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The relative importance of nitrogen vs. moisture stress may drive intraspecific variations in the SLA-RGR relationship: The case of Picea mariana seedlings

Summary

Published in American Journal of Plant Sciences 4: 1278-1284

Plants acclimate to nitrogen (N) or moisture stress by respectively increasing photosynthetic N use efficiency (PNUE) or water use efficiency (WUE), in order to maximize their relative growth rate (RGR). These two phenotypic adaptations have opposite effects on specific leaf area (SLA). Thus, intraspecific variations in the SLA-RGR relationship should reflect the relative importance of N vs. moisture stress in plants. In this study, we measured needle gas exchanges and N concentrations in order to derive PNUE and WUE, as well as SLA and RGR of black spruce (Picea mariana) seedlings growing on a rapidly drained site in the presence or absence of Kalmia angustifolia. The eradication of Kalmia had resulted in a ~140% increase in seedling growth over a 6 year period. We found a negative SLA-RGR relationship where Kalmia had been eradicated, and a positive one where Kalmia had been maintained. Kalmia eradication resulted in higher WUE when measurements were made directly on the seedlings, and in lower PNUE when twigs were rehydrated prior to gas exchange measurements. Our data suggest that the bigger seedlings on Kalmia-eradicated plots increase RGR by decreasing SLA, as a means of coping with moisture stress. By contrast, increasing SLA on non-eradicated plots may be a means of coping with nutrient stress exerted by Kalmia. The SLA-RGR relationship could potentially be used to identify the limiting resource for black spruce seedlings in different environments.

Sector(s): 

Forests

Categorie(s): 

Scientific Article

Theme(s): 

Forestry Research, Forests, Silviculture

Author(s)

LEBEL, Philippe, Robert L. BRADLEY and Nelson THIFFAULT

Year of publication :

2013

Format :

PDF available upon request

Keywords :

épinette noire, Kalmia à feuilles étroites, stress hydrique et nutritionnel, sylviculture et rendement des plantations, article scientifique de recherche forestière, silviculture and yield of plantations, Picea mariana, Kalmia angustifolia, black spruce, moisture and nitrogen stress, PNUE and WUE, SLA-RGR relationship

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