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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.

Of particular interest for extractivism in tropical forest areas are useful species that occur at high density, such as the palm tucuma ˜ (Astrocaryum tucuma Martius—syn. A. aculeatum G.F.W. Meyer), a colonizer of disturbed areas in the central Amazon, whose edible fruits have found an interesting market in that region. However, with an expected increase of tucumaplantations, the future of tucumaextractivism will depend on its capacity to produce fruits not only of sufficient quantity but also of consistently high quality. We studied the productivity and fruit quality of an extractively used population of tucumapalms in an area of 9 ha within a 25 ha shifting cultivation landscape composed of crop fields, homegardens, fallows and secondary forests in the proximity of Manaus during a 24-month period. The average density of tucumapalms was 30.4 ha � 1 , with highest values in secondary forests (43 ha � 1 ) and lowest values in homegardens (19 ha � 1 ). In contrast, the percentage of productive palms was higher in fields (93%) and homegardens (88%) than in fallows (66%) and secondary forests (50%), apparently as a combined effect of previous management and delayed reproduction under shade. Fruit yield per productive palm was significantly higher in homegardens (47 kg) than in fallows (16 kg) and secondary forests (15 kg), with intermediate values in the fields (27 kg). The most productive palms produced fruits of intermediate quality as measured through a taste index, while few palms producing high-quality fruits were also high yielding. A management plan was developed that allows maximization of fruit yields while progressively improving the quality characteristics of the extractively used population in an in situ domestication process. Being a low-cost and low-risk strategy, ''improved extractivism'' can be an appropriate way of growing the arboreal weed, tucuma ˜, and can contribute to increased farm income while increasing the economic value of disturbed areas in the central Amazon. # 2004 Elsevier B.V. All rights reserved.

Kahn, F. and Mejia, K., 1990. Palm communities in wetland forest ecosystems of Peruvian Amazonia. For. Ecol. Manage., 33/34 169-179. Palm surveys in most representative wetland forest ecosystems were carried out in the lower Ucayali and upper Huallaga River valleys, in the lowland and Andean piedmont regions of Peruvian Amazonia, respectively. These ecosystems are characterized by the species association, density, and vertical distribution of their palm communities. Palms may form almost monospecific stands, e.g., Mauritia flexuosa swamps (aguajal), or multispecific communities, e.g., the seasonal swamp forests in upland valleys (bosque de quebrada) which are dominated by Euterpeprecatoria, Jessenia bataua, Mauritia flexuosa, and Socratea exorrhiza, and the forests on periodically flooded alluvial soils (restinga) dominated by some species of the genera Astrocaryum, Phytelephas, and Scheelea. Palm diversity is very low in the forests which are periodically flooded by blackwater streams (tahuampa); palm density, however, is often high with a characteristic patchy distribution due to clustered species.