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The response of two stingless bees (Tetragonisca angustula and Melipona eburnea) to changes in vegetation cover was evaluated on seasonal and spatial scales. Seasonal variation was analysed for 15 months, with monthly melitopalinological assessments of hives located in three different vegetation covers: forests, fallows, and grasslands, in the Colombian Central Cordillera. Fallows, with an intermediate disturbance degree, presented the highest pollen taxa richness for both bee species (33 and 40 taxa for M. eburnea and T. angustula, respectively). Both bee species presented a high preference for plant families Melastomataceae, Sapindaceae, and Peraceae. Miconia minutiflora and Mi. prasina (Melastomataceae) were the most selected species, with an alternation in their use between dry and wet seasons. Clethra spp., Pera arborea, and Ilex laureola were also highly selected by both bee species. M. eburnea showed higher pollen richness values during the dry season, when the largest number of plant species flowered. Despite both bee species being polylectic, T. angustula presented higher pollen richness values during wet periods, which was reflected in a greater amplitude of trophic niche compared to M. eburnea. Both bee species showed a higher preference for typical plants in forest environments, enhancing meliponiculture as an economically sustainable practice that can promote forest conservation and the maintenance of stingless forest interactions.

En este artículo se explica el diseño de una estrategia de educación ambiental enmarcada en los modelos pedagógicos auto estructurantes que utiliza la lúdica como herramienta esencial para construir conceptos e incentivar la investigación. La estrategia se llevó a la práctica con 40 estudiantes de primaria y bachillerato de la Institución Educativa de Isla Fuerte, una localidad marginal afrodescendiente. Aunque no pudo aplicarse en su totalidad, las actividades realizadas permitieron hacer un análisis de la metodología y los resultados obtenidos. El ejercicio aprovechó la tradición oral de la comunidad, despertó la imaginación y la curiosidad, y logró interiorizar conceptos ambientales en los chicos. Aunque se cambiaron algunas actitudes apáticas hacia los problemas ambientales, y se despertó disposición y dedicación, es posible que se requiera tiempo para visibilizar los cambios de percepción alcanzados.

We studied the importance of pollen from mangrove plant species in the diet of Apis mellifera (a non-native honey bee species), the relationship between tree flowering and pollen contained in Apis ...

Coastal ecosystems like coral barrier reefs and mangrove forests have been designated as environments in need of protection. This is not only because they are threatened by climate change, but also because of the important role they play in coastal protection. Some field studies based on Rhizophora mangrove trees have analyzed the force induced by water flow over their roots and the wave dissipation capacity of these trees under tidal regimes and sea waves. Various methods have been used to calculate energy dissipation in the past, but these do not include the drag coefficient (CD) with field data calibration. The study presented here was conducted to investigate the capacity of a small natural Rhizophora mangrove patch (at experimental scale) located on Isla Grande in the Colombian Caribbean Sea to mitigate wave energy. The total energy dissipation, including the slope bottom and the effects of vegetation, was calculated. Parametric equations were used to calculate the effects of vegetation. The drag force (FD) was computed using Morrison’s equation and the CD was calculated using Mazda’s method. The results show a mean energy dissipation difference of 9.6% between the energy balance and dissipation coefficients where the CD was calculated for each sea state. The dissipation coefficients were calculated with constant CD values (0.06, 3.48 and 6.90). None of the three cases could explain the 90.4% energy flux, as in the case of vegetation dissipation (Dveg) with calculated and non-constant CD values. Despite the small size of the mangrove patch, the results show an increase in the CD (with values of up to 7.9) as a result of lower values of the Reynolds number (Re) (about 7.3 × 105). This demonstrates experimentally the role that even a small patch of mangrove vegetation plays in attenuating sea waves (as CD is a function of sea states), and higher magnitudes were obtained than those recorded in the literature using other vegetation types. A nonlinear contribution to energy flow by bottom dissipation and vegetation dissipation was observed. Our results highlight the need to scale measurements up to forest level in order to accurately quantify the impact of mangrove vegetation on wave attenuation and determine the possible impact on the protection of coastal ecosystems and infrastructure.

