Brazilian Amazonian palm-stem types and uses: a review

Palms may be an important source of renewable raw material to replace wood, however, the uses of the stems of native species of the Brazil are known only at the local or regional level. We carried out a literature review on the traditional knowledge of the uses of the stems of palm species native to the Amazon biome in Brazil, and related the types of uses with morphological characteristics of the stems. The review resulted in information on 45 species with solitary or cespitose stems, and six stem-size types: tall (15 species), medium-short (3), medium (5), small (17), acaulescent (1) and climbing (4). We found 80 indications of stem use in seven categories and 14 subcategories. A similarity analysis showed that, in general, tall, medium-short, medium, small (≥ 10 cm in diameter) and climbing stem types, solitary or cespitous, are used for construction, furniture, handicrafts, utensils, tools and musical instruments. Only small stems (< 10 cm diameter) are used to manufacture weapons for hunting and fishing, and climbing stems are used in the manufacture of ropes. Stems of Socratea exorrhiza, Euterpe oleracea and Desmoncus polyacanthos are the most frequently used to meet subsistence needs in traditional communities in the Brazilian Amazon. Our findings indicate that there is a potential for use of several native palm stems as sources for alternative materials in the manufacture industry and as sustainable income sources for Amazonian communities.


INTRODUCTION
There are about 378 species of 71 genera of palms (Arecaceae/ Palmae) in Brazil, distributed in all Brazilian biomes. The greatest diversity is known from the Amazon region, where 148 native species have been listed (Soares et al. 2020). Several Amazonian species are endemic and under increasing pressure due to deforestation (Alvez-Valles et al. 2018).
Palms are the main source of natural resources for populations living in the Amazon region (Santos and Coelho-Ferreira 2012), satisfying subsistence needs in various categories of use, such as food, construction, handicrafts, fibers, medicine, cosmetics, textiles and biodiesel, among others (Zambrana et al. 2007;Macía et al. 2011;Bernal et al. 2011;Pennas et al. 2019). Most species are only known regionally or locally and therefore their traditional use and VOL. 51(4) 2021: 334 -346 ACTA AMAZONICA contribution to human well-being and the regional economy are unknown to the general public . This traditional knowledge is of fundamental importance for the conservation and sustainable exploitation of useful palms, supporting programs for the management of natural resources and implementation of economic development in local communities (Zambrana et al. 2007). Furthermore, woody monocots, prominently including palms, are increasingly being considered as a source of renewable raw material to replace eudicotyledonous and coniferous wood (Trindade and Máximo 2017;El-Mously et al. 2019), and as options for crop diversification to create investment opportunities with the generation of new products (Corandin et al. 2018).
Despite not forming actual heartwood, stems are among the most commonly used parts of palms, reportedly for construction, handicrafts and daily utensils, among other purposes (Vilhena-Potiguara et al. 1987;Miranda et al. 2001;Rocha and Silva 2005;Oliveira et al. 2006;Araújo et al. 2016). In this context, the objective of this review was to survey the recorded uses of stems of palm species native to the Brazilian Amazon and to relate uses to stem morphological types.

Survey of palm species with recorded stem use
Palm species native to the Amazon biome in Brazil with some recorded use of its stem were surveyed in print and digital media. All phytophysiognomies occuring in the Brazilian Amazon were considered: terra firme forest, floodplain forest, swamp forest, ombrophylous forest, riparian or gallery forest, savanna forest, campina (white-sand grass/shrublands), campinarana (white-sand forest), restinga (sandy coastal plain vegetation) and ironstone outcrops. The following information was extracted for each species of surveyed palm: species, local name, habit, stem type, use category, use subcategory, forms of use, distribution in the Brazilian Amazon, references and distribution in Brazil ( Table 1). The uses of the stems surveyed in literature were classified in categories and subcategories according to Macía et al. (2011). The latter authors carried out a review on the use of palms in northern South America, and classified the ethnobotanical uses of specific plant parts into ten categories, each divided into subcategories. When the ethnobotanical information was not classifiable within any subcategory, it was assigned the subcategory 'other'. The compiled list of scientific names of species recovered from our survey was checked and updated, when necessary, using the lists of Flora do Brasil (2020) and SpeciesLink (2021). Recorded stem-use categories were mapped by state included in the Amazon biome based on the study areas in the literature sources, when provided.
Palm-stem types were defined according to , who classified tropical palm species of South America into eight forms of growth, based on maximum sizes of attributes such as leaf size, absence or presence of aerial stem and aerial stem length and diameter. Within each form of growth, the species are further classified as cespitose or solitary (Table 2).

