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Los ecosistemas secos ocupan casi la mitad del área total de franja tropical y están entre los más amenazados por las actividades humanas a escala global. El reconocimiento creciente de la importancia de conservar los pocos remanentes que quedan y de iniciar actividades de restauración, resalta la importancia de establecer programas de monitoreo del bosque seco. En 2001 se inició el establecimiento de parcelas permanentes de monitoreo del bosque seco Caribe, con el apoyo de instituciones nacionales e internacionales; a la fecha existen 11 ampliamente distribuidas en algunos de los remanentes de bosque seco más importantesnde la costa Caribe. Los resultados provenientes de la red incluyen el contenido de carbono y la diversidad del bosque en relaciónncon variables climáticas, tasas de fijación de carbono y dinámica de poblaciones de especies importantes para la restauración. No obstante, la falta de apoyo institucional a nivel nacional y regional, con algunas excepciones importantes, pone en peligro la continuidad de este proyecto de alta importancia para la conservación del bosque seco en el contexto de la adaptación al cambio climático. Actualmente, otras instituciones han replicado esta iniciativa y avanzado aisladamente en el establecimiento de nuevos sitios de monitoreo de los bosques del Caribe. Es altamente prioritario trabajar por la integración de estos esfuerzos ya que pueden ser la base para un programa de monitoreo más ambicioso de los bosques del Caribe. Para ello se requiere el interés y el compromiso de instituciones e investigadores de la región Caribe.

Canopy lianas differ considerably from trees in terms of wood anatomical structure, and they are suggested to have a demographic advantage—faster growth and higher survival—than trees. However, it remains unclear whether these anatomical and demographic differences persist at the seedling stage, when most liana species are self-standing and, consequently, might be ecologically similar to trees. We assessed how self-standing liana and tree seedlings differ in relation to wood anatomy, growth, and survival. We measured 12 wood traits and monitored seedling growth and survival over one year for 10 self-supporting liana and 10 tree seedling species from three tropical dry forests in Colombia. Liana and tree seedlings exhibited similar survival rates and wood anatomies for traits related to water storage and mechanical support. Yet, for traits associated with water transport, liana seedlings showed greater variability in vessel lumen size, while tree seedlings had higher vessel density. Also, the liana relative growth rate was significantly higher than for trees. These results indicate that, while self-supporting liana and tree seedlings are anatomically similar in terms of mechanical support and water storage—likely contributing to their similar survival rates—liana seedlings have a growth advantage, possibly due to more efficient water transport. These findings suggest that the well-documented anatomical and demographic differences between adult lianas and trees may depend on the liana’s developmental stage, with more efficient water transport emerging as a key trait from early stages.

Patterns of species diversity have been associated with changes in climate across latitude and elevation. However, the ecological and evolutionary mechanisms underlying these relationships are still actively debated. Here, we present a complementary view of the well-known tropical niche conservatism (TNC) hypothesis, termed the multiple zones of origin (MZO) hypothesis, to explore mechanisms underlying latitudinal and elevational gradients of phylogenetic diversity in tree communities. The TNC hypothesis posits that most lineages originate in warmer, wetter, and less seasonal environments in the tropics and rarely colonize colder, drier, and more seasonal environments outside of the tropical lowlands, leading to higher phylogenetic diversity at lower latitudes and elevations. In contrast, the MZO hypothesis posits that lineages also originate in temperate environments and readily colonize similar environments in the tropical highlands, leading to lower phylogenetic diversity at lower latitudes and elevations. We tested these phylogenetic predictions using a combination of computer simulations and empirical analyses of tree communities in 245 forest plots located in six countries across the tropical and subtropical Andes. We estimated the phylogenetic diversity for each plot and regressed it against elevation and latitude. Our simulated and empirical results provide strong support for the MZO hypothesis. Phylogenetic diversity among co-occurring tree species increased with both latitude and elevation, suggesting an important influence on the historical dispersal of lineages with temperate origins into the tropical highlands. The mixing of different floras was likely favored by the formation of climatically suitable corridors for plant migration due to the Andean uplift. Accounting for the evolutionary history of plant communities helps to advance our knowledge of the drivers of tree community assembly along complex climatic gradients, and thus their likely responses to modern anthropogenic climate change.

