Field efficiency and bias of snag inventory methods

2005 ◽  
Vol 35 (12) ◽  
pp. 2900-2910 ◽  
Author(s):  
Robert S Kenning ◽  
Mark J Ducey ◽  
John C Brissette ◽  
Jeffrey H Gove
Keyword(s):  
Sampling Method ◽  
Distance Sampling ◽  
Hardwood Forests ◽  
Horizontal Line ◽  
Forest Types ◽  
Time Saving ◽  
Tree Distance ◽  
Area Sampling ◽  
Fixed Area ◽  
Field Efficiency

Snags and cavity trees are important components of forests, but can be difficult to inventory precisely and are not always included in inventories because of limited resources. We tested the application of N-tree distance sampling as a time-saving snag sampling method and compared N-tree distance sampling to fixed-area sampling and modified horizontal line sampling in mixed pine-hardwood forests of southern Maine and New Hampshire. We also present a novel modification of N-tree distance sampling that limits the distance from plot center that an observer must search to find tally trees. A field test shows N-tree to be quick, but generally biased and characterized by high variability. Distance-limited N-tree sampling mitigates these problems, but not completely. We give recommendations for operational snag inventory in similar forest types.

Comparing N-Tree Distance Sampling with Point and Plot Sampling in Northern Michigan Forest Types

1994 ◽  
Vol 11 (1) ◽  
pp. 12-16 ◽  
Author(s):  
Veronica Lessard ◽  
David D. Reed ◽  
Nicholas Monkevich
Keyword(s):  
Distance Sampling ◽  
Basal Area ◽  
Forest Types ◽  
Upper Peninsula ◽  
Northern Hardwood ◽  
Tree Distance ◽  
Plot Sampling ◽  
Fixed Radius ◽  
Practical Demonstration ◽  
Northern Michigan

Abstract This study demonstrates the utility of n-tree distance sampling as an alternative to the more common point and plot sampling. This practical demonstration was conducted in Michigan's Upper Peninsula in three forest types: northern hardwood stands, plantation red pine stands, and clumped, mixed hardwood stands. Seven types of field sampling techniques were used: 1/5 ac and 1/10 ac fixed radius plot sampling, BAF 10 and BAF 20 variable radius point sampling, and n-tree distance sampling of 3, 5, and 7 trees. Estimates of mean board foot volume, cords, basal area, and number of trees per acre produced by n-tree distance sampling are biased, but when a bias correction factor is applied to the northern hardwood estimates, the results are equivalent to estimates from point and plot sampling. Investigation of bias in the plantation and clumped forests is ongoing. N-tree distance sampling is cost-competitive with the more traditional point and plot northern hardwoods. North. J. Appl. For. 11(1):12-16.

Comparison of three sampling methods in the characterizationof cork oak stands for management purposes

2005 ◽  
Vol 35 (10) ◽  
pp. 2295-2303 ◽  
Author(s):  
Maria João Paulo ◽  
Margarida Tomé ◽  
Albert Otten ◽  
Alfred Stein
Keyword(s):  
Sampling Method ◽  
Sampling Methods ◽  
Distance Sampling ◽  
Quercus Suber ◽  
Sampling Procedure ◽  
Cork Oak ◽  
Tree Distance ◽  
Plot Sampling ◽  
Fixed Radius ◽  
Evergreen Oak

The cork oak (Quercus suber L.) is an evergreen oak that has the ability to produce a continuous layer of cork tissue which regenerates after being removed. Cork oak stands can be diverse in structure. Young stands are often regularly spaced, whereas older stands usually show clustering and can be mixed with other species. Farmers assessing cork value use a zigzag sampling procedure within a stand. In this study we compare zigzag sampling with two other sampling methods, fixed-radius plot sampling and n-tree distance sampling, using a model for the costs of sampling. We used data from two cork oak stands in Portugal as well as data from six types of simulated stands. We found that zigzag is the poorest sampling method, as in most situations it produces estimators with larger bias and larger standard errors than that produced by the other two procedures. Fixed-radius plot sampling and n-tree distance sampling produce comparable results; however, fixed-radius plot sampling is preferred because it produces unbiased estimators.

