Performance to age 22 years of 49 eucalypts in the Wairarapa District, New Zealand, and review of results from other trials

摘要

Trials of 49 eucalypt species were established in 1979 in the Wairarapa district at Kahuiti and Pakaraka, New Zealand, originally to test species for their potential to stabilize erodable land for pastoral use. Trials were planted in a randomized complete block design with five replications of four-tree row plots of each seedlot (paired rows of four trees of species with only a single seedlot). The species included Corymbia maculata E. maculata, E. cladocalyx, four stringybarks (including E. muellerana and E. globoidea), nine ashes (including E. fastigata, E. regnans, and E. obliqua), seven peppermints, and 18 gums (including E. nitens). Because of heavy thinning at Pakaraka, the Kahuiti trial only was assessed at age 22 years on production forestry criteria: diameter at breast height (dbh), stem straightness, malformation, crown health, and number of potential 5-m sawlogs per tree. The 12 best-grown species for mean tree dbh at Kahuiti, were ranked: E. globoidea, E. muellerana (stringybarks),E. obliqua, E. fraxinoides, E. regnans (ashes), E. cordata (gum), E. delegatensis, E. fastigata, E. sieberi (ashes), E. cinerea, E. kartzoffiana, and E. nitens (gums). The ashes, with addition of E. nitens, showed a combination of best diameter growth (apart from the two stringybarks), straightest stems, least malformation, good crown health, and largest number of sawlogs per tree of all groups. The peppermints were generally slower-growing and more sinuous than the ashes. Some of the gums grew well andmost survived better on this adverse, eroded site than the other groups. Superiority of E. fastigata and E. obliqua was confirmed by other trials in Hawke's Bay and the Wairarapa region. The apparent good growth and health of E. globoidea and E. muellerana in the Wairarapa district, also reported in trials in Northland, hint at the potential of these known good sawtimber species.