Societal Impact Statement Tropical dry forests (TDF) underpin the wellbeing of millions, mostly rural populations; yet have suffered from severe clearing in Colombia, triggering cascading effects such as desertification. By engaging scientists, society, and institutions in the establishment of platforms for monitoring biodiversity and ecosystem functioning, crucial knowledge gaps will be bridged, helping to find a path toward sustainable development. Science‐led but socially and economically anchored information on biodiversity will help to incorporate nature's contributions to people into the society's cultural values. Ultimately, these transformative actions will translate into the comprehensive management of TDF through a greater impact in decision making. Summary Thousands of permanent plots have been established across the tropics with the purpose of monitoring tree communities. Research outcomes from these platforms, however, have been mainly directed toward the academic community, and their contribution to society has been limited so far. Here, we show how generating robust data on biodiversity has supported decision making in Colombian tropical dry forests (TDF), where less than 8% of their original cover remains. As a first step to build a national dialogue around the critical status of this ecosystem, a national collaborative network on TDF research and monitoring was born in 2014, the Red de Investigación y Monitoreo del Bosque Seco Tropical en Colombia (Red BST‐Col). Our main goal is to generate scientifically sound information that feeds into the comprehensive management of this ecosystem. To do so, a set of biodiversity monitoring platforms has been established across the country, which have already served to answer socio‐ecological questions related with deforestation drivers, citizen science, or the valuation of ecosystem services. Overall, this research agenda has nurtured the four lines that underpin the Program for the comprehensive management of dry forests in Colombia (knowledge management, preservation, restoration, and sustainable use), formulated by the Humboldt Institute, the United Nations Development Programme, and the Ministry of Environment in 2019. Many challenges are ahead, however, for a complex territory where multiple social actors and productive sectors coexist. The ultimate goal is to integrate all the dimensions of biodiversity to achieve a synthetic understanding of the functioning of the most endangered ecosystem in Colombia, and its relationship with local communities' wellbeing.

La especie nueva, nombrada Sciodaphyllum sonsonense, se encuentra en los bosques altoandinos del norte de la Cordillera Central en Antioquia, Colombia. Este taxón comparte algunas características morfológicas con S. huilense y S. pubens, pero difiere entre otros caracteres, en poseer una lígula blanquecina y bífida de 1/3 a 2/3 de su longitud total. La descripción e ilustración de S. sonsonense está acompañada por mapa de distribución, apuntes de habitat, tabla de afinidades taxonómicas y fotografías.

Se describen dos especies de Melastomataceae de frutos carnosos procedentes del departamento de Antioquia, Colombia: Miconia mailynii y Miconia hernandogarciae. Miconia mailynii se caracteriza por la presencia de mirmecófilos, hojas levemente anisófilas e inflorescencias terminales; los taxones más cercanos corresponden a especies del género Clidemia de Panamá y Costa Rica. Miconia hernandogarciae se asocia al clado Octopleura y se distingue por poseer inflorescencias terminales y hojas con venación basal. Estas dos especies se consideran endémicas al piedemonte asociado al Magdalena Medio de las cordilleras Central y Oriental de Colombia y, debido a su distribución restringida y especificidad de hábitat, se recomienda su categorización como En peligro (EN).

