Root system response of naturally regenerated Douglas-fir (Pseudotsuga menziesii) after complete overstory removal

2012 ◽  
Vol 42 (10) ◽  
pp. 1858-1864 ◽  
Author(s):  
Nathan A. Briggs ◽  
Christian Kuehne ◽  
Ulrich Kohnle ◽  
Jürgen Bauhus
Keyword(s):  
Pseudotsuga Menziesii ◽  
Root Elongation ◽  
Small Sample Size ◽  
Root Systems ◽  
Douglas Fir ◽  
Small Sample ◽  
System Response ◽  
Radial Increment ◽  
Advance Regeneration ◽  
Closed Canopy

Long regeneration periods, which result in two-layered or multilayered forest stands, are an important element of the close-to-nature forest management paradigm in central Europe. Such extended regeneration periods, however, may lead to undesirable development of advance regeneration, specifically in species such as Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) where root growth is strongly curtailed under competition. We hypothesized that root systems of naturally regenerated Douglas-fir that had grown under closed canopy for prolonged periods would be inhibited in their capacity to develop adequate structural root systems following release through removal of the canopy. Complete root systems of six approximately 25-year-old Douglas-fir that had grown for at least 12 years underneath a closed canopy before overstory removal were excavated using subterranean explosives. Root elongation, radial increment of primary lateral and vertical roots, and aboveground stem growth were investigated using retrospective analysis of growth rings. Structural roots of the previously suppressed Douglas-fir were capable of strongly responding to release from competition relative to growth prior to removal, but this response, particularly in the form of root elongation, was delayed. However, since the growth response of roots was not stronger than that above ground, an imbalanced root to shoot ratio, likely developed in trees when grown under the canopy, was not reverted. Generalizing interpretation of the derived findings of this study is limited because of the small sample size and the lack of freely grown control trees. Whether or not previously suppressed trees can develop the same physical stability as open-grown individuals therefore deserves further investigation.

CHARACTERISTICS OF DOUGLAS-FIR ROOT SYSTEMS

1963 ◽  
Vol 41 (1) ◽  
pp. 105-122 ◽  
Author(s):  
R. G. McMinn
Keyword(s):  
Pseudotsuga Menziesii ◽  
Root Systems ◽  
Douglas Fir ◽  
Forest Pathology ◽  
Rooting Density

The root systems of 28 Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) in four stands, aged 10, 25, 40, and 55 years, were excavated hydraulically to determine the rooting characteristics of trees in different crown classes at various ages. The extent, depth, configuration, rooting density, and mycorrhizal component of root systems were examined. The significance of the characteristics observed is discussed in relation to silviculture, nursery practice, and forest pathology.

Patterns of above- and below-ground response of understory conifer release 6 years after partial cutting

2002 ◽  
Vol 32 (2) ◽  
pp. 255-265 ◽  
Author(s):  
Daniel D Kneeshaw ◽  
Harry Williams ◽  
Eero Nikinmaa ◽  
Christian Messier
Keyword(s):  
Root Growth ◽  
Height Growth ◽  
Douglas Fir ◽  
Stem Growth ◽  
Radial Increment ◽  
Growth Responses ◽  
Partial Cutting ◽  
Size Classes ◽  
Clear Cutting ◽  
Advance Regeneration

An increased pressure to use silvicultural techniques not based on clear-cutting followed by planting has led to an interest in systems that take advantage of existing understory seedlings (advance regeneration). Earlier studies have suggested that following harvesting, understory seedlings may experience growth reductions before responding with growth increases. We hypothesize that this "growth shock" following release results because seedlings are ill adjusted to the new growing conditions and that this can be investigated through a comparison of growth in different parts of the tree over a 6-year period. This study compares the growth response of three size classes of lodgepole pine (Pinus contorta Dougl. ex Loud.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings to a partial overstory removal in relatively dry conifer forests of central British Columbia. Growth was evaluated in four parts of the studied trees: radial increment in roots, in the base of the stem, and in branches, as well as leader height growth extension. Our findings show that following release from the overstory, early growth increases were largest in the roots and stems irrespective of the species or the size class. Differences between the species were observed in greater absolute height growth for pine, whereas Douglas-fir invested in greater stem growth, especially in the larger individuals. Important differences also occurred temporally. Both species (and all size classes) responded with an immediate increase in root growth followed, after a 1-year delay, by an increase in stem growth. Branch radial increment (for pine) and leader height growth (both species), however, experienced 2 to 3 year growth reductions before responding. It is therefore suggested that individuals restore the root–shoot balance by greater initial investments to root growth to offset the increased transpiration losses associated with the greater light and higher temperature conditions and the relative changes in the photosynthetic versus nutrient uptake capacity following the canopy opening. Foresters may therefore be able to manipulate tree growth responses by using an appropriate degree of overstory removal or opening size.