Background and aims – Magnolia species are highly endangered in neotropical forests where they are highly endemic and often very rare. However, little is known about their nutritional and soil conditions in natural forests. In this study, we focused on two endangered Magnolia species that cohabit in the Colombian Andean cloud forests in order to identify their conservation and nutritional status. We hypothesize that these species might exhibit mycorrhizal colonization that enhance nutrients uptake in poor and disturbed soils. Methods – Individuals of Magnolia jardinensis and M. yarumalensis were assessed in 11 000 m2 of Andean forests remnants from Jardín municipality (Antioquia, Colombia). Foliar and soil samples were analysed in the lab. Through a Principal Component Analysis (PCA) we identified the relationship between soil conditions and foliar nutrition. Root fragments and rhizosphere samples from seedlings and juveniles up to 3 m tall were collected to verify mycorrhizal colonization and presence of other microorganisms. Adults were excluded of the sampling due to the difficulties to differentiate their roots among the rest of the species in the forest fragments. Key results – The surveys show that the M. yarumalensis population has an inverted J-shaped diametric distribution suggesting a potential recovering population while the smaller overall distribution of M. jardinensis in all diametric categories suggests that this species is likely to become extinct. Both species grow in acidic, infertile soils, although foliar nutrient concentrations did not correlate with soil-nutrient availability. Such a discrepancy and the high colonization levels of mycorrhizae (60–70%) and dark septate endophytes (40–45%), suggest that plant-microorganisms may facilitate nutrition and enhance survival of Magnolia species in stressed environments. Other fungi and bacteria were also found in their rhizosphere, but their role with respect to Magnolia species remains unclear.Conclusions - Mycorrhizal colonization of endangered Magnolia species seems to play a key role to their performance in natural disturbed Andean forests. Aspects related to soil and rhizosphere ecology should be included in conservation projects for endangered and endemic plants.

In the tropics, some agricultural lands are abandoned for economic or technical reasons, leading to the recovery of woody vegetation. Our research aimed to identify the main drivers of spontaneous recovery of vegetation in a basin located in the Colombian Andes. This was done by combining spatially explicit environmental and socioeconomic variables at landscape (e.g. distances to human settlements, to roads, and to forests and mean annual precipitation) and local scales (e.g. depth of the organic layer, soil bulk density, and canopy openness). These variables were measured in 28 temporal plots of 500 m2 each, established in land cover transitions that showed the recovery of woody vegetation. The recovered woody vegetation between 1986 and 2012 exhibited a gregarious spatial pattern at the landscape scale. Ordination analysis showed distinct floristic composition among transitions and remnant forests, and species associated to each one through an indicator species analysis. Multivariate analyses revealed the relationship between the transitions and variables at both scales. Woody vegetation recovery occurred near remnant forests and far from human settlements at the landscape scale. The soil conditions (content and depth of the organic horizon and bulk density) were the main drivers at the local scale. Our findings also highlight the necessity to define different restoration approaches such as incorporation of sites where socioeconomic and environmental conditions favor the spontaneous recovery of vegetation into the existing network of protected areas in the region, and to implement active restoration projects in perturbed sites to accelerate the recovery process of Andean forests.

Extreme events affect coastal vegetation in several ways. They cause massive tree defoliations and mortality that carry changes in vegetation structure and floristic composition. In order to assess these changes in dry tropical forests, coastal vegetation and mangroves in El Rosario archipelago, and their relationship with extreme events between 2002 and 2014, Quickbird and Worldview Satellite images with uneven periodicity were analyzed and the Normalized Difference Vegetation Index (NDVI) was calculated for these vegetation covers. Time series analysis was performed to oceanographic and climate variables such as maximum wind velocity, daily precipitation, significant wave height, peak wave period and maximum and minimum air temperatures. The first two axes of a redundancy analysis explained 65% of data variance (p value ≤ 0.05) and showed that the decrease of the NDVI and extension of beach vegetation were related to increases in wind frequency and intensity. However, mangrove vegetation was benefited by the increase in the frequency of short drought events, although their NDVI decreased when these drought events became longer. Drought events were related to El Nino Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) anomalies that had the strongest effects on coastal vegetation and dry forest, as shown by the minimum values of NDVI recorded in 2010. Mangrove vegetation was more resilient to such droughts and strong winds than coastal and dry forest vegetation due to their location along bays or surrounding internal lagoons.

