Northeastern British Columbia Research Articles

Soil properties, aspen, and white spruce responses 5 years after organic matter removal and compaction treatments

Retaining organic matter and preventing soil compaction are important factors affecting the sustainability of managed forests. To assess how these factors affect short-term ecosystem dynamics, pre-treatment and 1 year and 5 year post-treatment soil properties and post-treatment tree growth responses were examined in a boreal trembling aspen (Populus tremuloides Michx.) dominated ecosystem in northeastern British Columbia, Canada. The experiment used a completely randomized design with three levels of organic matter removal (tree stems only; stems and slash; stems, slash, and forest floor) and three levels of soil compaction (none, intermediate (2-cm impression), heavy (5-cm impression)). Removal of the forest floor initially stimulated aspen regeneration and significantly reduced height growth of aspen and white spruce (Picea glauca (Moench) Voss). The compaction treatments had no effect on aspen regeneration density. At year 5, heights of both aspen and white spruce were negatively correlated (r2 > 0.31, p < 0.0001) with upper mineral soil bulk density and were lowest on forest floor removal treatments, where minimal recovery from compaction was observed. There was some evidence for recovery of soil properties to preharvest conditions where expansion of herbaceous vegetation increased soil organic matter.

Regional subsurface correlations of Albian sequences north of the Peace River in NE British Columbia: northward extent of sandstones of the Falher and Notikewin members along the eastern flank of the foredeep

Abstract The highly explored Peace River Region and Elmworth Deep Gas Basin have yielded a large database of geophysical wireline well logs and cores. Recent exploration and research within the Trutch, Fort Nelson and the Liard Basin regions are providing a growing database of geological information, allowing for reliable correlations between these two regions, filling the gap between 55.5° N and 58° N. In northeastern British Columbia and northwestern Alberta, four major phases of marine inundation can be traced regionally outlining the geometries resulting from the presence of the foredeep to the west. These phases are referred to paleogeographically in ascending order, as the Moosebar/Clearwater Sea, Hulcross/ Harmon Sea, Joli Fou Seaway, and Mowry Sea. Within the western foredeep, Albian sedimentation to the northwest is preserved as distinct marine shales and mudstones of the Buckinghorse Formation. To the south, this shale package is interrupted by distinct stacked, coarsening-upward sandstone packages. Along the eastern margin of the foredeep, regional wireline cross-sections are interpreted to show northward extensions of the Falher and Notikewin members, and the preservation of a Notikewin lowstand facies attached to the highstand. The highstand shoreline is interpreted to have been oriented in a southwest to northeast trend, with sandstone progradation occurring in a northwesterly direction. A core located within the lowstand deposit also provides evidence of tidally influenced incised valley fill deposits. The northward extent of the sandstone may be a result of proximity to the eastern flank of the foredeep, transport of sand north during storms over an overall shallow shelf setting and strong basin-wide currents allowing for the northward transport of these coarser deposits. In the southeast, as a result of erosion between the Paddy and Cadotte members, deposits of the Joli Fou Formation are not well preserved. In the north and west, however, an equivalent conformable suite of mudstones is thinning in an easterly direction. The equivalent Viking Formation marker bed in the foredeep can only be detected by a subtle resistivity change.

Estimating harvest schedules and profitability under the risk of fire disturbance

Incorporating fire disturbance into sustainable forest management plans is necessary to provide estimates of variation around indicators for harvest levels, growing stock, profitability, and landscape structure. A fire disturbance model linked to a harvest simulator was used to estimate the probability of harvest shortages under a range of harvest levels and fire suppression scenarios. Results were then used to estimate "sustainable" harvest levels based on a risk tolerance to harvest shortages and the effects of fire suppression. On a 288 000 ha forest in northeastern British Columbia, the cost of historical fire disturbance was estimated at $4 million per year in terms of foregone harvest profits. Suppressing 98.3% of disturbance events to 30% of their historical size had a value of $1.8 million per year. Higher levels of risk tolerance were associated with increased harvest levels and short-term profits, but as timber inventories were drawn down, average long-term profits became volatile. The modelling framework developed here can help to determine resilient forest management strategies and estimate the future flow and variability of harvest volumes, profits, and landscape conditions.

