Branch Occlusion After Pruning In Four Contrasting Sub-Tropical Eucalypt Species

Smith, R.G.B., and Dingle, J., and Kearney, D., and Montagu, K., (2006) Branch Occlusion After Pruning In Four Contrasting Sub-Tropical Eucalypt Species. Journal of Tropical Forest Science, 18 (2). pp. 117-123. ISSN 0128-1283

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Affiliations

Forests New South Wales - Northern Research, Australia
Forests New South Wales - Northern Research, Australia
Forests New South Wales Research Division, Australia
Forests New South Wales Research Division, Australia

Abstract

Branch related defects are the major cause of degrade in eucalypts grown for solid wood. The effects of pruning on the growth and branch occlusion in Eucalyptus cloeziana, E. pilularis, E. dunnii and E. grandis were studied. Trees of each species were pruned to remove 30% of the green crown at 3.5 years of age. Diameters and the state of all branches in two 0.5 m sections of trunk were assessed at one, two and four years after pruning. Growth rates were unaffected two years after pruning in all species. In all species, except E. cloeziana, the rate of occlusion of dead branches was not significantly different between pruned and unpruned branches. In contrast, the greatest difference in occlusion rates was between pruned and unpruned live branches. Eucalyptus grandis and E. dunnii showed high early rates of occlusion compared with E. pilularis and E. cloeziana for the first year. The occlusion rates of unpruned branches generally showed a positive correlation between branch size and time to occlusion. Relationships were more complex in species that self-pruned less efficiently. Since occlusion rates in dead branches (pruned and unpruned) were similar, there would be little benefit in pruning dead branches and it may increase susceptibility to decay entry and the occurrence of loose knots. Pruning only green branches may be difficult in efficient self-pruning species.

Kecacatan dahan merupakan penyebab utama kemerosotan Eucalyptus yang ditanam untuk kayu padu. Kesan pemangkasan terhadap pertumbuhan dan taupan dahan E. cloeziana, E. pilularis, E. dunnii dan E. grandis dikaji. Pokok berumur 3.5 tahun dipangkas 30% daripada silara hijaunya. Semua dahan pada dua bahagian batang pokok yang berukuran 0.5 m direkod diameternya dan dinilai keadaannya pada satu, dua dan empat tahun selepas pemangkasan. Kadar pertumbuhan bagi semua spesies tidak berubah untuk dua tahun selepas pemangkasan. Untuk dahan mati, kadar taupan bagi dahan yang dipangkas tidak berbeza dengan ketaranya daripada dahan yang tidak dipangkas. Ini diperhatikan dalam semua spesies kecuali E. cloeziana. Sebaliknya, kadar taupan paling ketara antara dahan hidup yang dipangkas dengan dahan hidup yang tidak dipangkas. Eucalyptus grandis dan E. dunnii menunjukkan kadar taupan yang lebih tinggi daripada E. pilularis dan E. cloeziana untuk tahun pertama. Kadar taupan dahan tak pangkas secara amnya menunjukkan korelasi positif antara saiz dahan dengan masa taupan. Hubungan adalah lebih kompleks dalam spesies yang pemangkasan sendirinya kurang efisien. Oleh sebab kadar taupan dalam dahan mati (pangkas dan tak pangkas) adalah sama, memangkas dahan mati tidaklah berfaedah. Pemangkasan mungkin meningkatkan kerentanan terhadap jangkitan dan menggalakkan kejadian buku gegai. Pemangkasan dahan hijau mungkin susah dalam spesies yang pemangkasan sendirinya efisien.

Item Type:

Journal

Keywords:

Crown dynamics, self-pruning, wood quality, solid wood production, forests and forestry, eucalytus trees

Subjects:

S Agriculture, Forestry

ID Code:

9081