scholarly journals Analisis Hubungan Kelimpahan Plankton di Permukaan Terhadap Hasil Tangkapan Ikan Lemuru (Sardinella lemuru) di Selat Bali

2017 ◽  
Vol 4 (1) ◽  
pp. 151
Author(s):  
Hasanuddin Parulian Sihombing ◽  
I Gede Hendrawan ◽  
Yulianto Suteja
Keyword(s):  
Sampling Method ◽  
Strong Relationship ◽  
Zooplankton Abundance ◽  
Sampling Point ◽  
Water Sampling ◽  
Phytoplankton Abundance ◽  
Fish Food ◽  
Area Sampling ◽  
The Relationship

Lemuru fish is one of fishery commodity that has high economical value and one of fish that most catched by fisherman in Bali Strait. Lemuru fish had been caught in Bali Strait was fluctuating every month and every years. This condition was related with food source of Lemuru fish such as phytoplankton and zooplankton. So this research was conducted to explained the relationship phytoplankton and zooplankton abundance with Lemuru fish catched  in Bali strait. This study focus in Bali strait during March until May 2017. Determination of sampling point used area sampling method while water sampling occured in surface water with pouring method. Total of phytoplankton and zooplankton abundance in Bali strait in March until May had formed the sinusoidal model with their abundance ranged 301 ind/L – 604 ind/L and 7 ind/L – 12 ind/L. Plankton abundance in Bali strait in March until May (transisonal season 1) was categorized low abundance if compared with plankton abundance in another season. The low value of phytoplankton abundance caused by non upwelling phenomenon and grazing process and the low abundance of zooplankton caused by low rate of zooplankton and predation by Lemuru fish. Phytoplankton and zooplankton abundance had  strong relationship with Lemuru fish catched with correlation coefficient value 0.76 and 0.69. This condition caused by phytoplankton and zooplankton are source of Lemuru fish food.

scholarly journals Estimating brown bear abundance and harvest rate on the southern Alaska Peninsula

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245367
Author(s):  
Earl F. Becker ◽  
David W. Crowley
Keyword(s):  
Sampling Method ◽  
Distance Sampling ◽  
Brown Bear ◽  
Aerial Survey ◽  
Abundance Estimation ◽  
Game Management ◽  
Geographic Scale ◽  
Detection Function ◽  
Harvest Rate ◽  
Harvest Data

Abundance estimation of hunted brown bear populations should occur on the same geographic scale as harvest data analyses for estimation of harvest rate. Estimated harvest rates are an important statistic for managing hunted bear populations. In Alaska, harvest data is collected over large geographic units, called Game Management Units (GMUs) and sub-GMUs. These sub GMUs often exceed 10,000 km2. In the spring of 2002, we conducted an aerial survey of GMU 9D (12,600 km2) and GMU 10 (4,070 km2) using distance sampling with mark-resight data. We used a mark-resight distance sampling method with a two-piece normal detection function to estimate brown bear abundance as 1,682.9 (SE = 174.29) and 316.9 (SE = 48.25) for GMU 9D and GMU 10, respectively. We used reported hunter harvest to estimate harvest rates of 4.35% (SE = 0.45%) and 3.06% (SE = 0.47%) for GMU 9D and GMU 10, respectively. Management objective for these units support sustained, high quality hunting opportunity which harvest data indicate are met with an annual harvest rate of approximately 5–6% or less.

scholarly journals Estimating red deer abundance using the pellet-based distance sampling method

2016 ◽  
Vol 61 (No. 10) ◽  
pp. 422-430 ◽  
Author(s):  
Torres RT ◽  
Valente AM ◽  
Marques TA ◽  
C. Fonseca
Keyword(s):  
Sampling Method ◽  
Red Deer ◽  
Distance Sampling

The Impact of Celebrity Expertise on Advertising Effectiveness: The Mediating Role of Celebrity Brand Fit

2017 ◽  
Vol 21 (4) ◽  
pp. 367-374 ◽  
Author(s):  
Tijo Thomas ◽  
Johney Johnson
Keyword(s):  
Path Analysis ◽  
Significant Influence ◽  
Purchase Intention ◽  
Sampling Method ◽  
Advertising Effectiveness ◽  
Effectiveness Research ◽  
Mediating Role ◽  
Area Sampling ◽  
The Impact

The studies in the field of marketing have shown that characteristics of the source will influence persuasiveness of the advertisement. This study evaluates the effect of celebrity expertise on advertising effectiveness. Research participants ( N = 109) were selected based on area sampling method. The respondents completed a questionnaire that measured the respondent’s perception of celebrity’s expertise, celebrity brand fit, attitude towards advertisement, attitude towards brand and purchase intention. Path analysis was used to evaluate the hypothesis. The study found that celebrity expertise has got a very significant influence on purchase intention indicating that the practitioner should focus on celebrity’s field of expertise before deciding on the endorsement. The study also found that influence of celebrity brand fit on purchase intention is mediated by the attitude towards advertisement and attitude towards the brand.

scholarly journals ESTIMASI KEPADATAN ULAT API MELALUI METODE SAMPLING JARAK

2018 ◽  
Vol 3 (4) ◽  
Author(s):  
Cukri Rahmi Niani
Keyword(s):  
Oil Palm ◽  
Sampling Method ◽  
Distance Sampling ◽  
Sampling Techniques ◽  
Sampling Distance ◽  
Setora Nitens

Many types of pests which is found in oil palm plantations such as rats, bees and the caterpillars. Caterpillar and the bagworm, including a caterpillar eaters leaves oil palm plantations. This Research focuses on a caterpillar type Setora nitens at oil palm plantations Karya Tanah Subur in West Aceh. Many ways that has been done to overcome pests caterpillar in oil palm plantations from early monitoring and extermination caterpillar. To know the density caterpillar can be done by counting directly individual caterpillar or with other methods that in this research, the density caterpillar in the estimation through distance sampling techniques. Distance sampling is one of the methods used to estimate the density and the spread population. The sampling distance, a series point or lines are placed randomly on the districts census and measured the distance between individuals who were detected in handcuffs or this point. Ordered Distance, Point Quarter and Variable Area Transect the distance sampling method that used in the research. Based on the explanation, an extensive microinsurance is focused on the estimation density caterpillar using the distance sampling methods.Keywords: Setora nitens, Distance Sampling, Order Distance, Point Quarter, VariableArea Transect.

scholarly journals COMPARAÇÃO ENTRE OS MÉTODOS DE AMOSTRAGEM DE BITTERLICH E DE ÁREA FIXA COM PARCELA CIRCULAR EM PLANTAÇÃO DE Pinus taeda

FLORESTA ◽  
2010 ◽  
Vol 40 (4) ◽  
Author(s):  
João Paulo Druszcz ◽  
Nelson Yoshihiro Nakajima ◽  
Sylvio Péllico Netto ◽  
Mauro Yoshitani Júnior
Keyword(s):  
Pinus Taeda ◽  
Sampling Method ◽  
Sampling Methods ◽  
Basal Area ◽  
Plot Sampling ◽  
Fixed Area ◽  
Plot Area ◽  
The Mean ◽  
Pinus Taeda L

