An Instrument for the Continuous Determination of Leaf Thickness Changes in the Field

Abstract

The paper deals with the construction and use of an instrument which measures changes in leaf thickness. Results obtained in the field with four tree species are presented. Changes in thickness were of an individual nature for each leaf; collectively the leaves of one tree species differed in their thickness changes from those of others. Changes in leaf thickness were mainly due to changes in the volumes of special water-storage tissues. Leaf water content changes and leaf thickness changes determined simultaneously in the laboratory were well correlated, provided that the thickness changes did not exceed those occuring m the field. Several of the factors which influenced changes in leaf thickness were measured.The march of leaf temperature was found to be correlated most closely with the march of leaf thickness.