The effect of climate on the growth of Salix species in an experimental energy plantation environment

Dowsley, Barbara J. (1988) The effect of climate on the growth of Salix species in an experimental energy plantation environment. Masters thesis, Memorial University of Newfoundland.

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Abstract

The spatially diverse and often unsettled nature of the summer weather of insular Newfoundland suggests that the influence of climate on biomass production should be taken into consideration when examining potential sites for wood energy plantations. The growth of shoot height and base diameter of three willow (Salix) species in an experimental energy plantation environment at Pasadena, Newfoundland (49°01’N latitude, 57° 36'W longitude) was examined during the 1985 growing season. S.viminalis (clone number 0683, Sweden) was found to be the most successful clone, achieving a final mean shoot height of 209 cm and a final mean shoot base diameter of 1.49 cm. Salix purpurea (clone number 077, Sweden) and S.alba (clone number 5023, Romania) shoots attained final mean heights of 183 cm and 180 cm respectively, and final mean base diameters of 1.07 cm and 1.44 cm respectively. The three species were significantly different in their final mean height and base diameter attainment. -- The height and base diameter of S.viminalis, S.purpurea and S.alba clones was recorded on a weekly basis between June 10 and October 7, 1985. The seasonal pattern of shoot height and base diameter growth of S.viminalis and S.alba clones was effectively explained by second-order polynomial regression equations (multiple r² ≥ 98%). The seasonal pattern of S.purpurea shoot height growth was also described by a quadratic equation whereas base diameter growth during the 1985 growing season was described by a cubic or third-order polynomial regression equation. -- Total shoot height of the three species was recorded daily between June 21 and August 14, 1985 and climatic variables at the experimental plantation site were monitored simultaneously. Real and derived climatic variables recorded the current day and the previous day were tested for entry into multiple regression models with the daily shoot height increment change of each of the three species as the dependent variable. Maximum air temperature and the hours of daylight of the current day accounted for 69%, 59% and 55% of the variance in daily height growth of S.purpurea, S.viminalis and S.alba shoots respectively. Values of evapotranspiration determined for the previous day from measurements of net radiation and modeled values of the amount of water in the root zone, accounted for a further 10% and 3% of the variability in daily height growth of S.viminalis and S.purpurea shoots respectively. -- It is concluded from the results of this study that maximum biomass production of the three species examined will be realised at plantation sites where the climate of the growing season enables maximum photosynthetic efficiency via high inputs of solar energy and the avoidance of water deficit conditions.

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