The successful establishment of mangrove ecosystems depends on an intricate network of interactions among physical and biological factors that are highly dynamic through time. At millennial to centennial time scales, regional climates, sea levels, and local geomorphology play critical roles in the establishment of mangroves. Whereas fluvio-marine dynamics define coastal sedimentary settings, regional precipitation and freshwater input modulate salinity and seasonal flooding patterns. We analyzed a ~7800-year-old, continuous sedimentary record from the western coast of the Gulf of Mexico to shed light on regional biophysical coastal processes and the history of the mangroves that occupy the region today. We used a systematic sampling of mud-water interface sediments to generate a modern reference frame for interpreting fossil pollen assemblages. Our results indicate that the cored location that is currently approximately at sea level, was below sea level from ~7800 to 4000 calibrated years before present (cal BP). The establishment of dense mangrove stands took place around 3700 cal BP, when regional sea levels stabilized, resulting in a substantial increase of organic matter and therefore carbon stored in the sediments. However, the mangrove ecological succession that started at ~6000 cal BP was interrupted by a regional drought that extended from ~5400 to 3700 cal BP. From 3700 cal BP to Present, the lagoon has been characterized by relatively stable both substratum and sea level, that together have facilitated the establishment of mangrove forests. Overall, our record demonstrates the complexity of the interactions between local and regional factors in the development and evolution of both coastal geomorphology and ecosystems.

RESUMEN Los manglares presentan diferentes grados de interacción entre las condiciones oceanográficas, climáticas, geomorfológicas y edáficas. Estas interacciones tienen repercusiones fuertes sobre la condiciones locales de salinidad y disponibilidad de agua y nutrientes a nivel local, y sobre la estructura y composición de los manglares. Con base en el análisis de fotografías aéreas, muestreo en campo y análisis de componentes principales, se analizaron la composición florística y la estructura de los manglares presentes en la Reserva Natural Sanguaré. Se identificaron tres tipos de bosques según la clasificación fisiográfica de manglares. Un manglar de borde dominado por Rhizophora mangle L. en estado juvenil, con bajo desarrollo estructural, y dos tipos de manglar de interior o cuenca dominados por Avicennia germinans (L.) L. El primero de ellos, localizado detrás del manglar de borde, presentó alta salinidad en el suelo y en el agua intersticial, predominancia de sedimentos arenosos, y bajos valores de altura y diámetro a la altura de pecho (DAP) promedio de los árboles. El segundo, con un bajo número de árboles adultos en todas las categorías de diámetro, mayor área basal, bajo potencial de regeneración natural, y altas concentraciones de Fe y Cu en el suelo, probablemente asociado a la contaminación por vertimientos domésticos. La ubicación del primer manglar de interior detrás del manglar de borde revela la zonación típica descrita para muchos manglares del mundo. La composición florística, la estructura y la distribución de los manglares en la Reserva Sanguaré son el resultado de la interacción de variables ambientales locales como la salinidad y la textura del suelo, además de la intervención antrópica previa al establecimiento de la reserva y la actual presencia humana muy cerca de los manglares. Abstract Mangroves have different degrees of interaction between oceanographic, climatic, geomorphological and soil conditions. Those interactions have strong impacts on local salinity conditions and availability of water and nutrients at local level, and on mangrove structure and composition. Based on the analysis of aerial photographs, field sampling and statistical multivariate analysis, floristic composition and structure of the mangroves present in the Sanguaré Natural Reserve were analyzed. Three types of forests were identified according to the physiographic classification of mangroves. A fridge mangrove dominated by Rhizophora mangle L. in a juvenile state, with low structural development, and two types of inland or basin mangroves dominated by Avicennia germinans (L.) L. The first of them, located behind the fridge mangrove, showed high salinity in the soil and in the interstitial water, predominance of sandy sediments, and low values of height and diameter at breast height (DBH) average of the trees. The second, with a low number of adult trees in all diameter categories, high basal area, low natural regeneration potential, and high concentrations of Fe and Cu in the soil, probably associated with contamination by domestic spills. The location of the first inner mangrove behind the fridge mangrove reveals the typical zonation of many mangroves in the world. The floristic composition, structure and distribution of the mangroves in the Sanguaré Reserve are the result of the interaction of local environmental variables such as salinity and soil texture, as well as the anthropic intervention prior to the establishment of the reserve and the current human presence being very close to the mangroves.

