A line intersect distance sampling strategy for downed wood inventory

2008 ◽  
Vol 38 (8) ◽  
pp. 2262-2273 ◽  
Author(s):  
David L.R. Affleck
Keyword(s):  
Sampling Error ◽  
Distance Sampling ◽  
Sampling Strategy ◽  
Primary Interest ◽  
Sampling Protocol ◽  
Forest Fuels ◽  
Unbiased Estimators ◽  
Transect Sampling ◽  
Selection Protocol ◽  
Unbiased Estimates

Perpendicular distance sampling (PDS) has emerged as a compelling alternative to line intersect sampling (LIS) for the inventory of forest fuels and other downed woody materials (DWM), particularly where the aggregate volume of DWM is of primary interest. This article develops a selection protocol and design-unbiased estimators for a new probability proportional-to-volume sampling strategy, termed line intersect distance sampling (LIDS). LIDS combines the distance sampling protocol of PDS with the transect sampling protocol of LIS and provides unbiased estimates of aggregate DWM volume from counts of selected logs or log fragments. Simulations indicate that LIDS along multidirectional (e.g., Y-shaped) transects should perform similarly to PDS in terms of sampling error; however, it remains unclear how LIDS and PDS compare with LIS, especially when interest is attached to multiple DWM population parameters. It is argued that LIDS will be most useful in reducing implementation errors, particularly detection errors, relative to PDS under limited visibility field conditions.

Evaluation of line-transect sampling for estimating koala abundance in the Pine Rivers Shire, south-east Queensland

2003 ◽  
Vol 30 (2) ◽  
pp. 127 ◽  
Author(s):  
David S. Dique ◽  
Deidré L. de Villiers ◽  
Harriet J. Preece
Keyword(s):  
Confidence Interval ◽  
Distance Sampling ◽  
Line Transect ◽  
Similar Estimate ◽  
Line Transect Sampling ◽  
Detection Function ◽  
Pilot Survey ◽  
Transect Sampling ◽  
Line Transects ◽  
Urban Sites

Distance sampling using line transects has not been previously used or tested for estimating koala abundance. In July 2001, a pilot survey was conducted to compare the use of line transects with strip transects for estimating koala abundance. Both methods provided a similar estimate of density. On the basis of the results of the pilot survey, the distribution and abundance of koalas in the Pine Rivers Shire, south-east Queensland, was determined using line-transect sampling. In total, 134 lines (length 64 km) were used to sample bushland areas. Eighty-two independent koalas were sighted. Analysis of the frequency distribution of sighting distances using the software program DISTANCE enabled a global detection function to be estimated for survey sites in bushland areas across the Shire. Abundance in urban parts of the Shire was estimated from densities obtained from total counts at eight urban sites that ranged from 26 to 51 ha in size. Koala abundance in the Pine Rivers Shire was estimated at 4584 (95% confidence interval, 4040–5247). Line-transect sampling is a useful method for estimating koala abundance provided experienced koala observers are used when conducting surveys.

scholarly journals Distance sampling reveals Cambodia's Eastern Plains Landscape supports the largest global population of the Endangered banteng Bos javanicus

Oryx ◽  
2012 ◽  
Vol 46 (4) ◽  
pp. 563-566 ◽  
Author(s):  
Thomas N. E. Gray ◽  
Sovanna Prum ◽  
Chanrattana Pin ◽  
Channa Phan
Keyword(s):  
Protected Areas ◽  
Land Use Planning ◽  
Distance Sampling ◽  
Line Transect ◽  
Robust Estimate ◽  
Bos Javanicus ◽  
Transect Sampling ◽  
Line Transects ◽  
Dry Seasons ◽  
Global Population

