Plotless Sampling Trials in Appalachian Forest Types

Shanks, Royal E.

doi:10.2307/1931122

Cited by 25 publications

(25 citation statements)

References 36 publications

(18 reference statements)

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“…1984;Shanks 1954). The slopes of the latitude-elevation relationship based on mean annual temperatures are 50 to 90 percent greater than those based on summer temperatures.…”

Section: Analysis Of the Latitude-elevation Relationshipmentioning

confidence: 93%

The latitude-elevation relationship for spruce-fir forest and treeline along the Appalachian mountain chain

Cogbill¹,

1991

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Spruce-fir forests extend along the Appalachian Mountains of eastern North America from 35 ° to 49 ° N.This montane vegetation differs from boreal spruce-In" forest in that it is dominated by Picea rubens, has a higher vascular species richness, has wind, rather than fire, dominated dynamics, and has a mean annual temperature above 2 ° C. Using field reconnaissance, remote sensing, and literature review we described and modeled the latitude-elevation relationship for Appalachian spruce-fir. The elevation of the sprucefir/deciduous forest ecotone decreases from 1,680 m at 35 ° N to 150 m at 49 ° N, while the elevation of treeline (spruce-fir/tundra ecotone) decreases from 1,480 m at 44 ° N to 550 m at 55 ° N. Linear regressions gave latitude-elevation relationships of -100 m/1 ° Latitude for the spruce-fir/deciduous forest ecotone and -8 3 m/1 ° Latitude for treeline. These values compare to literature reports of -5 4 to -230 m/1 ° Latitude and are most similar to values reported from eastern Asia. The latitude-elevation relationship for mean July temperature ( -94 to -121 m/1 ° Latitude) was more similar to the slopes of these ecotones than is the slope for mean annual temperature ( -170 to -220 m/1 ° Latitude). The spruce-fir/deciduous forest ecotone was correlated with a mean July temperature of approximately 17 ° C. Treeline was correlated with a mean July temperature of approximately 13 °C.

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“…1984;Shanks 1954). The slopes of the latitude-elevation relationship based on mean annual temperatures are 50 to 90 percent greater than those based on summer temperatures.…”

Section: Analysis Of the Latitude-elevation Relationshipmentioning

confidence: 93%

The latitude-elevation relationship for spruce-fir forest and treeline along the Appalachian mountain chain

Cogbill¹,

1991

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“…The Shanks PDE is a fourth permutation of the four mathematical operations that calculates the inverse of the square of the average of the distances at a sample point (Shanks 1954, Cottam and Curtis 1956, Jones and Patton 1966, Anderson and Anderson 1975 …”

Section: Shanks Pdesmentioning

confidence: 99%

“…The Shanks PDE has not been formally described to the best of our knowledge, but was first applied by Shanks (1954) as a variation of Cottam's random-pairs estimator. The Shanks PDE has not been formally described to the best of our knowledge, but was first applied by Shanks (1954) as a variation of Cottam's random-pairs estimator.…”

Section: Shanks Pdesmentioning

confidence: 99%

A retrospective on the accuracy and precision of plotless forest density estimators in ecological studies

et al. 2018

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Sampling point-to-tree distances is a simple plotless technique for estimating forest density that is readily applied in modern stands and retroactively with historical surveys. Although plotless density estimators (PDEs) have been applied in over 1000 ecological publications, the accuracy and precision of the techniques remain poorly understood and depend on the statistical estimator used, the underlying spatial pattern of the forest sampled, and the tree survey methodology. The four most commonly applied PDEs are related formulations: Cottam, Pollard, Morisita, and Shanks, a family of equations that differ in the order of mathematical operations. Since the 1950s, the Cottam IV PDE has found common use as the "point-quarter method." The Pollard PDE prevails in the statistical literature. Both Cottam and Pollard PDEs are theoretically rigorous for trees distributed according to a complete spatial randomness (CSR) spatial point process. The Morisita PDE was developed in a 1957 publication, with four-tree (Morisita IV) and two-tree (Morisita II) variants, and is the basis for higher distance rank g-tree estimators. The Shanks PDE is formally described here for the first time. We review and evaluate the performance of these four PDEs on CSR and a variety of non-CSR forests using spatial patterns simulated from known spatial point processes, 14 mapped modern stands, and historical public land surveys (PLSs). We found that the Cottam and Pollard PDEs lacked accuracy for non-CSR patterns. The Morisita PDEs are appropriate for non-CSR forests, but the Morisita IV has sensitivity to local dispersion. The Morisita II PDE has high accuracy even under non-CSR distributions yielding density estimates within 10% of the true value for a variety of non-CSR patterns, but has considerable variability at small sample sizes. In conjunction with the Morisita II, the potentially biased Cottam and Pollard PDEs can be indicators of the type of non-CSR pattern. No plotless estimator is efficacious for use with small sample sizes such as found in a single stand. Morisita II PDE is recommended as a robust choice for sampling for large and non-CSR data sets such as the PLS witness tree database.

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“…1, the percentage bias of the angle-count method compared with complete measurement of the tract, for each of the three angles used by Husch (1955) taken from his Table 3-, is plotted against the proportional basal area. Table 3 gives data from two surveys published by Shanks ( 1954), extracted from his Tables 2 and 6. These show that the angle-count estimator has a negative bias, but it appears to be worse, the lower the basal area proportion.…”

Section: Hidden Treesmentioning

confidence: 99%

The Angle-Count Method

Holgate¹

1967

Biometrika

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Plotless Sampling Trials in Appalachian Forest Types

Cited by 25 publications

References 36 publications

The latitude-elevation relationship for spruce-fir forest and treeline along the Appalachian mountain chain

The latitude-elevation relationship for spruce-fir forest and treeline along the Appalachian mountain chain

A retrospective on the accuracy and precision of plotless forest density estimators in ecological studies

The Angle-Count Method

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