Identificar los determinantes de la composición de especies arbóreas entre tipos de bosques tropicales altitudinalmente contrastantes incrementarán nuestro conocimiento de los principales factores y procesos que controlan los patrones de diversidad y distribución de las especies. El área de estudio se localiza en la región noroeste de Colombia, principalmente en el departamento de Antioquia. Se empleó el análisis de redundancia (RDA) y un modelo semi-logarítmico linealizado para analizar la influencia del clima, fertilidad del suelo, y procesos espaciales, tales como la limitación en dispersión, sobre la composición de la comunidad arbórea. Se encontraron tres tipos de bosques: uno en tierras altas y dos en tierras bajas. En las tierras bajas, ambos modelos, el RDA y el modelo semi-logarítmico linealizado, identificaron las concentraciones de calcio como la variable que mejor explica la composición de especies (R2 adj = 0,24; p = 0,001 y RMantel = 0,68; p = 0,006, respectivamente). En las tierras altas, el RDA solo identificó la longitud como una variable explicativa significativa (R2 adj = 0,24; p = 0,001), determinada principalmente por la ubicación biogeográfica de los bosques en la cordillera Occidental o Central de los Andes. En estos bosques neotropicales, los factores que determinan la composición de especies de árboles entre tierras bajas y altas varió en magnitud y naturaleza. En general, nuestros resultados no apoyan la idea que existe una mayor especialización de hábitat en tierras altas que en tierras bajas debido a mayor variación geomorfológica y edáfica. Los ecosistemas tropicales andinos y en particular los bosques de tierras altas, han recibido menos atención que sus contrapartes de tierras bajas; nuestros hallazgos ayudan a ampliar el conocimiento actual de los factores y procesos que determinan la composición de las comunidades de los bosques montanos tropicales.

We assessed the expected historical and current speciesrichness of shrubs and trees in the Department of Antioquia,northwest region of Colombia. We used the Fisher´s alpha valueassociated with the pooled dataset of identified species in 16 1-haplots that were used to extrapolate the scaled species richness ofthe Antioquia Province under three different scenarios: 1) the entireregion before deforestation began, assuming an original forestcover of around 92% of the entire province (excluding paramos,rivers, and lakes). 2) The forest cover in 2010. 3) The expected forestcover in 2100 assuming the observed deforestation rate between2000 and 2010 as a constant. We found that, despite relativelylow local and global losses of species, global extinctions in termsof number of species could be dramatically high due to the highendemism and deforestation rates.

Los bosques tropicales almacenan grandes cantidades de carbono en su biomasa, y por ello juegan un papel determinante en el ciclo global de este elemento. Las variables biofísicas determinan la capacidad de almacenamiento de los bosques como reservorios de carbono. No obstante en los últimos años, la deforestación tropical ha hecho que estos ecosistemas se conviertan en fuente de emisiones de dióxico de carbono (CO2) a la atmósfera. El presente estudio quiso evaluar la distribución de la biomasa aérea (BA) y carbono en relación con la variación altitudinal de los bosques naturales del departamento de Antioquia (Colombia), así como las pérdidas potenciales asociadas con la deforestación, durante el periodo 2000-2007. Para ello se empleó información estructural (diámetro, biomasa aérea) proveniente de 16 parcelas permanentes de 1,0 ha, dentro de las cuales se midió la vegetación leñosa arbórea. Se cuantificó la deforestación a nivel departamental usando imágenes de sensores remotos MODIS para el período 2000-2007. Los resultados evidencian que la BA y los contenidos de carbono en los bosques naturales de Antioquia, presentan una relación inversa con la altitud. La BA promedio fue 244 ± 63 Mg ha-1 y la tasa de deforestación en el período 2000-2007 fue 25.279 ha año-1. Durante este período se perdieron en total 176.950 ha de bosque natural, con las cuales se emitieron potencialmente a la atmósfera 79.161,29 Gg CO2. En Antioquia posiblemente problemáticas como la deforestación, pueden llegar a destruir considerablemente estos ecosistemas, ocasionando la pérdida de servicios ecosistémicos importantes como el almacenamiento de carbono.Tropical forests store large amounts of carbon (C2) in their biomass, thus playing a key role in the global cycle of this element. The carbon storage capability of tropical forests is largely determined by biophysical factors. However, in recent years tropical deforestation has converted this ecosystem into a source of carbon emissions into the atmosphere. In this study, our goal was to evaluate the distribution of above-ground biomass (AGB) along a complex environmental gradient of natural forests in the Department of Antioquia (Colombia); as well as to assess the potential amount of carbon released into the atmosphere by deforestation between 2000 and 2007. We used structural information (diameter, aerial biomass) from 16 1-ha permanent plots where woody vegetation was sampled. Deforestation in the department was quantified using MODIS terra images obtained from 2000-2007. We found a negative relationship between AGB and altitude in natural forests in Antioquia. Mean AGB was 244 ± 63 Mg ha-1 and the deforestation rate in the 2000-2007 period was 25, 279 ha yr-1. During this time, 176,950 ha of natural forest were lost, which means a total of 79,161.29 Gg CO2 were released into the atmosphere. In Antioquia, problems such as deforestation may result in a considerable destruction to this ecosystem, causing the loss of important ecosystem services, such as carbon storage.