Stratigraphy, structure and tectonic history of the Pink Mountain Anticline, Trutch (94G) and Halfway River (94B) map areas, northeastern British Columbia

Abstract Pink Mountain Anticline stands out in front of the foothills of northeastern British Columbia (57°N, 123°W). Geologic mapping and prestack depth-migrated seismic sections show that it is localized above and west of a northwest-trending subsurface normal fault. Along with isopach maps these data demonstrate episodic normal movement on the fault during deposition of the Carboniferous Stoddart Group, Triassic Montney Formation and possibly the Jurassic–Cretaceous Monteith–Gething formations. West of this fault, during Laramide compression, a pair of backthrusts nucleated on either side of a minor east–west trending Carboniferous fault and propagated across it in an en echelon pattern. One backthrust ramped laterally across the area and separated the Pink Mountain and Spruce Mountain structures, both of which are contained within a 30+ km long pop-up structure above the Besa River Formation decollement. Glomerspirella fossils confirm the existence of the Upper Jurassic Upper Fernie Formation and Upper Jurassic to Lower Cretaceous Monteith Formation at Pink Mountain.

Regional heat flow pattern and lithospheric geotherms in northeastern British Columbia and adjacent Northwest Territories, Canada

Abstract A new heat flow map has been constructed for northeastern British Columbia, using log-heading temperature records corrected for drilling disturbance, at depths ranging from 200 m to over 4000 m. Geothermal gradient varies from 20 to 90 mK/m (°C/km). A significant regional trend of southward and southwestward decrease of geothermal gradient is observed in the map area. Effective thermal conductivity, based on an analysis of an evenly distributed network of wells throughout the area, shows variation in the range 1.2 to 2.4 W/mK. Very large variations of terrestrial heat flow, from 40 to 130 mW/m2, suggest a large imprint of highly variable heat generation in the upper crust. The lowest heat flow is observed in the southern part of the study area and especially in the southwest. The highest heat flow is in the north, with values commonly exceeding 100 mW/m2. However, lower heat flow values (<60 mW/2) are also observed in the north. In the deep western part of the basin, low heat flow in the south contrasts with high heat flow north of 59°N. Reduced (deep) heat flow in the north is probably 10 to 20 mW/m2 higher than the average of 33 mW/m2 proposed previously. Higher regional reduced heat flow and higher than average heat generation (2-4 μW/m3) of the basement rocks likely accounts for part of the northern high heat flow. It is estimated that the average temperature at a depth of 5 km is 180°C; however, temperatures as high as 140°C are recorded at the much shallower depth of 2 km in the northern and northeastern part of the study area.

Paleoenvironments and regional stratigraphic framework of the Middle-Upper Albian Lepine Formation in the Liard Basin, Northern Canada

Abstract The thick Middle to Late Albian Lepine Formation in the Liard Basin of northeastern British Columbia, southern Yukon and Northwest Territories preserves a continuous record of sedimentation during a time of multiple sea-level fluctuations that produced pronounced unconformities elsewhere in the Cretaceous Western Interior Seaway. Although sediment supply was high, the rapidly subsiding sub-basin produced sufficient accommodation to maintain offshore and shelf conditions throughout the interval. Using lithology, micropaleontology, well log correlations and Rock Eval pyrolysis, the 1000 m thick Lepine Formation is divided into five units in upper/lower offshore and shelf facies. The foraminiferal fauna differs substantially from that described from the Peace River Foothills and documents a continuous marine record during flooding of the Joli Fou Sea and the transition to the Mowry Sea. Regional well log correlations show significant thinning of the Lepine Formation southwards to the equivalent upper Buckinghorse and Hasler formations. Markers at transgressive surfaces can be traced for greater than 400 km along the foredeep. The thick, lower to middle part of the Lepine Formation (Units 1-3) contains foraminifera of the Ammobaculites wenonahae Zone and Ammomarginulina Assemblage Zone that record stressed oceanographic conditions related to periods of uplift west and northwest of the Liard Basin during the Joli Fou and lower Viking intervals. The transition between the two major inundations (Joli Fou and Mowry) is represented by a thick continuous interval in the Liard Basin. The Viking marker (lowermost Unit 3), traced in well logs and projected onto the outcrop section, has no obvious biostratigraphic definition. A major increase in foraminiferal diversity occurs near the base of the Bougie member (Unit 4), indicating more normal marine conditions within the Mowry Sea. A major flooding surface above the Bougie member is correlated with the 'Viking grits' (base of Unit 5) transgressive lag in the Peace River region of the Rocky Mountain Foothills.

