level processes in their management. Natural disturbance patterns provide one baseline for such management. What has been largely ignored is the pattern of human habitation patterns (i.e., housing), on landscapes…” The paper describes how historically, tree vegetation in the “The Northwest Wisconsin Pine Barrens has shifted between Fire regimes in the Pine Barrens varied before European immigrant settlement of the area. Within the region, there were at least three distinct subregions during presettlement times (Radeloff et al. 1999)(Figure 1). The southern Pine Barrens were shaped by frequent but low intensity ground fires, creating savannas with low tree density but often large red pine (Pinus resinosa) and burr oak (Quercus macrocarpa) (Radeloff et al. 1998). The central Pine Barrens exhibited very frequent, high intensity crown fires in stands composed almost exclusively of jack pine (P. banksiana). Fires created large openings, and even-aged jack pine regeneration was common in these areas. The northern Pine Barrens also exhibited high intensity crown fires, but their frequency was lower than in the central Pine Barrens. This resulted in mixed pine forest containing white (P. strobus), red, and jack pine as well as some red oak (Q. rubra). European settlers altered the Pine Barrens beginning in the 1860s. In the 19th century, logging and farming
removed forest cover almost entirely. Since the 1930s, reforestation and fire suppression have increased forest cover,
leading to denser forest cover than found before European settlement (Radeloff et al. 1999).The decrease of open habitat has been detrimental to an array of species adapted to openings previously created by fire. Grassland bird populations declined during the second
half of the 20th century, and certain open habitat species, such as the Karner Blue butterfly, have been listed as endangered and have required special management actions. Landscape pattern (i.e., the spatial allocation of openings) is a crucial aspect of the habitat requirements for these species. For example, the number of grassland bird species in an opening is positively correlated with its size (Niemuth 1995).The decline of many open habitat species prompted the Wisconsin Department of Natural Resources (WDNR) to investigate options for landscape level management (Borgerding et al. 1995)…As a result of these workshops, as well as further scientific study, the WDNR identified the lack of open habitat, and especially of large openings, as one of the major management problems in the Pine Barrens. The WDNR is currently seeking input from the scientific community to assist in developing feasible landscape management scenarios..”

The vegetation of the New Jersey pine barrens
McCormick, J. 1998/ in Forman, R. T. T. (Ed) Pine barrens: ecosystem and landscape.Rutgers University Press pp.229-242 “Abstract : The vegetation of the pine barrens is composed of two relatively distinct floristic complexes, namely lowlands on soil saturated for prolonged periods and uplands with a water table generally >0.7m below the soil surface. Lowland vegetation includes swamp forests and relatively small freshwater marshes. Although southern white cedar (Chamaecyparis thyoides) swamp forests were considered characteristic of the region, broadleaf swamp forests of trident red maple (Acer rubrum), blackgum (Nyssa sylvatica) and sweetbay (Magnolia virginiana) are now more widespread. Upland vegetation includes two shrub types, viz. the heath type in which lowbush blueberry (Vaccinium corymbosum) and black huckleberry (Gaylussacia baccata) are predominant and form a nearly continuous cover throughout the uplands, and the scrub oak type in which scrub oak (Quercus ilicifolia) projects above the heaths. The upland canopy layer is divided into two broad groupings, depending on the relative abundance of pitch pine (Pinus rigida) and several oak species, particularly chestnut (Q. prinus), scarlet (Q. coccinea), white (Q. alba), black (Q. velutina) to the north and southern red oak (Q. falcata) to the south. In pine-oak forest types pitch pine covers 30% or more of the ground, contributes 50% or more of the tree stems 2.5cm or greater in diameter, and forms 50% or more of the basal area. The types are pine-blackjack oak (Quercus marilandica), pine-post oak (Q. stellata), and pine-black oak. In oak-pine forest types larger tree-form oaks, including black oak, chestnut oak, scarlet oak and white oak cover 40% or more of the ground, contribute 50% or more of the stems, and form 35% or more of the basal area. Pitch pine is present in nearly all the stands but is less common than the broadleaved trees.”

An analysis of the vascular flora of Annapolis Heathlands, Nova Scotia
Carbyn et al., 2006. The Canadian Field-Naturalist, 120(3), 351-362.
In 1921, legendary Harvard botanist Merritt Lyndon Fernald visited the Annapolis valley. He found exten- sive open heathlands. He noted: “near Berwick and from there to Wilmot were vast uncultivated plains carpeted, wherever dry enough, with a close growth of the New Jersey Pine barren Corema conradii, and, … remnants of them near Middleton” (Fernald 1921). As recently as the 1960s open heathlands with scattered Red Pines (Pinus resinosa) occurred for many miles along the Evangeline Trail (Figure 1). It has been estimated that in pre-settlement times the actual area of heathland encompassed approximately 200 km2. Today less than 3% of the original heathland vegeta- tion remains in the Annapolis Valley (Catling et al. 2004), and even that is threatened by loss of natural ecological processes, invasive species and conversion of the landscape (Catling et al. 2004; Catling and Carbyn 2004). Protection of this ecosystem is impor- tant for the protection of (1) insect pollinators of adja- cent crops; (2) protection of wild relatives of crops for crop improvement; (3) benchmark research examples; (4) teaching examples; (5) nature-related recreational opportunities; and (6) protection of biodiversity gen- erally in connection with national and international accords…”