S. S. Ghosh , K. Ramesh Rao , S. K. Purkayastha

Abstract

Variations in structure and quality of some Indian hardwoods are discussed with special reference to rate of growth. Though considerable work has been done in India and other countries on non-porous and ring-porous woods, hardly any information is available on diffuse-porous woods. As Indian timbers mostly belong to this group an attempt has been made in this paper to bring out some salient trends, observed at the Forest Research Institute, Dehra Dun, which may be of interest to workers in other tropical countries.

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S. S. Ghosh , K. Ramesh Rao

Abstract

This paper deals with some abnormal aspects of growth and its effect on cell structure and properties of hardwoods. While considerable work has been done elsewhere, little information was available on this aspect of tree growth in India. Observations are recorded as made recently at the Forest Research Institute, Dehra Dun, India, on the occurrence of tension wood in Indian timbers and its influence on some of their properties.

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K. Ramesh Rao , S. K. Purkayastha , R. D. Tandon

Abstract

Study of several consecutive growth rings in two samples of teak from Mysore and Kerala showed no definite relationship between ring width and proportion of tissues. The two samples also showed significant differences in proportion of tbaues though the average rate of growth is comparable.

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Manju Sharma , K. Ramesh Rao

Abstract

Silica content of 134 species of wood belonging to 80 genera and 35 families has been investigated both anatomically and gravimetrically. It has been found to be absent in 66 species. In the remaining 68 species, the silica content varies from 0.05 per cent in Cleistanthus collinus Benth. to over 7 per cent in Elaeocarpus lanceaefolius Roxb. Silica occurs in the form of inclusions in 54 species and as vitreous silica in 13 species. One species Gironniera reticulata Thw. has both the types. Silica inclusions are very commonly found in ray cells, and also to some extent in vertical parenchyma but only rarely in fibres. The inclusions are extremely variable in shape and size. Vitreous silica, unlike inclusions occurs mostly in vessels, sometimes also in parenchyma and fibres. The importance of silica in timber identification and utilization and its significance in taxonomy are also discussed.

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S. K. Purkayastha , R. D. Tandon , K. Ramesh Rao

Abstract

Anatomical studies of some tested samples of teak from seven different localities have shown that fibre wall thickness is highly correlated with specific gravity. This relationship is influenced to some extent by the proportion of fibres. Highly significant correlation has also been found to exist between fibre wall thickness and maximum crushing stress in the samples in which the wall thickness is less than 4μ.

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S. K. Purkayastha , R. D. Tandon , K. Ramesh Rao

Abstract

Study of some increment cores from 36-year-old teak trees from four seed origins grown in South Coimbatore, indicates that seed source may have a significant effect on the density of the mature wood. Increment cores from trees of two of the seed origins were also studied from another locality viz. Nilambur. Analysis of the data from these two localities suggests that the influence of environment on wood density may be greater than that of seed origin.

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S. K. Purkayastha , Krishna Lal , K. Ramesh Rao , G. S. Negi

Abstract

Variation in anatomical structure and density has been studied in the main hole of a 25 year old tree of Michelia champaca grown at Newforest, Dehra Dun. For studying the variation from pith to periphery, consecutive blocks comprising 2-3 rings were taken along one radius and at two heights. For variations from bottom to top, two growth sheaths were investigated at eight levels. All anatomical data except fibre length were collected from cross sections by the point sampling method. There is no evidence of any consistent pattern in the variation in anatomical structure within the tree. However the fibre length shows a tendeney to increase from the pith outwards and to decrease from the bottom upwards though the trend in both cases is somewhat irregular. Density values within the tree also show a similar irregular trend. Both anatomical structure and density on the whole vary within rather narrow limits within a growth sheath except near the ground level. Study of the correlation between anatomical structure and density has shown that wall thickness, diameter and length of fibres account for 77 per cent of the variation in density. The proportion of fibres appears to have no significant effect on density.

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