Measuring light in uneven-aged hardwood stands

Abstract

Light, essential in the development of a forest, can be controlled within a stand by silvicultural practices. Measuring it, however, has always been a problem for silvicultural researchers. And accurate measurements are necessary, especially in studying the relation between light and reproduction. The desired objective is to measure the total visible light in specific units at a given place and for a given period in the forest stand. Often it is also necessary to compare the amount of light received at many different places in a forest during the same period. The Integrating Light Meter (1, 4) (fig. 1) fulfills all the requirements for a good instrument but it is too expensive to be used in large numbers. The problem then is to find a way to get similar results with less expensive and more portable instruments. Atkins (1) compared a Norwood Director incident light meter, which gave instantaneous readings in foot-candles, with the Integrating Light Meter measuring cumulative light in even-aged white pine stands. These two meters gave closely corresponding results when exposed at the same time and place. The purpose here is to describe an extension and adaptation of Atkins' work for measuring cumulative light within hardwood stands, and to illusstrate the method by some study results. The validity of the light data obtained by this method is shown by a comparison with data taken with the Integrating Light Meter (4).

Citation

Minckler, Leon S. 1961. Measuring light in uneven-aged hardwood stands. Tech. Pap. No. 184. Columbus, OH: U.S. Department of Agriculture, Forest Service, Central States Forest Experiment Station. 9 p.