Feasibility of estimating stem size distribution from measurement on the largest trees in even-aged pure stands

2001 ◽  
Vol 31 (5) ◽  
pp. 910-918 ◽  
Author(s):  
Akira Osawa ◽  
Anatoly P Abaimov
Keyword(s):  
Size Distribution ◽  
Power Distribution ◽  
Environmental Changes ◽  
Stand Structure ◽  
Size Variation ◽  
Stand Density ◽  
Distribution Functions ◽  
Stem Volume ◽  
Type Distribution ◽  
Stem Size

Reconstruction of the size distribution of trees in stands provides critical information for assessing the effects of environmental changes on forests and for forest management. For furthering a method of such reconstruction, feasibility of estimating size distribution in stem volume from measurement of the largest trees was examined for even-aged pure stands of Pinus banksiana Lamb.and Larix gmelinii (Rupr.) Rupr. We tested what percentage of the largest trees should be included in obtaining a frequency distribution in stem volume that is not statistically different from the observed size distribution patterns. The –3/2 power, beta-type, and adjusted beta-type distribution functions were applied. Comparison of the observed stem frequencies and those estimated from measurement of the largest trees in a stand suggested that (i) the –3/2 power distribution, beta-type distribution, or adjusted beta-type distribution may be used for reconstruction of stem size variation in pure stands, if the overall size variation could be approximated by one of these functions; (ii) we can be at least 95% sure that the tree size pattern be expressed successfully with the –3/2 power distribution with tree samples of only the largest 20% in the stand, or with the beta-type distribution with the largest 30% in the stand; and (iii) the reliability decreases somewhat for the adjusted beta-type distribution. The second observation implies that reconstruction of the temporal changes in stand structure may be reliable up to the time when the stand density was about five times that of the trees used for fitting the –3/2 power distribution curve. Reliability may be warranted up to the stand density of about three times as the number of trees used for fitting the beta-type distribution. Other considerations and limitations are also discussed.

Reconstructing structural development of even-aged larch stands in Siberia

2000 ◽  
Vol 30 (4) ◽  
pp. 580-588 ◽  
Author(s):  
Akira Osawa ◽  
Anatoly P Abaimov ◽  
Olga A Zyryanova
Keyword(s):  
Power Distribution ◽  
Volume Growth ◽  
Stand Density ◽  
Stem Volume ◽  
Volume Distribution ◽  
Structural Development ◽  
Individual Tree ◽  
Stem Size ◽  
Tree Ring Data ◽  
Time Observation

A method was proposed for quantitatively reconstructing structural development over time of even-aged monospecific forests and was applied to a larch (Larix gmelinii (Rupr.) Rupr.) stand in Siberia. It relies on samples obtained at one-time observation and some simple assumptions considered general in even-aged stands. Tree-ring data taken from breast height of a group of the largest trees and those measured at various stem heights of several individuals representing the range of tree sizes in the plot are used for the estimation. Stand density and parameters of stem volume distribution at a given time in the past were calculated with the "stem slenderness index," and with an assumption of the -3/2 power distribution for the distribution function of stem size, respectively. By developing time-dependent allometric relationships for individual tree attributes, the whole-stand values of stem volume and its increment were reconstructed for several decades of stand development. Estimated history of the changes in stand density, total stem volume, and stem volume growth for the dense larch stand examined, mostly agreed with a separate estimation by the self-thinning assumption.

Stand structure and growing space efficiency following thinning in an even-aged Douglas-fir stand

1988 ◽  
Vol 18 (7) ◽  
pp. 859-866 ◽  
Author(s):  
K. L. O'Hara
Keyword(s):  
Stand Structure ◽  
Volume Growth ◽  
Basal Area ◽  
Stand Density ◽  
Douglas Fir ◽  
Stem Volume ◽  
Projection Area ◽  
Individual Tree ◽  
Space Efficiency ◽  
Individual Trees

The growth of individual trees from four thinning treatments in a 64-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) stand was analyzed to determine desirable residual stand structures after thinning. Dominant and codominant trees had the highest individual tree stem volume growth rates over the previous 5 years, and accounted for most stand volume growth in thinned and unthinned stands. Two measures of growing space, crown projection area and sapwood basal area (a surrogate for leaf area), were used to measure how efficiently individual trees used their growing space. Crown classes were useful in characterizing growing space efficiency (volume growth per unit of growing space) only in the unthinned treatment. In thinned treatments, tall trees with medium-sized crowns were most efficient, while in the unthinned treatment, tall trees with relatively large crowns were most efficient. A large crown in an unthinned stand was comparable in size to a medium-sized crown in a thinned stand. Results suggest growing space is not limiting individual tree growth in thinned stands and that thinning to a particular stand structure is more appropriate than thinning to a particular level of stand density.

