Nuevos registros para la flora vascular de Colombia presentes en la Orinoquia y reseña histórica de las expediciones botánicas a la región

18 new records to the vascular flora of Colombia found in the Orinoquia region are recorded: Duguetia riberensis Aristeg. ex Maas & Boon, Trigynaea duckei (R .E. Fr.) R. E. Fr. (Annonaceae); Tassadia medinae (Morillo) Morillo (Apocynaceae); Jaracanda orinocensis Sandw. (Bignoniaceae); Polycarpaea corymbosa (L.) Lam. var. brasiliensis (Cambess.) Chodat & Hassl. (Caryophyllaceae); Murdannia burchellii (C. B. Clarke) M. Pell. y M. aff. triquetra (Wall. ex C. B. Clarke) G.Brückn (Commelinaceae); Enterolobium barinense L. Cárdenas & Rodr.-Carr., Machaerium tovarense Pittier, Muellera crucisrubierae (Pittier) M. Sousa, and Tachigali davidsei Zarucchi & Herend. (Leguminosae); Nectandra bartlettiana Lasser (Lauraceae); Lindernia brachyphylla Pennell ex Steyerm. (Linderniaceae); Campomanesia aromatica (Aubl.) Griseb. (Myrtaceae); Christiana africana DC. (Malvaceae); Dulacia cyanocarpa Sleumer (Olacaceae); Phyllanthus microphyllus Kunth (Phyllanthaceae), and Gouania wurdackii Steyerm. (Rhamnaceae). These species were collected in the states of Arauca and Vichada in Colombia. Aspects related with the taxonomy and nomenclature of these new records, geographical distributions, and affinities with the flora of the Llanos of Venezuela as well as other regions with floristic similarities are discussed, and information about the exploration in the region is documented.Se registran 18 novedades para la flora vascular de Colombia a partir de ejemplares recolectados en la región dela Orinoquia. Los nuevos registros corresponden a: Duguetia riberensis Aristeg. ex Maas & Boon, Trigynaeaduckei (R. E. Fr.) R. E. Fr. (Annonaceae); Tassadia medinae (Morillo) Morillo (Apocynaceae); Jaracandaorinocensis Sandw. (Bignoniaceae); Polycarpaea corymbosa (L.) Lam. var. brasiliensis (Cambess.) Chodat &Hassl. (Caryophyllaceae); Murdannia burchellii (C. B. Clarke) M. Pell. y M. aff. triquetra (Wall. ex C. B. Clarke)G. Brückn (Commelinaceae); Enterolobium barinense L. Cárdenas & Rodr.-Carr., Machaerium tovarense Pittier,Muellera crucisrubierae (Pittier) M. Sousa y Tachigali davidsei Zarucchi & Herend. (Leguminosae), Nectandrabartlettiana Lasser (Lauraceae); Lindernia brachyphylla Pennell ex Steyerm. (Linderniaceae); Campomanesiaaromatica (Aubl.) Griseb. (Myrtaceae); Christiana africana DC. (Malvaceae); Dulacia cyanocarpa Sleumer(Olacaceae); Phyllanthus microphyllus Kunth (Phyllanthaceae) y Gouania wurdackii Steyerm. (Rhamnaceae).Estas especies fueron recolectadas en los departamentos de Arauca y Vichada. Se discuten aspectos relacionadoscon la taxonomía y nomenclatura de estos nuevos registros, su distribución geográfica, sus afinidades con la florapresente en la Orinoquia venezolana y regiones con características florísticas similares. Se agrega una reseñahistórica de las exploraciones en los llanos colombianos

Nuevos registros para la flora vascular de Colombia presentes en la Orinoquia y reseña histórica de las expediciones botánicas a la región

Se registran 18 novedades para la flora vascular de Colombia a partir de ejemplares recolectados en la región de la Orinoquia. Los nuevos registros corresponden a: Duguetia riberensis Aristeg. ex Maas & Boon, Trigynaea duckei (R. E. Fr.) R. E. Fr. (Annonaceae); Tassadia medinae (Morillo) Morillo (Apocynaceae); Jaracanda orinocensis Sandw. (Bignoniaceae); Polycarpaea corymbosa (L.) Lam. var. brasiliensis (Cambess.) Chodat & Hassl. (Caryophyllaceae); Murdannia burchellii (C. B. Clarke) M. Pell. y M. aff. triquetra (Wall. ex C. B. Clarke) G. Brückn (Commelinaceae); Enterolobium barinense L. Cárdenas & Rodr.-Carr., Machaerium tovarense Pittier, Muellera crucisrubierae (Pittier) M. Sousa y Tachigali davidsei Zarucchi & Herend. (Leguminosae), Nectandra bartlettiana Lasser (Lauraceae); Lindernia brachyphylla Pennell ex Steyerm. (Linderniaceae); Campomanesia aromatica (Aubl.) Griseb. (Myrtaceae); Christiana africana DC. (Malvaceae); Dulacia cyanocarpa Sleumer (Olacaceae); Phyllanthus microphyllus Kunth (Phyllanthaceae) y Gouania wurdackii Steyerm. (Rhamnaceae). Estas especies fueron recolectadas en los departamentos de Arauca y Vichada. Se discuten aspectos relacionados con la taxonomía y nomenclatura de estos nuevos registros, su distribución geográfica, sus afinidades con la flora presente en la Orinoquia venezolana y regiones con características florísticas similares. Se agrega una reseña histórica de las exploraciones en los llanos colombianos