Properties of hydrocarbon- and salt-contaminated flare pit soils in northeastern British Columbia (Canada)

Many contaminated sites in Canada are associated with flare pits generated during past petroleum extraction operations. Flare pits are located adjacent to well sites, compressor stations and batteries and are often subjected to the disposal of wastes from the flaring of gas, liquid hydrocarbons and brine water. This study was conducted to evaluate the physical, chemical, electrical and mineral properties of three flare pit soils as compared to adjacent control soils. Results showed that particle size distribution, pH, total N, cation exchange capacity, exchangeable Mg 2+, and sodium adsorption ratio were similar in soils from flare pits and control sites. Total C, exchangeable Ca 2+, K + and Na +, soluble Ca 2+, Mg 2+, K + and Na + and electrical conductivity were higher in flare pit soils compared to control soils. X-ray diffraction and scanning electron microscopic analyses showed the presence of gypsum [CaSO 4 · 2H 2O], dolomite [CaMg(CO 3) 2], pyrite [FeS 2], jarosite [KFe 3(OH) 6(SO 4) 2], magnesium sulphate, oxides of copper and iron + copper in salt efflorescence observed in flare pit soils. Soils from both flare pits and control sites contained mica, kaolonite and 2:1 expanding clays. The salt-rich materials altered the ionic equilibria in the flare pit soils; K Mg–Ca selectivity coefficients in control soils were higher compared to contaminated soils. The properties of soils (e.g., high electrical conductivity) affected by inputs associated with oil and gas operations might render flare pit soils less conducive to the establishment and growth of common agricultural crops and forest trees.

Managing forest and marginal agricultural land for multiple tradeoffs: compromising on economic, carbon and structural diversity objectives

In this paper, we use compromise programming to solve a multiple-objective land use and forest management planning model. Long- and short- (‘fast’) term carbon uptake, maintenance of structural diversity, and economic (net returns to forestry and agriculture) objectives are simultaneously achieved by minimizing the distance between current objective values and the ideal ones. Two distance metrics are used, representing a risk neutral and highly risk-averse decision maker. An application of the model to public forestland and adjacent private agricultural lands in the (boreal) Peace River region of northeastern British Columbia indicates that both short- and long-term carbon uptake, and maintenance of structural diversity, can be achieved only at the high financial costs. Contrary to earlier studies, we also find conflict between both short- and long-term carbon uptakes and maintenance of landscape structural diversity. Targeting short-term carbon uptake results in the greatest deviation from desired structural diversity, although the deviation is somewhat smaller with respect to the long-term carbon uptake goal. Further, risk neutral and risk-averse decision makers will employ significantly different land use and forest management strategies. Finally, the ‘balanced’ strategy (which underachieves attainment of the ‘ideal’ by the same degree for all objectives) attains diversity targets quite closely, but significantly underachieves economic and carbon objectives. Maximization of the weighted sum of objective deviations results in an ‘average’ strategy that performs much better in attaining carbon objectives, but diversity is sacrificed.

Boreal mixedwood species composition in relationship to topography and white spruce seed dispersal constraint

In this study we integrated digital terrain models, forest inventory maps, optical remote sensing and field data to analyze the spatial structure of a 4850 km 2 boreal mixedwood forest landscape in northeastern British Columbia. We built independent maps of forest cover and landform using a Bayesian classification algorithm and quantitative surface analysis. These data were used to test the strength of the association between topographic position and forest cover using a modified electivity index. We then used logistic regression to test whether the probability of a site being occupied by either mixedwood or hardwood is correlated to its distance from white spruce ( Picea glauca) seed sources. The relationship between forest cover and topography showed significant departures from randomness, with white spruce preferentially associated with channels and concave slopes, and hardwoods preferentially associated with ridges and convex slopes. The analysis of mixedwood and hardwood stand distribution showed a positive correlation between hardwood occurrence and distance from spruce stands, suggesting that the dispersal limitations of white spruce is a significant influence on landscape vegetation dynamics. Overall, the results support the hypothesis that mixedwood dynamics are the product of ecological processes at multiple scales. Furthermore, these dynamics are only revealed by taking a varied approach to both data gathering and analyses.

