The relative dominance hypothesis explains interaction dynamics in mixed species Alnus rubra/Pseudotsuga menziesii stands

Abstract

1 We used repeated measurements of tree growth and population-level and neighbourhood conditions from three mixed Alnus rubra/Pseudotsuga menziesii forests in the Pacific Northwest, USA to investigate why previous results regarding the importance of neighbourhood competition as a determinant of plant growth were inconsistent. 2 We propose that relative dominance of a particular species determines the importance of neighbourhood interactions, and tested whether growth performance of both species at various stand ages agrees with this relative dominance hypothesis. 3 Neighbourhood and relative dominance interaction indices were modified to accommodate two-species mixtures and were incorporated into a growth model predicting relative diameter growth rates. The corrected Akaike Information Criterion ( AIC c ) was used to identify the optimum interaction measures and model forms for each species and measurement period. 4 Interaction indices reflecting the size of a tree relative to the population were the best predictors of growth of the dominant (i.e. taller) species and neighbourhood interaction indices of the subordinate species. 5 Performance of interaction measures as predictors of relative growth rates in our study varied in agreement with the relative dominance hypothesis for both species and on all sites. Results from other studies suggest that the hypothesis may explain growth performances on a species and individual plant level and for a variety of life forms. 6 These findings suggest that the spatial scale of plant interactions is influenced by the size structure of plant populations. The relative dominance hypothesis offers a framework to provide insight into the mechanism of competition, based on the relative performance of competition indices.

Early responses to thinning treatments designed to accelerate late successional forest structure in young coniferous stands of western Oregon, USA

“…A positive relationship often exists between the size of an individual relative to the population and growth rate (Schmitt et al 1987;D'Amato and Puettmann 2004), a pattern also found in this study. Individual tree growth is strongly limited by the number of larger trees near the subject tree (D' Amato and Puettmann 2004;Puettmann et al 2009b).…”

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

“…The next superior competition selection approach, CZR 0.4h , was simple in practice and in accordance with studies showing that, the optimal influence zone radius strongly depended on the tree's initial dimensions (D'Amato & Puettmann, 2004;Sims et al, 2009). Considering the third suitable competitor selection method, similar to several other studies, the opening angle of 50°-60° performed well (Biging & Dobbertin, 1995;Pretzsch, 2009;Oheimb et al, 2011) where bigger angles (80° and 100° in this study) mainly de-11 Analysis of Competition Between Individual Trees young stands, where the stands are usually dense, because these types of indices give more weight to trees that are closer to the subject tree.…”

Individual-tree growth dynamics of mature Abies alba during repeated irregular group shelterwood (Femelschlag) cuttings

“…Evidence is mounting that tree interactions are a spatially explicit process (e.g., Wagner and Radosevich 1998;D'Amato and Puettmann 2004;Roberts and Harrington 2008). In contrast to even-aged, even-spaced stands, the spatial variability in growing conditions within stands with high spatial variability renders stand-level indices less suitable for predicting growth of individual trees (Bigging and Dobbertin 1995).…”