Shade Shoot Structure and Productivity of Evergreen Conifer Stands Tests of Three Alternative Hypotheses

The current annual increment (wood volume) of stands of evergreen conifers on a research site in Sweden, was found to be significantly correlated with the maximum ratio of shoot to leaf silhouette area of shade-acclimated shoots (R-max). Neither the slope nor the intercept of the regression was significantly different from that published earlier relating maximum mean annual increment of British stands to R-max. Moreover, a strong correlation between wood volumen increment and R-max also occurs when data from four countries are combined. Wood density was not significantly correlated with R-max. Harvest index for stand grown conifers more than 25 year old, was also not correlated with R-max. Estimated net biomass production (excluding fine roots) was significantly correlated with R-max (R-2 = 0.82, F = 17.7). These new analyses could not be used to disprove the hypothesis that variation in shade shoot structure of evergreen conifers has a measurable effect on maximum biomass production.