On some physical properties of six aspen clones

Abstract Basic physical properties including density, permeability, water sorption characteristics and diffusion coefficients in desorption were measured with specimens taken from for six aspen clone trees harvested in northeastern British Columbia. Results showed that there are significant differences among the clones in their specific permeability and somewhat in the heat of wetting, but very little was found among density, diffusion coefficients and desorption isotherms. These results indicate that the porous structure could be variable among clones whereas the sorption site distribution and availability might not.

MIDDLE TRIASSIC PTERIOMORPHIAN BIVALVIA (MOLLUSCA) FROM THE NEW PASS RANGE, WEST-CENTRAL NEVADA: SYSTEMATICS, BIOSTRATIGRAPHY, PALEOECOLOGY, AND PALEOBIOGEOGRAPHY

The parautochthonous Anisian and Ladinian rocks of the New Pass Range previously referred to as the Augusta Mountain Formation have a unique, endemic assemblage of pteriomorphian bivalves with Triassic Northern Hemisphere biogeographic relationships, especially to the Carnian cratonal faunas of northeastern British Columbia as well as to Ladinian faunas of the Shoshone Mountains and the Gillis Range. A new suborder Prospondyloidina is described, as well as three new genera, Promysidiella, Loxochlamys, and Nevadapecten, a new subgenus, Gervillaria (Baryvellia), and 17 new species either named or referred to by letters: Promysidiella planirecta, P. desatoyensis, Bositra favretensis, Enteropleura species a, Gervillaria (Baryvellia) ponderosa, Atrina sinuata, Antiquilima ladinica, Palaeolima newpassensis, Plagiostoma acutum, Leptochondria shoshonensis, Asoella? species a, b, and c, Oxytoma (Oxytoma) grantsvillensis, Pleuronectites newelli, Loxochlamys corallina, and Nevadapecten lynnae. Promysidiella aff. otiosa is a new combination for Mytilus otiosus McLearn; Mysidiella newtonae n. sp., Norian, Wallowa terrane, is based on Krumbeckiella cf. timorensis (Krumbeck) of Newton, 1987. Triassic “Posidonia” is placed in Bositra de Gregorio, 1886, regarded as a senior synonym of Peribositria Kurushin and Trushchelev, 1989. The morphological and stratigraphic sequence Bositra-Enteropleura-Daonella-Aparimella-Halobia is rooted in Paleozoic Caneyella and Posidonia and indicates declining dependence on and eventual loss of byssal attachment as well as a possible shift from low to high dispersal ability (between Bositra and Enteropleura). There is no evidence for trans-Panthalassan dispersal of bivalves in low latitudes within the interval of Ladinian coral beds. So-called Tethyan and Muschelkalk species are endemics in slowly evolving genera or are phylogenetically convergent on west Tethyan species.

Giant ichthyosaurs of the Triassic—a new species of Shonisaurus from the Pardonet Formation (Norian: Late Triassic) of British Columbia

ABSTRACT The ichthyosaur Shonisaurus sikanniensis sp. nov. is described from the Pardonet Formation (Norian, Late Triassic) of northeastern British Columbia. The type specimen is considerably larger than Shonisaurus popularis, with an estimated length of 21 m. It also differs from S. popularis in having a fan-shaped scapula, and relatively longer vertebral centra. Studies of this new species, along with re-examination of S. popularis, suggests that Shonisaurus was not as deep-bodied as previously reconstructed. Teeth are set in sockets, but are known only in a few, small individuals. This implies that teeth were present only in juveniles, and that adults were edentulous. The new species extends the geographical and stratigraphical range of Shonisaurus to the middle Norian of British Columbia.

Hydrocarbon source rock characterization and thermal maturity of the Upper Triassic Baldonnel and Pardonet formations, northeastern British Columbia, Canada

