In a study conducted by Roucoux et al. (2013) in Amazon forest, a total of 14 species were recorded in an area of 0.5 ha, being the most representative: M. flexuosa, Mauritiella armata (Mart) and Tabebuia insignis (Miq.) Sandwith. Endress et al. (2013), in a M. flexuosa swamps in an Amazon forest on Peru, identified 138 tree species in 12 plots with 0.1 ha each where M. flexuosa was also the most representative. In the Mauritia flexuosa palm swamps in the Brazilian savanna (veredas), the floristic richness is generally high (Araújo et al. 2002), however, most species are herbaceous, when analyzed only with DBH> 10cm, these areas are also shows low richness.
The families with greatest species richness were: Melastomataceae with seven species; Annonaceae, Malvaceae and Salicaceae with four species each, Anacardiaceae, Arecaceae, Burseraceae, Moraceae with three species. The families with the greatest number of individuals were Arecaceae (224), Vochysiaceae (82), Meliaceae (56), Malvaceae (42), Salicaceae (42) and Melastomataceae (23), which combined comprised 94.6% of the total of individuals recorded. The greater number of species of the family Arecaceae is expected, considering that the area has a monodominant species. M. flexuosa was the most abundant species with 222 individuals, having more than twice as many individuals as the second most abundant species Qualea acuminata Spruce ex Warm., with 82 individuals and five times more than the third most abundant Trichilia cipo with 43 individuals (Table 1).
M. flexuosa had the highest IVI (46.19%) and was the dominant specie at the study area. M. flexuosa combined with Q. acuminata (9.21%) and T. cipo (4.69%), composed more than 60.0% of the 55 species IVI (Table 2). M. flexuosa also showed the highest basal area (26.81 m2 / ha), relative density (37.88%), relative dominance (87.53%) and
171 Natural resources in wetlands: from Pantanal to Amazonia
Of 54 species sampled, 24 species had a single individual, classifying it as “rare” or “locally rare” species, an expressive number, representing almost 50% of the species. Sander et al. (2017) obtained a smaller percentage, 9 of 25 species were considered rare in a monodominant M. flexuosa forest in southwest Mato Grosso. In this case, the high concentration of rare species can be explained by the fact that this community is under the influence of the flood pulse. According to Junk and Da Silva (1999) e Junk and Wantzen (2004), floods are a preponderant factor for the distribution of plants and favors species that present ecological adaptation to floods. The plots of this study are not located in areas of floods with great amplitude duration, not presenting this driver as regulator or conditioning factor.