Analysis of Individual Tree Competition on Diameter Growth of Silver Birch in Estonia

Maleki, Kobra; Kiviste, Andres; Korjus, Henn

doi:10.5424/fs/2015242-05742

Cited by 50 publications

(39 citation statements)

References 53 publications

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“…Our results concerning the thresholds of uniform angel index under complete spatial randomness in different structure units also provided evidence to apply it with other numbers of neighbors instead of four neighbors. Several studies showed that appropriate selection of potential neighboring competitors of a subject tree depended on the radius of influence zone (Pukkala & Kolström, 1987) and different selection approaches (Aakala et al, 2013;Maleki et al, 2015) have been used among competition indices. However, our results showed that the influence of structure unit size on mingling and dominance structural indices depended on tree species and size spatial arrangement patterns to a great extent.…”

Section: Discussionmentioning

confidence: 99%

The influence of sampling unit size and spatial arrangement patterns on neighborhood-based spatial structure analyses of forest stands

et al. 2016

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Aim of the study: Neighborhood-based stand spatial structure parameters can quantify and characterize forest spatial structure effectively. How these neighborhood-based structure parameters are influenced by the selection of different numbers of nearestneighbor trees is unclear, and there is some disagreement in the literature regarding the appropriate number of nearest-neighbor trees to sample around reference trees. Understanding how to efficiently characterize forest structure is critical for forest management.Area of study: Multi-species uneven-aged forests of Northern China Material and methods: We simulated stands with different spatial structural characteristics and systematically compared their structure parameters when two to eight neighboring trees were selected.Main results: Results showed that values of uniform angle index calculated in the same stand were different with different sizes of structure unit. When tree species and sizes were completely randomly interspersed, different numbers of neighbors had little influence on mingling and dominance indices. Changes of mingling or dominance indices caused by different numbers of neighbors occurred when the tree species or size classes were not randomly interspersed and their changing characteristics can be detected according to the spatial arrangement patterns of tree species and sizes.Research highlights: The number of neighboring trees selected for analyzing stand spatial structure parameters should be fixed. We proposed that the four-tree structure unit is the best compromise between sampling accuracy and costs for practical forest management.Keywords: Stand spatial structure; number of neighboring trees; uniform angle index; mingling; dominance. Citation: Wang, H., Zhang, G., Hui, G., Li, Y., Hu, Y., Zhao, Z. (2016). The influence of sampling unit size and spatial arrangement patterns on neighborhood-based spatial structure analyses of forest stands. Forest Systems, Volume 25, Issue 1, e056. http:// dx

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Section: Discussionmentioning

confidence: 99%

The influence of sampling unit size and spatial arrangement patterns on neighborhood-based spatial structure analyses of forest stands

et al. 2016

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“…It was desirable to keep the total sample size of subject and competing trees manageable by using a BAF AC ≥ 3. One recent investigation arrived at the conclusion that the Bitterlich angle count method was not the best method for selecting competitor trees [6]. Here, we contend that Bitterlich method should not be used exclusively for just selecting competitor trees, but rather the point sampling expansion factors should also be employed to scaling the competition indices up to a per ha level.…”

Section: Discussionmentioning

confidence: 99%

“…The BAF V estimator also has desirable features, such as additivity and efficiency, when used for estimating change with permanent plots. The general consensus of the literature suggests that the Grosenbaugh growth estimator, Equation (7), is more efficient than the additive estimator, Equation (6), for most forest conditions and remeasurement intervals [25,31,32]. The drawback of the Grosenbaugh estimator is that it is non-additive (incompatible), so that volume (V 2 = [V 1 + ∆V]).…”

Section: Discussionmentioning

confidence: 99%

“…Several authors have indicated the superiority of selecting neighbor trees for the first step with angle count sampling (also known as point sampling, variable plot sampling, or the Bitterlich method [3,4]). Other authors [5,6] have presented alternative methods for selection of competitor trees in forests of Eucalyptus globulus and Betula pendula, respectively. It is affirmed, however, that any fixed-radius method proves disadvantageous when it is utilized in long-term growth studies [2].…”