Tropical dry forests (TDFs) have been defined as a single biome occurring mostly in the lowlands where there is a marked period of drought during the year. In the Neotropics, dry forests occur across contrasting biogeographical regions that contain high beta diversity and endemism, but also strong anthropogenic pressures that threaten their biodiversity and ecological integrity. In Colombia, TDFs occur across six regions with contrasting soils, climate, and anthropogenic pressures, therefore being ideal for studying how these variables relate to dry forest species composition, successional stage and conservation status. Here, we explore the variation in climate and soil conditions, floristic composition, forest fragment size and shape, successional stage and anthropogenic pressures in 571 dry forest fragments across Colombia. We found that TDFs should not be classified solely on rainfall seasonality, as high variation in precipitation and temperature were correlated with soil characteristics. In fact, based on environmental factors and floristic composition, the dry forests of Colombia are clustered in three distinctive groups, with high species turnover across and within regions, as reported for other TDF regions of the Neotropics. Widely distributed TDF species were found to be generalists favored by forest disturbance and the early successional stages of dry forests. On the other hand, TDF fragments were not only small in size, but highly irregular in shape in all regions, and comprising mostly early and intermediate successional stages, with very little mature forest left at the national level. At all sites, we detected at least seven anthropogenic disturbances with agriculture, cattle ranching and human infrastructure being the most pressing disturbances throughout the country. Thus, although environmental factors and floristic composition of dry forests vary across regions at the national level, dry forests are equally threatened by deforestation, degradation and anthropogenic pressures all over the country, making TDFs a top priority for conservation in Colombia.

Identifying the determinants of tree species composition among contrasting altitudinal tropical forest types will improve our understanding of the main factors and processes controlling tree species' distributions and patterns of diversity. The study area is located in the northwest region of Colombia. We used Redundancy Analysis (RDA) and a semi-log distance-decay model to analyze the influence of climate, soil fertility, and spatial processes, such as dispersal limitation, on community composition. There were 3 distinct forest types: one in the highlands and two in the lowlands. In the lowlands, both the RDA and the semi-log linear models identified calcium concentrations as the most important explanatory variable for species composition (R²adj = 0.24; p = 0.001 and R Mantel = 0.68; p = 0.006, respectively). In the highlands, the RDA only identified longitude as being a significant explanatory variable (R²adj = 0.24; p = 0.001), primarily determined by the biogeographical location of forests on either the West or the Central Cordillera of the Andes. In these neotropical forests, the factors determining tree species composition between lowlands and highlands varied in both extent and nature. Overall, our findings do not support the idea of a higher habitat-plant specialization in highlands than in lowlands due to greater geomorphologic and edaphic variation. Since tropical Andean ecosystems, and in particular highland forests, have received less attention than their lowland counterparts, our findings help to expand the current knowledge of factors and processes determining community composition of tropical montane forests.