What loggers leave behind: Impacts on big-leaf mahogany (Swietenia macrophylla) commercial populations and potential for post-logging recovery in the Brazilian Amazon

Technical and financial analysis of enrichment planting in logging gaps as a potential component of forest management in the eastern Amazon

“…Light-demanding emergent species, including some of the highest value timber species, have been found in logging gaps at densities too low to replace harvested adults (Grogan, 2001;Pariona et al, 2003;Schulze, 2003;Vidal, 2004;Park et al, 2005). An additional management problem posed by natural regeneration in logging gaps is the tendency for saplings of timber species to become suppressed by pioneers and lianas early in succession (d 'Oliveira, 2000;Pariona et al, 2003;Vidal, 2004;Grogan et al, 2008). While saplings of many species are capable of surviving long periods of suppression until the canopy opens again through senescence of pioneers or natural wind throw, suppressed stems do not grow at rates that will allow them to attain commercial size in 50-70 years (projected time of the third harvest).…”

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“…For example, does Swietenia macrophylla (big-leaf mahogany) require large tracts of land opened by catastrophic disturbance for successful recruitment into the forest canopy (Gullison et al, 1996;Snook, 2003), or can it establish and grow to canopy dominance in much smaller single-or multiple-tree forest gaps (Brown et al, 2003;Grogan et al, 2003)? Grogan et al (2008) indicate that size-class distributions in Brazil belie the catastrophic disturbance hypothesis of regeneration and recruitment. Norghauer et al (2008) found greater germination success in the shaded understory, but better seedling growth and survival in canopy gaps.…”

“…Grogan et al (2008) found that the average cutting cycle of 30 years in Brazil does not allow for commercial population recovery of S. macrophylla if the time required to recruit from seed to commercial size is 60 years or more. Longer cutting cycles in natural forests or rotation lengths in plantations should result in higher value boles, because heartwood volume growth rate increases after diameter growth slows (Wadsworth and González, 2008).…”

“…The high-value Swietenioideae are usually early-to-late secondary, long-lived trees that reach or surpass the canopy of mature forest, and require moderate to high light for successful establishment and vigorous early growth (FAO et al, 2001;Grogan et al, 2008). Regeneration after logging is the main issue for sustaining natural forest populations.…”

Natural re generation in tropical forests

“…Several studies have used this quantification of the entire world's rainforests (Jardim & Hosokawa, 1986;Holmgren;Persson, 2002;Grogan et al, 2008;Assis & Wittmann, 2011;Gómez, 2011;Mendes et al, 2013). In this sense, the size limit of the NR is very arbitrary and depends on the objectives of the evaluation.…”