Point relascope sampling of downed coarse woody debris

Gove, Jeffrey H.; Ringvall, Anna; Ståhl, Göran; Ducey, Mark J.

doi:10.1139/x99-119

Cited by 51 publications

(26 citation statements)

References 3 publications

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“…A variety of methodologies are available, including lineintersect sampling (LIS) (Kaiser, 1983;Van Wagner, 1968;Warren and Olsen, 1964), fixed-area sampling (FAS) (Harmon and Sexton, 1996), transect relascope sampling (Ståhl, 1997) and point relascope sampling (Gove et al, 1999). Lineintersect, transect relascope, and point relascope sampling are all probability-proportional-to-size sampling methods.…”

Section: Introductionmentioning

confidence: 99%

Preliminary study on the assessment of deadwood volume by the French national forest inventory

Cros¹,

Lopez²

2009

Ann. For. Sci.

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Abstract• As the French national forest inventory does not currently monitor the lying compartment of the forest deadwood, the figures obtained on this topic are therefore partial. This study provides cost estimates and guidelines for assessing stumps, and standing and lying deadwood.• Comparisons were made between a fixed-area sampling method and a line-intersect one. LIS was judged more time-efficient, especially in dense understorey. Computer simulations were performed in order to estimate the gain in precision with increasing transect lengths. The results showed a continuous improvement in precision associated with increases in transect length. The longest transect tested (50 m) still had a large coefficient of variation, suggesting that improvement in precision at the plot level could still be gained with longer transects.• Therefore, from a practical standpoint in terms of fieldwork, we suggest that on a national scale lying deadwood should be measured by line-intersect sampling, whereas stumps, standing dead trees and snags can be monitored using standard fixed-area plots. To meet needs at the national level, we consider that local imprecision could be compensated for by the large number of plots measured each year. Mots-clés :bois mort / échantillonnage linéaire / échantillonnage par placette à surface fixe / inventaire forestier national Résumé -Étude préliminaire de l'évaluation du volume de bois mort à l'Inventaire forestier national français.• L'inventaire forestier national français ne réalise pas l'inventaire du bois mort au sol, les résultats à ce sujet sont donc partiels. Cette étude donne des orientations en termes de coûts et de méthode pour l'échantillonnage des souches, arbres morts debout et le bois mort au sol.• Les méthodes d'inventaire par placette à surface fixe et échantillonnage linéaire ont été comparées. L'échantillonnage linéaire a été jugé plus rapide surtout lorsque le sous-bois est dense. Des simulations ont été réalisées pour estimer le gain de précision avec l'augmentation de la longueur de transect. Les résultats ont montré une amélioration continue de la précision associée à l'augmentation de la longueur de transect. Le transect le plus long testé (50 m) a toujours un coefficient de variation élevé ; ce qui suggère que l'amélioration de la précision à l'échelle du point peu être obtenue avec un transect plus long.• Du point de vue pratique au niveau du travail de terrain, nous suggérons qu'à l'échelle nationale le bois mort au sol soit mesuré par transect alors que les souches, arbres morts debout et chandelles soit mesurées avec la méthode standard des placettes fixes. Afin de satisfaire aux besoins de l'échelle nationale, nous avons considéré que l'imprécision locale peut être compensée par le nombre important de points mesurés chaque année.

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Section: Introductionmentioning

confidence: 99%

Preliminary study on the assessment of deadwood volume by the French national forest inventory

Cros¹,

Lopez²

2009

Ann. For. Sci.

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“…for each sampling method that yield inclusion zones that are, on average, approximately the same size. While this method is useful and has been applied in several studies (e.g., [36,38]), it can be difficult to find design parameters that yield approximate conformity, especially under PPS designs that often have quite different inclusion zone shapes such as perpendicular distance sampling (PDS) [39], point relascope sampling (PRS) [40] and sausage sampling [41] for downed coarse woody debris. Indeed, when discussing this issue in the comparison of different PDS protocols, Gove et al [38] noted that "the goal of equality is elusive, however, and it is only possible to approximate as the inclusion zones scale differently" under the differing protocols; this caveat also applies to the many other sampling methods used on standing trees and downed coarse woody debris, and a more general example might be the comparison of line-based methods to those already mentioned.…”

Section: Smith Plotsmentioning

confidence: 99%

Some Refinements on the Comparison of Areal Sampling Methods via Simulation

Gove

2017

Forests

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Abstract:The design of forest inventories and development of new sampling methods useful in such inventories normally have a two-fold target of design unbiasedness and minimum variance in mind. Many considerations such as costs go into the choices of sampling method for operational and other levels of inventory. However, the variance in terms of meeting a specified level of precision is always among the most important criteria. Similarly, in designing new sampling methods, one always seeks to decrease the variance of the new method compared to existing methods. This paper provides a review of some graphical methods that may prove useful in these endeavors. In addition, in the case of the comparison of variances between new and existing methods, it introduces the use of wavelet filtering to decompose the sampling variance associated with the estimators under consideration into scale-based components of variance. This yields an analysis of variance of sorts regarding how the methods compare over different distance/area classes. The graphical tools are also shown to be applicable to the wavelet decomposition. These graphical tools may prove useful in summarizing the results for inventory design, while the wavelet results may prove helpful as we begin to look at sampling designs more in light of spatial processes for a given population of trees or downed coarse woody debris.

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“…Apart from standing trees, angle count sampling has also been developed for the assessment of lying dead wood. A first description can be found in Ståhl (1998) for sample lines, later complemented by an application for points by Gove et al (1999). With these methods, angle gauges with large opening angles are used to aim at logs that lay on the forest floor.…”

Section: Introductionmentioning

confidence: 99%

Relascope sampling for crown ratio estimation

2013

Self Cite

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In this study, we apply vertical angle count sampling to estimate the crown ratio of trees in unthinned forest stands. The rationale is to be able to quickly assess the relative crown size of forest stands to support thinning decisions by simply counting trees. We provide estimators and discuss their precision based on pilot studies in Scots pine (Pinus sylvestris L.) plantations in northern Sweden. A separate study was conducted to investigate the amount of measurement errors, i.e., how many trees are wrongly selected or overlooked when using the method. Sampling errors for estimating crown ratio were found to be remarkably low, partly due to high correlation between crown length and tree height and partly due to low variability in the study sites. Measurement errors were in the range of what is commonly obtained with horizontal angle count sampling for basal area estimation.

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Point relascope sampling of downed coarse woody debris

Cited by 51 publications

References 3 publications

Preliminary study on the assessment of deadwood volume by the French national forest inventory

Preliminary study on the assessment of deadwood volume by the French national forest inventory

Some Refinements on the Comparison of Areal Sampling Methods via Simulation

Relascope sampling for crown ratio estimation

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