This paper presents the first modern pollen, non-pollen palynomorphs and grain size data from a pristine mangrove tidal creek on the South Andaman Island, Andaman and Nicobar Islands, India. The surface sediment samples were collected from different mangrove environments of the Wright Myo Creek, South Andaman to study the relationship between the pollen-spore data and present vegetation cover. Results show that pollen from local vegetation more abundant, whereas regional vegetation surrounding the depositional site is poorly represented. Heritiera littoralis, Ceriops tagal, Excoecaria agallocha and Bruguiera gymnorrhiza are markedly abundant in the landward zone. The transitional and seaward pollen assemblages are characterized by Rhizophora mucronata, Avicennia marina and Bruguiera gymnorrhiza pollen types. Pollen from mangroves are locally restricted and reflect the distributions of the source plants and mangrove types. However, the greatest concentrations of allochthonous taxa of evergreen, deciduous and montane components are derived from the surrounding lands. This area receives high rainfall during monsoon favouring long distribution of palynomorphs i.e. allochthonous species from hinterland to the depositional site through connecting drainage system. Abundance of non-pollen palynomorphs suggest not only humid as well as wet conditions, but also the particular salinity and pH characteristics of mangrove types in the area. Such relationships were evident in the Redundancy Analysis (RDA), which revealed that the first two axes of the RDA with self-values of 0.63 and 0.06 respectively explained 68.4% of data variation and 95.2% of the correlation between pollen and the environment. Additionally, the RDA analysis between Non-Pollen Palynomorph (NPP) data and the environmental variables showed that the first and second axes with self-values of 0.60 and 0.04 respectively, explained 68.4% and 96.1% of NPP data variance, respectively. The granulometric analysis clearly indicates that sand fraction is maximum towards sea, whereas suspended sediments (silt and clay) are significantly higher towards transitional and landward zones. This is well corroborated with pollen preservation in this area. At the mouth of the creek, strong hydrodynamic flow and low pollen percentages is observed, while abundant pollen are noticed in the suspended sediments probably due to weak hydrodynamic forces towards land. Therefore, the effects on pollen assemblages from sediment dynamic conditions must be taken into consideration during the reconstruction of palaeovegetation and palaeoclimate. The presented dataset provides new information on modern pollen assemblages and their relationship to the vegetation types and environmental conditions, which can also be effectively applied to other mangrove ecosystems of South and South East Asian regions to reconstruct palaeovegetation and palaeoclimatic changes.

Within the tropics, the species richness of tree communities is strongly and positively associated with precipitation. Previous research has suggested that this macroecological pattern is driven by the negative effect of water-stress on the physiological processes of most tree species. This implies that the range limits of taxa are defined by their ability to occur under dry conditions, and thus in terms of species distributions predicts a nested pattern of taxa distribution from wet to dry areas. However, this ‘dry-tolerance’ hypothesis has yet to be adequately tested at large spatial and taxonomic scales. Here, using a dataset of 531 inventory plots of closed canopy forest distributed across the western Neotropics we investigated how precipitation, evaluated both as mean annual precipitation and as the maximum climatological water deficit, influences the distribution of tropical tree species, genera and families. We find that the distributions of tree taxa are indeed nested along precipitation gradients in the western Neotropics. Taxa tolerant to seasonal drought are disproportionally widespread across the precipitation gradient, with most reaching even the wettest climates sampled; however, most taxa analysed are restricted to wet areas. Our results suggest that the ‘dry tolerance' hypothesis has broad applicability in the world's most species-rich forests. In addition, the large number of species restricted to wetter conditions strongly indicates that an increased frequency of drought could severely threaten biodiversity in this region. Overall, this study establishes a baseline for exploring how tropical forest tree composition may change in response to current and future environmental changes in this region. © 2016 The Authors

