Temperature-dependent rate models of vascular cambium cell mortality

2004 ◽  
Vol 34 (3) ◽  
pp. 546-559 ◽  
Author(s):  
Matthew B Dickinson ◽  
Edward A Johnson
Keyword(s):  
Cell Death ◽  
Populus Tremuloides ◽  
Pinus Contorta ◽  
Elevated Temperatures ◽  
Rocky Mountain ◽  
Process Models ◽  
Vascular Cambium ◽  
Irreversible Damage ◽  
Surface Fires ◽  
Cell Mortality

We use two rate-process models to describe cell mortality at elevated temperatures as a means of understanding vascular cambium cell death during surface fires. In the models, cell death is caused by irreversible damage to cellular molecules that occurs at rates that increase exponentially with temperature. The models differ in whether cells show cumulative effects of heating. The temperature dependencies of the models' rate parameters were estimated from cell-count data after exposing live-bark tissues from four Canadian Rocky Mountain tree species to a range of fixed temperatures in a water bath. Based on both models, lodgepole pine's (Pinus contorta Dougl. ex Loud.) growing season vascular cambium cells experienced lower mortality rates at elevated temperatures than those of aspen (Populus tremuloides Michx.), Engelmann spruce (Picea engelmannii Parry ex Engelm.), and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). Growing and dormant season differences were marginal. With reservations for lodgepole pine, both models predicted cell survival after exposures to rising and falling temperatures such as would be experienced by live tissues during fires. A simulation involving conduction heat transfer from flames and vascular cambium cell mortality suggests that differences among species in thermal tolerance are small compared with the effects of bark thickness. Although stem vascular cambium cell mortality was complete when tissues reached 60 °C during simulated surface fires, it may not be warranted to apply the 60 °C threshold to other tissues exposed to contrasting temperature regimes during fires.

scholarly journals Tree Growth Response Along Seismic Lines in Alberta

1986 ◽  
Vol 62 (1) ◽  
pp. 29-34 ◽  
Author(s):  
I. E. Bella
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Pinus Contorta ◽  
Forest Cover ◽  
Black Spruce ◽  
Rocky Mountain ◽  
Radial Increment ◽  
Growth Data ◽  
Breast Height ◽  
Seismic Lines

Stem growth data from breast height were collected from about 2000 trees on 192 sample transects (plots) located adjacent to seismic lines. Sampled stands represented the most important forest cover types between 10 and 100 years of age over a range of site conditions in the foothills of western Albetra from Rocky Mountain House to Grande Prairie. Line clearing stimulated breast height radial increment fairly consistently in the 20% range of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.), white spruce (Picea glauca (Moench) Voss), and black spruce (Picea mariana (Mill.) B.S.P.) trees. This improvement expressed in terms of stand growth, however, fell far short of that required to make up for the loss of wood production over these lines if the cut trees are not utilized. The lack of significant stimulation from line clearing in aspen (Populus tremuloides Michx.) stands indicates a complete loss of production due to the lines.

A biophysical process model of tree mortality in surface fires

2008 ◽  
Vol 38 (7) ◽  
pp. 2013-2029 ◽  
Author(s):  
S. T. Michaletz ◽  
E. A. Johnson
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Pinus Contorta ◽  
Process Model ◽  
Tree Mortality ◽  
Mortality Data ◽  
Sapwood Area ◽  
First Order ◽  
Surface Fires ◽  
Engelmann Spruce

The mechanisms governing tree mortality in surface fires are poorly understood, owing in large part to the absence of a process-based framework for defining and evaluating these mechanisms. This paper begins the development of such a framework by deriving a first-order process model of tree mortality in surface fires (intensities less than approximately 2500 kW·m–1). A buoyant line-source plume model is used to drive heat transfer models of vascular cambium and vegetative bud necroses, which are linked to tree mortality using an allometrically-based sapwood area budget. Model predictions are illustrated for white spruce ( Picea glauca ), lodgepole pine ( Pinus contorta ), and trembling aspen ( Populus tremuloides ) and are compared with independent mortality data for Engelmann spruce ( Picea engelmannii Parry ex Engelm.) and Pinus contorta Dougl. Results help define first-order mortality mechanisms and suggest second-order mortality mechanisms that should be incorporated into future modeling efforts.

scholarly journals A Landscape Approach to Aspen Restoration: Understanding the Role of Biophysical Setting in Aspen Community Dynamics

2002 ◽  
Vol 26 ◽  
pp. 97-102
Author(s):  
Kathryn Brown ◽  
Andrew Hansen ◽  
Robert Keane ◽  
Lisa Graumlich
Keyword(s):  
Populus Tremuloides ◽  
Community Dynamics ◽  
Rocky Mountain ◽  
Small Sample ◽  
Quaking Aspen ◽  
Climatic Fluctuations ◽  
Conifer Encroachment ◽  
Considerable Debate ◽  
Fire Exclusion

Considerable debate surrounds the persistence of quaking aspen (Populus tremuloides) communities in western North America. Loss of aspen cover has been documented in several studies in various Rocky Mountain ecosystems (Loope and Gruel 1973; Romme et al. 1995; Renkin and Despain 1996; Wirth et al. 1996; Baker et al. 1997; Kay 1997; Bartos and Campbell 1998; White et al. 1998; Gallant et al. 2003). Explanations for loss of aspen include conifer encroachment, fire exclusion, herbivory, and climatic fluctuations (Loope and Gruell 1973; Mueggler 1985; Bartos et al. 1994; Romme et al. 1995; Kay 1997; White et al. 1998). However, many studies documenting aspen decline have been geographically limited or based on a small sample of subjectively chosen stands (Barnett and Stohlgren 2001; Hessl 2002; Kaye et al. 2003).

The Douglas-fir forests of Banff and Jasper National Parks, Canada

1970 ◽  
Vol 48 (10) ◽  
pp. 1703-1726 ◽  
Author(s):  
Paul W. Stringer ◽  
George H. La Roi
Keyword(s):  
National Parks ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
Pinus Contorta ◽  
Vegetation Change ◽  
Floristic Composition ◽  
Stand Age ◽  
Physical Habitat ◽  
Regression Equations ◽  
Habitat Differences

Twenty stands of uniform, mature, undisturbed Pseudotsuga menziesii var. glauca forest were selected in Banff and Jasper National Parks, using a combination of airphoto and ground surveys. Quantitative sampling methods were used to describe their floristic composition, vegetation structure, and physical habitats.Scattered trees of Pinus contorta, Picea glauca, and Populus tremuloides occurred in the Pseudotsuga forests. The poorly developed shrub strata contained Shepherdia canadensis, Rosa acicularis, Spiraea lucida, Juniperus communis. Major herb, dwarf shrub, bryophyte, and lichen species were Elymus innovatus, Calamagrostis rubescens, Fragaria virginiana, Astragalus decumbens, Aster conspicuus; Arctostaphylos uva-ursi, Linnaea borealis; Hylocomium splendens, Abietinella abietina, Tortula ruralis; Peltigera canina. A cyclical pattern of vegetation change is related to the death, replacement, and maturation of Pseudotsuga trees.Relations between vegetation and physical habitat were analyzed by simple correlation and multiple regression. Available potassium in soil, stand age, and slope exposure were most influential in regression equations for tree stratum development. Understory strata were primarily correlated with tree stratum development.A two-dimensional stand ordination based on the vegetational similarity of subordinate vascular strata showed a pronounced separation of Banff and Jasper Pseudotsuga forests, and prompted recognition of two new climax associations (sensu Daubenmire): Pseudotsuga / Elymus innovatus in Jasper; Pseudotsuga / Calamagrostis rubescens – Elymus innovatus in Banff. Habitat differences between the two associations include macroclimate, parent materials, and soil moisture.

Decadal observations of tree regeneration following fire in boreal forests

2004 ◽  
Vol 34 (2) ◽  
pp. 267-273 ◽  
Author(s):  
Jill F Johnstone ◽  
F S Chapin III ◽  
J Foote ◽  
S Kemmett ◽  
K Price ◽  
...  
Keyword(s):  
British Columbia ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
Boreal Forests ◽  
Pinus Contorta ◽  
Stand Structure ◽  
Stand Density ◽  
Tree Regeneration ◽  
Direct Observations ◽  
Highly Correlated

This paper presents data on early postfire tree regeneration. The data were obtained from repeated observations of recently burned forest stands along the Yukon – British Columbia border and in interior Alaska. Postfire measurements of tree density were made periodically for 20–30 years, providing direct observations of early establishment patterns in boreal forest. Recruitment rates of the dominant tree species in both study areas were highest in the first 5 years after fire, and additional net establishment was not observed after 10 years. The postfire population of spruce (Picea mariana (Mill.) BSP and Picea glauca (Moench) Voss s.l.) remained constant after the first decade in the two study areas. Populations of aspen (Populus tremuloides Michx.) and lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) both declined after 10 years in mixed-species stands along the Yukon – British Columbia border. Mortality rates of aspen and pine were positively correlated with their initial densities, indicating that thinning occurred as a density-dependent process. At all sites, measurements of stand density and composition made early were highly correlated with those made late in the monitoring period, indicating that patterns of stand structure initiated within a few years after fire are maintained through subsequent decades of stand development.