Feasibility of estimating total stem volume and aboveground biomass from measurement on the largest trees in even-aged pure stands

2001 ◽  
Vol 31 (11) ◽  
pp. 2042-2048 ◽  
Author(s):  
A Osawa ◽  
A P Abaimov ◽  
T Kajimoto
Keyword(s):  
Distribution Function ◽  
Aboveground Biomass ◽  
Power Distribution ◽  
Present Method ◽  
Size Distribution Function ◽  
Stem Volume ◽  
Systematic Bias ◽  
Type Distribution ◽  
Predicted Values ◽  
Paired T Test

Feasibility was tested of estimating the total stem volume and aboveground biomass from data of only the largest trees in even-aged pure stands. We applied a method of fitting a size-distribution function to data that exclude information of smaller individuals in a stand and compared the predicted stem volume and aboveground biomass with those calculated with data of all living trees in the stand. The paired t test showed that the predicted values of the total stem volume and aboveground biomass were not different (p = 0.05) from those observed even if only the largest 10% of the trees were used for estimation with the –3/2 power distribution. Results were similar with the beta-type distribution; however, data from at least the largest 30% of the trees in the stand must be included. Absolute values of the relative error of the predicted total stem volume or aboveground biomass were generally in the range 10–20%, indicating that the present method is accurate enough to be used for calculation of these variables. However, there is systematic bias in the predictions of the total stem volume and aboveground biomass of a stand. Possible causes of the indicated biases and potential ways for improvement of the predictions were discussed.

scholarly journals Current understanding on the Cambrian Explosion: questions and answers

PalZ ◽  
2021 ◽  
Author(s):  
Xingliang Zhang ◽  
Degan Shu
Keyword(s):  
Environmental Changes ◽  
Size Variation ◽  
Progressive Increase ◽  
Cambrian Explosion ◽  
Time Interval ◽  
Early Cambrian ◽  
Ecological Processes ◽  
Questions And Answers ◽  
Evolutionary Event ◽  
History Of

AbstractThe Cambrian Explosion by nature is a three-phased explosion of animal body plans alongside episodic biomineralization, pulsed change of generic diversity, body size variation, and progressive increase of ecosystem complexity. The Cambrian was a time of crown groups nested by numbers of stem groups with a high-rank taxonomy of Linnaean system (classes and above). Some stem groups temporarily succeeded while others were ephemeral and underrepresented by few taxa. The high number of stem groups in the early history of animals is a major reason for morphological gaps across phyla that we see today. Most phylum-level clades achieved their maximal disparity (or morphological breadth) during the time interval close to their first appearance in the fossil record during the early Cambrian, whereas others, principally arthropods and chordates, exhibit a progressive exploration of morphospace in subsequent Phanerozoic. The overall envelope of metazoan morphospace occupation was already broad in the early Cambrian though it did not reach maximal disparity nor has diminished significantly as a consequence of extinction since the Cambrian. Intrinsic and extrinsic causes were extensively discussed but they are merely prerequisites for the Cambrian Explosion. Without the molecular evolution, there could be no Cambrian Explosion. However, the developmental system is alone insufficient to explain Cambrian Explosion. Time-equivalent environmental changes were often considered as extrinsic causes, but the time coincidence is also insufficient to establish causality. Like any other evolutionary event, it is the ecology that make the Cambrian Explosion possible though ecological processes failed to cause a burst of new body plans in the subsequent evolutionary radiations. The Cambrian Explosion is a polythetic event in natural history and manifested in many aspects. No simple, single cause can explain the entire phenomenon.

scholarly journals How Many and Why? Size Variation of National Delegations to Plenary Meetings of International Organizations

2021 ◽  
Vol 56 (1) ◽  
pp. 7-33
Author(s):  
Václav Vlček
Keyword(s):  
United Nations ◽  
International Organizations ◽  
Power Distribution ◽  
Regional Cooperation ◽  
Size Variation ◽  
Structural Factors ◽  
Opportunity Structure ◽  
National Sovereignty ◽  
Geographical Patterns ◽  
Financial Benefits

This article provides new insights into size variation of national delegations to plenary meetings of international organizations. Plenary meetings represent a symbol of national sovereignty and equality which is, however, often sidelined by structural opportunities and internal incentives which states have in practice. This article addresses the puzzle of whether the size of national delegations varies and what factors can explain possible geographical patterns. Drawing upon opportunity structure-incentive approach and using a newly created dataset covering 14 major agencies of the United Nations family, I suggest that it is mainly the structural factors what affects the size of national delegations, especially the power distribution. The findings also indicate that complex negotiations in large IOs motivate states to increase their delegation size, while regional cooperation allows them to delegate less representatives and rely on regional partners. Domestic incentives, on the contrary, seem to play little role, except for anticipated financial benefits from membership in the particular IOs.