Mangroves are ecosystems that are seriously threatened by climate change, particularly sea level rise and an increase of droughts. They are resilient to short droughts but their response to longer ones remains arguable. In this work, we studied the responses of R. mangle dominated forests on a carbonate island (El Rosario Island) to climate anomalies and their drivers at inter-annual, decadal and inter-decadal scales during the last centuries. Palynological analysis of a sediment core retrieved from an R. mangle dominated forest was used to reconstruct vegetation changes during the last 400 years. Time series, Multi-taper spectral, Fourier and correlation analyses of PDO, AMO and ENSO series were performed to identify the matches between these series and mangrove changes during this time. The pollen record showed the influence of coastal dynamics on mangrove vegetation changes on a local scale and the influence of climate on a regional one. Changes in coastal vegetation and mangroves were influenced by beach ridge formations and lagoon closing, which were, in turn, determined by shifts in wave and wind intensity. The simultaneous diminution of both types of vegetation were related to both natural (earthquake and extreme droughts) and anthropogenic disturbances. Our results also showed the replacement of the Rhizophora dominated forest by an Avicennia dominated forest when droughts became longer. The peaks of Rhizophora pollen percentages identified along the pollen record showed a 64 year recurrence cycle that dominated during the Little Ice Age (1610–1862) and a 32 year cycle during the Current Warm Period (1866–1954). While the first cycle was positively correlated with the warm phase of PDO and AMO time series, the second cycle showed a negative significant correlation with PDO, AMO and ENSO time series. During warm periods, mangroves were stressed by droughts, but as these cycles became shorter, mangroves could recover more rapidly. From 1954 to the present, no significant correlations were observed between vegetation changes and climate drivers, which is likely related to the increased anthropogenic disturbance beyond that period of time. Our results show the high resilience of mangroves to cyclic climate changes that involve droughts, winds and sea level rises but low recovery and species turnover with extreme and longer droughts and strong anthropogenic disturbances.