Este estudo objetivou comparar o método de amostragem de Bitterlich e o de área fixa com Parcela Circular. Estes dois métodos foram avaliados quanto à precisão e eficiência na estimativa das variáveis DAP médio, número de árvores, área basal e volume total, por hectare. Foram selecionadas três condições de plantios de Pinus taeda, localizados na fazenda Boa Vista, no município de Carambeí – PR. Na análise simultânea das três condições para as estimativas das variáveis DAP médio e número de árvores, por hectare, o método de amostragem de área fixa com Parcela Circular foi o mais preciso e eficiente. Já para a análise de área basal e volume total, por hectare, o método de amostragem de Bitterlich foi o mais preciso e eficiente. Conclui-se que o método de área fixa com Parcela Circular foi mais preciso e eficiente para a estimativa das variáveis DAP médio e número de árvores, já que se trata de um método no qual a seleção dos indivíduos é proporcional à área da parcela. O método de Bitterlich, por ser um método que faz a seleção dos indivíduos com probabilidade à área basal, foi mais preciso e eficiente para a estimativa das variáveis área basal e volume total.Palavras-chave: Método de amostragem; precisão e eficiência; Pinus taeda. AbstractComparison between Bitterlich and fixed area circular plot sampling methods in Pinus taeda L plantation. This study aimed to compare the Bitterlich sampling method to the fixed area circular plot. These two methods were evaluated with respect to the accuracy and efficiency for estimating the variables mean DBH, number of trees, basal area and total volume per hectare. Three conditions for Pinus taeda plantations were selected. They were located in Boa Vista farm, Carambeí County, State of Paraná. Results showed that the fixed area circular plot was more efficient and accurate to estimate the mean DBH and the number of trees per hectare because it is a method where the trees selection is proportional to the plot area, whereas the Bitterlich method was more efficient and accurate to estimate the basal area and the total volume per hectare because the trees selection is related to the basal area.Keywords: Sampling methods; accuracy and efficiency; Pinus taeda.

Comparaison de plusieurs types d'unités d'échantillonnage dans la perspective d'un inventaire forestier régional

1994 ◽  
Vol 70 (3) ◽  
pp. 304-310 ◽  
Author(s):  
H. Lecomte ◽  
J. Hébert ◽  
J. Rondeux
Keyword(s):  
Forest Inventory ◽  
Basal Area ◽  
Ease Of Use ◽  
Rectangular Grid ◽  
Area Sampling ◽  
Different Types ◽  
Minimum Number ◽  
Fixed Area ◽  
Concentric Circles ◽  
Regional Forest

This study has been conducted in order to define the guidelines of a permanent forest inventory methodology that could be applied to heterogenous forests located in the southern part of Belgium. Different types of sampling units generally used in European national inventories have been compared: fixed area sampling units (based upon 3 concentric circles), non fixed-area sampling units (Bitterlich plots using basal area factor of 2 and 4) and sampling units based upon a minimum number of trees (including nearly 15 measurable trees). In true conditions of application 259 sampling points have been selected according to a systematic rectangular grid (1.000 m × 500 m).Taking into account different criteria such as precision, cost and ease of use, the fixed-area sampling unit looks like the most adequate among the four types investigated. Key words: regional forest inventory, sampling units.

What factors affect the density of cane toads (Rhinella marina) in the Solomon Islands?

2015 ◽  
Vol 21 (3) ◽  
pp. 200 ◽  
Author(s):  
Patrick Pikacha ◽  
Tyrone Lavery ◽  
Luke K.-P. Leung
Keyword(s):  
Solomon Islands ◽  
Distance Sampling ◽  
Information Criterion ◽  
Forest Types ◽  
Coastal Forests ◽  
Cane Toad ◽  
Breeding Sites ◽  
Rhinella Marina ◽  
Disturbed Areas ◽  
Parsimonious Model

Cane toads (Rhinella marina) were introduced to the Solomon Islands in the 1940s, and quickly spread across the archipelago. Between May 2009 and August 2012, cane toads were recorded on 11 of 13 islands surveyed, and the densities of toads were estimated by distance sampling on seven of these islands. Modified Akaike’s Information Criterion (AICc) tests were used to find the most parsimonious model for cane toad density in the Solomon Islands. The results showed that mean toad density was higher on Gatokae and Guadalcanal than on Bougainville, Choiseul, Kolombangara and Rendova. A plausible explanation for this is that Guadalcanal had an abundance of breeding sites, and that Gatokae may have been recently colonised with a typical sharp rise in toad densities. The model also showed that mean toad density was higher in coastal forests than in other forest types (e.g lowland, hill and montane forests). Coastal forests have higher disturbance levels as a result of villages and towns. Disturbance was associated with increased toad densities in the model. These findings suggest that cane toad management efforts should target coastal forests and disturbed areas along roads and tracks leading to important biodiversity reserves.

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