Recruitment dynamics of two low-density neotropical multiple-use tree species

Abstract

In the present study, we describe the temporal and spatial variability in recruitment, growth, and mortality rates of seedlings and saplings of two low-density neotropical tree species, Dipteryx odorata and Copaifera reticulata in Eastern Amazonia, Brazil. As both species have important timber and non-timber uses, for each species we compare regeneration parameters among different management scenarios (sites used for timber logging, nontimber product extraction, and undisturbed forests). Results suggest that both species share similar natural regeneration characteristics. These include temporally and spatially asynchronous germination, existence of individuals that have more abundant and frequent fruit production than the average of the population and a positive influence of the mother tree crown on seedling and sapling density. The management activities analyzed did not influence the regeneration parameters of both species, which suggests that timber logging the way it was performed and current rates of D. odorata seed gathering and C. reticulata tapping at the study site are not sufficiently intense to threaten species population. However, some species characteristics, such as their reproductive strategies, light-demanding syndromes, low-dispersal ranges, and high-mortality rates of seedlings make both species vulnerable to exploitation. (Résumé d'auteur

Population structure of two low-density neotropical tree species under different management systems

“…These heavy fruiting events are frequent in tropical forests (de Steven, 1994;Norden et al, 2007), and include the two species studied (Herrero-Jáuregui et al, 2011). Based on the results of this study and those published by Herrero-Jáuregui et al (2011), it is reasonable to attribute light-demanding characteristics to these two species, which has major implications for their sustainable management. The comparison of the diameter structure in the different management situations studied can shed some light on the impacts of management, particularly in the case of D. odorata.…”

Mid-term effects of reduced-impact logging on the regeneration of seven tree commercial species in the Eastern Amazon

“…Despite an increase in recruitment rate of D. odorata in the first year after harvesting, RIL did not affect its density. Herrero-Jáuregui et al (2011), in the same national forest, found no effects of logging on the recruitment of D. odorata. Although low numbers of individuals, H. courbaril increased its density in the logged areas by year six after logging.…”

“…In tropical forests, regeneration may depend on natural disturbances (Fredericksen and Putz, 2003). Disturbances caused by logging may affect regeneration of valuable tree species in different ways (Gómez, 2011;Herrero-Jáuregui et al, 2011). Canopy opening increases the density and growth rates of both light-demanding (Nabe-Nielsen et al, 2007) as well as shade-tolerant species (Toledo-Aceves et al, 2009).…”

Determining the optimal harvest cycle for copaíba (Copaifera spp.) oleoresin production

“…This three-year figure has already been given by empirical studies (Leite et al, 2001 andPinto et al, 2010), although Newton et al (2011) disagree with this minimum interval between successive extractions. Some papers do suggest longer cycles (e.g., 8 years in Herrero-Jáuregui et al, 2011). In summary, no consensus exists in the literature on the optimal cycle of copaíba oleoresin harvesting.…”

“…Also unknown is how much oleoresin can be removed without causing damage to the wider ecological and physiological processes surrounding this species, which management factors influence production, (Plowden, 2003(Plowden, , 2004Medeiros and Vieira, 2008) and the level that can be extracted sustainably. Some researchers (Herrero-Jáuregui et al, 2011) argue that the extraction of copaíba oleoresin does not affect the regeneration of the species.…”