Abstract Numerous gas and oil fields are hosted in the Baldonnel and Pardonet formations of northeastern British Columbia, Canada. The source of the hydrocarbons in these fields has not been demonstrated using organic geochemical methods. However lithologic characteristics, interpreted depositional settings, and some published organic carbon content values have led to speculation that Upper Triassic strata of northeastern British Columbia, in particular the Pardonet Formation, may include important hydrocarbon source rocks. In order to assess the hydrocarbon source rock potential of Upper Triassic strata in northeastern British Columbia, nine outcrops and seven drillcores were measured, described and sampled for geochemical analyses. Geochemical analyses using Rock-Eval/TOC pyrolysis indicate a total organic carbon (TOC) content ranging from 0.03 to 2.08 weight percent for the Baldonnel (majority Geochemical data from outcrop and core suggest that the Pardonet Formation in northeastern B.C. had good to very good initial hydrocarbon potential, and has generated economically significant quantities of hydrocarbon. However, gas isotopic and gas compositional data, as well as biomarker analysis of oils and source rock extracts, are required to demonstrate whether the Pardonet, or some other, deeper unit, was the source of hydrocarbons found in Upper Triassic reservoirs in northeastern B.C. Mass balance calculations based on the geochemical data presented here for the Pardonet Formation, suggest that current initial in-place reserve estimates for Upper Triassic reservoir strata are four to five times less than expected. We speculate that some proportion of this calculated volume of hydrocarbons may have been retained within the Pardonet Formation itself, suggesting some potential as a fractured shale play. The Baldonnel Formation had only poor to fair initial hydrocarbon potential, and was not a significant hydrocarbon source.

Soil temperatures and suckering response of trembling aspen (Populus tremuloidesMichx.) following disposal of hog on winter-logged cutblocks

Bark and wood residue, commonly referred to as "hog fuel" or "hog," from a portable pulp chipper was deposited on aspen cutblocks in replicated 10 x 10 m treatment plots during winter logging operations in northeastern British Columbia. The treatments emulated disposal of hog under conditions that simulated on-site chipping operations. Three different rates of hog disposal were applied; 34, 68 and 102 kg m-2, and three cutblocks were treated, one each during February of 1997, and March of 1998 and 1999. We originally hypothesized that the deposition of hog would lower soil temperatures in the treated plots and reduce aspen sucker density during the following growing season. However, our observations showed an initial lag in soil warming in the treatments followed by temperature levels that rose above that exhibited in the control plots. Higher soil temperatures were correlated with greater rates of hog disposal. Increased suckering was not observed in response to higher soil temperatures and stem densities decreased as hog application rates increased. Key words: in-woods, on-site, chipping, Populus tremuloides, hog fuel, soil temperature

Sedimentology of the Upper Triassic Charlie Lake, Baldonnel and Pardonet formations from outcrop exposures in the southern Trutch region, northeastern British Columbia

Abstract Upper Triassic strata in the Trutch (94 G) NTS map area consist of the Charlie Lake, Baldonnel and Pardonet formations. These units comprise a mixed siliciclastic-carbonate succession, approximately 350 to 400 m thick. Sediments accumulated along a low gradient continental ramp deposited on the northwestern margin of Pangaea. Twenty-two lithofacies, deposited in distal offshore through supratidal settings are documented. Seven recurrent facies associations are identified in these strata; four reflecting deposition in continental to marginal marine settings, and three reflecting shallow to deep water marine deposition. Facies association 1 (FA1) consists of interbedded dolomitic mudstone/siltstone and dolomitic sandstone that was deposited in an intertidal flat depositional setting. Facies association 2 (FA2) consists of normally graded, trough cross-bedded to current ripple-laminated lenticular beds of mudclast-rich fine- to medium-grained sandstone, and was deposited by a series of small tidal channels. Facies association 3 (FA3) consists of well-sorted fine-grained sandstone beds characterized by high-angle tabular to wedge-shaped cross-beds, low-angle planar cross-beds, low-relief, translatent ripples and inversely graded lamina sets. FA3 is interpreted to represent deposition by a series of elongate, shore-parallel aeolian dunes. Facies association 4 (FA4) consists of a heterogeneous succession of solution collapse breccias, rooted, pedogenically-altered mudstone and siltstone, and wave-rippled very fine- to fine-grained sandstone. It is interpreted as ephemeral lacustrine and/or supratidal sabkha. Facies association 5 (FA5) consists of variably bioclastic quartzose sandstone, crinoidal packstone-grainstone and bivalve-dominated packstone beds. It is interpreted as a wave-dominated shoreface to foreshore on a shallow (inner) ramp. Facies association 6 (FA6) is dominated by very fine-grained calcareous sandstone and thin to thick-bedded bivalve-dominated wackestone, packstone and grainstone. It is interpreted as medial ramp (i.e., offshore transition to proximal offshore). Facies association 7 (FA7) consists primarily of organic-rich calcareous siltstone and mudstone (commonly with abundant carbonate concretions) and variably thick tightly packed bivalve packstone/grainstone beds. It is interpreted as outer ramp (proximal to distal offshore). Siliciclastic sediment in the study area was derived from a variety of sources, including fluvial input from the east-northeast, longshore drift from the north, and aeolian input sourced from marginal marine dune fields. Carbonate sediment in the study interval consists primarily of bioclastic detritus, although non-skeletal grains, particularly faecal pellets, and ooids are locally common. Skeletal carbonate material is dominated by disarticulated mollusc valves and crinoid skeletal debris but also includes ammonoids, articulate brachiopods, gastropods. Vertebrates (fish and reptiles) are also common.

