Effects of irrigation and artificial drought on the growth and health of Pinus radiata near Canberra, A.C.T. [Australian Capital Territory]
1991
Snowdon, P. | Waring, H.D. (Commonwealth Scientific and Industrial Research Organisation, Canberra (Australia). Div. of Forestry)
A series of plots comparing: irrigation at 12.5 mm per week; normal rainfall; and artificial drought was established in a 9-year old stand of Pinus radiata D. Don. The degree of drought-induced dieback was inversely proportional to water supply. Mortality was at first greatest on the droughted plots but later these plots became more resistant to mortality caused by natural drought than plots which received normal rainfall. After 12 years of treatment of total basal area production was 64, 46 and 33 cu m per ha on the irrigated, normal and droughted plots respectively. Examination of seasonal growth patterns revealed that stem shrinkage occurred in all but the wettest summers. Although the treatments affected growth rates there were no clear effects on the pattern of seasonal growth. Total annual water input (rainfall plus irrigation) was an important determinant for annual volume and basal area increments. Production functions based on the outputs from a process-based model of P. radiata growth (BIOMASS) were of comparable accuracy to empirical multiple regression models.
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