Statistical analysis
In order to evaluate the association between stem characteristics and uses, data of the stem-type, use categories and use subcategories (Table 1) were organized in a binary matrix of presence (1) and absence (0). The matrix was subjected to cluster analysis performed with the Vegan 2.5-7 package, in the R software (R Core Team 2021). Species with greater similarity in relation to the analyzed characteristics were grouped using the unweighted pair-group method with arithmetic mean (UPGMA) (Sneath and Sokal 1973) with the Jaccard coefficient.

SPECIES WITH RECORDED STEM USE
We recovered 43 literature references with records of the use of stems of 45 species of native palms in the Brazilian Amazon (Table 1). The work of Miranda et al. (2001) had the highest number of cited palm species (24), followed by Lorenzi et al. (2010) (16), Miranda and Rabelo (2008) (16) and Shanley and Medina (2005) (7). More than 50% of the studies mentioned only one or two palm species regarding stem use.

Species
Local

AMAZONICA
Knowledge on the uses of palm stems was retrived from riverine, quilombola (settlements originating from runaway slaves), rubber tapper, family farmer, artisan and extractivist communities, as well as indigenous communities of the Yanomami tribe in the state of Amazonas (Anderson 1977), the Yawanawá and Kaninawá in the state of Acre (Campos and Ehringhaus 2003), the Ti Araçá in the state of Roraima (Ribeiro 2010) and the Karipuna in the state of Amapá (Fonte et al. 2015). Most studies were carried out in riverine communities. At the state level, most citations were from Pará (25), followed by Amazonas (13), Acre (12), Roraima (6), Mato Grosso (5), Maranhão (3) and Rondônia and Amapá with one citation each ( Table 1).
The 45 surveyed palm species belong to the subfamilies Arecoideae and Calamoideae (Table 1). Arecoideae had the greatest number of representatives, with 41 species distributed in two tribes, six subtribes and 15 genera, four of which with spiny stems (Table 1). Calamoideae was represented by only four species belonging to one tribe, two subtribes and three genera (Table 1).
Oenocarpus Mart. and Euterpe Mart. were the genera with the highest number of species with stem-use citations relative to the total number of species known for the genus in the Brazilian Amazon (five of six species, and three of four species, respectively), followed by Desmoncus Mart. (four of nine species), Astrocaryum G.Mey (six of 21), Bactris Jacq. ex Scop. (11 of 35), and Attalea Kunth (two of 14) and Syagrus Mart. (two of six species) ( Table 2). Iriartea deltoidea was citeded in an area of the Brazilian Amazon where there is no confirmed occurrence record of this species (Table 1).
The 45 cited species represent about 28% of the 161 palm species recognized for the northern region of Brazil, and 30% of the 148 species recognized for the Brazilian Amazon (Soares et al. 2020). In northwestern South America, information on the use of palm stems was retrieved for 59% of the 134 species occurring in the Amazon region (Macía et al. 2011). The record of use of Iriartea deltoidea is evidence of its presence in the state of Pará (Alves et al. 2014), which expands its area of occurrence in Brazil. This finding is relevant, as palms remain a poorly sampled group with little representation in Amazonian herbaria (Rocha and Silva 2005;Henderson 2011). Palms are frequently difficult to collect due to the presence of spines, the large size of vegetative and reproductive structures, the high and unbranched stems and to that individuals are frequetly sterile (Anderson 1977;Miranda et al. 2001;Ammann 2014;Rocha 2017), resulting in that most records are field observations (Henderson et al. 1995;Miranda and Rabelo 2008).
Traditional knowledge on the uses of Brazilian Amazonian palm parts, especially their woody or fibrous stems, has been investigated in local communities in the states of Pará and Amazonas (Anderson 1977;Vilhena-Potiguara 1987;Miranda et al. 2001;Rocha and Silva 2005;Oliveira et al. 2006;Santos and Coelho-Ferreira 2012;Germano et al. 2014;Santos et al. 2016). Publications for other parts of the biome are still rare (e.g., Flores and Lima 2013). Although indigenous peoples have broad and diverse ethnobotanical knowledge about the use of palms in the Amazon (Bernal et al. 2011;Macía et al. 2011;Wallace 2014;Smith 2015), few publications mentioned palm-stem uses by indigenous communities in the Brazilian Amazon (Anderson 1977;Campos and Ehringhaus 2003;Ribeiro 2010;Fonte et al. 2015). Most studies have focused on the subsistence, economic and sociocultural importance of palm species in riverine communities, which are more easily accessible (e.g., Jardim and Cunha 1998;Rodrigues et al. 2006;Santos and Coelho Ferreira 2011;Almeida and Jardim 2012;Lima et al. 2013;Germano et al. 2014;Araujo et al. 2016).
The surveyed literature generally did not present detailed information about the study areas or the charcteristics of the palms, such as development stage or height and diameter of the used stems. In this sense, the use of the classification by Balslev et al. (2011), though preliminary, was useful, as it is based on very basic characteristics, allowing categorization in the absence of detailed information. More standardized and informative surveys will be necessary to account for the wider amplitude in forms of growth and stem architectures, and the plasticity resulting from the development in different types of soil, hydrology, temperature, topography, incidence of sunlight and disturbance levels (Kahn and de Graville 1992; Balslev et al. 2011;Salm et al. 2011;Muscarella et al. 2020).

