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- A complete model of growth and branching of European black pine
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Interview
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The
European black pine, a native of Corsica and Calabria, has been widely used for reforestation in France since the nineteen-fifties. It is the third most popular conifer for the purpose, covering 144,000 hectares. Its excellent growth rate cannot rival the Douglas fir's but may still be as high as 20 m3 per hectare per year, 30% better than its closest direct competitor, the Scots pine.Its trunk is remarkably
straight, the straightest of all the pines.
It does however exhibit a handicap which may detract from the quality of its
timber: it forks frequently, especially in fertile locations.
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Plot on black pine plantation thinned to 800 stems per hectare |
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From plant to plank
Most of the black pine stands in France are less than thirty years old and sylvicultural practices may vary. Yet it is a little-known tree and it gradually became apparent that a decision-making aid was needed to assess the effect of management practices on the quality of the timber produced. In 1995, Cemagref, IDF and INRA undertook a joint 'complete pine' research programme, aiming to produce a suite of computer programs simulating the consequences of different sylvicultural operations on growth and timber quality. The four-year study was the subject of a doctoral thesis by Céline Meredieu. It was made possible by virtue of the data from fifteen years' monitoring records from an experimental network compiled by Cemagref at Nogent sur Vernisson and IDF. More data was gathered by means of specific field investigations: stem analysis (reconstitution of past growth in terms of height and diameter), branching measurements (branch diameter and length) and timber quality determinations (laboratory measurements of wood density and strength).
Unique complete model
The unique feature of the model is that it combines a model of tree growth in a stand with a model referring to timber quality in sawmill terms. The black pine growth model was based on the Austrian black pine on calcareous soil developed by INRA. It develops five principal dynamic relationships describing dominant tree height growth, individual diametrical growth, height versus diameter of each tree, annual mortality probability, and stem and bark profiles. The model's branching components are statistical relationships between stem and branch characteristics describing the branching of a tree of a given age.
These models were incorporated into INRA's CAPSIS growth simulation software which can run simulations on real or fictitious stands, providing a basis for selecting the sylvicultural methods which best suit objectives and available resources. Number, date, type and nature of tasks required on the stand, any scenario can be considered and compared. All that is needed is input data which is readily available in the field. By coupling it with INRA's WINEPIFN program, one can predict quality.
Better understanding of forest ecology
Besides helping forest managers take decisions, the study yielded many scientific results. The black pine findings even contested an established law in forestry science. The density of the stand was found to have a significant effect on dominant tree height, yet the Eichorn law states that height growth is dependent only on forest site fertility. With the black pine, Céline Meredieu successfully demonstrated that tree height growth depends on the space allotted them (on the competition). Another new finding was that timber density and growth rate are relatively independent of each other, an exceptional situation with a conifer.
The complete suite is now operational. An economics model is in preparation son be added. Now Cemagref and its partners have to pursue their work on validating these models, on the possibility of extensions, and on making them available to practising forest managers.
- Interview
with Francis Colin, research scientist, INRA (Nancy)
and with Philippe Riou-Nivert, engineer, forestry development institute IDF
© Cemagref, updated 2003
Contact : info@cemagref.fr |
