21 - Tree growth
Woodlots ranging in area from 0.18 to 0.5 ha were established within the Cicerone Project farmlet trial on the Northern Tablelands of New South Wales, Australia, due to a lack of physical protection in most paddocks across the farmlets. Two percent of each farmlet was planted to trees to examine the commercial and environmental potential of seven species to provide shade and shelter for livestock, increase biodiversity or contribute to cash flow through farm forestry diversification. Eucalyptus caliginosa (timber), E. nitens (timber, pulp wood), E. radiata (essential oil) and Pinus radiata(timber) were planted in four upslope plots (1059–1062 m a.s.l.) in different paddocks. Casuarina cunninghamiana(timber, shelter), E. acaciiformis (shade, shelter and biodiversity), E. dalrympleana (timber, biodiversity), E. nitens (timber, pulp wood), E. radiata (essential oil) and P. radiata (timber) were planted in four low-lying plots (1046–1050 m a.s.l.) in separate paddocks, 400–1200 m distant. The pines and natives were planted in August and October 2003, respectively, into a well prepared, weed-free, mounded, planting bed. After 5 years, P. radiata (98% survival) and E. nitens (83%) survived best in upslope plots, reaching maximum heights of 7.8 and 8.8 m and exhibiting no or only modest insect damage, respectively. In low-lying plots, E. acaciiformis (75% survival) and E. dalrympleana (80%) survived best, reaching maximum heights of 5.5 and 4.5 m, and exhibiting little or only moderate insect damage, respectively. P. radiataexhibited 17–69% survival in the two lowest-lying plots but 100% survival in the other two lowland plots. On average, <50% of C. cunninghamiana, E. nitens and E. radiata survived in low-lying plots and survivors grew poorly. Early frosts in March 2004 were the primary cause of losses in low-lying plots, and frost, waterlogging, insect attack and some inadvertent livestock browsing explain the slower growth of species in low-lying plots compared with their performance upslope. P. radiata and perhaps E. nitens have commercial promise for timber production on Northern Tablelands farms, but only in higher (well drained, less frost-prone) parts of the landscape. E. acaciiformis can withstand the stressful growing conditions in open pasture in low-lying plots, and should be planted more widely for on-farm shade and shelter.E. dalrympleana can also be considered for amenity and biodiversity plantings in lower parts of the landscape.
Five-year survival and growth of farm forestry plantings of native trees and radiata pine in pasture affected by position in the landscape
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