Performance ofPodocarpus falcatusProvenances in South Africa

Abstract

SYNOPSIS Podocarpus falcatus, a canopy tree of the mixed evergreen forests in South Africa, is planted in riparian zones in commercial forestry areas. In 1982 provenance trials were initiated to evaluate the performance of 11 provenances in three experimental sites: De Hoek in the northeastern Transvaal; Frankfort in the eastern Transvaal; and Witfontein in the southern Cape. Only five provenances were planted in all three sites. The great variation in fruit and seed mass could not be related to latitudinal or locality differences of origin of the provenances. Germination capacity ranged between 3 and 94%, but the differences were related to periodically unsuitable environmental conditions during fertilisation of the ovule rather than genetic variation. For most provenances the germination rate over time followed the normal pattern of a sharp increase in germination during October, about 50 weeks after sowing. However, seed from the sub tropical Zululand coast germinated after 10 weeks and continued to germinate without a dormancy period, which suggested a genetic shift with adaptation to the warm, moist conditions along the coast. Tree growth rate showed much promise. At De Hoek the Wonderwoud provenance, the closest source area, performed best with mean DBH of 14,2 em and mean height of 8,2 m for the 25 tallest trees after 11 years. At Frankfort the Mariepskop provenance, the closest source area, performed best with mean DBH of 10,5 em and mean height of 8,2 m for the tallest 10 trees after 11 years. At Witfontein the Amatole forest provenances performed best with mean DBH of 9,0 cm and mean height of 5,6 m for the tallest 15 trees after 8,5 years. MAI20years for P. falcatus Woodbush provenance at De Hoek was calculated as 5,8 m3/ha compared to 17,3 m3/ha for Pinus elliottii for the De Hoek plantation. The monetary value of the timber of P. falcatus at age 20 years is, however, higher than that of the timber of P. elliottii. Several recommendations are made: the three experimental plantings should be maintained with application of appropriate silvicultural treatment; for future commercial plantings seed should be collected from several trees of good form and vigour in the immediate source area of the planting site; clonal gains trials should be established for demonstration purposes and to obtain information on which top selections are clonally repeatable; if commercial plantings are to be continued, studies should be initiated on water use of the species, genetic variation of ecotypes of the species, and variation in timber properties of the provenances.