Northern Cape Breton Island Research Articles

Small‐scale spatial distributions of long‐finned pilot whales change over time, but foraging hot spots are consistent: Significance for marine wildlife tourism management

AbstractData collected opportunistically aboard marine wildlife tourism vessels are an inexpensive source of spatial information on the target species. Although these data are often challenging to analyze, they can be used to monitor spatiotemporal changes in species distribution and behavior. Disruptions from whale‐watching vessels to behaviors such as foraging can be particularly harmful to cetaceans, but impacts could be reduced if areas essential for these sensitive behaviors are identified. We used data collected onboard whale‐watching vessels to explore space‐use patterns in long‐finned pilot whales (Globicephala melas) off northern Cape Breton Island, Canada, an area where tourism is essential. Encounters with pilot whales between 2011–2016 occurred twice as far offshore than during 2003–2006 and 2008, and foraging activity decreased. Despite the changes in distribution and activity budgets, we identified two hot spots of foraging activity that persisted through time. These identified foraging hot spots comprised only a small proportion (20 km2) of the range used by whale‐watching vessels. Adaptive local management (e.g., voluntary codes of conduct) focused on limiting interactions in these energetically important areas may help reduce any potential impacts from whale‐watching and promote the continued viability of the whale population and the tourism industry that relies on it.

Petrology, age, and tectonic setting of the rapakivi-bearing Margaree pluton, Cape Breton Island, Canada: evidence for a Late Devonian posttectonic cryptic silicic-mafic magma chamber

The Margaree pluton extends for >40 km along the axis of the Ganderian Aspy terrane of northern Cape Breton Island, Nova Scotia. The pluton consists mainly of coarse-grained megacrystic syenogranite, intruded by small bodies of medium-grained equigranular syenogranite and microgranite porphyry, all locally displaying rapakivi texture. The three rock types have similar U–Pb (zircon) ages of 363 ± 1.6, 364.8 ± 1.6, and 365.5 ± 3.3 Ma, respectively, consistent with field and petrological evidence that they are coeval and comagmatic. The rare earth elements display parallel trends characterized by enrichment in the light rare earth elements, flat heavy rare earth elements, moderate negative Eu anomalies, and, in some cases, positive Ce anomalies. The megacrystic and rapakivi textures are attributed to thermal perturbation in the magma chamber caused by the mixing of mafic and felsic magma, even though direct evidence of the mafic magma is mainly lacking at the current level of exposure. Magma evolution was controlled by fractionation of quartz, K-feldspar, and Na-rich plagioclase in molar proportions of 0.75:0.12:0.13. The chemical and isotopic (Sm–Nd) signature of the Margaree pluton is consistent with the melting of preexisting continental crust that was enriched in heat-producing elements, likely assisted by intrusion of mantle-derived mafic magma during Late Devonian regional extension. The proposed model involving magma mixing at shallow crustal levels in a cryptic silicic-mafic magma chamber during post-Acadian extension is consistent with models for other, better exposed occurrences of rapakivi granite in the northern Appalachian orogen.

Formation of Anorthositic Rocks within the Blair River Inlier of Northern Cape Breton Island, Nova Scotia (Canada)

Abstract Rocks from the Blair River inlier of Northern Cape Breton Island (Nova Scotia, Canada) have been correlated with either the Grenville basement of eastern Laurentia or the accreted Avalon terrane. Additional zircon U-Pb dates of spatially associated anorthositic dykes (425.1±2.2 Ma) and a metagabbro (423.8±2.5 Ma) from the Fox Back Ridge intrusion of the Blair River inlier reveal Late Silurian emplacement ages. Their contemporaneity suggests that they may be members of a larger intrusive complex. The anorthositic rocks have high Eu/Eu∗ values (>2.5), and bulk compositions are similar to the mineral compositions of labradorite (An50-70) and andesine (An30-50). The metagabbro is compositionally similar to alkali basalt and does not seem to have been affected by crustal contamination (Nb/U>24; Th/NbPM≤1.1) although it was metamorphosed. The high Tb/YbN (1.8-1.9) ratios suggest that the parental magma of the metagabbro was derived from a garnet-bearing peridotite. Fractional crystallization and mass balance calculations indicate that the anorthositic rocks can be derived by mineral accumulation from a mafic parental magma similar in composition to the metagabbro of this study. The Late Silurian ages suggest that the rocks were emplaced into the Avalon terrane after the closure of the Iapetus Ocean but before Early Devonian (415-410 Ma) sinistral transpression.

