A new empirical approach for estimation in k-tree sampling

Kleinn, Christoph; Vilčko, František

doi:10.1016/j.foreco.2006.09.072

Cited by 56 publications

(66 citation statements)

References 13 publications

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“…By using the echoes in the tree-less sectors of the PCQ quadrants along with the echoes of the trees associated with those sectors we got a fairly realistic distribution of number of echoes in the different categories, although it is likely that the proportion of tree echoes was somewhat higher than the true proportion because the PCQ method tend to be positively biased [56]. However, we still got about 20 to 100 times more non-tree echoes than tree echoes.…”

Section: Discussionmentioning

confidence: 92%

Discrimination between Ground Vegetation and Small Pioneer Trees in the Boreal-Alpine Ecotone Using Intensity Metrics Derived from Airborne Laser Scanner Data

Næsset¹

2016

Remote Sensing

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Abstract:It has been shown that height measurements obtained by airborne laser scanning (ALS) with high point density (>7-8 m´2) can be used to detect small trees in the alpine tree line-an ecotone sensitive to climate change. Because the height measurements do not discriminate between trees and other convex structures with positive height values, this study aimed at assessing the contribution of ALS backscatter intensity to classification of trees and non-trees. The study took place in a boreal-alpine ecotone in southeastern Norway and was based on 500 precisely georeferenced small trees and non-tree objects for which ALS height and intensity were derived from four different ALS acquisitions, representing different sensors, pulse repetition frequencies (PRF), and flying altitudes. The sensors operated at 1064 nm. Based on logistic regression modeling, it was found that classification into three different tree species ((1) spruce; (2) pine; and (3) birch)) and two different non-tree object types (objects with: (1) vegetated surface; and (2) rock) was significantly better (p < 0.001-0.05) than a classification based on models with trees and non-trees as binary response. The cause of the improved classification is mainly diverse reflectivity properties of non-tree objects. No effect of sensor, PRF, and flying altitude was found (p > 0.05). Finally, it was revealed that in a direct comparison of the contribution of intensity backscatter to improve classification models of trees and non-trees beyond what could be obtained by using the ALS height information only, the contribution of intensity turned out to be far from significant (p > 0.05). In conclusion, ALS backscatter intensity seems to be of little help in classification of small trees and non-trees in the boreal-alpine ecotone even when a more detailed discrimination on different species and different non-tree structures is applied.

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Section: Discussionmentioning

confidence: 92%

Discrimination between Ground Vegetation and Small Pioneer Trees in the Boreal-Alpine Ecotone Using Intensity Metrics Derived from Airborne Laser Scanner Data

Næsset¹

2016

Remote Sensing

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“…One useful and rapid method for forest inventory is c-tree sampling-also referred to as n-tree distance sampling (Lessard et al, 1994; Spatial Distribution and Composition of Trees in an Aging Coppice Forest 37 Lynch and Rusydi, 1999;Lessard et al, 2002;Lynch and Wittwer, 2003), density-adapted sampling (Jonsson et al, 1992), k -tree sampling (Kleinn and Vilčko, 2006) or plotless ordered distance sampling (Engeman et al, 1994). The advantage of using c-tree sampling is mostly in its simple design and its ability to reduce the cost of field surveys when compared with conventional methods used in forestry (Jonsson et al, 1992;Lessard et al, 1994;Lynch and Rusydi, 1999;Husch et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Spatial Distribution and Composition of Trees in an Aging Coppice Forest in Japan

Trifkovic

2013

FORMATH

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Abstract:The importance of studying the ecology of coppice forests in Japan has risen recently amid growing demands to reestablish utilization of their tangible resources. The objective of the paper is to assess whether the spatial distribution of trees at an undisturbed agingcoppice follows some common pattern and how its composition changes with time. Coppice forests in Japan usually grow on steep lands and conventionally used forest inventory methods and methods used in ecological studies are time-consuming. Therefore, a rapid sampling approach based on measurements of angles and distances was used to achieve the objectives of this study. The field survey was conducted at coppice stands harvested 48, 60 and 77 years ago. Results suggest that distribution of the trees at aging-coppices shifts toward a regular spatial pattern. However, the process toward this regularity is slow and the distributions of individual trees were still not significantly different from a random pattern. Use of the combined angle-distance methodology is rapid and the data collected can be useful for planning ecologically-friendly management of coppice forests.

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“…In general those protocols are a form of unequal probability sampling for populations of discrete objects (Affleck et al 2005). They present the analyst with difficult measurements if the determination of design-unbiased inclusion probabilities is targeted (Kleinn and Vilčko 2006b).…”

Section: Introductionmentioning

confidence: 99%

“…In these cases a bias of unknown magnitude presumably is an acceptable tradeoff for the relatively easy implementation of the sampling techniques in the field (Kleinn and Vilčko 2006b;Barabesi 2001;Magnussen et al 2008b). The main argument for plotless approaches is that the fixed number of population units included per sample point result in a constant survey effort per sample point (Kronenfeld 2009;Nothdurft et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Triangulation based inclusion probabilities: a design-unbiased sampling approach

2011

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A probabilistic sampling approach for design-unbiased estimation of arearelated quantitative characteristics of spatially dispersed population units is proposed. The developed field protocol includes a fixed number of 3 units per sampling location and is based on partial triangulations over their natural neighbors to derive the individual inclusion probabilities. The performance of the proposed design is tested in comparison to fixed area sample plots in a simulation with two forest stands. Evaluation is based on a general approach for areal sampling in which all characteristics of the resulting population of possible samples is derived analytically by means of a complete tessellation of the areal sampling frame. The example simulation shows promising results. Expected errors under this design are comparable to sample plots including a much greater number of trees per plot.

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A new empirical approach for estimation in k-tree sampling

Cited by 56 publications

References 13 publications

Discrimination between Ground Vegetation and Small Pioneer Trees in the Boreal-Alpine Ecotone Using Intensity Metrics Derived from Airborne Laser Scanner Data

Discrimination between Ground Vegetation and Small Pioneer Trees in the Boreal-Alpine Ecotone Using Intensity Metrics Derived from Airborne Laser Scanner Data

Spatial Distribution and Composition of Trees in an Aging Coppice Forest in Japan

Triangulation based inclusion probabilities: a design-unbiased sampling approach

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