Patterns of inter-annual variation in the size asymmetry of growth in Pinus banksiana

Abstract

A large body of literature suggests that asymmetric competition, where large individuals suppress the growth of smaller individuals by intercepting a disproportionate share of incoming light, is a dominant process in tree population development. This has not been examined extensively for long-lived tree species that accumulate growth over many years under varying growing conditions. Using dendrochronological techniques, we reconstructed annual growth and mortality rates at ten stands of jack pine (Pinus banksiana Lamb.) in Western Canada. We used these data to calculate an annual index of the size asymmetry of growth for each stand for the last 50 years. Jack pine is a shade-intolerant species found in even-aged monoculture stands, so the simple hypothesis is that large trees should consistently perform relatively better than small trees. Inter-annual variation in the index of size-asymmetric growth was positively associated with interannual variation in stand productivity at eight of ten sites. The size asymmetry of growth also showed a positive trend with age at eight of ten sites, even though all sites were in a period of declining leaf area. This should have reduced the intensity of asymmetric competition for light and reduced the size asymmetry of growth over time. Alternate hypotheses for this trend are (1) that physical collisions between crowns result in asymmetric competition for growing space because they are more damaging to small trees, or (2) that a differential build up of diseases in susceptible trees suppresses their growth, even in the absence of competition.

Regime shift in groundwater temperature triggered by the Arctic Oscillation

“…The period covered by the analysis is 1978–2000, for which the density of available data was optimal. All three tests are commonly used to detect abrupt shifts in climatic and environmental time‐series [ Rodionov and Overland , 2005; Hari et al , 2006; Metsaranta and Lieffers , 2010].…”

Succession, climate and neighbourhood dynamics influence tree growth over time: an 87‐year record of change in aPinus resinosa‐dominated forest, Minnesota,USA

“…; Hartmann & Messier ; Castagneri et al. ) and external stressors (Metsaranta & Lieffers ) introduce additional variability by causing fluctuations in resources that also influence interactions over time. The complicated and dynamic nature of tree‐to‐tree interactions may explain why no single index for estimating the influence of tree‐to‐tree interactions on growth works effectively across all forest types and developmental stages (Burton ; Biging & Dobbertin ; D'Amato & Puettmann ).…”

Patterns of seed bank and size asymmetry of plant growth across varying sites in the invasive Lantana camara L. (Verbenaceae)

“…This approach has been used frequently to distinguish between linear, size-proportional and non-linear, size-disproportional increase in growth rate, and to infer an alternative mode of plant interference (Dolezal et al 2004;Metsaranta and Lieffers 2010;Pretzsch and Dieler 2011). Under this model, if plants grow in proportion to their sizes (q 1 = 1), thereby depleting limited resources without any individual obtaining a monopoly, then competitive interactions among them are weak and symmetric; if larger individuals grow disproportionately more than others (q [ 1), thereby pre-empting resources at the expense of smaller plants, then competition is intense and positively size-asymmetric, further increasing size inequality.…”

“…Information contained in a set of size measurements (height, diameter, and volume/ biomass) for a population of plants can be used to make inferences about past or present competitive environments within that population (Thomas and Weiner 1989;Weiner 1990;Vega and Sadras 2003;Dolezal et al 2009;Metsaranta and Lieffers 2010;Pretzsch and Dieler 2011;Méndez-Alonzo et al 2012). While there is a prevalence of such studies across many plant life forms and ecological groups, including forest and commercially utilized species, equivalent study on invasive plants as a group is scant (but see Arenas et al 2002).…”

“…We also hypothesized that short-term variability in size asymmetry will be increased by factors that increase productivity (e.g. high precipitation) in response to intense competition for growth (Metsaranta and Lieffers 2010).…”