Studying interactions between pastures and Pinus radiata in Canterbury's subhumid temperature environment - the first in two years

Authors: D.J. Mead, R.J. Lucas, E.G. Mason
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1993, Issue N.Z.J.For. 38(1) 1993, pp 26-31, May 1993
Publisher: New Zealand Institute of Forestry

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Abstract: An agroforestry experiment, established in 1990, was designed to study both the potential of a range of pastures for growing under Pinus radiata in a dryland Canterbury climate and the competitive processes between the trees and pasture. The main trial consists of five pasture treatments plus a bare ground control (no competition to the trees). Within these main plots are subplots of five tree types of radiata pine; four are tissue culture clones and the fifth is a GF14 seedlot of "850" selections. Trees were planted at 1.4 by 7 m spacing. A second part of the trial consists of pasture treatments without trees. Until sheep are introduced at age three the pasture is being cut for silage.
After two growing seasons both lucerne and phalaris with clovers were causing a marked reduction to tree height and diameter growth. Pine N and K foliar levels were lower in these plots while Mg was increased. There were no statistical interactions between pasture and tree type for growth or nutrients, suggesting that specific breeds of radiata pine are unlikely to help overcome competitive effects from pasture.
At age two years the experiment has also shown that seedlings are more prone to toppling and have more malformation than the trees derived from tissue culture. While the larger trees within a tree type are more liable to topple, the fastest growing genotype from tissue culture had almost no toppling, indicating that there is also a clonal effect not related to growth rate.
Detailed process studies have begun. A better understanding of these and relative pasture!tree performance should assist the design of appropriate silvo-pastoral systems for subhumid climatic zones.

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