A 30-year study of the effects of selective logging on a stem-less palm (Astrocaryum sociale) in a central-Amazon forest

We studied the long-term effects of different selective-logging intensities on the stem-less palm Astrocaryum sociale in a central Amazonian forest 90 km north of Manaus. The experiment consisted of three blocks of 24 ha, each divided into six 4 ha plots in which the treatments were allocated randomly. Each block had a control plot. Within each block, commercial timber was logged with intensities of 44%, 50% and 67% of basal area in 1987, 1988 and 1993 respectively. Stem-less palms in each plot were measured in 1996 and 2016. The number of individuals decreased slightly from 3229 in 1996 to 2997 in 2016, and there was an increase in the proportion of large palms. The degree of change in size structure was related to time since logging (p = 0.012), which also affected the total number of leaves (p = 0.0001), the sum of all leaf lengths (p = 0.01) and the number of adults (p = 0.056). The volume of timber extracted and in standing dead trees was not related to size-structure change. In the control block, the number of individuals changed slightly during the study period. As the different cutting intensities had little, if any, effect of the size-structure of this understory palm up to 30 years after logging, management concessions can contribute to the conservation of some elements of palm biodiversity.