Silurian U[sbnd]Pb zircon intrusive ages for the Red River anorthosite (northern Cape Breton Island): Implications for the Laurentia-Avalonia boundary in Atlantic Canada

Current interpretations of the geology of Cape Breton Island suggest that it exposes a complete cross-section of the Appalachians from Laurentia across Iapetan vestiges to Avalonia. Crucial to this view is the presence of ca. 1 Ga plutons, including anorthosites, which have been regarded as correlatives of Grenvillian basement, a correlation that overlooks the fact that Avalonia is also underlain by a ca. 1 Ga basement. We analyzed zircons from the Red River anorthosite (Blair River Complex, northwestern Cape Breton Island) previously dated as ca. 1.1 Ga: they yielded 421 ± 3 Ma intrusive ages with older ages between 865 ± 18 Ma and 1044 ± 20 Ma inferred to be either xenocrysts derived from the country rock or from the source. Implications of these data suggest that the accompanying low pressure granulite-amphibolite facies metamorphism of the Blair River Complex is either the root of a 440–410 Ma, magmatic belt produced during slab break-off or relict ca. 1 Ga basement. The Blair River Complex occurs in a NNE-SSW, sinistral positive flower structure that progresses upwards from a Neoproterozoic rifted arc through a low grade upper Ordovician-Silurian overstep sequence to amphibolite facies fault slices, capped by the low-pressure, granulite facies rocks (Blair River Complex). The correlation of Neoproterozoic, rifted arc units across most of Cape Breton Island suggests it represents the deformed northwestern margin of Avalonia intruded by a Silurian-Lower Devonian magmatic belt. As the geological record in the Blair River Complex is similar to both Grenvillian and Avalonian basements, its provenance is equivocal, however Pb isotopic data suggest the Blair River Complex has Amazonian (≈Avalonia) affinities. Thus, Cape Breton Island, rather than representing a complete cross-section of the Appalachian orogen, is part of pristine—deformed Avalonia with a positive flower structure exposing a cross-section of Avalonian crust.

Social structure of long-finned pilot whales (Globicephala melas) off northern Cape Breton Island, Nova Scotia

Cetacean social structures include fluid and stable elements. Long-finned pilot whales (Globicephala melas) live in units that interact forming labile groups. In this study conducted off Cape Breton Island, between 1998–2011, we confirm unit membership predicts associations between individuals. We determine how units are structured and interact. We delineated 21 nearly-stable social units, with an average 7 members. For units where multiple individuals are sexed, both sexes are present. Most units showed long-term stability, while one showed evidence of splitting. Three units shared individuals with the largest unit (K, average size = 29). Splitting is likely triggered by size and difficulties maintaining associations between all individuals. Pilot whales face many pressures driving sociality at a range of temporal and social scales producing a multilevel society. While we have produced a more detailed model of long-finned pilot whale social structure, there are still unanswered questions, particularly whether units are strict matrilines.

