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International Statistics and Research Corporation

Brentwood, Canada
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Nemec A.F.L.,International Statistics and Research Corporation | Parish R.,1540 Ash Road | Goudie J.W.,British Columbia Ministry of forests
Canadian Journal of Forest Research | Year: 2012

A compound, nonhomogeneous Poisson process was used to model the number, vertical distribution, and size of branches on four coniferous tree species: 134 western hemlock (Tsuga heterophylla (Raf.) Sarg.) on six sites, 45 amabilis fir (Abies amabilis Douglas ex J. Forbes) (three sites), 60 lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Watson) (six sites), and 60 white spruce (Picea glauca (Moench) Voss) trees (five sites) and two varieties: 66 coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) (five sites) and 50 interior Douglas-fir (Pseudotsuga menziesii var. glauca (Mayr) Franco) (four sites). Branches of these species are typically more or less clustered and have a characteristic, nonuniform vertical distribution along annual shoots. Total number and relative positions of clusters varied with shoot age. Clustering patterns in three of four species and two varieties appeared to scale proportionally with shoot length. However, in lodgepole pine, which has fewer clusters per metre and more branches per cluster, the vertical distribution of clusters along shoots ≤5 years old was consistent with a gamma-Poisson model but converged to a nonhomogeneous Poisson process model in shoots >5 years old. Separate mixed-effect regression models were developed for each species relating length and diameter of live branches to tree (crown), shoot, and branch (cluster) predictor variables.

Nemec J.M.,Camosun College | Nemec J.M.,International Statistics and Research Corporation | Cohen J.G.,California Institute of Technology | Ripepi V.,National institute for astrophysics | And 6 more authors.
Astrophysical Journal | Year: 2013

Spectroscopic iron-to-hydrogen ratios, radial velocities, atmospheric parameters, and new photometric analyses are presented for 41 RR Lyrae stars (and one probable high-amplitude δ Sct star) located in the field-of-view of the Kepler space telescope. Thirty-seven of the RR Lyrae stars are fundamental-mode pulsators (i.e., RRab stars) of which sixteen exhibit the Blazhko effect. Four of the stars are multiperiodic RRc pulsators oscillating primarily in the first-overtone mode. Spectroscopic [Fe/H] values for the 34 stars for which we were able to derive estimates range from -2.54 ± 0.13 (NR Lyr) to -0.05 ± 0.13 dex (V784 Cyg), and for the 19 Kepler-field non-Blazhko stars studied by Nemec et al. the abundances agree will with their photometric [Fe/H] values. Four non-Blazhko RR Lyrae stars that they identified as metal-rich (KIC 6100702, V2470 Cyg, V782 Cyg and V784 Cyg) are confirmed as such, and four additional stars (V839 Cyg, KIC 5520878, KIC 8832417, KIC 3868420) are also shown here to be metal-rich. Five of the non-Blazhko RRab stars are found to be more metal-rich than [Fe/H] ∼-0.9 dex while all of the 16 Blazhko stars are more metal-poor than this value. New P - [Fe/H] relationships are derived based on ∼970 days of quasi-continuous high-precision Q0-Q11 long- and short-cadence Kepler photometry. With the exception of some Blazhko stars, the spectroscopic and photometric [Fe/H] values are in good agreement. Several stars with unique photometric characteristics are identified, including a Blazhko variable with the smallest known amplitude and frequency modulations (V838 Cyg). © 2013. The American Astronomical Society. All rights reserved.

Newsome T.A.,Borland | Heineman J.L.,J. Heineman Forestry Consulting | Nemec A.F.L.,International Statistics and Research Corporation | Comeau P.G.,University of Alberta | And 2 more authors.
Forest Ecology and Management | Year: 2010

