Growth and Mortality of a 1925 Planting of Pinus radiata on Pumice

Authors: S.H. Spurr
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1959, Issue N.Z.J.For. 8(4) 1962, pp 560-569, Jan 1962
Publisher: New Zealand Institute of Forestry

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Abstract: Annual measurements of seven sample plots totalling 1.97 acres in area in a 1925 planting of Pinus radiata (D.Don) on Taupo pumice in the North Island were made available by N.Z. Forest Products Ltd., and analysed in detail to provide records of yearly mortality and gross forest production. These data document the life of this stand from 8 to 35 years with a gap of 5 years from ages 13—17 inclusive.
At age 35, gross mean annual increment (MAI) was 516 cu.ft total volume inside bark per acre per year and nett MAI 332. Gross current annual increment (CAI) reached a maximum of 714 cu.ft per acre per year for the 5 years ending at age 20, but still amounted to 565 for the 5 years ending at age 35.
Mortality was persistent from age 12 through age 33, with 6436 cu.ft total volume per acre being lost, a value amounting to 55 percent of the nett volume of 11618 cu.ft standing at age 35, and 36 percent of gross total production to that age.
By carrying forward separately the computations of each annual mortality group of pines, it was found that trees destined to die in a given year invariably declined in annual basal area increment over at least the 12 years prior to death, whereas trees surviving at age 35 maintained their annual basal area increment to a much greater degree. When their annual basal area increment dropped below 0.02 sq.ft, trees on the average had 8 years to live regardless of the actual cause of death. Removing such trees would inevitably increase overall health in the residual stand.

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