BROAD-SCALE PREDICTORS OF CANADA LYNX OCCURRENCE IN EASTERN NORTH AMERICA

The Canada lynx (Lynx canadensis) is listed as a threatened species throughout the southern extent of its geographic range in the United States. Most research on lynx has been conducted in the western United States and Canada; little is known about the ecology of lynx in eastern North America. To fill critical knowledge gaps about this species, we modeled and mapped lynx occurrence using habitat and weather data from 7 eastern states and 3 Canadian provinces. Annual snowfall, road density, bobcat (L. rufus) harvest, deciduous forest, and coniferous forest were compared at 1,150 lynx locations and 1,288 random locations. Nineteen a priori models were developed using the information–theoretic approach, and logistic regression models were ranked using Akaike's Information Criterion (AIC) and by our ability to correctly classify reserved data (Kappa). Annual snowfall and deciduous forest predicted lynx presence and absence for a reserved dataset (n = 278) with 94% accuracy. A map of the probability of lynx occurrence throughout the region revealed that 92% of the potential habitat (i.e., >50% probability of occurrence) was concentrated in a relatively contiguous complex encompassing northern Maine, New Brunswick, and the Gaspé peninsula of Quebec. Most of the remaining potential habitat (5%) was on northern Cape Breton Island in Nova Scotia. Potential habitat in New Hampshire, Vermont, and New York was small (1,252 km2), fragmented, and isolated (>200 km) from known lynx populations. When federally listed as threatened in the contiguous United States in 2000, inadequate regulations on federal lands were cited as the primary threat to Canada lynx. However, the majority of potential lynx habitat in the eastern United States is on private lands and continuous with potential habitat in Canada. Therefore, lynx conservation in eastern North America will need to develop partnerships across national, state, and provincial boundaries as well as with private landowners.

Spatial prediction of tree and shrub succession in a small watershed in Northern Cape Breton Island, Nova Scotia, Canada

This paper describes the development of a spatially-explicit forest transition model for the Clyburn River Valley watershed in northern Cape Breton Island, Nova Scotia, Canada. The model links spatial quantities of available sunlight, degree-day accumulation and soil water content to the establishment and growth of individual tree and shrub species. Environment-species interactions are captured by way of an artificial neural network (ANN) trained to detect temporal patterns produced with a forest gap model (GIZELA) calibrated for environmental and forest species conditions encountered in northern Cape Breton Island. Impact of environmental conditions on forest succession is expressed through numerical adjustments of the ANN-produced forest-transition projections for several representative landscape types. The ANN-transition modelling approach used is largely automated, making it easy to apply at the species level. ANN calculations explain >95% of the variation present in all GIZELA simulations. Forest-transition calculations are subsequently applied to a representative area of the Cape Breton Highlands as a demonstration of the landscape application of the ANN. Forest-transition modelling can aid in the understanding and prediction of natural forest succession at the landscape level, facilitating the development of long-term conservation plans.

Petrology and Isotopic Composition of a Grenvillian Basement Fragment in the Northern Appalachian Orogen: Blair River Inlier, Nova Scotia, Canada

Mesoproterozoic metaplutonic rocks in northern Cape Breton Island, INTRODUCTION Nova Scotia, occur in a tectonic inlier within the Appalachian In eastern North America, Mesoproterozoic Laurentian orogen. Although they have been multiply metamorphosed and basement rocks and their Neoproterozoic to mid-Paleovariably deformed, the petrology and geochemistry of these rocks zoic volcanic and sedimentary cover preserve a record provide insight into the tectonomagmatic evolution of easternmost of the Proterozoic to mid-Paleozoic geologic history of Laurentia. Anorthosite, syenite, and granitoid plutons eastern Laurentia. The record includes Mesoproterozoic (1100–980 Ma) intruded the Sailor Brook and Polletts Cove River orogeny on the ancient North American craton, breakgneisses. New Nd isotopic data are presented from a biotite-rich up of a Neoproterozoic supercontinent, development of part of the Sailor Brook gneiss ( Ndi = −0·7), two anorthosite a passive continental margin, and mid-Paleozoic orogeny. samples ( Ndi = +2·1 and +2·8), and a charnockite unit Exposures of Mesoproterozoic Laurentian basement in ( Ndi = −0·4). New U–Pb zircon data from the anorthosite yield easternmost Canada and the USA occur in a disPb/Pb ages between 975 and 1095 Ma. Disrupted U–Pb continuous band of inliers in the Appalachian orogen systematics preclude a unique age interpretation, but the >1095 Ma from Newfoundland to Alabama (Fig. 1). They consist single-grain date is a minimum age for the anorthosite. Field relations, mostly of rocks formed or deformed during major and trace-element geochemistry, and isotopic characteristics >1190–980 Ma Grenvillian tectonic and magmatic indicate that the anorthosite and charnockite were probably coexisting events, and are distinct from Neoproterozoic and melts, but not differentiates of a single parent magma. The lithological Paleozoic units of accreted Appalachian terranes in that and chemical characteristics of the Lowland Brook Syenite are they include granulite-facies metamorphic rocks and, similar to those of a contemporaneous belt of ultrapotassic plutons in many cases, anorthosite–charnockite–mangerite suites in the southern Grenville Province, and both have the chemical (Bartholomew, 1984, and papers therein; Pettingill et al., characteristics of certain modern continental-margin arc magmas. 1984; Rankin et al., 1989, 1993; Owen & Erdmer, 1990; These data indicate that the Mesoproterozoic units in the Blair Hughes et al., 1997). River inlier were juvenile crustal additions to eastern Laurentia The sinuous trend of the band of basement inliers during Grenville-related orogenic events. broadly reflects promontories and re-entrants that formed