Nuevos registros para la flora vascular de Colombia presentes en la Orinoquia y reseña histórica de las expediciones botánicas a la región

18 new records to the vascular flora of Colombia found in the Orinoquia region are recorded: Duguetia riberensis Aristeg. ex Maas & Boon, Trigynaea duckei (R .E. Fr.) R. E. Fr. (Annonaceae); Tassadia medinae (Morillo) Morillo (Apocynaceae); Jaracanda orinocensis Sandw. (Bignoniaceae); Polycarpaea corymbosa (L.) Lam. var. brasiliensis (Cambess.) Chodat & Hassl. (Caryophyllaceae); Murdannia burchellii (C. B. Clarke) M. Pell. y M. aff. triquetra (Wall. ex C. B. Clarke) G.Brückn (Commelinaceae); Enterolobium barinense L. Cárdenas & Rodr.-Carr., Machaerium tovarense Pittier, Muellera crucisrubierae (Pittier) M. Sousa, and Tachigali davidsei Zarucchi & Herend. (Leguminosae); Nectandra bartlettiana Lasser (Lauraceae); Lindernia brachyphylla Pennell ex Steyerm. (Linderniaceae); Campomanesia aromatica (Aubl.) Griseb. (Myrtaceae); Christiana africana DC. (Malvaceae); Dulacia cyanocarpa Sleumer (Olacaceae); Phyllanthus microphyllus Kunth (Phyllanthaceae), and Gouania wurdackii Steyerm. (Rhamnaceae). These species were collected in the states of Arauca and Vichada in Colombia. Aspects related with the taxonomy and nomenclature of these new records, geographical distributions, and affinities with the flora of the Llanos of Venezuela as well as other regions with floristic similarities are discussed, and information about the exploration in the region is documented.Se registran 18 novedades para la flora vascular de Colombia a partir de ejemplares recolectados en la región dela Orinoquia. Los nuevos registros corresponden a: Duguetia riberensis Aristeg. ex Maas & Boon, Trigynaeaduckei (R. E. Fr.) R. E. Fr. (Annonaceae); Tassadia medinae (Morillo) Morillo (Apocynaceae); Jaracandaorinocensis Sandw. (Bignoniaceae); Polycarpaea corymbosa (L.) Lam. var. brasiliensis (Cambess.) Chodat &Hassl. (Caryophyllaceae); Murdannia burchellii (C. B. Clarke) M. Pell. y M. aff. triquetra (Wall. ex C. B. Clarke)G. Brückn (Commelinaceae); Enterolobium barinense L. Cárdenas & Rodr.-Carr., Machaerium tovarense Pittier,Muellera crucisrubierae (Pittier) M. Sousa y Tachigali davidsei Zarucchi & Herend. (Leguminosae), Nectandrabartlettiana Lasser (Lauraceae); Lindernia brachyphylla Pennell ex Steyerm. (Linderniaceae); Campomanesiaaromatica (Aubl.) Griseb. (Myrtaceae); Christiana africana DC. (Malvaceae); Dulacia cyanocarpa Sleumer(Olacaceae); Phyllanthus microphyllus Kunth (Phyllanthaceae) y Gouania wurdackii Steyerm. (Rhamnaceae).Estas especies fueron recolectadas en los departamentos de Arauca y Vichada. Se discuten aspectos relacionadoscon la taxonomía y nomenclatura de estos nuevos registros, su distribución geográfica, sus afinidades con la florapresente en la Orinoquia venezolana y regiones con características florísticas similares. Se agrega una reseñahistórica de las exploraciones en los llanos colombianos

Evenness mediates the global relationship between forest productivity and richness