AbstractThe banteng Bos javanicus is a globally threatened species of wild cattle restricted to South-East Asia. We report the first robust estimate of banteng density and population size from anywhere in the species' global range, using distance-based line transect sampling within two protected areas, Mondulkiri Protected Forest and Phnom Prich Wildlife Sanctuary, which form part of the Eastern Plains Landscape, Cambodia. We surveyed 110 line transects multiple times during the dry seasons of 2009–2010 and 2010–2011. In a total survey effort of 1,310 km there were 63 encounters with banteng. The mean estimate of the population across the 3,406 km2 study area is 3,200 (95% confidence interval 1,980–5,170). This suggests that the protected area complex of the Eastern Plains Landscape supports the majority of the global population of banteng. Stronger protection, both in the form of increased anti-hunting and poaching patrols and integrated land-use planning to prevent habitat loss within protected areas, is essential for securing wild cattle populations in the Eastern Plains Landscape.

scholarly journals The application of sampling theory in bauxite protocols

2014 ◽  
Vol 67 (2) ◽  
pp. 215-220 ◽  
Author(s):  
Daniel Armelim Bortoleto ◽  
Ana Carolina Chieregati ◽  
Antônio Henrique Rietra Pereira ◽  
Raiza Cavalcante Oliveira
Keyword(s):  
Representative Sample ◽  
Sampling Error ◽  
Sampling Theory ◽  
Sampling Protocol ◽  
Experimental Procedure ◽  
Heterogeneity Test ◽  
Calibration Methods

The applications of Gy's formula are appropriate for calculating variances of the fundamental sampling error (FSE) at any stage of the sampling protocol and before samples are collected as well. However, the formula can be inaccurate because general factors are used to estimate the ore characteristic. In order to allow the calculation of fundamental sampling error and the minimum representative sample masses without using Gy's factors, there are experiments to calibrate the sampling parameters, namely: the heterogeneity test (HT); the sampling tree experiment (STE) and the segregation free analysis (SFA). The present work describes the experimental procedure for the three calibration methods using bauxite and shows the correlation between them.

Simultaneous unbiased estimates of multiple downed wood attributes in perpendicular distance sampling

2008 ◽  
Vol 38 (7) ◽  
pp. 2044-2051 ◽  
Author(s):  
Mark J. Ducey ◽  
Michael S. Williams ◽  
Jeffrey H. Gove ◽  
Harry T. Valentine
Keyword(s):  
Surface Area ◽  
Unbiased Estimator ◽  
Distance Sampling ◽  
Area Coverage ◽  
Unbiased Estimation ◽  
General Design ◽  
Perpendicular Distance ◽  
Simple Measurement ◽  
Unbiased Estimates ◽  
Downed Wood

Perpendicular distance sampling (PDS) is a fast probability-proportional-to-size method for inventory of downed wood. However, previous development of PDS had limited the method to estimating only one variable (such as volume per hectare, or surface area per hectare) at a time. Here, we develop a general design-unbiased estimator for PDS. We then show how that estimator can be used to develop simple measurement protocols that allow simultaneous, unbiased estimation of multiple downed wood variables, including logs per hectare, length of logs per hectare, surface area or area coverage per hectare, and volume per hectare.

A sampling strategy to assess the effects of land use on microbial functional diversity in soils

Soil Research ◽  
1999 ◽  
Vol 37 (4) ◽  
pp. 593 ◽  
Author(s):  
Bradley P. Degens ◽  
Maja Vojvodi´c-Vukovi´c
Keyword(s):  
Land Use ◽  
Functional Diversity ◽  
Sampling Strategy ◽  
Sampling Strategies ◽  
Land Uses ◽  
Microbial Functional Diversity ◽  
Transect Sampling ◽  
Catabolic Response ◽  
Response Profiles ◽  
Effects Of Land Use

A suitable sampling strategy is necessary for broad-scale investigations of the effects of land use on microbial functional diversity in soils. We report on the development of procedures for sampling and handling field soils for assessment of heterotrophic functional diversity [by analysis of catabolic response profiles (CRPs)]. Individual CRPs were subject to factor analysis and the results were used for statistical comparisons of the soils. Transect sampling comparing CRPs in forest with pasture showed that most variation was attributable to differences between land uses, followed by field replication and laboratory replication. Differences in CRPs between pasture compared with pine forest, horticultural cropping, or maize cropping could also be determined by a similar sampling strategy. Variation in CRPs between land uses by using these sampling approaches was greater than variation within land uses. CRPs varied little between seasons in 2 land uses and samples could also be stored up to 5 months at 5°C with little change in CRPs. We recommend that microbial functional diversity (CRPs) can be assessed in different land uses without laboratory replication and that transect sampling strategies are suitable for distinguishing clear differences between land uses.