Biophysical and potential vegetation growth surfaces for a small watershed in northern Cape Breton Island, Nova Scotia, Canada

Surfaces of potential vegetation growth in this paper represent the spatial distribution of growing conditions (habitat) for six deciduous tree species native to the Clyburn River valley watershed of northeastern Cape Breton Island, Nova Scotia. Development of potential growth surfaces is based on integrating point calculations of (i) net potential solar radiation, (ii) net long-wave radiation, (iii) growing season degree-day accumulation, and (iv) mean summer soil water content with species-specific evaluations of long-term species environmental response. Functions describing potential species response to available environmental resources are based on generalised mathematical functions that scale species response values between 0 and 1, where 0 represents unsuitable growing conditions and 1, optimal growing conditions. Limitation effects of resource deficits on potential growth are addressed as a multiplication of individual environmental responses. Derived species distributions of potential growth are compared with aerial photo-interpreted distributions of forest vegetation found within the Clyburn River valley watershed. Modelled and photo-interpreted valley distributions demonstrate nearly similar geographic ranges. Actual percent cover for shade-tolerant species displays a positive correlation with modelled potential growth (r2 = 0.5). This is not the case for shade-intolerant species considered, whereby r2 [Formula: see text] 0.

Biophysical and potential vegetation growth surfaces for a small watershed in northern Cape Breton Island, Nova Scotia, Canada

Surfaces of potential vegetation growth in this paper represent the spatial distribution of growing conditions (habitat) for six deciduous tree species native to the Clyburn River valley watershed of northeastern Cape Breton Is - land, Nova Scotia. Development of potential growth surfaces is based on integrating point calculations of ( i) net poten- tial solar radiation, ( ii) net long-wave radiation, (iii) growing season degree-day accumulation, and (iv) mean summer soil water content with species-specific evaluations of long-term species environmental response. Functions describing potential species response to available environmental resources are based on generalised mathematical functions that scale species response values between 0 and 1, where 0 represents unsuitable growing conditions and 1, optimal grow- ing conditions. Limitation effects of resource deficits on potential growth are addressed as a multiplication of individual environmental responses. Derived species distributions of potential growth are compared with aerial photo-interpreted distributions of forest vegetation found within the Clyburn River valley watershed. Modelled and photo-interpreted val - ley distributions demonstrate nearly similar geographic ranges. Actual percent cover for shade-tolerant species displays a positive correlation with modelled potential growth (r 2 = 0.5). This is not the case for shade-intolerant species con - sidered, whereby r 2 ∪ 0.

