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The aim of the study was to evaluate the effects of thinning intensity on wood properties, such as heartwood proportion, wood basic density, and stem form of teak (Tectona grandis L.f.). The thinning trial was established on a teak plantation in a humid tropical site in northern Costa Rica. The moderate and heavy thinnings yielded the highest percentage of heartwood volume (25 to 30% of total stem volume). The differences between stem form factors under different treatments were not statistically significant after separating thinning effects from timing effects. Both the highest (> 0.65 g cm) and the lowest (< 0.50 g cm) wood density values were observed under light thinnings, making it difficult to establish a relationship. Large variations in wood properties found under different thinning regimes suggest that at early stages teak stands can be managed under different thinning programs without negatively affecting the quality of wood under humid tropical conditions.â3â3

The aim of this study was to evaluate the heartwood, sapwood and bark content, and wood dry density in young and mature teak (Tectona grandis) trees. For this, 17 plantations were selected from 11 sites representing different climatic conditions and plantation densities (156 to 1600 trees haâ1, and line planting). From these plantations, a total of 87 trees with ages between 5 and 47 years were felled for stem analysis. The highest heartwood proportion of stem volume (over bark) was 61% and the lowest 0.4%. The sapwood proportion ranged between 24 and 72%, while bark represented from 14 to 37% of the total volume. Heartwood proportion was significantly different (P < 0.05) among climatic zones: âwetâ sites producing less heartwood than âdryâ sites. Stem diameter (under bark) and heartwood diameter at different stem heights differed among sample trees, even when plotted in relative values to avoid dependency with stem size. Dry density was statistically different between 8-year-old trees or younger and 47-year-old trees, and between line planting trees and 13-year-old trees or younger, but did not differ statistically between line planting trees and mature trees. No significant differences were found between climatic zones or between different stand densities. Dry density values for T. grandis plantations in Costa Rica are similar to those reported elsewhere.

The aim of the study was to compare the behaviour of three selected provenances of F. Muell. that were likely to respond differently to drought. For this purpose, we studied the effects of vapour pressure deficit and soil water content on leaf water potential in an irrigated plantation in Bura, eastern Kenya.Eucalyptus microthecaEucalyptus microtheca

Shoot elongation of Royle ex Gordon was studied using 2-year old grafts in a clonal seed orchard of the Pine Improvement Centre, located at the Huey Bong Experimental Station near Chiangmai, Thailand (19° 17â N, 99° 15â E, 900 m a.s.l.).Pinus kesiyaP. kesiya

This paper describes the design and functioning of an electronic auxanometer designed for field use, and some results obtained with it. The changes in stem radius are monitored with a micrometer screw turned by an electirc motor. A potentiometer transforms the position of the screw into an electronic signal, which is recorded. The accuracy of the device is approximately 1â2 μm. Field experiments with the auxanometer are described and discussed. The accuracy of the device was found to be sufficient for measuring hourly changes in stem radius. The PDF includes a summary in Finnish.

Branching and terminal growth of lateral shoots and needle growth of Scots pine ( L.) is investigated as a function of the whorlâs position and age and prevailing light climate. Number of buds per whorl was linearly and positively related to the whorlâs position and prevailing light climate. The growing whorlâs number counting from the apex was associated with declining bud number. The terminal growth of lateral shoots increased exponentially within the values 0.6â1.0 of the whorls position. Under these values the terminal growth was negligible. The growing whorlâs number indicated curvlinear decrease in shoot growth respectively, and only negligible growth occurred when the whorlâs age exceeded 10 years. The shoot growth was linearly related to the prevailing light climate but differences between dominating and dominated trees were apparent. The distribution of needle growth in the crown system was similar to that of shoot growth.Pinus sylvestris

Crown and stem growth of young Scots pines ( L.) were studied in relation to photosynthate supply and light condition in a stand. The magnitude of needle and bud formation, and radial and height growth were to a great extent dependent on the photosynthate supply. However, in shaded conditions the growth of each characteristics was greater than expected on the basis of photosynthate supply. In the stem system this was especially apparent for height growth. Consequently, height growth was favoured at the expense of radial growth in shaded conditions. It also appeared that the basic density of wood was negatively related to both tree position and photosynthate supply.Pinus sylvestris

A system for measuring the net photosynthesis, transpiration and environmental factors within the canopy and ground cover vegetation is described. The system operates continuously throughout the growing season in a young Scots pine ( L.) stand. A data-logging unit controls the system and carries out the measurements on the readings of the sensors of photosynthesis, transpiration, light intensity outside the canopy, light climate inside the assimilation chambers, and dry and wet temperatures from selected points. These measurements are shown digitally and automatically punched onto paper tape.Pinus sylvestris

The architecture of Scots pine ( L.) was studied in an eight-year-old progeny test. The measurements included characteristics of crown structure, spatial distribution of shoots and yield components. The spatial distribution of shoots showed striking between-tree differences, and two extreme distribution patterns were detected. One represented a non-layered structure with a vertically relative even shoot distribution, and the other a layered structure with a vertically highly uneven shoot distribution.Pinus sylvestris

The daily height growth rate of several larch species and progenies (, ) grown in a plastic greenhouse and in the open was measured. The growth pattern indoors was completely different compared with the normal outdoor growth pattern. The onset of growth took place in the greenhouse much earlier than outdoors and the phase of increasing growth was much shorter, as was expected. However, the phase of maximum growth was unexpectedly long. This fact suggests that there is great potential for using greenhouse cultivation to change the growth pattern of cultivated plants in order to obtain more complete utilization of the potential growing season.Larix deciduaLarix sibirica, Larix laricina, Larix leptolepis