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Classification Based on "Temperament" of Species

Classification based on the growth and reproductive pattern of individual species is also useful in forest management. Oldeman and van Dijk (1991) described two contrasting growth patterns or "temperament" (sic) of tropical trees that occur within the closed forest. One type of species is called "gamblers", the other "strugglers." Species with a gambler strategy, such as Didy-mopanax morototoni in French Guyana, produce large numbers of seedlings. These cannot survive in the shaded understory but need a light gap in which they can grow rapidly. Light gaps are openings in the forest caused by the death of large canopy trees. The reproductive efforts of gamblers are high in order to increase the likelihood that at least one individual juvenile will find a gap in which to grow.

Species with a "struggler" strategy, such as Casearia bracteifa, a small un-derstory species found in French Guyana, produce small numbers of very persistent seedlings. These seedlings struggle but survive, growing very slowly within the densely shaded understory and sometimes even completing their life cycle there. The reproductive efforts of strugglers may be much lower because the life expectancy of each individual juvenile is comparatively high. Oldeman and van Dijk go on to further subdivide. For example, there are "strugglers in extreme", which are capable of completing their life cycle within the shade. Other strugglers produce juveniles that are shade-tolerant but need light gaps to mature and grow into the canopy. This type of physiological understanding about the functional role of particular species is necessary for management of that species. For example, shelterwood forestry (discussed in Chap. 5) is particularly suitable for species that are shade-tolerant but respond to opening up of a light gap. The creation of a gap by the harvest of an individual tree mimics the naturally occurring gaps.

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