We investigated survival and growth responses of planted and advance natural regeneration species of varying shade tolerance to partial retention harvesting in moist warm Interior Cedar-Hemlock (ICHmw2) and dry cool Montane Spruce (MSdk) ecosystems of southeastern British Columbia, Canada. Treatments included three levels of overstory basal area retention (none, light (∼25%), or heavy (∼50%)) installed by two harvest methods (handfelled or a pushover falling technique being tested for its ability to control the spread of root disease). After 10 years, growth of both planted and natural regeneration species of varying shade tolerance tended to increase with decreasing overstory retention and associated increases in light availability. In contrast, significant survival responses to retention level were lacking except in the case of shade-intolerant western larch. Harvest method had a variable effect on regeneration survival and growth. Where significant responses did occur, they were generally attributed to harvesting effects on the characteristics of planting microsites rather than root disease spread. Natural regeneration densities at the ICHmw2 site were high at all retention levels, whereas stocking was less consistent at the MSdk site. We concluded that moderately shade-tolerant to shade-tolerant interior spruce and western redcedar can, under conditions similar to those of our study sites, be successfully established under overstories of up to approximately 25 m2/ha basal area, but that growth performance is likely to be significantly lower than in clearcuts. Despite early survival issues, conclusions regarding Douglas-fir were similar. Poorer survival and vigour of shade-intolerant western larch suggested this species is not suitable for regeneration in partial retention systems where timber production is the primary objective. Where non-timber objectives predominate, survival and acceptable growth of even a small proportion of larch could add to the diversity of the regenerating stand. © 2010 Elsevier B.V. All rights reserved.

Boateng J.O.,British Columbia Ministry of forests | Heineman J.L.,J. Heineman Forestry Consulting | Bedford L.,British Columbia Ministry of forests | Linnell Nemec A.F.,International Statistics and Research Corporation | And 2 more authors.
New Forests | Year: 2012

We examined the effects of various mechanical site preparation methods and windrow burning on container-grown planted lodgepole pine (Pinus contorta var. latifolia) survival and growth for 20 years after treatment at a sub-boreal site in north-central British Columbia, Canada. Survival was uniformly high (≥80%) regardless of treatment, indicating that site preparation was not necessary to establish pine on this site. Significant treatment effects on height, diameter, and stem volume were present at all assessment dates, but only the windrow burning treatment was associated with growth gains over the untreated control after two decades. Pine planted at the disk trench hinge were significantly larger than control pine only until year five. Of the mechanical treatments, only coarse mixing (by bedding plow) continued to have a significant effect on pine growth for as many as 9 years after treatment. Despite the disappearance of significant differences between mechanical treatments and the untreated control by year 20, the magnitude of stand volume increases suggests the potential for mechanical site preparation to have a beneficial effect on future timber supply. Repeated measures analysis confirmed that trends in early diameter growth differed between the untreated control and the windrow burning or coarse mixing treatments. These data are also potentially valuable for verifying growth and yield or carbon budgeting modelling tools. © 2011 Springer Science+Business Media B.V.

Nemec A.F.L.,International Statistics and Research Corporation | Goudie J.W.,British Columbia Ministry of forests | Parish R.,British Columbia Ministry of forests
Canadian Journal of Forest Research | Year: 2010

The aim of this work was to model the vertical location and number of branch primordia (buds) on the leader of lodgepole pine (Pinus contorta Doug, ex Loud.) trees in central British Columbia. For species such as lodgepole pine, where branches occur in clusters rather than individually, the Gamma-Poisson model provides a natural framework for describing and simulating the distribution of buds on the annual shoot. Parameters in the model are identifiable with measurable attributes, that is, the average number of clusters per unit length of the annual shoot and the average number of buds per cluster, and can be related to explanatory variables via a log link. Applicability of the Gamma-Poisson model was demonstrated for a sample of 58 lodgepole pine trees ranging in age from 29 to 103 years old. The agreement between observed and expected cluster counts and spacing, cluster sizes, and total number of branches was good. Height to crown base and length of the annual shoot were selected as the best predictors of the number of clusters and number of buds per cluster, respectively, although other single variables were also identified as having significant predictive value.