Expansion of the Known Range of Two Bog-Dwelling Beetles into Nova Scotia

Two species of aquatic beetle are reported from northern Cape Breton Island, Nova Scotia. Helophorus lineatus Say (Hydrophilidae) was not known from Atlantic Canada (except New Brunswick) whereas Dytiscus alaskanus Balfour-Browne (Dytiscidae) has not previously been reported from the Maritime Provinces. Both were collected in boggy barrens, the former found in streams and the latter in ponds. Two legs of an expedition to the Caribou Barrens, Cape Breton Highlands National Park, were undertaken in June and July of 1996 to investigate species of flora and fauna considered rare in Nova Scotia. Two beetle species, Helophorus lineatus Say (Hydrophilidae) and Dytiscus alaskanus Balfour-Browne (Dytiscidae) were collected which had not been recorded in Nova Scotia before. All specimens from this project have been deposited in the Nova Scotia Museum of Natural History. The Caribou Barrens (46°43' N, 60041' W) is a boggy barrens bor- dered by boreal forest which went through a spruce budworm (Choristoneura fumiferana (Clemens)) defoliation in the late 1970s and early 1980s (Fig. 1). The only older trees around the barrens are white birches (Betula papyrifera), although conifers are regrowing. The Bar- rens is dotted with many ombrotrophic ponds. These were of diverse sizes from quite small, having less than one meter square surface area, to quite large, well over 500 m2. Dwarf birches (Betula michauxii) and several herbaceous plants (e.g. Carex spp., Eriophorum tenellum Nutt) occupied the upper littoral zone. The streams which drain the barren (Fig. 2) flow into the North Aspy River. The banks of the streams and ponds are sometimes steep, with the stream banks often displaying a half-meter or more of exposed peat. Three specimens of Helophorus lineatus were collected in July in the lotic waters of the barrens. The streams were rarely over a meter wide and reasonably fast flowing (no flow measurements were taken). The

Magmatism and metamorphism in a Grenvillian fragment: U-Pb and 40Ar/39Ar ages from the Blair River Complex, northern Cape Breton Island, Nova Scotia, Canada

The Blair River Complex in northern Cape Breton Island, Nova Scotia, is interpreted to be an exposure of Grenvillian basement which formed the southeastern tip of a promontory on the proto-Atlantic continental margin of North America. U-Pb (zircon) data reported here confirm Grenvillian ages for the major components in the Blair River Complex. The locally granulite-facies Sailor Brook gneiss has a minimum protolith age of 1217 Ma and was metamorphosed at 1035 +12/−10 Ma. The Lowland Brook Syenite has an igneous crystallization age of 1080 +5/−3 Ma, and the Otter Brook granitic orthogneiss yielded an igneous crystallization age of 978 +6/−5 Ma. An igneous crystallization age could not be obtained for anorthositic rocks in the Blair River Complex, but the Red River Anorthosite Suite was metamorphosed at 996 +6/−5 Ma. Silurian thermal activity is recorded in the Blair River Complex by granitic magmatism dated at 435 +7/−3 Ma and a widespread amphibolite-facies metamorphic overprint of similar age. These events are corroborated by 206Pb/238U ages of ca. 423 Ma for titanite from seven widely distributed samples from both Silurian and Proterozoic units, interpreted to represent cooling from igneous or peak-metamorphic conditions through temperatures of ca. 550–600°C. Rutile in one sample gave a U-Pb age of 410 ± 2 Ma, which may represent postmetamorphic cooling through 405°C. The U-Pb cooling ages are supported by similar 40Ar/39Ar ages of ca. 420 Ma for phlogopite and muscovite from rare calc-silicate lenses in the Blair River Complex, and for hornblende from a Silurian diorite intrusion. The widespread Silurian metamorphism of this inlier is similar in age to that in western Newfoundland and indicates involvement of the Blair River Complex in Silurian orogenesis. Our data support the interpretation that the Blair River Complex represents Laurentian Grenvillian basement, analogous to basement exposures in the Humber Zone of western Newfoundland.

Anorthosltes and Gabbroic Bodies in northern Cape Breton Island, Nova Scotia

Several lensoidal anorthositic bodies of probable Precaabrian age, are exposed in northern Cape Breton Island within a central fault-banded block of quartzofeldspathlc gneisses. One of these, the Red River anorthoslts coaplex Cell ka long and up to 1 ka Hide) ranges free anorthosite to anorthositlc gabbro with high Al2O3 and Sr contents and large positive Eu anomalies resulting mainly from plagloolase accumulation.
 