1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all important properties of a community, including community evenness, which may mediate the relationship between biodiversity and productivity. If the evenness of a community correlates negatively with richness across forests globally, then a greater number of species may not always increase overall diversity and productivity of the system. Theoretical work and local empirical studies have shown that the effect of evenness on ecosystem functioning may be especially strong at high richness levels, yet the consistency of this remains untested at a global scale.2. Here, we used a dataset of forests from across the globe, which includes composition, biomass accumulation and net primary productivity, to explore whether productivity correlates with community evenness and richness in a way that evenness appears to buffer the effect of richness. Specifically, we evaluated whether low levels of evenness in speciose communities correlate with the attenuation of the richness–productivity relationship.3. We found that tree species richness and evenness are negatively correlated across forests globally, with highly speciose forests typically comprising a few dominant and many rare species. Furthermore, we found that the correlation between diversity and productivity changes with evenness: at low richness, uneven communities are more productive, while at high richness, even communities are more productive.4. Synthesis. Collectively, these results demonstrate that evenness is an integral component of the relationship between biodiversity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community diversity. Our research suggests that evenness is a fundamental component of biodiversity–ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions

A new data-driven map predicts substantial undocumented peatland areas in Amazonia

Tropical peatlands are among the most carbon-dense terrestrial ecosystems yet recorded. Collectively, they comprise a large but highly uncertain reservoir of the global carbon cycle, with wide-ranging estimates of their global area (441 025–1700 000 km2) and below-ground carbon storage (105–288 Pg C). Substantial gaps remain in our understanding of peatland distribution in some key regions, including most of tropical South America. Here we compile 2413 ground reference points in and around Amazonian peatlands and use them alongside a stack of remote sensing products in a random forest model to generate the first field-data-driven model of peatland distribution across the Amazon basin. Our model predicts a total Amazonian peatland extent of 251 015 km$^2$ (95th percentile confidence interval: 128 671–373 359), greater than that of the Congo basin, but around 30% smaller than a recent model-derived estimate of peatland area across Amazonia. The model performs relatively well against point observations but spatial gaps in the ground reference dataset mean that model uncertainty remains high, particularly in parts of Brazil and Bolivia. For example, we predict significant peatland areas in northern Peru with relatively high confidence, while peatland areas in the Rio Negro basin and adjacent south-western Orinoco basin which have previously been predicted to hold Campinarana or white sand forests, are predicted with greater uncertainty. Similarly, we predict large areas of peatlands in Bolivia, surprisingly given the strong climatic seasonality found over most of the country. Very little field data exists with which to quantitatively assess the accuracy of our map in these regions. Data gaps such as these should be a high priority for new field sampling. This new map can facilitate future research into the vulnerability of peatlands to climate change and anthropogenic impacts, which is likely to vary spatially across the Amazon basin

The global biogeography of tree leaf form and habit

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, evergreen and deciduous trees. To address these gaps, we conducted a global, ground-sourced assessment of forest leaf-type variation by integrating forest inventory data with comprehensive leaf form (broadleaf vs needle-leaf) and habit (evergreen vs deciduous) records. We found that global variation in leaf habit is primarily driven by isothermality and soil characteristics, while leaf form is predominantly driven by temperature. Given these relationships, we estimate that 38% of global tree individuals are needle-leaved evergreen, 29% are broadleaved evergreen, 27% are broadleaved deciduous and 5% are needle-leaved deciduous. The aboveground biomass distribution among these tree types is approximately 21% (126.4 Gt), 54% (335.7 Gt), 22% (136.2 Gt) and 3% (18.7 Gt), respectively. We further project that, depending on future emissions pathways, 17–34% of forested areas will experience climate conditions by the end of the century that currently support a different forest type, highlighting the intensification of climatic stress on existing forests. By quantifying the distribution of tree leaf types and their corresponding biomass, and identifying regions where climate change will exert greatest pressure on current leaf types, our results can help improve predictions of future terrestrial ecosystem functioning and carbon cycling

Native diversity buffers against severity of non-native tree invasions

Determining the drivers of non-native plant invasions is critical for managing native ecosystems and limiting the spread of invasive species$^{1,2}$. Tree invasions in particular have been relatively overlooked, even though they have the potential to transform ecosystems and economies$^{3,4}$. Here, leveraging global tree databases$^{5–7}$, we explore how the phylogenetic and functional diversity of native tree communities, human pressure and the environment influence the establishment of non-native tree species and the subsequent invasion severity. We find that anthropogenic factors are key to predicting whether a location is invaded, but that invasion severity is underpinned by native diversity, with higher diversity predicting lower invasion severity. Temperature and precipitation emerge as strong predictors of invasion strategy, with non-native species invading successfully when they are similar to the native community in cold or dry extremes. Yet, despite the influence of these ecological forces in determining invasion strategy, we find evidence that these patterns can be obscured by human activity, with lower ecological signal in areas with higher proximity to shipping ports. Our global perspective of non-native tree invasion highlights that human drivers influence non-native tree presence, and that native phylogenetic and functional diversity have a critical role in the establishment and spread of subsequent invasions

Consistent patterns of common species across tropical tree communities

Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations$^{1-6}$ in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth's 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories$^{7}$, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world's most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors