A Coefficient for Describing Size Variation among Neighboring Trees

Hagner, Mats; Nyquist, Hans

doi:10.2307/1400623

Cited by 2 publications

(1 citation statement)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The index of aggregation (R, Clark and Evans 1954) was used to capture horizontal structure, ranging from 0 (maximum aggregation/clustering of trees) to 2.1491 (a regular hexagonal arrangement) with a value of 1 when the spatial distribution is random. The dissimilarity coefficient (DC) of Hagner and Nyquist (1998) was used to quantify vertical structure as size differences among pairs of neighboring trees, ranging from 0 to 1 with a value of 0.5 when tree sizes are drawn independently from an exponential distribution. Vertical structure was also measured as the difference in tree size among four nearest neighbors (T, the diameter differentiation index of Füldner 1995, ranging from 0 to 1).…”

Section: Parametersmentioning

confidence: 99%

Structure area curves in Eastern Hardwoods: implications for minimum plot sizes to capture spatially explicit structure indices

Peck

Zenner

2021

Annals of Forest Science

View full text Add to dashboard Cite

Key message Sampling needs differ by forest type for timber inventory and structural complexity metrics. We demonstrate in a typical mixed Eastern Hardwoods forest that optimal sampling of timber inventory metrics and spatially explicit structure indices may be achieved in one large plot plus a cruise for large diameter trees, but accurately capturing inventory metrics may not be possible with sparse large-scale sampling.• Context Managing forest stand structures for multiple objectives require accurate and precise estimates of structural features that may be best estimated at different scales.• Aims We document minimum necessary plot sizes for structural metrics and spatially explicit indices to characterize structure in a mature North American Eastern hardwoods forest.• Methods Metrics and indices (Index of Aggregation, Diameter Differentiation Index, Dissimilarity Coefficient, Structural Complexity Index) were calculated within 0.05-1.75-ha plots for 1000 iterations of random placement in two 2.0-ha macroplots. Estimation adequacy required (1) precision (varied < 10% among plots) and ( 2) accuracy (within 10% of the 2.0-ha value at 5th and 95th percentiles).• Results Minimum single plot sizes to achieve estimation adequacy were 0.25-0.75 ha for spatially explicit indices and 0.5-2 ha for stand metrics. A minimum of five 0.10-ha subplots would be needed for most indices and 6-25 for most metrics, but an untenable 375+ for the density of large diameter trees.• Conclusion Estimation adequacy for structural complexity requires no greater sampling intensity than for timber metrics, except for density of large trees. A single large plot may be most cost-effective. National inventories in Eastern hardwoods may not estimate structural complexity well due to inadequate sampling intensity.

show abstract

Section: Parametersmentioning

confidence: 99%