Juliana Stropp’s research while affiliated with The Joint Commission and other places

Biodiversity inventories present excellent opportunities for ecological investigations and the classification of different threats to the community, nonetheless these applications are not frequently employed. Our main objective was to determine the tree and palm community within a one-hectare areas, also exploring the association between functional attributes and the projected threat of category for the future (by 2050) in a conservation unit situated within the Brazilian Amazon Deforestation Arc. We established a rectangular plot (10x1000m) to assess the community structure. Information on seed and fruit size attributes was obtained from the literature, along with data on the projected threat category. Overall, two taxa (Rubiaceae sp.and Rhizophoraceae sp.) were characterized only at the family level, 106 at the genera level (morpho-species) and 124 until binomial name. We found information about seed size for 55 genera. Medium-sized seeds were the most frequent, occurring in 22 genera, followed by large seeds (16), small seeds (6), and very small seeds (5). As for the projected threat status for 2050, we found that 28 species were classified as vulnerable and 16 species as endangered. In our plot we founded a few numbers of species with many individuals. We conclude that floristic studies associated with ecological approach carried out in the southwestern region of the Brazilian Amazon are rare and our study, provides a significant contribution to biodiversity knowledge.

Peatlands are some of the world’s most carbon-dense ecosystems and release substantial quantities of greenhouse gases when degraded. However, conserving peatlands in many tropical areas is challenging due to limited knowledge of their distribution. To address this, we surveyed soils and plant communities in Colombia’s eastern lowlands, where few peatlands have previously been described. We documented peat soils >40 cm thick at 51 of more than 100 surveyed wetlands. We use our data to update a regional peatland classification, which includes a new and possibly widespread peatland type, “the white-sand peatland,” as well as two distinctive open-canopy sub-types. Analysis of peat bulk density and organic matter content from 39 intact peat cores indicates that the average per-area carbon densities of these sites (490 to 1230 Mg C ha-1, depending on type) is 4 to 10 times the typical carbon stock of a (non-peatland) Amazonian forest. We used remote sensing to upscale our observations, generating the first data-driven peatland map for the region. The total estimated carbon stock of these peatlands of 1.91 petagrams (Pg C) (2-sigma confidence interval, 0.60 to 4.22) approaches that of South America’s largest known peatland complex in the northern Peruvian Amazon, indicating that substantial peat carbon stores on the continent have yet to be documented. These observations indicate that tropical peatlands may be far more diverse in form and structure and broadly distributed than is widely understood, which could have important implications for tropical peatland conservation strategies.

Understanding how the traits of lineages are related to diversification is key for elucidating the origin of variation in species richness. Here, we test whether traits are related to species richness among lineages of trees from all major biogeographical settings of the lowland wet tropics. We explore whether variation in mortality rate, breeding system and maximum diameter are related to species richness, either directly or via associations with range size, among 463 genera that contain wet tropical forest trees. For Amazonian genera, we also explore whether traits are related to species richness via variation among genera in mean species-level range size. Lineages with higher mortality rates—faster life-history strategies—have larger ranges in all biogeographic settings and have higher mean species-level range sizes in Amazonia. These lineages also have smaller maximum diameters and, in the Americas, contain dioecious species. In turn, lineages with greater overall range size have higher species richness. Our results show that fast life-history strategies influence species richness in all biogeographic settings because lineages with these ecological strategies have greater range sizes. These links suggest that dispersal has been a key process in the evolution of the tropical forest flora.

Although species taxonomy is an ever-evolving discipline, taxonomic change is rarely accounted for in macroecological studies. By tracking the history of species description and synonymizations of more than 900 described names of Amazonian palms, we reveal shifts in species counts across space and time, the factors associated with taxonomic lumping, and the time needed to detect synonyms. The Amazonian palm flora results from a gradual accumulation of new descriptions, followed by decline due to the recognition of approximately 800 heterotypic synonyms. Most of these synonyms were detected in the mid-1990s, leading to a 4.5-fold decrease in species counts in ten years. The time to detect synonyms ranged from 3 to 227 years. Species with large populations, widespread distributions, early descriptions, also those that occur in Western Amazonia were more frequently lumped. The impact of taxonomic change on species counts is dependent on taxa, region, and time period considered. Biases in these counts are pronounced in the absence of taxonomic revisions, as undetected synonyms can inflate estimates of species richness. By quantifying the magnitude of such bias, this study offers conceptual and methodological insights on how incorporating taxonomic progress into macroecological analyses can provide a more accurate understanding of biodiversity patterns.