scholarly journals Stand density biases the estimation of the site index especially on dry sites

2020 ◽  
Author(s):  
Astor Toraño Caicoya ◽  
Hans Pretzsch
Keyword(s):  
Norway Spruce ◽  
Stand Structure ◽  
Local Density ◽  
Generalized Additive Models ◽  
Stand Density ◽  
Moisture Stress ◽  
Site Index ◽  
Additive Models ◽  
Climate Conditions ◽  
Density Control

The Site Index (SI) has been widely used in forest management and silviculture. It relies on the assumption that the height of dominant trees in a stand is independent from the local density. However, research on climate change suggests that under certain moisture stress conditions, this may not hold. Here, based on 29 plots from 5 long-term research experiments, we have tested the effect of local stand density on the SI of Norway spruce (Picea abies (L.) H. Karst). With generalized additive models (GAMM), we analyzed the effect of stand structure and climate predictors on SI. The two evaluated models revealed that local stand density and age had a significant effect on SI (p≤0.001 ), showing a clear negative trend especially significant on sites with poor and dry soils, which may reduce the site index by a maximum of approximately 4 m for an increase in density between 400 and 600 trees/ha. We stress that the physiological characteristics of Norway spruce, flat-rooting system and xeromorphism, especially when growing in pure stands, may explain these effects. Thus, density control and growth in mixtures may help to reduce the water stress and losses in height growth under future climate conditions.

scholarly journals Stand structure links up canopy processes and forest management

2009 ◽  
Vol 51 (1) ◽  
pp. 40-48
Author(s):  
Toomas Frey
Keyword(s):  
Forest Management ◽  
Stand Structure ◽  
Net Primary Production ◽  
Stand Density ◽  
Tree Height ◽  
Belowground Biomass ◽  
Unit Mass ◽  
Total Biomass ◽  
Individual Tree ◽  
Mean Values

Stand structure links up canopy processes and forest management Above- and belowground biomass and net primary production (Pn) of a maturing Norway spruce (Picea abies (L.) Karst.) forest (80 years old) established on brown soil in central Estonia were 227, 50 and 19.3 Mg ha correspondingly. Stand structure is determined mostly by mean height and stand density, used widely in forestry, but both are difficult to measure with high precision in respect of canopy processes in individual trees. However, trunk form quotient (q2) and proportion of living crown in relation to tree height are useful parameters allowing describe stand structure tree by tree. Based on 7 model trees, leaf unit mass assimilation activity and total biomass respiration per unit mass were determined graphically as mean values for the whole tree growth during 80 years of age. There are still several possible approaches not used carefully enough to integrate experimental work at instrumented towers with actual forestry measurement. Dependence of physiological characteristics on individual tree parameters is the missing link between canopy processes and forest management.

scholarly journals Tree diversity, stand structure and community composition in tropical forest of Rajaji tiger reserve, Northern India

2018 ◽  
Vol 10 (3) ◽  
pp. 945-953 ◽  
Author(s):  
Akash . ◽  
Navneet . ◽  
B.S. Bhandari
Keyword(s):  
Tropical Forest ◽  
Community Composition ◽  
Stand Structure ◽  
Diversity Index ◽  
Stand Density ◽  
Tree Diversity ◽  
Importance Value Index ◽  
Importance Value ◽  
Northern India ◽  
Tiger Reserve

In present study, we present data on tree diversity, stand structures and community composition in six sites of tropical forest in Rajaji tiger reserve, Northern India. The enumeration of 72 plots results a total of 19,050 individuals, 47 species, 42 genera, 25 families in which Holoptelia integrifolea, Dalbergia sissoo, Shorea robusta, Cassia fistula and Trewia nudiflora were the species which showed higher importance value index (IVI) in the study area. The stand density of the six sites ranges from 149.99 - 397.91 hac-1 where as the total basal area of trees ranges from 3.612 - 46.813 m2/hac-1. The Shannon diversity index ranged from 1.35 to 2.51, Simpson index ranged from 0.097 - 0.446, Margalef index ranged 2.584 - 4.9, The Evenness index ranged from  0.551 - 0.852 in the study area. Further the studied area has showed ample evidences from indices in supporting the higher floristic diversity and stand structure after providing the present area as a status of tiger reserve.

Size distribution functions for rock fragments

2014 ◽  
Vol 71 ◽  
pp. 381-394 ◽  
Author(s):  
José A. Sanchidrián ◽  
Finn Ouchterlony ◽  
Pablo Segarra ◽  
Peter Moser
Keyword(s):  
Size Distribution ◽  
Distribution Functions ◽  
Rock Fragments
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