Partitioning of Environmental and Taxonomic Controls on Brazilian Foliar Content of Carbon and Nitrogen and Stable Isotopes

Abstract

The Neotropics harbor some of the most diversified woody species in the world, and to understand the nutrient dynamics in these ecosystems, it is crucial to understand the role of plant taxonomy. In addition, biological nitrogen (N) fixation (BNF) in the tropics is one of the key processes affecting the global N cycle. Our objective was to (i) investigate the role of taxonomy and sampling site as predictors of foliar carbon (C) and N concentration and its stable isotopes (i.e., δ13C and δ15N); (ii) assess differences in foliar N, C:N ratio, and δ15N among three functional groups: species of N2-fixers and non-fixers of the Fabaceae family, as well as non-Fabaceae species; and (iii) examine the effect of wood density on tree foliar properties. We hypothesized that Fabaceae specimens in symbiosis with N2-fixers would possess a higher foliar N than non-fixing plants, including those of the Fabaceae family, as well as high-density trees would have higher foliar C and C:N ratio relative to low-density trees, where the latter invest in nutrients instead of structural C. We used a data set composed of 3,668 specimens sampled in three main biomes of Brazil: Amazon, Atlantic Forest, and Cerrado. The partitioning of variance had a higher influence of taxonomy on leaf C, N, and C:N ratio. Conversely, foliar δ13C and δ15N were environmentally constrained. While family was the most important taxonomy level for C, N, and C:N ratio, species played a major role for δ13C and δ15N. Foliar N followed the pattern fixers > non-fixers > non-Fabaceae, while C:N ratio had an opposite trend. In addition, foliar C was correlated with wood density, where high-density > medium-density and low-density woods. The large variability of δ15N was observed among Fabaceae species, demonstrates the complexity of using δ15N as an indicator of BNF. The higher foliar N of Fabaceae non-fixers than non-Fabaceae specimens support the hypothesis that an N-demanding lifestyle is an inherent pattern in this family. Lastly, although observed in some studies, the prediction of foliar properties using wood density is challenging, and future research on this topic is needed.

Wood trait preferences of Neotropical xylophagous beetles (Coleoptera: Cerambycidae)

“…Cerambycines tended to emerge in greater numbers from host plants belonging to Fabaceae, the legume family (Figure 2); this could explain why cerambycines emerged in greater numbers from wood that contained lower δN15 levels (Figures 2 and 3d; Table 3). Many legumes have a notable symbiotic association with bacteria that can fix atmospheric nitrogen into a form that is usable for the plant (Martin et al., 2014; Martinelli et al., 2021). Plants that have symbioses with bacteria that fix atmospheric nitrogen tend to have lower δN15 levels relative to plants that do not have these symbioses because 15 N is discriminated against in biochemical processes as a heavier isotope than 14 N (He et al., 2009).…”

Phylogenetic patterns of rarity and vulnerability in the flora of a temperate mountain range

“…To better understand how rarity is distributed among different taxonomic levels, we fitted a Bayesian random effect model for each rarity type (binomial for endemism and Gaussian for scaled and centered RGR, HS and LA) with rarity as dependent variable and a random effect consisting of genus nested within family and both nested within order. This method partitions the variation (variance for RGR, HS and LA, and deviance for endemism) of each rarity type among taxonomic levels and an unexplained residual component, while considering the nested nature of taxonomic classification (Asner and Martin 2016, Oliveras et al 2020, Martinelli et al 2021). Models were fitted using uninformative priors and four Markov chains with 4000 iterations each, a thinning interval of 10 and a burn‐in period of 1000 iterations.…”

Post-Extraction Novel Ecosystems Support Plant and Vegetation Diversity in Urban-Industrial Landscapes

“…One gene altering the tolerance of a plant to stress can significantly increase the amount of biomass in a particular ecosystem. The differences in species composition and abundance of Fabaceae in vegetation patches can influence the nitrogen cycle [64]. The wide range of adaptive abilities of living organisms allows them to grow in de novo established habitats.…”