Plantations vs. Advance Regeneration: Height Growth Comparisons for Southwestern Oregon

1992 ◽  
Vol 7 (2) ◽  
pp. 44-47 ◽  
Author(s):  
Ed J. Korpela ◽  
Steven D. Tesch ◽  
R. Lewis
Keyword(s):  
Species Composition ◽  
Pseudotsuga Menziesii ◽  
Height Growth ◽  
Douglas Fir ◽  
Abies Concolor ◽  
Initial Height ◽  
Advance Regeneration ◽  
White Fir ◽  
Time Required ◽  
Site Classes

Abstract Model projections of newly planted Douglas-fir (Pseudotsuga menziesii) seedlings grown under three competition regimes were compared across three site classes with growth of three height classes of Douglas-fir and white fir (Abies concolor) advance regeneration for 20 years following overstory removal. Plantations growing without competition were projected to grow about as fast as advance regeneration on the best sites and slower on the poorer sites. However, over the 20-year period, the projected height of planted trees exceeded only that of released small white fir. Competing vegetation reduced projected plantation growth, thus increasing the height advantage of advance regeneration over planted trees after 20 years. Comparisons such as these are influenced by the time required to establish new plantations, competition faced by released and planted trees, and the species composition, vigor, and initial height of the advance regeneration. These results suggest that managing advance regeneration may be a viable reforestation alternative in southwestern Oregon, particularly on poorer sites. West. J. Appl. For. 7(2):44-47

Probing the ultrastructure of the mitotic and meiotic spindle in eggs: An expeditious approach based on semi-thin (0.25 μm) serial sections

1983 ◽  
Vol 41 ◽  
pp. 552-555
Author(s):  
Conly L. Rieder ◽  
S. Bowser ◽  
R. Nowogrodzki ◽  
K. Ross ◽  
G. Sluder
Keyword(s):  
Small Sample Size ◽  
Small Sample ◽  
Meiotic Spindle ◽  
Serial Sections ◽  
Mitotic Apparatus ◽  
Thin Sections ◽  
Cell Cycles ◽  
Ultrastructural Studies

Eggs have long been a favorite material for studying the mechanism of karyokinesis in-vivo and in-vitro. They can be obtained in great numbers and, when fertilized, divide synchronously over many cell cycles. However, they are not considered to be a practical system for ultrastructural studies on the mitotic apparatus (MA) for several reasons, the most obvious of which is that sectioning them is a formidable task: over 1000 ultra-thin sections need to be cut from a single 80-100 μm diameter egg and of these sections only a small percentage will contain the area or structure of interest. Thus it is difficult and time consuming to obtain reliable ultrastructural data concerning the MA of eggs; and when it is obtained it is necessarily based on a small sample size.We have recently developed a procedure which will facilitate many studies concerned with the ultrastructure of the MA in eggs. It is based on the availability of biological HVEM's and on the observation that 0.25 μm thick serial sections can be screened at high resolution for content (after mounting on slot grids and staining with uranyl and lead) by phase contrast light microscopy (LM; Figs 1-2).

Validating the Factor Structure of the Stigma of Suicide Scale–Short Form Spanish Version Among Healthcare Students

Crisis ◽  
2020 ◽  
pp. 1-5
Author(s):  
Ruthmarie Hernández-Torres ◽  
Paola Carminelli-Corretjer ◽  
Nelmit Tollinchi-Natali ◽  
Ernesto Rosario-Hernández ◽  
Yovanska Duarté-Vélez ◽  
...  
Keyword(s):  
Factor Structure ◽  
Structural Equation ◽  
Short Form ◽  
Small Sample Size ◽  
Small Sample ◽  
Spanish Version ◽  
Equation Modeling ◽  
Cross Sectional ◽  
Healthcare Students ◽  
Spanish Speaking

Abstract. Background: Suicide is a leading cause of death among Spanish-speaking individuals. Suicide stigma can be a risk factor for suicide. A widely used measure is the Stigma of Suicide Scale-Short Form (SOSS-SF; Batterham, Calear, & Christensen, 2013 ). Although the SOSS-SF has established psychometric properties and factor structure in other languages and cultural contexts, no evidence is available from Spanish-speaking populations. Aim: This study aims to validate a Spanish translation of the SOSS-SF among a sample of Spanish-speaking healthcare students ( N = 277). Method: We implemented a cross-sectional design with quantitative techniques. Results: Following a structural equation modeling approach, a confirmatory factor analysis (CFA) supported the three-factor model proposed by Batterham and colleagues (2013) . Limitations: The study was limited by the small sample size and recruitment by availability. Conclusion: Findings suggest that the Spanish version of the SOSS-SF is a valid and reliable tool with which to examine suicide stigma among Spanish-speaking populations.