Cruickshank M.G.,Natural Resources Canada | Jaquish B.,British Columbia Ministry of forests | Nemec A.F.L.,International Statistics and Research Corporation
Canadian Journal of Forest Research | Year: 2010

The objectives of this study were to (i) develop a methodology for screening conifer seedlings for resistance to Armillaria ostoyae (Romagn.) Herink and (ii) screen a population of interior Douglas-fir (Pseudotsuga menziesii var. glauca (Biessn.) Franco) population for resistance to A. ostoyae. Eighteen potted seedlings from each of 86 half-sib interior Douglas-fir families were challenged with inoculum in a 3-year greenhouse trial. The seed originated from four geographically distinct tree breeding zones that represent physically and biologically different environments in southeastern British Columbia. Mortality and the final percent survival of inoculated trees showed differences among the families (survival range 0%-61.1%) and breeding zones (survival range 6.6%-25.3%). Maximum heritability index (0.19) occurred at 28 months. Survival analyses revealed that most of the differences in survival could be explained by the zone from which the family originated. The less susceptible seedlings originated from the drier and warmer zones and limited the spread of the fungus in the root system. Moderate levels of family variation in resistance to A. ostoyae and low-moderate heritability suggest that, in interior Douglas-fir, gains in resistance can be achieved through breeding.

Boateng J.O.,British Columbia Ministry of forests | Heineman J.L.,J. Heineman Forestry Consulting | Bedford L.,British Columbia Ministry of forests | Nemec A.F.L.,International Statistics and Research Corporation
Scandinavian Journal of Forest Research | Year: 2010

This study examined mechanical site preparation and windrow burning effects on soil properties and lodgepole pine (Pinus contorta var. latifolia) foliar nutrients on a sub-boreal site in northcentral British Columbia, Canada. After two decades, there were no adverse long-term effects on soil bulk density. Rather, bulk densities to 20 cm depth declined continuously in all treatments including the control. Coarse mixing was associated with lasting increases in organic matter-related properties [total carbon (C) and nitrogen (N), ammonium-N, C/N] compared with the control, whereas plow-inverting, disk trenching, fine mixing and windrow burning had no lasting effects on these attributes. In contrast, windrow burning caused persistent increases in pH and related properties (cation exchange capacity, exchangeable calcium and potassium) relative to the control. Mechanical treatments had more short-lived effects on these properties, with the exception that coarse mixing caused significant 20-year reductions in pH relative to the control. There were slight deficiencies of foliar N, sulfur (S) and boron according to published thresholds. None of the treatments affected foliar N, and the effects on total S and sulfate-S were highly variable and not statistically significant. Boron deficiency in the control and mechanical treatments worsened between years 10 and 20, whereas levels on burned windrows were continuously high. © 2010 Taylor & Francis.

Derekas A.,Hungarian Academy of Sciences | Derekas A.,Eötvös Loránd University | Derekas A.,University of Sydney | Szabo G.M.,Hungarian Academy of Sciences | And 14 more authors.
Monthly Notices of the Royal Astronomical Society | Year: 2012

We present a detailed period analysis of the bright Cepheid-type variable star V1154 Cygni (V1154 Cyg; V = 9.1mag, P ≈ 4.9d) based on almost 600d of continuous observations by the Kepler space telescope. The data reveal significant cycle-to-cycle fluctuations in the pulsation period, indicating that classical Cepheids may not be as accurate astrophysical clocks as commonly believed: regardless of the specific points used to determine the O - C values, the cycle lengths show a scatter of 0.015-0.02d over 120 cycles covered by the observations. A very slight correlation between the individual Fourier parameters and the O - C values was found, suggesting that the O - C variations might be due to the instability of the light-curve shape. Random-fluctuation tests revealed a linear trend up to a cycle difference 15, but for long term, the period remains around the mean value. We compare the measurements with simulated light curves that were constructed to mimic V1154 Cyg as a perfect pulsator modulated only by the light travel time effect caused by low-mass companions. We show that the observed period jitter in V1154 Cyg represents a serious limitation in the search for binary companions. While the Kepler data are accurate enough to allow the detection of planetary bodies in close orbits around a Cepheid, the astrophysical noise can easily hide the signal of the light-time effect. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

Newsome T.A.,Borland | Heineman J.L.,J. Heineman Forestry Consulting | Nemec A.F.L.,International Statistics and Research Corporation
Forest Ecology and Management | Year: 2010

We used manual cutting to manipulate trembling aspen (Populus tremuloides Michx.) density and spatial arrangement in relation to crop lodgepole pine (Pinus contorta Dougl. Ex Loud. var. latifolia Engelm.) on two sites in contrasting dry, cool to cold ecosystems of south-central British Columbia. In the dry, cool interior Douglas-fir ecosystem (IDFdk3), we reduced the density of tall aspen (aspen at least as tall as target pine) to 0 (broadcast removal), 1000, 2500, or 4000 stems/ha when the planted lodgepole pine was 6 years old. Eight years later, pine height/diameter ratio (HDR) was significantly lower in the broadcast removal and 1000 stem/ha treatments than in the control. There were no other significant growth responses and pine survival and vigour were good regardless of treatment. In contrast, in a dry, cold sub-boreal pine spruce ecosystem (SBPSxc) where treatments were applied at a stand age of 11 years, naturally regenerated lodgepole pine stem diameter increased significantly in the broadcast removal treatment relative to the untreated control within 2 years. After 4 years, HDR had declined significantly relative to the control where tall aspen density was ≤1000 stems/ha. There were no significant pine responses where 2500 tall aspen stems/ha were retained or where tall aspen were removed only within a 1-m radius around pine. The greater difference in height (height differential) between aspen and pine at the SBPSxc than the IDFdk3 site may partly explain the differing response of lodgepole pine to treatment. Trends of decreasing sucker density with increasing aspen retention were evident at both sites, but differences were significant (p ≤ 0.05) only at the SBPSxc site. We also used regression analysis to compare the ability of tall aspen density and three competition indices to predict lodgepole pine size when stands were 14-15 years old. Tall aspen density predicted a maximum of 26% of the variation in pine diameter, whereas the Lorimer index, which considered both aspen density and the size differential between aspen and pine, predicted as much as 75% of diameter variation. © 2010.

Newsome T.A.,Borland | Brown K.R.,A K associates | Linnell Nemec A.F.,International Statistics and Research Corporation
Forest Ecology and Management | Year: 2016

Old-growth, high-elevation spruce-fir forests of the Quesnel Highland in south-central British Columbia provide winter habitat for threatened mountain caribou (Rangifer tarandus caribou (Gmelin)) and contain valuable wood resources. A group selection silvicultural system may protect caribou habitat and allow some timber extraction, if combined with timely regeneration and an extended rotation length. Sporadic seed production can limit natural regeneration and planting may be required to ensure successful regeneration after harvest. However, the opening sizes and planting microsites required for adequate tree growth and survival in these high-elevation sites are unknown. We examined, for 15 years following planting, how growth and survival of planted subalpine fir (Abies lasiocarpa (Hook.) Nutt.), Engelmann spruce (Picea engelmannii Parry ex. Engelm.), and lodgepole pine (Pinus contorta Dougl. Ex Loud.) varied with harvest opening size (0.03, 0.13, 1.0 ha), planting microsite (raised, protected, rotten wood, scarified, and a control) and elevation. Survival and growth was less in the higher elevation sites and generally increased with opening size, with the increase greater in the lower elevation sites. Survival varied from 12% for lodgepole pine in small openings at higher elevation to 82% for fir in large openings at lower elevation. Overall, fir had the greatest survival. Fir growth increased the most with opening size at higher elevation; pine growth increased the most with opening size at lower elevation. Survival was generally greater on raised, protected, or rotten wood microsites. Growth varied less across microsites than did survival and also varied less across microsites than across opening sizes or elevations. Increased seedling growth and survival for all species was associated with treatments that had earlier snowmelt and higher soil temperatures. Two cycle budworm (Chroistoneura biennis Freeman) decreased seedling growth in years of heavy infestation. In higher elevation sites, pine had the greatest average height, but relatively low survival and vigor. The poor survival of pine, its lower long-term projected growth rates, and a crown structure which does not facilitate lichen accumulation and its accessibility to caribou, make pine unsuitable for regenerating these forests managed for mountain caribou. Using the group selection silvicultural system on appropriate sites with openings greater than 0.13 ha and with optimal planting microsites should allow for some extraction of timber while maintaining the old-growth attributes needed for caribou habitat in these subalpine forests. © 2016.

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