Techniques for Management of Secondary Forests

The techniques used in management of secondary forests are generally similar to those used in management of primary forests, consisting of some type of selective management, generally followed by silvicultural treatments. Forest enrichment techniques are also often used as a way to increase the biological and economic value of secondary forests (Montagnini et al. 1997). Forest enrichment techniques are discussed in Chapter 6.

In refining secondary tropical forests, foresters select crop trees according to their prospective marketability, present size relative to maturity, form, freedom from injuries, and apparent health. If there is advanced regeneration of shade-tolerant, late-successional species (preferred crop trees) and the canopy is dominated by light-demanding mid-successional species, the only way to successfully regenerate another secondary stand is to remove all commercial volume at once in a monocyclic system (Guariguata 2000). In contrast, if a stand has plenty of shade-tolerant poles of good commercial value, a polycyc-lic system may be possible. Finegan (1992) suggested rotations of 15-25 years for neotropical secondary forests with light-demanding commercial species, depending on species composition and production goals. Silvicultural treatments should be applied when a closed canopy of longer-lived species has been formed. Under a monocyclic system, treatments will focus on liberating light-demanding crop trees from competition in the canopy, while under a polycyclic system, both light-demanding canopy species and advanced regeneration of shade-tolerant species are considered for liberation (Kammesheidt 2002; Box 5.4).

Table 5.2. Annual median diameter increment (in cm) of crop trees of the species studied, 2 years after thinning in a young secondary forest in the Caribbean lowlands of Costa Rica. (Data from Guariguata 1999)

Species Control Thinned

Table 5.2. Annual median diameter increment (in cm) of crop trees of the species studied, 2 years after thinning in a young secondary forest in the Caribbean lowlands of Costa Rica. (Data from Guariguata 1999)

Species Control Thinned

Laetia procera

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