Section: Introductionmentioning

confidence: 99%

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Individual-Tree Competition Indices and Improved Compatibility with Stand-Level Estimates of Stem Density and Long-Term Production

McTague

Weiskittel

2016

Forests

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Abstract:When explaining the dynamics of individual trees, the incorporation of size and distance of neighboring trees into a model can improve the prediction of growth and mortality. Several methods have been proposed to define the number of competing trees based on variable zone radii and the principles of angle count sampling. The task of measuring position-dependent competition indices appears to be ideally suited for permanent sample plots and long-term studies of growth and yield (production), where the marginal effort of remeasurement is concentrated on measuring size attributes of survivor trees and the occasional distance of a new sample tree. The proposed competition index is based on point sampling with a variable basal area factor (BAF V ) that is partially derived from the Spurr (1962) competition index. Point sampling is a fast, easy, and inexpensive methodology for selecting the number of competing trees, and the new BAF V methodology proved to be very efficient for estimating growth. With the selection of an appropriate basal area factor, it is possible to reduce the number of subject trees and competition trees in the sample, and eliminate the need for edge correction methods. Although the index value assigned to the subject tree using the BAF V is biased, an appropriate correction is presented and discussed. The average competition index obtained from using the corrected value for the subject tree and the BAF V for the competing trees equals the stand level estimate of basal area.

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“…Based on the concept of the influencezone (Staebler 1951) we assumed an imaginary circle in which the center is defined by a tree, and its radius is 40% of the average height of trees in the first storey on each plot , Maleki et al 2015. In order to avoid biased estimations due to the interference from immediate non-measured neighboring trees outside the plot boundary, we established a boundary strip (buffer zone) inside the monitoring plot with a width equal to the radius of the influence zone.…”

Section: Predictors Of Tree Mortalitymentioning

confidence: 99%

Individual tree mortality of silver birch (Betula pendula Roth) in Estonia

Maleki¹,

Kiviste²

2016

iForest

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The functioning of complex forest ecosystems is intimately related to their structural properties. Tree mortality is a major driver of forest stand dynamics and therefore plays an important role in the formation of forest structure. Data from the Estonian Network of Forest Research Plots (ENFRP) was used to estimate the mortality probability of silver birch trees (Betula pendula Roth) by using logistic models. In this study several spatial and non-spatial variables were tested to determine the most important mortality explanatory factors. Additionally, thinning variables were defined and implemented into the mortality models, to examine whether thinning practices could modify the stand structure and density, then leading to a lower mortality rate. The results of this study showed that tree mortality models that included either a five-year diameter growth rate (id5) as a measure of tree vitality, or the tree relative diameter (drel) as a measure of competition, or both these two variables, were substantially better than any models not including these variables. In addition, any measures of spatial aggregation (agg) and species proportion (sp) within the zone of influence markedly improved the model predictions, though the mortality probability of trees declined where there was higher aggregation and species mixture. Our results also suggested that if thinning were conducted around the birch trees, depending on the thinning intensity, the number of neighbors is effectively reduced, and consequently the competition load within the influence zone decreases, leading to healthier growth and lower mortality rates of the shade-intolerant birch trees. We thus recommend to adopt thinning regimes in mixed forest stands to foster tree species diversity, and at the same time provide adequate growing space for birch trees within the stands. This will improve the forest structure and increase the adaptive capacity of forests, which is increasingly important under changing climatic conditions.

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Analysis of Individual Tree Competition on Diameter Growth of Silver Birch in Estonia

Cited by 50 publications

References 53 publications

The influence of sampling unit size and spatial arrangement patterns on neighborhood-based spatial structure analyses of forest stands

The influence of sampling unit size and spatial arrangement patterns on neighborhood-based spatial structure analyses of forest stands

Individual-Tree Competition Indices and Improved Compatibility with Stand-Level Estimates of Stem Density and Long-Term Production

Individual tree mortality of silver birch (Betula pendula Roth) in Estonia

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