Leaf and wood functional traits of trees are related to growth, reproduction, and survival, but the degree of phylogenetic conservatism in these relationships is largely unknown. In this study, we describe the variability of strategies involving leaf, wood and demographic characteristics for tree genera distributed across the Amazon Region, and quantify phylogenetic signal for the characteristics and their relationships. Leaf and wood traits are aligned with demographic variables along two main axes of variation. The first axis represents the coordination of leaf traits describing resource uptake and use, wood density, seed mass, and survival. The second axis represents the coordination between size and growth. Both axes show strong phylogenetic signal, suggesting a constrained evolution influenced by ancestral values, yet the second axis also has an additional, substantial portion of its variation that is driven by functional correlations unrelated to phylogeny, suggesting simultaneously higher evolutionary lability and coordination. Synthesis. Our results suggest that life history strategies of tropical trees are generally phylogenetically conserved, but that tree lineages may have some capability of responding to environmental changes by modulating their growth and size. Overall, we provide the largest‐scale synopsis of functional characteristics of Amazonian trees, showing substantial nuance in the evolutionary patterns of individual characteristics and their relationships. Read the free Plain Language Summary for this article on the Journal blog.

Tree growth and longevity trade-offs fundamentally shape the terrestrial carbon balance. Yet, we lack a unified understanding of how such trade-offs vary across the world’s forests. By mapping life history traits for a wide range of species across the Americas, we reveal considerable variation in life expectancies from 10 centimeters in diameter (ranging from 1.3 to 3195 years) and show that the pace of life for trees can be accurately classified into four demographic functional types. We found emergent patterns in the strength of trade-offs between growth and longevity across a temperature gradient. Furthermore, we show that the diversity of life history traits varies predictably across forest biomes, giving rise to a positive relationship between trait diversity and productivity. Our pan-latitudinal assessment provides new insights into the demographic mechanisms that govern the carbon turnover rate across forest biomes.

We describe the geographical variation in tree species composition across Amazonian forests and show how environmental conditions are associated with species turnover. Our analyses are based on 2023 forest inventory plots (1 ha) that provide abundance data for a total of 5188 tree species. Within-plot species composition reflected both local environmental conditions (especially soil nutrients and hydrology) and geographical regions. A broader-scale view of species turnover was obtained by interpolating the relative tree species abundances over Amazonia into 47,441 0.1-degree grid cells. Two main dimensions of spatial change in tree species composition were identified. The first was a gradient between western Amazonia at the Andean forelands (with young geology and relatively nutrient-rich soils) and central–eastern Amazonia associated with the Guiana and Brazilian Shields (with more ancient geology and poor soils). The second gradient was between the wet forests of the northwest and the drier forests in southern Amazonia. Isolines linking cells of similar composition crossed major Amazonian rivers, suggesting that tree species distributions are not limited by rivers. Even though some areas of relatively sharp species turnover were identified, mostly the tree species composition changed gradually over large extents, which does not support delimiting clear discrete biogeographic regions within Amazonia.

Understanding the spatiotemporal distribution of species is fundamental for ecology, evolution and conservation. However, this and other aspects of biodiversity knowledge suffer from shortcomings and biases. Quantifying and mapping biodiversity knowledge shortfalls is therefore crucial to ascertain the current quality and completeness of biodiversity data, prioritize sites for (re)sampling, or plan conservation interventions. Here, we compile a comprehensive dataset of Orthoptera occurrences, and use it to create a global 'ignorance map' based on taxonomic, survey and temporal completeness, and on survey and temporal evenness of the inventories. We hypothesize that knowledge of Orthopteran biodiversity is relatively poorer in tropical regions compared to temperate regions, and in the south compared to the northern hemisphere. Due to biocultural factors, we expect regions in the tropics and the Global South to have lower levels of completeness and evenness in time and space for all the studied aspects of biodiversity information. Our findings show gaps in the knowledge of orthopteran distributions, which are characterized by low survey and temporal evenness in tropical regions, but also in many temperate regions (e.g., most of the countries in temperate Asia). The combination of multiple dimensions of biodiversity knowledge (taxonomic, spatial and temporal) reveals that biogeographic interpretations based on only one component can lead to an illusion of completeness. We believe that the novel framework used in our study can guide future research towards building more accessible maps of biogeographical ignorance for entire groups.

Aim Aposematic animals, i.e., those that are defended and warn potential predators through signals, are suggested to have resource‐gathering advantages against non‐aposematic ones. We here explore this in a biogeographic framework expecting that aposematic species are better dispersers, which translates into larger geographic range size. Location South America. Taxon Poison frogs (Amphibia; Aromobatidae and Dendrobatidae). Methods We use 43 toxic and 26 non‐toxic poison frog species from the lowlands only as representatives of aposematic and non‐aposematic study organisms, respectively. Realised and potential geographic ranges are calculated using minimum convex polygon and species distribution modelling methods, respectively. Accounting for species body size and phylogeny, we test if both range and aposematism are correlated using linear mixed‐effects models. Results Aposematic and non‐aposematic species neither differ in realised nor in potential geographic range size. There was no effect on body size. Main Conclusions The role of aposematism is not yet as clear as suggested and determinants of poison frog range sizes are multifaceted. A more integrative approach is needed using the information on behaviour, predation risk, and reproductive biology to assess the role of aposematism on observed species distributions. Such data are not yet available for most species, neither poison frogs nor other aposematic animals.