espanolSe realizo una revision de los efectos del incremento en el nivel del mar, los cambios en la salinidad y las perturbaciones humanas sobre la dinamica de los manglares. Los efectos de estos factores se analizaron a escalas seculares en seis registros palinologicos tomados en el Caribe Colombiano. A pesar del incremento acelerado en el nivel del mar, los incrementos en las temperaturas del mar y del aire y las disminuciones en la precipitacion en los dos ultimos siglos, los manglares han aumentado su representacion en los registros de palinologicos en varios sitios de la region, ubicados tanto en el continente como en las islas oceanicas. Tal expansion de los manglares se asocia con su capacidad de mantener el substrato contrarrestando el incremento en el nivel mar con el aumento en las cargas de sedimentos aluviales, desde 1850 AD en los sitios continentales, y con el aumento en la acumulacion de turba autoctona en los suelos de la isla de San Andres. Las perdidas de manglares en el pasado, se asociaron a la erosion costera, y/o al efecto combinado del incremento regional en las sequias y en la salinidad. Estos procesos han ocasionado la muerte de los manglares o cambios en la composicion de especies. Cuando se incrementan la salinidad del substrato y la deposicion de arenas, pasan de ser manglares dominados por Rhizophora mangle a los dominados por Avicennia germinans. La capacidad de rebrote de los tallos danados de Avicennia germinans parece ser el rasgo que le ha permitido a esta especie expandirse despues de la ocurrencia de sequias intensas y prolongadas y de vientos fuertes, tormentas tropicales y huracanes. Las perturbaciones humanas se representaron por la expansion de Laguncularia racemosa y Avicennia germinans a expensas de Rhizophora mangle, o por el reemplazo de la vegetacion arborea por vegetacion herbacea (pastizales o cultivos) y especialmente dominada por el helecho Acrostichum aureum. Alrededor de 1850 AD, los manglares y al vegetacion de playa fueron reemplazados por plantaciones de coco en la isla de San Andres y en la bahia de Cispata las areas pantanosas fueron cubierta con cultivos de arroz. Aunque despues de 1900 AD se abandonaron estos cultivos debido a una incursion marina, ha prevalecido la dominancia de Laguncularia racemosa en los registros de polen indicando la intervencion humana permanente desde entonces. EnglishWe review the main effects of sea level rise, salinity changes, and human disturbances on mangrove forest dynamics. The effects of these drivers on mangrove communities are evaluated at centennial time scales in the light of six palynological records from the Colombian Caribbean. Despite the accelerated rates of sea level rise, increases in sea surface and air temperatures, and decreases in precipitation of the last two centuries, mangroves have shown an increasing representation in pollen records at continental and marine locations of the region. In continental settings, such expansions have been related to the offsetting of sea levels by the increasing loads of fluvial sediments since 1850 AD, and by increases in autochthonous peat accumulation in San Andres Island. Losses of mangrove cover in the past have been related to coastal erosion, regional droughts, and salinity increases. Such processes have commonly caused mangrove die-off or changes in forest species composition. When the substrate has become more saline, or sand sedimentation has increased significantly, the composition of mangrove communities has switched towards the dominance of Avicennia germinans at expenses of Rhizophora mangle. Resprout capacity of damaged stems of Avicennia germinans seems to have been the trait that has allowed this species to increase after strong and prolonged droughts, and occurrence of strong winds, tropical storms, and hurricanes. Human disturbances are represented either by the expansion of Laguncularia racemosa and Avicennia germinans and decreases of Rhizophora mangle, or by mangrove replacement by herbaceous vegetation (grasses or crops), especially the fern Acrostichum aureum. Around 1850 AD, mangroves and beach vegetation were replaced by coconut plantations in San Andres Island, and in the Cispata bay swampy areas were covered with rice crops. Although after 1900 AD these crops were abandoned because of a marine incursion, Laguncularia racemosa has prevailed so far indicating pervasive anthropogenic disturbances.

Throughout the last 15 years, researchers at the National University of Colombia at Medellin have studied Colombian mangroves. Remote sensing, pollen analysis of superficial and deep sediments, Holocene coastal vegetation dynamics, sediment dating using 14 C and 210 Pb, sampling in temporary plots, sampling in temporary and permanent plots, and other techniques have been applied to elucidate long- and shortterm mangrove community dynamics. The studied root fouling community is structured by several regulatory mechanisms; habitat heterogeneity increases species richness and abundance. Fringe mangroves were related to Ca concentration in the soil and the increased dominance of Laguncularia racemosa and other nonmangrove tree species, while the riverine mangroves were associated with Mg concentration and the dominance of Rhizophora mangle. The seedling and mangrove tree distributions are determined by a complex gradient of natural and anthropogenic disturbances. Mangrove pollen from surface sediments and the existing vegetation and geomorphology are close interrelated. Plant pollen of mangrove and salt marsh reflects environmental and disturbance conditions, and also reveals forest types. Forest dynamics in both coasts and their sensitivity of to anthropogenic processes are well documented in the Late Quaternary fossil record. Our studies of short and long term allow us to predict the dynamics of mangroves under different scenarios of climate change and anthropogenic stress factors that are operating in Colombian coasts. Future research arises from these results on mangrove forests dynamics, sea-level rise at a fine scale using palynology, conservation biology, and carbon dynamics.

