140 E. R. C.REYNOLDS AND L.LEYTON 



pretation would be incomplete without reference to other phases of the 

 cycle. For example, evaporation from a forest includes both transpiration 

 and evaporation of intercepted water, and because these two phenomena 

 are related, measurements of one or the other alone are of hmited value ; 

 similarly, studies on soil moisture must also take into account the pattern 

 of throughfall distribution. 



In view of their importance, it has been the purpose of this communica- 

 tion to stress the need for techniques, which by virtue of their precision 

 and practicability, can be incorporated into water balance studies. It has 

 been shown that reasonably precise estimates of throughfall could be 

 obtained by using troughs with relatively large collecting areas, but a 

 suitable technique has still to be developed for the ineasurement of pre- 

 cipitation incident on the stand, since precipitation measurements made 

 on nearby open ground are inadequate. Attention has been largely restricted 

 to these two measurements, but investigations arc continuing on the 

 development of techniques to measure the other components of the water 

 balance. 



ACKNOWLEDGMENTS 



Mr. J. F. Scott (Unit of Biometry, Oxford University) has given invaluable 

 advice and help with the statistical aspects of this study. Dr. A. Carlisle 

 (Nature Conservancy) was associated with the initial work. Mr. J. Kemp, 

 through the co-operation of the Forestry Commission, has considerably 

 assisted the investigation. We are pleased to acknowledge the financial 

 support of the Department of Scientific and Industrial Research. 



REFERENCES 



BuRGY, R.H. & POMEROY, C.R. (1958) Interception losses in grassy vegetation. 



Trans. Amcr. Geophys. Un. 39, 1095-1100. 

 Delfs, J. (1955) Die Niederschlagszuriickhaltung ini Walde (Interception). Mitt. 



Arhcitskr. 'Wald mid IVasser'. (Koblenz); 2, 7-54. 

 KiTTREDGE, J., LouGHEAD, H.J. & Mazurak, A. (1941) Interception and stem flow in 



a pine plantation. J. For. 39, 505-522. 

 Law, F. (1957) Measurements of rainfall, interception and evaporation losses in a 



plantation of Sitka Spruce. Paper read to nth Gen. Assem. (Toronto) Int. Ass. 



Hydrology. 

 NiEDERHOF, C.H. & WiLM, H.G. (1943) Effect of cutting mature Lodgepole Pine 



stands on rainfall interception. J. For. 41, 57-61. 

 VoiGT, O.K. (i960) Distribution of rainfall under forest stands. For. Set. 6, 2-10. 

 Wight, C.L. (1941) An approach to the study of rainfall interception by forest 



canopies. J. S. Afr. For. Ass. 6, 54-7°. 



