The aim of this work was to determine
the structural characteristics of the condensed tannins isolated from the
aqueous extract of black spruce (Picea
mariana Mill) bark. This is the first report on the structural
characterization of condensed tannins from black spruce bark. The condensed
tannins from the hot water extract prepared from Picea mariana bark were isolated by column chromatography on
Sephadex LH-20 media. In this study, UV-visible and 13C-NMR spectroscopic techniques, along with pyrolysis-gas
chromatography/mass spectrometry (Py-GC/MS) and liquid chromatogramphy analyses were applied to determine the
structural characteristics of black spruce bark tannins. We have confirmed for
the first time the presence of methoxylated B-rings in the flavanol units of
condensed tannins from black spruce bark, which could be regarded as further
contribution to the chemotaxonomy of the genus Picea. The methoxylation of Norway spruce bark condensed tannins have been demonstrated previously.
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 noneradicated plots may be a means of
coping with nutrient stress exerted by Kalmia.