 Following an episode of polyphase deformation and amphilbolite facles metamorphism, a monzodlorite-gabbro body of unknown age was intruded into both the anorthosite and Its host rocks. The geochemistry of this Intrusion indicates that It Is calc-alkaline. Granite sheets, Intrusive Into the aonzodlorlte-gabbro body, do not appear to be comagmatic based upon the trace element chemistry. These sheets may be correlated with granitic plutons in the Cape North area which have been dated at 330 ±23 Ma.
 
 RÉSUMÉ
 Plusieurs masses anorthositiques, vraisemblablement d'âge précambrien, affieurent de manière lentlculaire eu sein d'un amas central de gneiss quartzofeldspathique, bordé par des failles, dans la nord de l’ile du Cap-Breton. Paral celles-ci, le compiexe d'anorthosite de Red River (d'environ 11 ka da longueur et jusqu'à 1 km de largsur) s'étage des anorthosites aux gabbros anorthositlques, montre de haute contenus en Al2O3 et Sr et a fouml des anomalies élevées en Eu résultant prlncipalament de L’accummulation des plagloclasses.
 
 Aprte un épisode de déformation polyphasée et métamorphisme au faciès amphibolite, un corps de monzonite et gabbro d'âge inconnu s'est introduit tant dans l'anorthosite que dans ses ancalssants. La géochimis de cette intrusion trahit une nature calco-alcaline. La chimie des éléments en traces tend à nier le comagmatisme des granites en nappe intruslfs dans le corps de monzodiorite-gabbro. Ceux-ci s'apparentent plutôt aux plutons granitiques dans la région de Cape North qui sent dates à 330 ±23 Ma.
 
 [Traduit par le journal]

A note on post-Mississippian thrust faulting in northwestern Cape Breton Island

Thrust faulting, apparently of major proportions, has been observed at five localities in northwestern Cape Breton Island and inferred at several more. The thrust blocks of Precambrian crystalline rocks and Horton Group clastic sedimentary rocks have over-ridden Windsor Group (Viséan–Namurian) rocks but not Riversdale Group rocks (Westphalian). Thrusting can be explained by sliding of material from an elongate horst extending from northern Cape Breton Island to southwestern Newfoundland which rose throughout Tournaisian and Viséan time.

Silvical Characteristics of Sugar Maple, Acer saccharum, in Northern Cape Breton Island

Silvical Characteristics of Sugar Maple, Acer saccharum, in Northern Cape Breton Island

Origin and Emplacement of Acadian Granitic Rocks, Northern Cape Breton Island

Acadian granitic rocks in northern Cape Breton Island consist entirely of even-grained leucocratic granodiorite and adamellite. The compositional range is small, and the average composition corresponds well with melts that could be generated in the crust. Abundant pegmatites in the contact zone suggest high water content.Within the major plutons these granitic rocks show: (1) high scatter on a Rb–Sr isochron (Cormier 1972), (2) apparently random areal variation in K and Ca, but a systematic areal variation in K/Rb and Ca/Sr, and (3) high scatter of Na2O and K2O on plots against differentiation index. The minor compositional heterogeneity indicated by these relations could have originated within the source region of melting or by assimilation during emplacement.The granitic plutons are elongate north–south and occur in an en echelon pattern within a NNE-trending migmatite zone. The spatial arrangement of pre-emplacement structures in the country rock and the distribution of xenoliths in the intrusions suggest that emplacement was accommodated by east–west expansion, upbowing of the surrounding country rock, faulting, and minor stoping.

