Discerning responses of down wood and understory vegetation abundance to riparian buffer width and thinning treatments: an equivalence–inequivalence approach

2009 ◽  
Vol 39 (12) ◽  
pp. 2470-2485 ◽  
Author(s):  
Paul D. Anderson ◽  
Mark A. Meleason
Keyword(s):  
Pseudotsuga Menziesii ◽  
Null Hypothesis ◽  
Structural Complexity ◽  
Riparian Buffers ◽  
Shrub Cover ◽  
Equivalence Tests ◽  
Second Growth ◽  
Point Null Hypothesis ◽  
Buffer Width ◽  
Small Wood

The combined effectiveness of thinning and riparian buffers for increasing structural complexity while maintaining riparian function in second-growth forests is not well documented. We surveyed down wood and vegetation cover along transects from stream center, through buffers ranging from <5 to 150 m width into thinned stands, patch openings, or unthinned stands of 40- to 65-year-old Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) forests in western Oregon, USA. Small-wood cover became more homogeneous among stream reaches within 5 years following thinning, primarily due to decreases for reaches having the greatest pretreatment abundance. Mean shrub cover converged, predominantly because of decreases in patch openings. Herbaceous cover increased, particularly in patch openings. Relative to unthinned stands, herbaceous cover was similar in wide buffers and increased in the narrowest buffers and in narrow buffers adjacent to patch openings. Moss cover tended to increase in thinned areas and decrease in patch openings. Both conventional point-null hypothesis tests and inequivalence tests suggested that wood and vegetation responses within buffers of ≥15 m width were insensitive to the treatments. However, inherently conservative equivalence tests infrequently inferred similarity between thinned stands or buffers and untreated stands. Difficulties defining ecologically important effect size can limit the inferential utility of equivalence–inequivalance testing.

scholarly journals With Bayesian Estimation One Can Get All That Bayes Factors Offer, and More

2019 ◽  
Author(s):  
Henk Kiers ◽  
Jorge Tendeiro
Keyword(s):  
Probability Density Function ◽  
Probability Density ◽  
Bayesian Estimation ◽  
Density Function ◽  
Null Hypothesis ◽  
Posterior Odds ◽  
Close Link ◽  
Posterior Odds Ratio ◽  
Spike And Slab Prior ◽  
Point Null Hypothesis

Null Hypothesis Bayesian Testing (NHBT) has been proposed as an alternative to Null Hypothesis Significance Testing (NHST). Whereas NHST has a close link to parameter estimation via confidence intervals, such a link of NHBT with Bayesian estimation via a posterior distribution is less straightforward, but does exist, and has recently been reiterated by Rouder, Haaf, and Vandekerckhove (2018). It hinges on a combination of a point mass probability and a probability density function as prior (denoted as the spike-and-slab prior). In the present paper it is first carefully explained how the spike-and-slab prior is defined, and how results can be derived for which proofs were not given in Rouder et al. (2018). Next, it is shown that this spike-and-slab prior can be approximated by a pure probability density function with a rectangular peak around the center towering highly above the remainder of the density function. Finally, we will indicate how this ‘hill-and-chimney’ prior may in turn be approximated by fully continuous priors. In this way it is shown that NHBT results can be approximated well by results from estimation using a strongly peaked prior, and it is noted that the estimation itself offers more than merely the posterior odds ratio on which NHBT is based. Thus, it complies with the strong APA requirement of not just mentioning testing results but also offering effect size information. It also offers a transparent perspective on the NHBT approach employing a prior with a strong peak around the chosen point null hypothesis value.

scholarly journals Dichotomous Keys for Scaling and Grading Merchantable Quality Sawlogs

2003 ◽  
Vol 18 (4) ◽  
pp. 250-258
Author(s):  
Steve Bowers
Keyword(s):  
Pseudotsuga Menziesii ◽  
Tsuga Heterophylla ◽  
Picea Sitchensis ◽  
Advisory Group ◽  
Time Scaling ◽  
Dichotomous Key ◽  
Second Growth ◽  
Group A ◽  
Length Scaling ◽  
Log Scaling