Early growth of white spruce underplanted beneath spaced and unspaced aspen stands in northeastern British Columbia

We examined the growth of white spruce planted underneath a 33-year-old stand of trembling aspen following thinning and fertilization. Thinning the stand to 2000 stems·ha–1 resulted in increased light reaching spruce seedlings and significant increases in height and diameter growth of seedlings over that observed in either the unspaced or 3000 stems·ha–1 treatments. Fertilization (applied 3 years prior to planting) stimulated development of understory vegetation and did not benefit the planted spruce. While growth was improved by thinning, the benefits of the thinning treatment to establishment of white spruce appeared to be small, and amounted to increasing seedling height from 62 cm (unthinned) to 73 cm (thinned to 1000 or 2000 stems·ha–1) at the end of 5 years. Results indicated that when stands are thinned for the purpose of accelerating growth rates of underplanted spruce, residual basal areas above 25 m2·ha–1 should be retained to suppress growth of understory vegetation. Comparison of height at age 5 for seedlings planted under untended stands at Fort Nelson with three sites near Dawson Creek indicated no differences between locations, when height at the time of planting was included as a covariate.

Variation of the understory composition and diversity along a gradient of productivity in Populus tremuloides stands of northern British Columbia, Canada

Although various conceptual models exist to explain the pattern of diversity along a productivity gradient, studies of forest understory vegetation along a natural gradient of productivity are often confounded with changes in overstory cover types. We investigated how understory vegetation composition, cover, structure, and diversity change along a productivity gradient in 60 monodominant Populus stands in northeastern British Columbia. A partial canonical correspondence analysis indicated that understory vegetation composition was significantly related to aspen site index – dominant aspen tree height at breast-height age 50 years and several climate and soil variables, but not to stand basal area, density, or aboveground biomass, values that served as an index of light availability to forest understory. Indicator species analysis showed that Cornus sericea, Galium trifidum, and Equisetum pratense were associated with the higher productivity class, while Geocaulon lividum, Vaccinium vitis-idaea, Vaccinium myrtilloides, and bryophytes like Polytrichum juniperinum and Pleurozium schreberi occurred only on poor sites. Total cover of all understory plants, woody plants, and herbaceous species did not vary, but that of bryophytes and lichens decreased from poor to intermediate sites, and diversity indices of total, woody, and herbaceous plants increased significantly with the site index. The greater diversity on more productive sites may be associated with greater spatial and resource heterogeneity.Key words: trembling aspen, forest productivity, site index, understory vegetation, species composition, diversity index.

The Gordondale Member: designation of a new member in the Fernie Formation to replace the informal “Nordegg Member” nomenclature of the subsurface of west-central Alberta

Abstract New biostratigraphic data and revised lithostratigraphic correlations reveal that the current stratigraphic nomenclature for the Lower Jurassic portions of the Fernie Formation in the subsurface of west-central Alberta is inadequate. This paper introduces a new member, the Gordondale Member, for highly radioactive, fine-grained strata previously referred to as either the lower Fernie Formation, the Lower Fernie shelf limestone and clastics, the Nordegg Member, or the “Nordegg Member”. A new occurrence of a late Toarcian ammonite, which constrains the age of the top of the Gordondale Member, is also reported. The Hettangian to upper Toarcian Gordondale Member is an important hydrocarbon source rock and consists of dark brown, finely laminated, organic-rich, phosphatic and highly radioactive calcitic mudstones, calcilutites and fine-grained calcarenites. Fish fragments, pectinoid bivalves, Ostrea, belemnoids, ammonites, coccoliths and radiolarians are abundant. The Gordondale Member is laterally extensive and thins westward from a maximum thickness of approximately 50 m in the subsurface of west-central Alberta to 19 m at Pink Mountain in northeastern British Columbia.