An Initial Investigation of Suicide Attempt Disclosures Among US Veterans

Crisis ◽  
2020 ◽  
pp. 1-7
Author(s):  
Brooke A. Ammerman ◽  
Sarah P. Carter ◽  
Heather M. Gebhardt ◽  
Jonathan Buchholz ◽  
Mark A. Reger
Keyword(s):  
Suicide Attempt ◽  
Mental Health Professionals ◽  
Help Seeking ◽  
Psychiatric Treatment ◽  
Small Sample Size ◽  
Romantic Partners ◽  
Small Sample ◽  
Professional Care ◽  
Patient Disclosure ◽  
Previous Suicide Attempt

Abstract. Background: Patient disclosure of prior suicidal behaviors is critical for effectively managing suicide risk; however, many attempts go undisclosed. Aims: The current study explored how responses following a suicide attempt disclosure may relate to help-seeking outcomes. Method: Participants included 37 veterans with a previous suicide attempt receiving inpatient psychiatric treatment. Veterans reported on their most and least helpful experiences disclosing their suicide attempt to others. Results: Veterans disclosed their suicide attempt to approximately eight individuals. Mental health professionals were the most cited recipient of their most helpful disclosure; romantic partners were the most common recipient of their least helpful disclosures. Positive reactions within the context of the least helpful disclosure experience were positively associated with a sense of connection with the disclosure recipient. Positive reactions within the most helpful disclosure experience were positively associated with the likelihood of future disclosure. No reactions were associated with having sought professional care or likelihood of seeking professional care. Limitations: The results are considered preliminary due to the small sample size. Conclusion: Findings suggest that while positive reactions may influence suicide attempt disclosure experiences broadly, additional research is needed to clarify factors that drive the decision to disclose a suicide attempt to a professional.

Investigating the Dynamics of Suicidal Ideation

Crisis ◽  
2018 ◽  
Vol 39 (1) ◽  
pp. 65-69 ◽  
Author(s):  
Nina Hallensleben ◽  
Lena Spangenberg ◽  
Thomas Forkmann ◽  
Dajana Rath ◽  
Ulrich Hegerl ◽  
...  
Keyword(s):  
Suicidal Ideation ◽  
Small Sample Size ◽  
Unipolar Depression ◽  
Small Sample ◽  
History Of ◽  
Severity Of Depression ◽  
Ecological Momentary ◽  
Depressive Episodes ◽  
Ema Method ◽  
Shed Light

Abstract. Background: Although the fluctuating nature of suicidal ideation (SI) has been described previously, longitudinal studies investigating the dynamics of SI are scarce. Aim: To demonstrate the fluctuation of SI across 6 days and up to 60 measurement points using smartphone-based ecological momentary assessments (EMA). Method: Twenty inpatients with unipolar depression and current and/or lifetime suicidal ideation rated their momentary SI 10 times per day over a 6-day period. Mean squared successive difference (MSSD) was calculated as a measure of variability. Correlations of MSSD with severity of depression, number of previous depressive episodes, and history of suicidal behavior were examined. Results: Individual trajectories of SI are shown to illustrate fluctuation. MSSD values ranged from 0.2 to 21.7. No significant correlations of MSSD with several clinical parameters were found, but there are hints of associations between fluctuation of SI and severity of depression and suicidality. Limitations: Main limitation of this study is the small sample size leading to low power and probably missing potential effects. Further research with larger samples is necessary to shed light on the dynamics of SI. Conclusion: The results illustrate the dynamic nature and the diversity of trajectories of SI across 6 days in psychiatric inpatients with unipolar depression. Prediction of the fluctuation of SI might be of high clinical relevance. Further research using EMA and sophisticated analyses with larger samples is necessary to shed light on the dynamics of SI.

