Resin duct density and size predicts mortality in ponderosa pine trees of Northern Arizona

Jeffrey Kane,Thomas Kolb

doi:10.1038/npre.2009.3736.1

Abstract

AbstractIn the presence of herbivores, plants must allocate a portion of their accumulated carbon towards defense to survive. For example, trees susceptible to bark beetle attack are primarily reliant on resin production for protection. Tree mortality may be reflected by individual differences in the ability of plants to produce defensive structures and compounds. We compared the radial growth rates, resin duct production, density, and size between living and dead ponderosa pine trees in northern Arizona using standard dendrochronology techniques. As a result, we found four main findings: 1) living ponderosa pines had 33% more resin ducts than dead pines (t = 2.97, P < 0.003); 2) resin duct size was 13% larger in living than in dead pines (t = 3.00, P < 0.003); 3) both resin duct density and size were predictive of mortality (Wald’s Z = 1.9, P < 0.05); and 4) resin duct production was positively correlated with growth rate. Our results suggest dendrochronology can quantify defense structure production and predict tree mortality in ponderosa pine forests in northern Arizona.

Highlights

Plants, in the presence of herbivores, must differentially allocate carbon between growth and defense (Loomis 1932, Herms and Mattson 1992)
Living ponderosa pines had 33% greater resin duct density in the 10 yrs growth preceding death of the dead pine (t = 2.97, P < 0.004; Fig. 2 & 3)
Living ponderosa pines had 13% wider resin ducts compared to dead pines (t = 3.00, P < 0.003; Fig. 2 & 3)

Summary

Results

Living ponderosa pines had 33% greater resin duct density in the 10 yrs growth preceding death of the dead pine (t = 2.97, P < 0.004; Fig. 2 & 3). Living ponderosa pines had 13% wider resin ducts compared to dead pines (t = 3.00, P < 0.003; Fig. 2 & 3). Mean ring width was positively correlated with mean resin duct production over a 10 year time period for both living (r2 = 0.725, P < 0.0001) and dead (r2 = 0.556, P < 0.0001) pine trees (Fig. 4a), while both living and dead mean ring width were negatively correlated to mean resin duct production (Fig. 4b). Ponderosa pine survivorship, based on logistic regression, was significantly predicted by both resin duct density (Wald’s Z = 1.90, P = 0.057) and width (Wald’s Z = 1.99, P < 0.05), with 68.0% of the observations correctly classified

Introduction

Methods

Conclusions

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Literature Cited