The application of a hierarchical, decision-support system to evaluate multi-objective forest management strategies: a case study in northeastern British Columbia, Canada

Increases in the environmental awareness of global consumers coupled with pressure from regional stakeholders has forced forest managers to demonstrate the potential implications of forest management activities for a broad range of indicators. This paper describes the construction and application of a hierarchical decision-support system for evaluating multi-objective management options for a 288,000 ha forest in northeastern British Columbia. The decision-support system includes a stand-level model, a forest estate model, a habitat model and a visualization model. A set of criteria and indicators, developed in conjunction with a public advisory committee, were used to identify key economic, ecological and social objectives. Indicators include volume harvested, gross profit, active road density, ecosystem carbon storage, age-class distribution, patch-size distribution, snag density, visual aesthetics and backcountry recreation area. A natural disturbance baseline and two alternative harvest strategies that include natural disturbance are projected and assessed with the decision-support system. The first strategy represents a dispersed harvesting approach in which cut blocks are limited to sizes <60 ha. The second strategy represents an aggregated harvesting approach in which a range of cut block sizes (up to 2000 ha) and shapes is created that more closely follows the distribution of openings generated from natural disturbance events in the region. Spatial and temporal changes in each indicator are presented and evaluated for the harvest strategies, and compared to the natural disturbance baseline where appropriate. The application of the decision-support system for strategic analysis of management options is discussed, including a review of the importance of representing the impacts of natural disturbance and the benefits and risks associated with the use of visualization techniques for presenting results to stake holder groups.

The ichnological expression of marine and marginal marine conglomerates and conglomeratic intervals, Cretaceous Western Interior Seaway, Alberta and northeastern British Columbia

ABSTRACT Although uncommon, conglomeratic successions and their associated interbeds do contain trace fossils that attest to their marine or marginal marine origins. Intervals within the Cretaceous of the Western Interior Seaway of Alberta and northeastern British Columbia contain ichnological assemblages consistent with open bay, estuarine incised valley, shoreface, and transgressive ravinement settings. Conglomerates and conglomeratic sandstones of open bays are largely confined to bay margins, and are markedly heterolithic, commonly trough cross-stratified, and moderately bioturbated with Diplocraterion, Skolithos, Palaeophycus, Conichnus and Ophiomorpha. Interbedded sandstones and mudstones contain Teichichnus, Planolites, Terebellina, Arenicolites, Bergaueria, Rosselia, Asterosoma, Cylindrichnus, Thalassinoides, and fugichnia. Burrowed incised valley conglomerates and pebbly sandstones mainly record channel fills of tidal inlets or flood-tidal deltas at wave-dominated estuary mouths. Trace fossil suites comprise Teichichnus, Ophiomorpha, Skolithos, Diplocraterion, Arenicolites, Rosselia, Cylindrichnus, and fugichnia. Intercalated sandstone and mudstone beds are moderately burrowed with Planolites, Teichichnus, Terebellina (sensu lato), Ophiomorpha, Palaeophycus, Asterosoma, Chondrites, Conichnus and fugichnia. Upper shoreface and foreshore conglomerates are well sorted, clast supported, and display good clast segregation. Bioturbation is uncommon, comprising Palaeophycus, Ophiomorpha, Cylindrichnus, Rosselia and fugichnia. Interbedded sandstones and pebbly sandstones may contain Macaronichnus and Palaeophycus. The Cardium Formation locally contains conglomeratic intervals interpreted to reflect the entire shoreface succession. These conglomeratic intervals are unburrowed, though they overlie Glossifungites ichnofacies-demarcated discontinuities, and grade upward into burrowed shelf mudstones. Conglomeratic transgressive lags and pebbly sandstones mantle wave or tidal scour ravinement surfaces, and commonly infill palimpsest Diplocraterion, Skolithos, Arenicolites, Thalassinoides, and Rhizocorallium of the Glossifungites ichnofacies, which demarcate these discontinuities. Transgressive lags may be variably burrowed with virtually any softground suite, depending on the depositional setting. Tidal scour ravinement lags at incised valley mouths, for example, may be weakly burrowed with an impoverished Skolithos ichnofacies, whereas wave ravinement lags produced during regional transgression can contain open marine, diverse mixed Skolithos-Cruziana ichnofacies assemblages. End_Page 77-------------------------