A test of a nonparametric distance-based estimator for seedling density

1989 ◽  
Vol 19 (9) ◽  
pp. 1169-1173 ◽  
Author(s):  
Stephen E. Fairweather ◽  
John F. Amrhein
Keyword(s):  
Spatial Distribution ◽  
Sampling Methods ◽  
Distance Sampling ◽  
Nonparametric Estimator ◽  
Seedling Density ◽  
Quadrat Sampling ◽  
Clear Cut ◽  
Central Pennsylvania ◽  
Unbiased Estimates ◽  
Simulated Sampling

Two sampling methods were used to estimate the number of seedlings per acre on a 15-month-old clear-cut in central Pennsylvania. The seedling population was very dense, and the spatial distribution was highly aggregated. The first method used distance sampling and a nonparametric estimator, and the second method used conventional quadrat sampling (milacre plots (1 milacre = 0.0004 ha)). Based on simulated sampling trials on the mapped seedling population, the distance sampling estimator was severely biased, whereas quadrat sampling yielded unbiased estimates of density.

Combining satellite lidar, airborne lidar, and ground plots to estimate the amount and distribution of aboveground biomass in the boreal forest of North America

2015 ◽  
Vol 45 (7) ◽  
pp. 838-855 ◽  
Author(s):  
Hank A. Margolis ◽  
Ross F. Nelson ◽  
Paul M. Montesano ◽  
André Beaudoin ◽  
Guoqing Sun ◽  
...  
Keyword(s):  
Boreal Forest ◽  
North American ◽  
Aboveground Biomass ◽  
Sampling Error ◽  
Sampling Strategy ◽  
Airborne Lidar ◽  
Eastern Canada ◽  
Forest Inventories ◽  
The North ◽  
Regression Error

We report estimates of the amount, distribution, and uncertainty of aboveground biomass (AGB) of the different ecoregions and forest land cover classes within the North American boreal forest, analyze the factors driving the error estimates, and compare our estimates with other reported values. A three-phase sampling strategy was used (i) to tie ground plot AGB to airborne profiling lidar metrics and (ii) to link the airborne estimates of AGB to ICESat-GLAS lidar measurements such that (iii) GLAS could be used as a regional sampling tool. We estimated the AGB of the North American boreal forest at 21.8 Pg, with relative error of 1.9% based on 256 GLAS orbits (229 086 pulses). The distribution of AGB was 46.6% for western Canada, 43.7% for eastern Canada, and 9.7% for Alaska. With a single exception, relative errors were under 4% for the three regions and for the major cover types and under 10% at the ecoregion level. The uncertainties of the estimates were calculated using a variance estimator that accounted for only sampling error, i.e., the variability among GLAS orbital estimates, and airborne to spaceborne regression error, i.e., the uncertainty of the model coefficients. Work is ongoing to develop robust statistical techniques for integrating other sources of error such as ground to air regression error and allometric error. Small ecoregions with limited east–west extents tended to have fewer GLAS orbits and a greater percent sampling error. AGB densities derived from GLAS agreed closely with the estimates derived from both forest inventories (<17%) and a MODIS-based interpolation technique (<26%) for more southern, well-inventoried ecoregions, whereas differences were much greater for unmanaged northern and (or) mountainous ecoregions.

The description-experience gap: Beyond sampling error and recency

2008 ◽  
Author(s):  
Robin Hau ◽  
Timothy J. Pleskac ◽  
Ralph Hertwig
Keyword(s):  
Sampling Error
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