A 30-year study of the effects of selective logging on a stem-less palm (Astrocaryum sociale) in a central-Amazon forest
Introduction
Well-planned forest management can contribute to global biodiversity conservation (Chaudhary et al., 2016). Reduced-impact logging (RIL) techniques are considered useful tools for decreasing the rate of tropical-forest deforestation (Darrigo et al., 2016, Putz et al., 2012, Schwartz et al., 2012), can produce more profit than conventional logging (Barreto et al., 1998, Boltz et al., 2001, Holmes et al., 2002, Johns et al., 1996) and purportedly guarantee wood for the next logging cycle (Holmes et al., 2002, Johns et al., 1996, Verissimo et al., 1992). There are many studies concerning the effects of RIL on regeneration of commercial trees (Darrigo et al., 2016, de Carvalho et al., 2017, Doucet et al., 2009, Karsten et al., 2013, Rivett et al., 2016, Schwartz et al., 2012, Schwartz et al., 2013, Schwartz et al., 2017, Soriano et al., 2011), but few studies of regeneration of species with little commercial value in selectively logged areas (Clark et al., 2001, Costa et al., 2002, Dekker and De Graaf, 2003, Magnusson et al., 1999) and fewer studies evaluating the effects of logging techniques on palms (Arevalo et al., 2016).
Palms are an abundant and distinctive element in the central Amazon, found from sub-canopy to canopy, in all types of soil and topography and they exhibit a large range of growth forms (Kahn and Castro, 1985). The stem-less palm, Astrocaryum sociale, is endemic to the central Amazon region. It occurs on well drained, flat to slightly sloping areas (Kahn and Castro, 1985); the types of areas that are usually selected for logging. In these areas, stem-less palms are often the dominant component of the forest sub-canopy (Guillaumet, 1987, Kahn, 1986).
Several studies have evaluated the effects of selective logging on commercial and non-commercial species in the Manaus region (Costa and Magnusson, 2003, Lima et al., 2002, Magnusson et al., 1999). However, there are no studies of the effects of selective logging on A. sociale. The aim of this study was evaluate the effects of different logging intensities on A. sociale in an area that was selectively logged in 1987, 1988 and 1993 (Higuchi et al., 1985).
Section snippets
Study site
The study was carried out in the ZF2 Forest-Management Station (2°37′S latitude, 60°11′W longitude) of the Instituto Nacional de Pesquisas da Amazônia, 90 km north of Manaus, Brazil. The site is covered by terra firme dense tropical rainforest (Braga, 1979), with an average altitude of 124 m above sea level and undulating topography. The Bionte project was initiated in 1985 to evaluate the effects of different intensities of basal-area reduction due to selective logging. The experiment was
Results
In 1996, there were 3229 individuals in the plots, none of which had flowers or fruits. In 2016, 2997 individuals were found of which 7 had produced fruit. The number of individuals decreased over the years since logging (Fig. 1).
Part of this is explained by the time elapsed since logging (p = 0.075), but there was no evidence that reduction in wood volume affected the number of individuals (p = 0.884) (Table 1).
Although the number of individuals changed only slightly during the study, the
Discussion
The Bionte Project used a wide range of levels of selective logging and tree mortality was even greater than that estimated from the volume of wood removed (Magnusson et al., 1999). Nevertheless, effects of the intervention on the density and sizes of Astrocaryum sociale were small or nonexistent, and could not be distinguished from changes that occurred in the control blocks. Arevalo et al. (2016) evaluated the effect of reduced-impact logging (2.7 ind. ha−1) on five species of palms and they
Acknowledgment
EMH thanks FAPEAM (Fundação de Amparo a Pesquisa do Estado do Amazonas – Amazon State Research Support Institution) for granting a scholarship, Niro Higuchi for authorizing the field work in the Bionte experiment and Adriano, Armando and Sidnei for help in the field. LBA allowed João Araujo de Souza to help during field work. The CENBAM team, Andresa de Melo Viana, Michael R. de Oliveira, Ilderlan Viana and Maria Aparecida de Freitas provided logistic support and guidance. WEM received a
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