[Aboveground biomass input of Myristicaceae tree species in the Amazonian Forest in Peru]. / Aporte de biomasa aerea de las especies arb6reas de la familia Myristicaceae en los bosques Amazonicos del Peri.

Amazonian forests are a vast storehouse of biodiversity and function as carbon sinks from biomass that accumulates in various tree species. In these forests, the taxa with the greatest contribution of biomass cannot be precisely defined, and the representative distribution of Myristicaceae in the Peruvian Amazon was the starting point for designing the present study, which aimed to quantify the biomass contribution of this family. For this, I analyzed the databases that corresponded to 38 sample units that were previously collected and that were provided by the TeamNetwork and RAINFOR organizations. The analysis consisted in the estimation of biomass using pre-established allometric equations, Kruskal-Wallis sample comparisons, interpolation-analysis maps, and nonparametric multidimensional scaling (NMDS). The results showed that Myristicaceae is the fourth most important biomass contributor with 376.97 Mg/ha (9.92 Mg/ha in average), mainly due to its abundance. Additionally, the family shows a noticeable habitat preference for certain soil conditions in the physiographic units, such is the case of Virola pavonis in "varillales", within "floodplain", or Iryanthera tessmannii and Virola loretensis in sewage flooded areas or "igapo" specifically, and the preference of Virola elongata and irola surinamensis for white water flooded areas or "varzea" edaphic conditions of the physiographic units taken in the study.

Aporte de biomasa aérea de las especies arbóreas de la familia Myristicaceae en los bosques Amazónicos del Perú / Aboveground biomass input of Myristicaceae tree species in the Amazonian Forest in Perú

Amazonian forests are a vast storehouse of biodiversity and function as carbon sinks from biomass that accumulates in various tree species. In these forests, the taxa with the greatest contribution of biomass cannot be precisely defined, and the representative distribution of Myristicaceae in the Peruvian Amazon was the starting point for designing the present study, which aimed to quantify the biomass contribution of this family. For this, I analyzed the databases that corresponded to 38 sample units that were previously collected and that were provided by the TeamNetwork and RAINFOR organizations. The analysis consisted in the estimation of biomass using pre-established allometric equations, Kruskal-Wallis sample comparisons, interpolation-analysis maps, and nonparametric multidimensional scaling (NMDS). The results showed that Myristicaceae is the fourth most important biomass contributor with 376.97Mg/ha (9.92Mg/ha in average), mainly due to its abundance. Additionally, the family shows a noticeable habitat preference for certain soil conditions in the physiographic units, such is the case of Virola pavonis in “varillales”, within “floodplain”, or Iryanthera tessmannii and Virola loretensis in sewage flooded areas or “igapó” specifically, and the preference of Virola elongata and Virola surinamensis for white water flooded areas or “várzea” edaphic conditions of the physiographic units taken in the study.

Los bosques amazónicos son un gran almacén de biodiversidad y funcionan como sumideros de carbono debido a la biomasa aérea que acumulan en las diversas especies arbóreas, sin embargo, no se puede definir con exactitud cuál es el taxón con el mayor aporte de biomasa aérea. La representativa distribución de las Myristicaceae R. Br. en la Amazonía peruana fue el punto de inicio para plantear el presente estudio, el cual pretende cuantificar el aporte de biomasa aérea de esta familia en estos bosques. Para este estudio se utilizaron las bases de datos de 38 unidades muestrales recolectadas y proporcionadas por las organizaciones RAINFOR y TeamNetwork. Con estos datos se realizó la estimación de la biomasa aérea por medio de ecuaciones alométricas pre-establecidas, contraste de muestras con la prueba de Kruskal-Wallis, mapas de interpolación y un análisis de ordenamiento de escalamiento multidimensional no paramétrico (NMDS). Los resultados sugieren que Myristicaceae R. Br. es la cuarta familia más importante en aporte de biomasa aérea acumulada con 376.97Mg/ha (9.92Mg/ha en promedio) debido principalmente a su abundancia. Adicionalmente, la familia muestra una evidente preferencia de hábitat por determinadas condiciones edáficas dentro las unidades fisiográficas, tal es el caso de Virola pavonis en los “varillales”, dentro de “planicies inundables”, o de Iryanthera tessmannii y Virola loretensis en áreas inundadas de aguas negras o “igapó” específicamente, y de Virola elongata y Virola surinamensis en áreas inundadas de aguas blancas o “várzea”.

Taxonomic scale-dependence of habitat niche partitioning and biotic neighbourhood on survival of tropical tree seedlings.

In order to differentiate between mechanisms of species coexistence, we examined the relative importance of local biotic neighbourhood, abiotic habitat factors and species differences as factors influencing the survival of 2330 spatially mapped tropical tree seedlings of 15 species of Myristicaceae in two separate analyses in which individuals were identified first to species and then to genus. Using likelihood methods, we selected the most parsimonious candidate models as predictors of 3 year seedling survival in both sets of analyses. We found evidence for differential effects of abiotic niche and neighbourhood processes on individual survival between analyses at the genus and species levels. Niche partitioning (defined as an interaction of taxonomic identity and abiotic neighbourhood) was significant in analyses at the genus level, but did not differentiate among species in models of individual seedling survival. By contrast, conspecific and congeneric seedling and adult density were retained in the minimum adequate models of seedling survival at species and genus levels, respectively. We conclude that abiotic niche effects express differences in seedling survival among genera but not among species, and that, within genera, community and/or local variation in adult and seedling abundance drives variation in seedling survival. These data suggest that different mechanisms of coexistence among tropical tree taxa may function at different taxonomic or phylogenetic scales. This perspective helps to reconcile perceived differences of importance in the various non-mutually exclusive mechanisms of species coexistence in hyper-diverse tropical forests.