Se realizó un estudio de la geomorfología y vegetación en playa Palmeras a partir del levantamiento de un modelo digital de elevación, mediciones sistemáticas de perfiles de playa durante 15 meses, análisis de la planta de equilibrio, mediciones de coberturas vegetales, conductividad eléctrica del agua de inundación y granulometría en 15 parcelas establecidas a lo largo de la playa. La playa se puede dividir en dos sectores. El sector NE se caracteriza por una forma en planta cóncava, cúspides de playa, mayor pendiente, mayor elevación, amplia zona seca, mayor variabilidad de la forma en planta y en perfil y mayor tendencia a la acreción, con vegetación herbácea dominada por Rhynchospora polystachys. El sector SW tiene una forma en planta convexa, es menos elevado, el ancho de zona seca es mínimo, la variabilidad de la planta y perfil son menores y tiende a la erosión. La vegetación herbácea en este sector está dominada por Sphagneticola trilobata y hay mayor proporción de palmas muertas. Aunque la longitud de las observaciones limita las conclusiones sobre la variabilidad estacional e interanual de la playa, la cota de inundación aumenta en la época húmeda y hay mayor pérdida de sedimentos. Asimismo, durante años El Niño se evidenció un incremento de la energía del oleaje, que estaría asociado con erosión costera. En el largo plazo hay evidencias de un cambio en la dirección del oleaje y una basculación de la playa con acreción hacia el NE y erosión hacia el SW.

Local geomorphology plays an important role in the response of mangrove communities to both sea-level rise and precipitation changes, mostly because it exerts an important control of the erosion–progradation balance. Here we present contrasting changes in the palynological records of two sediment cores retrieved from locations occupied by mangroves in the northeastern Caribbean coast of Colombia: Calancala and Navio Quebrado. Sediments were treated with standard procedures used in palynologycal analysis, and dated with AMS 14C and 210Pb. Age-depth models of both cores were constructed by linear interpolation between dated samples. The main modern differences between the studied sites are fresh water availability and sediment supply throughout the year. While Calancala, located at the Rancheria River Delta, has direct fresh water influence throughout the year, coastal lagoon Navio Quebrado is only sporadically influenced by fresh water sources. According to our findings, two main factors contributed to mangrove establishment in the Colombian Caribbean: i) high and accelerated sea-level rise around 6000 cal yr BP originating coastal lagoons that favored mangrove establishment, and ii) marine still stand and high precipitation around 3000 cal yr BP leading to a second wave of mangrove expansion. A drought between about 2850 and 2450 cal yr BP and the strengthening of easterly trade winds caused a change from Rhizophora-dominated to Avicennia-dominated stands. Increased precipitation after 2500 cal yr BP and subsequent increase of fluvial sediment input promoted recovery of Rhizophora-dominated mangroves. Sea-level rise during the last 150 yr has caused landward mangrove expansions in deltas and progradation of coastal environments. However, the general pattern shows a net loss of mangrove vegetation as the result of coastal erosion.

Mauritia flexuosa is a keystone species with a broad geographic distribution throughout the Amazon. Environmental changes can impact the reproductive success in a keystone species such as M. flexuosa, which results in a cascade of events that impacts many other species. The present study examined the reproductive phenology in the palm M. flexuosa between December 2010 and November 2012. A 1-ha plot was established in the central Amazon and all palms ≥14 m tall were labelled for measuring. The following five phenophases were recorded monthly for each labelled palm: (i) spadix formation; (ii) buds; (iii) open flowers; (iv) infructescences with green fruits; and (v) infructescences with ripe fruits. ANOVA and multiple range tests were used to evaluate significant differences among variables for each year. The phenological activity index for each phase was related with regional climate variables, including maximum and minimum daily temperature, monthly accumulated precipitation, cloudiness, flood and water table levels in the plot using a redundancy analysis. Overall, fruiting and flowering AIs exhibited significant differences; however, increased synchronous flowering was recorded during the first year associated with maximum temperatures and a drought period; the second year indicated precipitation sufficient for higher fruit production. Climate also influenced seedling mortality, recruitment, and establishment. Kluwer Academic Publishers