scholarly journals The Antifungal Action Mode of N-Phenacyldibromobenzimidazoles

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5463
Author(s):  
Monika Staniszewska ◽  
Łukasz Kuryk ◽  
Aleksander Gryciuk ◽  
Joanna Kawalec ◽  
Marta Rogalska ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Wall ◽  
Cell Membrane ◽  
Chitinolytic Activity ◽  
Irreversible Damage ◽  
Fungal Cell ◽  
Action Mode ◽  
Structure Activity ◽  
Dependent Inhibition ◽  
Antifungal Action

Our study aimed to characterise the action mode of N-phenacyldibromobenzimidazoles against C. albicans and C. neoformans. Firstly, we selected the non-cytotoxic most active benzimidazoles based on the structure–activity relationships showing that the group of 5,6-dibromobenzimidazole derivatives are less active against C. albicans vs. 4,6-dibromobenzimidazole analogues (5e–f and 5h). The substitution of chlorine atoms to the benzene ring of the N-phenacyl substituent extended the anti-C. albicans action (5e with 2,4-Cl2 or 5f with 3,4-Cl2). The excellent results for N-phenacyldibromobenzimidazole 5h against the C. albicans reference and clinical isolate showed IC50 = 8 µg/mL and %I = 100 ± 3, respectively. Compound 5h was fungicidal against the C. neoformans isolate. Compound 5h at 160–4 µg/mL caused irreversible damage of the fungal cell membrane and accidental cell death (ACD). We reported on chitinolytic activity of 5h, in accordance with the patterns observed for the following substrates: 4-nitrophenyl-N-acetyl-β-d-glucosaminide and 4-nitrophenyl-β-d-N,N′,N″-triacetylchitothiose. Derivative 5h at 16 µg/mL: (1) it affected cell wall by inducing β-d-glucanase, (2) it caused morphological distortions and (3) osmotic instability in the C. albicans biofilm-treated. Compound 5h exerted Candida-dependent inhibition of virulence factors.

scholarly journals Cellular aspects of gonadal atrophy in P-M hybrid dysgenesis

2016 ◽  
Author(s):  
Natalia Dorogova ◽  
Elena Bolobolova ◽  
Lyudmila Zakharenko
Keyword(s):  
Cell Death ◽  
Germ Cell ◽  
Elevated Temperatures ◽  
Cell Formation ◽  
Hybrid Dysgenesis ◽  
Cell Degeneration ◽  
Early Stages ◽  
Cell Death Pathways ◽  
Gonadal Atrophy ◽  
Mitochondrial Pathology

Gonadal atrophy is the most typical and dramatic manifestation of intraspecific hybrid dysgenesis syndrome leading to sterility of Drosophila melanogaster dysgenic progeny. The P-M system of hybrid dysgenesis is primarily associated with germ cell degeneration during the early stages of Drosophila development at elevated temperatures. In the present study, we have defined the phase of germ cell death as beginning at the end of embryogenesis immediately following gonad formation. The early stages of germ cell formation in dysgenic flies showed sensitivity to developmental temperature increases at any stage of the Drosophila life cycle including the imago. Analysis of germ cell reactions to hybrid dysgenesis induction revealed significant changes in subcellular structure, especially mitochondria, prior to germ cell breakdown. The mitochondrial pathology can be the reason for the activation of cell death pathways in dysgenic germ cells and lead to gonadal atrophy.

scholarly journals Hypogeous Fungi Occurrence, Distribution and Mycorrhizal Hosts in Grand Teton National Park and John D. Rockefeller, Jr. Memorial Parkway

1990 ◽  
Vol 14 ◽  
pp. 13-14
Author(s):  
Steven Miller
Keyword(s):  
Populus Tremuloides ◽  
National Park ◽  
Pinus Contorta ◽  
Quaking Aspen ◽  
Abies Lasiocarpa ◽  
Hypogeous Fungi ◽  
Grand Teton National Park ◽  
Subalpine Fir ◽  
Field Season ◽  
Speckled Alder

The 1990 field season constituted the last of a three year study to survey the hypogeous fungi of Grand Teton National Park and the Greater Yellowstone ecosystem. The objectives were to: 1. collect and identify hypogeous fungi found in association with ectomycorrhizal tree hosts such as lodgepole pine (Pinus contorta), subalpine fir (Abies lasiocarpa), Douglas-frr (Pseudotsuga menziesii), quaking aspen (Populus tremuloides), and speckled alder (Alnus tenuifolia), and several species of willow (Salix sp.) throughout the area; and 2. to gain an initial understanding of the importance of these fungi as food for small mammals.

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