Interception of rainfall by a redwood canopy in the north coast of California

Rainfall interception losses and net throughfall amounts were compared with gross rainfall in a redwood (Sequoia sempervirens ABSTRACT: (D. Don) Endl.) stand in the fall season of 1970. A total of 15 storms were studied. Since stemflow was shown to be insignificant, interception loss was the difference between gross rainfall and net through- fall. The study area was the NW1/4, SE1/4, Sec. 28, T5N, R1E in Freshwater, California. Five study plots were used, each containing six sample trees. Trees of dominant, co-dominant, and intermediate crown classes were used. Basic number 10 cans were used as "catch cans" and placed at intervals of 2, 4, and 6 feet from the tree bole. Recording raingages were used to measure gross rainfall. Net throughfall ranged from 60.4% to 82.8% of gross rainfall. Net throughfall is a linear function of gross rainfall and is closely correlated to storm intensity, rainfall amount, and crown length. There also seems to be a relationship between net throughfall and basal area per acre but since I only sampled certain clusters of trees as a part of the entire stand and thus do not have acceptable "samples" of stand stocking, this can only be stated as a possible relation. Average interception losses were found to range from 17.2% to 36.9% of gross rainfall and crown length, and is also closely related to storm intensity, storm frequency, rainfall amount and possibly to basal area per acre.