The purpose of this study was to evaluate the effects of buttress root pruning on tree stability and to compare different methods of correlating various root parameters to force levels. Ten plantation-grown Acer rubrum (red maple) trees were pulled to an angle of one degree from vertical with measured force, then roots were individually severed near the trunk and the pull tests were repeated until roots had been pruned from 50% of the circumference. Test trees had 6 to 10 buttress roots. There was a nearly direct linear relation between the number of roots removed and the force applied. When comparing four assessment methods to determine pull force change associated with root pruning, the method that had the greatest amount of variability explained by the regression was the comparison of the cross-sectional area of roots cut to the force. However, relating the percentage of buttress roots cut to the force provided only slightly less accurate information, and was more easily collected prior to tree removal.

(With I figure in the text) F OLLOWING upon research on the anatomical structure of the seedlings and the morphology of the seed of the pineapple-the results of which were published in the New Phytologist (Thomas and Holmes (15))-interest was aroused in the food-storage products of the seed. Various hybrid forms oi Ananas seed, obtained from Hawaii, were placed at my disposal by Dr E. N. Miles Thomas, who suggested that I should begin an investigation to try and discover if any differences could be detected in the food storage products of these seeds. As the different varieties of pineapple differ in the flavour of their fruits and therefore must differ slightly in the chemical composition of their fruits it was thought that small differences might also reveal themselves in the composition of the seeds. This has been found to be the case.A study of the literature of the subject showed how complex is the problem of the composition of seeds-many factors, both environmental and hereditary, being involved in determining the products stored in any seed.The influence of heredity on seed composition has been shown in several cases by comparing the proportion of compounds fotmd in different varieties of the same plant when grown under the same external conditions. It has been shown in the case of wheat (Roberts (13)), maize (Guerrant(6)), peas (Guerrant(6)), soy-beans (Fellers(4), Lewkowitsch(iO)), cotton seed (Schwartze and Alsberg{i4)), etc., that different varieties of these plants when grown under the same conditions produce differing amounts of the various chemical products 1 I. "The development and structure of the seedling and young plant of the Pineapple." New Phyt. 29, 1930. -Part of thesis approved for the Master of Science degree of the University of London.

No abstract

Sapwood may be lost due to wood decay fungi or mechanical damage. Assessing the impact of sapwood loss on the likelihood of tree failure has not been empirically tested. The purpose of this research was to determine the effect of the loss of sapwood on the flexural stiffness of tree trunks for different species and trunk sizes. Three tree species (Acer rubrum, Liquidambar styraciflua, and Quercus acutissima) were tested at two sites using pull testing techniques. A portion of the stem was mechanically removed and the trees were again pull tested. As the percent reduction in cross-sectional area increased, the percent reduction in stress to deflect trunks decreased linearly, regardless of species. Stress from sapwood loss was compared to an equivalent calculated loss in heartwood with the same cross-sectional area. The calculated loss of heartwood to cause an equivalent magnitude of stress was almost twice as large as cut area of sapwood. Trees were also tested by pulling in opposite directions with respect to sapwood loss. The percentage reduction in stress was greater for trees tested in compression.