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FALSE RING OCCURRENCES AND THEIR IDENTIFICATION IN TEAK (TECTONA GRANDIS) IN NORTH-EASTERN THAILAND

K Palakit, S Siripattanadilok and K Duangsathaporn
Journal of Tropical Forest Science
Vol. 24, No. 3 (July 2012), pp. 387-398
Stable URL: http://www.jstor.org/stable/23617123
Page Count: 12
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
FALSE RING OCCURRENCES AND THEIR IDENTIFICATION IN TEAK (TECTONA GRANDIS) IN NORTH-EASTERN THAILAND
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Abstract

The objectives of this research were to identify and locate the position of false ring occurrences in natural teak (Tectona grandis) and to relate their formation to local climate variability. Vessel diameters were measured and standardised from pith towards the bark in order to identify false rings and define annual ring boundaries. Two types of false rings were classified as false ring type I and II in earlywood and latewood respectively. False ring type I had one or more rows of axial parenchyma associated with large vessels at the beginning of the annual ring. False ring type II was divided into two groups based on their characteristics. The first group had an aggregation of large vessels associated with paratracheal parenchyma while the second group did not have any paratracheal parenchyma. The occurrences of false rings could be explained by the fluctuations of rainfall and temperature during the growing season. False ring type I occurred during drought following heavy rainfall at the beginning of the monsoon period. After dense fibre occurrences in latewood, heavy rainfall and warm temperature at the end of the monsoon period re-stimulated large vessels and/or parenchymatous cells to form false ring type II. Objektif kajian ini adalah untuk mengenal pasti dan menentukan kedudukan gelang palsu dalam kayu jati (Tectona grandis) serta membuat kaitan antara pembentukan gelang tersebut dengan perubahan iklim. Diameter pembuluh diukur dan dipiawaikan dari arah empulur ke kulit kayu untuk mengenal pasti gelang palsu dan menentukan sempadan gelang tahunan. Dua jenis gelang palsu dikenal pasti iaitu jenis I dan jenis II yang masing-masing terbentuk dalam kayu awal dan kayu akhir. Gelang palsu jenis I mempunyai satu baris atau lebih parenkima aksial yang berhubung dengan pembuluh besar pada permulaan gelang tahunan. Gelang palsu jenis II terbahagi kepada dua kumpulan berdasarkan cirinya. Kumpulan pertama mempunyai pengagregatan pembuluh besar yang berhubung dengan parenkima paratrakea. Kumpulan kedua pula tidak mempunyai sebarang parenkima paratrakea. Kejadian gelang palsu dapat dijelaskan dengan turun naiknya jumlah hujan serta suhu semasa musim pertumbuhan. Gelang palsu jenis I terbentuk semasa kemarau setelah hujan lebat pada awal musim monsun. Setelah gentian tumpat terbentuk dalam kayu akhir, hujan lebat serta suhu yang panas pada akhir musim monsun merangsang semula pembuluh besar dan/atau sel parenkima untuk membentuk gelang palsu jenis II.

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