ISOMETRIC AND ALLOMETRIC RELATIONSHIPS BETWEEN LARGE AND SMALL‐SCALE TREE SPACING STUDIES

Abstract Basic differences in the relationship between diameter and height have been observed in small and large trees. Small trees (less than 5 m) have little danger of buckling under their own weight, and diameter is proportional to height. Large trees (greater than 5 m) are at risk of buckling under their own weight and are subject to damage from ice and wind. For large trees, diameter cubed is proportional to height squared. This relationship is suggested by the physics of limits to height of cylinders before they buckle under their own weight and has been shown to hold for large trees. Data from large‐scale spacing studies are compared with data from one‐sixteenth scale small spacing studies to determine the validity of this theory. The impact of scaled spacing on scaled diameters at equivalent scaled heights is examined. Results suggest that trees grown at small scales can be “scaled up” to reflect isometric and allometric relationships of trees grown at large scales.     

Unbalanced-bridge Computational Techniques and Accuracy for Automated Multichannel Strain-measuring Systems

While much of the current literature and practice is concerned with balance-bridge strain measurements, this paper outlines a straightforward method for measuring strain using unbalanced-bridge techniques. Exploiting the performance and stability available in today's digital voltmeters and low-cost computers, it will be shown that the use of unbalanced bridges is well suited to automated strain measurements. The paper also presents a method for assessing the accuracy of a strain-measurement system by using the specifications of the individual components. Additionally, a comparison of accuracy for balanced and unbalanced conditions is included in this assessment.