STEM TYPES AND USES
The cited palm species have solitary or cespitose habit, with six types of stem-growth form (Figure 1; Table 1). The species with the greatest number of uses have cespitose stems (29 species, 64%) and are especially small palms (Bactris) or climber palms (Desmoncus) (Figure 2a; Table 1). Among species that do not branch, i.e., with solitary stems (16 species, 36%), the tall stem type was the most representative ( Figure 2a; Table 1).
The stems were used mainly for utensils and tools (41 citations), construction (22), cultural (8), environmental uses  (5), human food (2), fuel (1) and other uses (1), for a total of 80 indications of use. Utensils and tools are manufactured with all six stem types of all size categories (Figure 2b; Table  1). Tall-stem types were the most used in all categories of use, except for utensils and tools (Figure 2b). Only the stems of tall, medium and small palms were reportedly used for making musical instruments, such as flutes, drums, reco-recos (scraper percussion instrument), spears with rattle, trumpets and violas.  Figures 1l; 3i-l), in the form of handicrafts marketed in municipal markets, fairs, warehouses and specialised shops in the states of Pará and Roraima (Flores and Lima 2013;Santos et al. 2016). The cluster analysis formed four distinct groups ( Figure  4). The first group contained only one solitary tall species that is used for construction. The second group comprised tall, medium and acaulescent palms with solitary stems also used for construction, environmental uses, utensils and tools, except for one species that is only recorded as used for utensils and tools (Mauritia carana). The third group was formed by cespitose, small palms (10 species of Bactris) and climbing palms (four species of Desmoncus), which were used, respectively, for handicrafts (arrowheads) and handicrafts, utensils and fishing traps, except for four species that were also used in construction: Bactris brongniatii (roofs and walls), Bactris maraja (fishing corrals), Iriartella setigera (floors and walls) and Wettinia augusta (floors and walls). The fourth group was composed of tall, medium-short and medium cespitose palms used for construction, utensils and tools, except for four species that were exclusively cited for construction (Astrocaryum murumuru, Euterpe catinga, Raphia taedigera and Mauritia armata). One species was used for firewood (Euterpe oleracea) and another as organic fertilizer (Bactris gasipaes). In the first group, two species of tall-stem palms were used for starch (Astrocaryum aculeata and Mauritia flexuosa) and two for larvae food (turus) (Mauritia flexuosa and Oenocarpus bacaba). Five species distributed in the three largest groups were used for manufacturing musical instruments (Astrocaryum jauari, Bactris gasipaes, Iriartea deltoidea, Iriatella setigera and Socratea exorrhiza) (Figure 4; Table 1).
Despite being broad-scaled, our analysis indicated that species with both solitary or cespitose stems are employed in all use categories, although specific stem types are associated with specific forms of use. In particular, small cespitose stems of Geonoma deversa, Hyospathe elegans, Iriartea setigera, Oenocarpus minor and ten species of Bactris were used by indigenous peoples to make hunting tools such as blowgun, bows, arrows, harpoons and spears for being hard but flexible (Miranda et al. 2001;Campos and Ehringhaus 2003;Miranda and Rabelo 2008;Lorenzi et al. 2010). Cespitose climbing