Igneous and Tectonic Events in Northeastern Cape Breton Island, Nova Scotia

The geology of northern Cape Breton Island is characterized by two structurally and compositionally distinct metamorphic units and an extended history of igneous activity ranging in age from Precambrian to Devonian. The older metamorphic unit (George River Group(?)) is composed of metamorphosed psammitic and semipelitic rocks with some distinctive quartzite and coarse-grained marble layers. It was deformed and probably metamorphosed, prior to emplacement of Precambrian diorites. A younger metamorphic unit (Fourchu Group(?)) consists mostly of metamorphosed intermediate to acidic volcanic and volcaniclastic rocks and rests with angular unconformity on the George River Group (?) and the diorites. Shallow-level plutonic activity was contemporaneous with the Fourchu Group(?). Younger leucocratic granodiorites (410 m.y.) were emplaced at a depth of about 15 km and require deposition of a thick surficial sequence during the early Paleozoic (between 560 and 410 m.y.). Mississippian sedimentary rocks rest unconformably on all of the older rocks.Igneous rocks of the Precambrian are dominantly andesitic and are similar to present-day suites in island arcs associated with subduction zones. Their composition requires that they be generated in the mantle. The average compositions of igneous rocks emplaced from late Precambrian to Devonian time become more granitic and probably reflect increasing generation of magma from crustal sources.

Moisture Distribution Patterns in the Secondary Xylem of Sugar Maple, Acer saccharum Marsh

The annual and seasonal patterns of moisture distribution in the wood of sugar maple, Acer saccharum Marsh., have been investigated. Moisture content is reduced to a minimum in midsummer and subsequently, during and after leaf fall, begins to rise. A maximum is reached in the period March-April, after which water content again decreases. During the growing season, the moisture content of the sapwood usually is lowest in the butt region and highest in the crown. Commonly the outermost sapwood, at all levels, is slightly higher in moisture than the contiguous area, with a gradient of increasing moisture content toward the heartwood. In the dormant period, deviations from the foregoing patterns are not great, but there is an overall increase in moisture content throughout the tree. Less consistent trends in moisture content levels obtain in the heartwood. Information is presented bearing on moisture content levels in trees growing on a specific site and sampled in a wet versus a dry year. Consideration is given also to differences in moisture content in trees sampled on very different sites in a single growing season. INTRODUCTION Several years ago a study of various aspects of the movement and storage of moisture in the secondary xylem of forest trees was initiated in Nova Scotia. Observations were made originally in several taxa, but recently the investigation has narrowed to a single species, the sugar maple, Acer saccharum Marsh. Information bearing on the distribution of water in the wood of sugar maple obtained from sample trees felled at different times, or growing under unlike conditions, is presented here. MATERIALS AND METHODS Dominant and codominant trees occurring in undisturbed oldgrowth and second-growth stands were selected for study. These stands were located, with one exception, in northern Cape Breton Island. Sampling was continued for several years in vigorous, secondgrowth bottomland stands, and in stands situated on the lower flanks of the interior Plateau in the Lake O'Law region of north-central Cape Breton Island. In addition, samples were taken from trees in undisturbed stands located both on the uppermost flanks of the Plateau, and on the surface of the tableland. Two additional series of moisture content determinations were made in sample trees located on widely separated but similar, moist, well-drained sites, one in north-central Cape Breton and the other in central Nova Scotia. Each series was of 24 months' duration. The technique of Gibbs (1935) was followed in investigating

Patterns of Distribution of Sugar Maple, Acer saccharum Marsh., in Northern Cape Breton Island

An investigation has been made of the distribution patterns of Acer saccharum Marsh. on, and in close proximity to the limit of the range of the species in, northern Cape Breton Island. The limit of the range of the species cannot now be clearly delineated at sea level, but at greater elevations varies from altitudes of the order of 800 feet on seaward slopes to 1300 feet inland. In both primeval and second growth areas the density and dominance of the species vary widely, with a trend toward lower stocking with increasing altitudes. In some areas the limit of the range is marked by widely scattered trees whereas in others the density of the species is fairly high. Irrespective of stocking, there is no gradual transition in size toward a depauperate form or a marked decrease in vigour upon approaching the limit of the range of the species. On the basis of present evidence it is difficult to decide whether the limit of the range is stationary, advancing or retreating.

Peltigera on Longs Peak, Colorado, and in Iowa County, Iowa

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