Abstract This study documented and field-tested a simplified version of the Westside Grading Guidelines as published in the Official Rules Handbook by the Northwest Log Rules Advisory Group. A four-step dichotomous key was documented and field-tested to determine merchantable vs. nonmerchantable logs. The study also documented and field-tested an individual seven-step dichotomous log grading key for evaluating second-growth Douglas-fir (Pseudotsuga menziesii), Sitka spruce (Picea sitchensis), western hemlock (Tsuga heterophylla), and grand fir (Abies grandis) as derived from the Rules For Grading Logs section of the Official Rules Handbook. Results were compared with certified scalers employed by Yamhill Log Scaling & Grading Bureau and Columbia River Log Scaling & Grading Bureau. Eighty-four individuals measured the length, scaling diameter, determined merchantability versus nonmerchantability and assigned log grade for 440 logs. Results showed participants in the study correctly measuring log length 99% of time, scaling diameters were recorded correctly at an 89% rate, and merchantability and log grade at 98 and 97%, respectively. West. J. Appl. For. 18(4):250–258.

scholarly journals Interval-Based Hypothesis Testing and Its Applications to Economics and Finance

Econometrics ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 21
Author(s):  
Jae H. Kim ◽  
Andrew P. Robinson
Keyword(s):  
Hypothesis Testing ◽  
Null Hypothesis ◽  
Medical Science ◽  
Point Of View ◽  
Economic Time Series ◽  
New Era ◽  
Null Hypothesis Testing ◽  
Point Null Hypothesis ◽  
Economic Time ◽  
Linear Restrictions

This paper presents a brief review of interval-based hypothesis testing, widely used in bio-statistics, medical science, and psychology, namely, tests for minimum-effect, equivalence, and non-inferiority. We present the methods in the contexts of a one-sample t-test and a test for linear restrictions in a regression. We present applications in testing for market efficiency, validity of asset-pricing models, and persistence of economic time series. We argue that, from the point of view of economics and finance, interval-based hypothesis testing provides more sensible inferential outcomes than those based on point-null hypothesis. We propose that interval-based tests be routinely employed in empirical research in business, as an alternative to point null hypothesis testing, especially in the new era of big data.

Manipulation of density of Pseudotsuga menziesii canopies: preliminary effects on understory vegetation

2001 ◽  
Vol 31 (9) ◽  
pp. 1513-1525 ◽  
Author(s):  
David R Thysell ◽  
Andrew B Carey
Keyword(s):  
Exotic Species ◽  
Pseudotsuga Menziesii ◽  
Native Species ◽  
Variable Density ◽  
Unintended Consequences ◽  
Managed Forest ◽  
Forest Canopies ◽  
Dead Trees ◽  
Second Growth ◽  
Closed Canopy

Managing second-growth forests to conserve biodiversity has been proposed by both foresters and conservation biologists. Management, however, can have unintended consequences, including reduction in native species diversity and increased invasion by exotic species. Our goal was to determine if inducing heterogeneity in managed forest canopies could promote a diversity of native species without contributing markedly to invasion by exotic species. We examined 1- and 3-year responses of understory plants to variable-density thinning of 55- to 65-year-old stands of Pseudotsuga menziesii (Mirb.) Franco. Our study stands had been managed either with retention of old-growth legacies (large live trees, dead trees, and fallen trees) and no thinning or with removal of legacies and twice-repeated conventional thinning. Variable-density thinning initially resulted in decreased understory cover but increased importance of 20 native species, including 2 species of trees. Two native species, however, decreased in importance, and 11 exotic species increased in importance. Within 3 years, understory cover recovered, species richness increased by >150%, only four exotic species persisted with increased importance, eight native species (including four graminoids) increased in importance, and seven native species decreased in importance. Variable-density thinning shows promise as part of holistic silvicultural systems applied across landscapes throughout stand rotations and as a technique to restore vegetative complexity to closed-canopy second-growth forests.

scholarly journals Terrestrial and Riparian Organisms, Lakes and Streams (TROLS)

2016 ◽  
Vol 92 (01) ◽  
pp. 50-52
Author(s):  
Sheena A. Spencer ◽  
Kevin Devito ◽  
Ellen Macdonald
Keyword(s):  
Water Quality ◽  
Aquatic Ecosystem ◽  
Aquatic Ecosystems ◽  
Riparian Buffers ◽  
Forest Harvest ◽  
Landscape Water ◽  
Buffer Width ◽  
Forest Managers ◽  
Buffer Effects

The Terrestrial and Riparian Organisms, Lakes and Streams Project studied the impacts of forest harvest and riparian buffers on terrestrial and aquatic ecosystems in twelve fish-bearing lakes in the boreal mixed-wood forests of Alberta. Major results are outlined based on forest harvest and buffer effects on the landscape, water quality, and the aquatic ecosystem. Results from this project suggest that forest managers should be flexible in buffer width recommendations and should consider the entire watershed when determining the effects of disturbance due to complexities in the landscape.

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