stems of Desmoncus are used to make baskets, ropes and various utensils, such as tipitis, an indigenous technology found only in the Brazilian Amazon, developed to remove the toxic liquid from bitter cassava (Manihot esculenta Crantz) (Carney and Hiraoka 1997;Smith 2015). Desmoncus polyacanthos fibers are considered more flexible and resistant than those of other species used to make tipitis, such as the petiole of Ischnosiphon obliquus (Rudge) Körn (Marantaceae) and the leaves of Mauritia flexuosa and Oenocarpus bacaba (Miranda et al. 2001;Wallace 2014;Smith 2015). The fibrous climbing stems of Desmoncus are used in a similar way as Asian rattan (Uhl and Dransfild 1987), and are the only type of stems commercialized in northern Brazil, as household utensils and decoration (Flores et al. 2013;Santos et al. 2016). Yet, its potential for industrial use remains little explored (Miranda et al. 2001). In fact, the uses of many species of palm trees are not recorded in the literature (T. Kikuchi, pers. obs.), such as the tall stems of the Patauá palm (Oenocarpus sp.), which are used to manufacture utensils that can be found in craft stores and fairs (Figure 3m), highlighting the need for further studies that focus on ethnobotanical knowledge of useful palm species in the Amazon region (Macía et al. 2011).
The stems of tall, medium-short and medium, solitary or cespitose palms are the most valuable for construction and production of utensils, accessories, tools and handicrafts, due to the resistance and workability of their wood (Anderson 1977;Miranda et al. 2001;Miranda and Rabelo 2001). Stems of acaulescent, medium-short and small types are less valuable and used only as an alternative when there is a shortage of more suitable species (e.g., Attalea spectabilis) (Anderson 1977), or when certain species are locally abundant (e.g., Astrocaryum vulgare, Bactris brongniatii, B. maraja, Iriartella setigera and Oenocarpus minor) (Souza et al. 2010;Jardim and Cunha 1998). Locally abundant, resistant species are also associated with a higher number of use citations (Germano et al. 2014), both in floodplain and terra firme environments, such as Astrocaryum aculeata, A. aculeatum, A. jauari, A. rodriguesii, A. tucuma, A. vulgare  in harvesting these palms, which have been replaced as raw material over the years in construction and manufacture of utensils by industrialized materials (Rocha and Silva 2005;Germano et al. 2014;Smith 2015).
Only the stems of Astrocaryum jauari, Bactris gasipaes, Iriatella setigera, Iriartea deltoidea and Socratea exorrhiza were mentioned for the manufacture of musical instruments, especially by indigenous Kaxinawá in Acre state (Campos and Ehringhaus 2003). The wood of these species probably has the anatomical, physical and mechanical properties to provide ideal resonance features. These species were also reported in most other use categories, showing their importance to meet the basic subsistence needs of traditional communities in the Brazilian Amazon (Santos and Coelho-Ferreira 2012;Gernano et al. 2014).
