Canopy and litter interception of rainfall by hardwoods of eastern United States

All available reports of rainfall interception by hardwoods of the eastern United States were reviewed and, where possible, combined. Results from these independently designed and analyzed experiments showed that hardwood throughfall and stemflow vary over a surprisingly narrow range. Combined regression analysis describes the relation between inches of gross rainfall (P), throughfall (T), and stemflow (S) for summer as T = 0.901P ‐ 0.031, S = 0.041P ‐ 0.005; for winter as T = 0.914P − 0.015, S = 0.062P ‐ 0.005. These equations can be modified for specified forest conditions or for use with seasonal rainfall. Fifteen standard gages were found necessary to sample the growing season throughfall within 5% error limits, and 6 were necessary for the dormant season. Hardwood litter interception, studied inadequately in most parts of the east, amounted to 2 to 5% of the annual rainfall in the southern Appalachians. Applicability of equations to research and to practical problems is discussed as well as need for further research.