Participant Reactions to Suicide-Focused Research

Crisis ◽  
2020 ◽  
Vol 41 (5) ◽  
pp. 367-374
Author(s):  
Sarah P. Carter ◽  
Brooke A. Ammerman ◽  
Heather M. Gebhardt ◽  
Jonathan Buchholz ◽  
Mark A. Reger
Keyword(s):  
Medical Records ◽  
Research Study ◽  
Small Sample Size ◽  
Psychiatric Inpatient ◽  
Small Sample ◽  
Inpatient Unit ◽  
Online Laboratory ◽  
Psychiatric Inpatient Unit ◽  
Before And After ◽  
Participant Reactions

Abstract. Background: Concerns exist regarding the perceived risks of conducting suicide-focused research among an acutely distressed population. Aims: The current study assessed changes in participant distress before and after participation in a suicide-focused research study conducted on a psychiatric inpatient unit. Method: Participants included 37 veterans who were receiving treatment on a psychiatric inpatient unit and completed a survey-based research study focused on suicide-related behaviors and experiences. Results: Participants reported no significant changes in self-reported distress. The majority of participants reported unchanged or decreased distress. Reviews of electronic medical records revealed no behavioral dysregulation and minimal use of as-needed medications or changes in mood following participation. Limitations: The study's small sample size and veteran population may limit generalizability. Conclusion: Findings add to research conducted across a variety of settings (i.e., outpatient, online, laboratory), indicating that participating in suicide-focused research is not significantly associated with increased distress or suicide risk.

Measurements method of the audio recordings acoustic quality indicator prepared for registration and processing in the Unified Biometric System

2019 ◽  
pp. 40-46 ◽  
Author(s):  
V.V. Savchenko ◽  
A.V. Savchenko
Keyword(s):  
Quality Control ◽  
Small Sample Size ◽  
Personal Data ◽  
Digital Processing ◽  
Small Sample ◽  
Practical Implementation ◽  
Acoustic Measurements ◽  
Pitch Frequency ◽  
Wide Range ◽  
Automated Quality Control

We consider the task of automated quality control of sound recordings containing voice samples of individuals. It is shown that in this task the most acute is the small sample size. In order to overcome this problem, we propose the novel method of acoustic measurements based on relative stability of the pitch frequency within a voice sample of short duration. An example of its practical implementation using aninter-periodic accumulation of a speech signal is considered. An experimental study with specially developed software provides statistical estimates of the effectiveness of the proposed method in noisy environments. It is shown that this method rejects the audio recording as unsuitable for a voice biometric identification with a probability of 0,95 or more for a signal to noise ratio below 15 dB. The obtained results are intended for use in the development of new and modifying existing systems of collecting and automated quality control of biometric personal data. The article is intended for a wide range of specialists in the field of acoustic measurements and digital processing of speech signals, as well as for practitioners who organize the work of authorized organizations in preparing for registration samples of biometric personal data.

A randomized, double-blind, placebo-controlled study of polyunsaturated fatty acids efficacy in adolescents with anorexia nervosa

2020 ◽  
Vol 36 (2) ◽  
pp. 95-106
Author(s):  
Agnieszka M. Piróg-Balcerzak ◽  
Anna K. Bażyńska ◽  
Katarzyna Biernacka ◽  
Joanna Brągoszewska ◽  
Lidia Popek ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Anorexia Nervosa ◽  
Polyunsaturated Fatty Acids ◽  
Small Sample Size ◽  
Small Sample ◽  
Female Adolescent ◽  
Eating Attitude ◽  
Controlled Study ◽  
Omega 3 ◽  
Eat 26

Objective. Omega–3 polyunsaturated fatty acids (PUFAs) were tested in adolescent depression and in several neurodevelopmental disorders with partial success. Anorexia nervosa (AN) is characterised by deficiencies in fatty food intake and frequent comorbidity, including depressive and cognitive symptoms. Thus supplementation with PUFAs may be beneficial in this group of patients. The aim of the study was to assess whether PUFAs as an add-on treatment is associated with better improvement of body mass index (BMI) and psychopathological symptoms than placebo in patients with AN. Method. 61 female adolescent inpatients with AN were randomly allocated to omega–3 PUFAs supplementation or placebo for 10 weeks. Patients also participated in the behavioural programme and eclectic psychotherapy (treatment as usual, TAU). At baseline and follow-up visits, patients’ BMI and psychopathology were assessed with Clinical Global Impression Scale (CGI), Patient Global Impression Scale (PGI), and Eating Attitude Test (EAT-26). Results. After 10 weeks, both groups showed improvement in all parameters. Improvement in CGI scores was observed greater in placebo vs. PUFA-s group (p = 0.015) while other differences were not statistically significant. Omega–3 PUFAs supplementation appears not to be effective as an add-on treatment in inpatient adolescent girls with anorexia nervosa. Conclusions. The results should be analysed with caution due to small sample size and heterogeneity in TAU. As the TAU turned out to be highly effective, additional therapeutic effect of PUFA might not be visible. Nevertheless, that does not explain the tendency for better improvement in the placebo group.

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