In the environmental use category, stems were used to make organic fertilizer (Figure 3p), fences and enclosures for vegetable gardens and gardens (Lorenzi et al. 2010;Germano et al. 2014). In the fuel category, wood from Euterpe oleracea is used for heat bricks (Miranda et al. 2001). In the human food category, sap, and starch similar to the sago used for porridge are obtained, respectively, from the stems of Acrocomia aculeata and Mauritia flexuosa (Miranda et al. 2001;Miranda and Rabelo 2008). In the category of other uses, it was mentioned that the wood from rotten stems of Mauritia flexuosa and Oenocarpus bataua that were in contact with water from floodplains or rivers, are consumed by molluscs called turu, which, in turn, are used as a food source by many riverine communities (Miranda et al. 2001;Gomes-Silva 2005). The use of palm stems as a source of larvae of Rhyncophorus palmarum (Coleoptera), which are used for human consumption, is the most cited in the other use category in the Amazon of Colombia, Ecuador, Peru and Bolivia (Macía et al. 2011). More forms of use for the stems of many palm species could probably have been registered in the utensils and tools category if they had been described in detail by the citing authors beyond generic terms such as "handicrafts" and "artifacts".
In the western Amazon, the stems of Bactris gasipaes, Iriartea deltoidea, Oenocarpus bataua, O. mapora and Socratea exorrhiza were the most used by traditional peoples, especially indigenous peoples, in various categories of use, such as construction, cultural, environmental uses, fuel, human food, medicines and veterinary medicine, utensils and tools and other uses (Macía et al. 2011). Among these species, Bernal et al. (2011) described the stems of Euterpe oleracea, Iriartea deltoidea, Socratea exorrhiza and Desmoncus polyacanthos as the most important for construction and crafts in South America, but their uses are still restricted to local or regional domestic consumption. The stem uses of these same species were also the most cited for the Brazilian Amazon.
The traditional knowledge on the uses of palm species contributes to the conservation of palm-trees and to devise sustainable alternative sources of income for local communities (Thoma et al. 2016), and provides an invaluable information source for prospection of new materials and biotechnological applications. Among current studies on industrial applications of palm-stem products, coconut palm (Cocos nucifera L.) stems have been used in the production of biocomposites for parcial or total replacement of conventional building materials such as steel, concrete and bricks (González et al. 2019), in addition to stems of Astrocaryum aculeatum and Bactris gasipaes (Figure 3n-o), that have potential for the development of new products for the furniture industry (Miranda and Rabelo 2008;Trindade and Máximo 2017). The formulation of public policies is necessary to systematize the knowledge on the use of Brazilian Amazonian palm species and to promote the rational use and appreciation for products generated from the woody or fibrous palm stems, in all cases ensuring the conservation and sustainability of the extraction.

ACKNOWLEDGMENTS
We are grateful to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -CAPES (Brazil) -Finance Code 001, and Conselho Nacional de Desenvolvimento Científico e Tecnológico -CNPq (Brazil) for fellowships and research grants; to Dr Warlen Silva da Costa for support in the statistical analysis. We would also like to thank the reviewers and editors for all of their careful, constructive and insightful comments on our manuscript. This study was financed in part by CNPq and by Fundação Carlos Chagas Filho de Amparo à Pesquisa do Rio de Janeiro (FAPERJ). The study was part of the doctoral thesis of the first author at Programa de Pós-Graduação em Biologia Vegetal of Universidade do Estado do Rio de Janeiro.