The precise characterisation of present-day mangrove ecosystems from modern pollen rain facilitates the accurate use of fossil pollen data for late Quaternary sea level and environmental reconstructions. Here, we investigate whether the analysis of pollen rain data corroborates existing floristic and structural characterisation of different mangrove types at the Caribbean island of San Andres, Colombia. At 82 plots along 20 transects of four distinct mangrove types, samples were obtained of (i) surface sediments for pollen analysis, and (ii) a range of environmental parameters (including inundation levels, salinity and pH). This information was compared to previously sampled mangrove composition and tree basal area. In surface sediment samples 82 pollen taxa were found, from which 19 were present in the vegetation plots. However, because pollen may be transported by wind and/or watercourses, the overall floristic composition of the different forest types may not necessarily be reflected by the pollen spectra. Local vegetation (i.e. mangroves and beach) represented > 90% of the pollen spectra, while the regional one (i.e. hinterland forests) represented The groups were characterised based on (i) the dominance of at least one of the true mangrove species from pollen data ordination and the presence of associated species, and (ii) their relationship with environmental parameters. Rhizophora was present in all plot samples, but did not contribute to forest type separation. In fact, just three true mangrove species proved reliable indicators of (i) high salinity and fringe mangroves (i.e. Avicennia), (ii) high pH levels and landward mangroves (i.e. Conocarpus), and (iii) natural or anthropogenic caused disturbance of forest stands (Laguncularia and associated Acrostichum fern). Hence our study confirms that mangrove pollen spectra can be accurately used to describe different mangrove environments for fossil based palaeoecological reconstructions.

Article history:Received 18 September 2008Received in revised form 23 March 2009Accepted 1 April 2009Available online 15 April 2009Keywords:mangrovespollen analysissurface sedimentsCaribbean Distribution patterns of mangrove pollen taxa in recent surface sediments of the lagoon system of Cispata arecompared with geomorphological and vegetational patterns. The pollen spectra of 51 samples show the floralcomposition and structure of mangrove stands in three main geomorphic units in the study area. The oldestmangrove stands, with the highest tree mean diameter at breast height and total height, are represented inthe pollen spectra by the highest mean percentages (N65%) mainly Rhizophora mangle. The area withestuarine conditions shows, mean mangrove pollen percentages between 35 and 50% reflecting themangrove colonization process since 1930, as well as current anthropogenic disturbance. Lowest proportionsof mangrove pollen (b25%) are found in the foothills, reflecting high disturbance of mangroves and thetransition from mangroves to terra firme forest. Distribution patterns of the pollen and spores indicate thatwater transport is more important than wind transport over short distance and reflect local vegetation. Fernspores and pollen grains of secondary forest taxa and grasslands are widely distributed and reflect regionalvegetation. Rhizophora pollen proportions reflect its relative abundance in the forest stands. Even lowproportions of Avicennia pollen indicate this species’ dominance in sparse stands and saline back swampconditions. Conocarpus presence provides evidence of supratidal location of stands. An inverse relationshipbetween proportions of Laguncularia pollen and Acrostichum spores demonstrates successional processestriggered by anthropogenic disturbance. This is the first report on pollen in surface sediments in theColombian Caribbean. As such, the data should prove valuable in efforts to apply interpretations of marinerecords to reconstruct past environmental and climate changes in the Caribbean.© 2009 Elsevier B.V. All rights reserved.

The Gulf of Uraba is the largest estuary on the Caribbean coast of Colombia. The aim of this research was to analyse the oceanic, climatic and environmental variables that influence mangrove structure and composition in the gulf. Based on the availability of remote sensing, the study area was divided into western and eastern zones. The spatial pattern of environmental variables (water salinity, pH and percentage of organic matter, sand, silt and clay in the soils) and oceanic and climatic variables (winds, wave height and wave period) was analysed. The relationship of these variables with variables of vegetation structure (basal area, diameter at breast height, tree height, and abundance of seedlings of mangrove species in 1 m2 subplots) was analysed in 27 plots of 500 m2 containing fringe mangroves and 5 plots containing basin mangroves. Mangroves of the western zone showed a higher structural development and were dominated by Rhizophora mangle (red mangrove). This zone is supplied by fresh water and sediments, and the soils have a high content of organic matter and clay and a low degree of anthropogenic disturbance. The eastern zone was characterized by higher pore water salinity due to lower freshwater input from rivers. In this area there is a smaller impact of waves and winds, higher sedimentation rates, high anthropogenic disturbance and mangroves are dominated by Avicennia germinans (black mangrove). Although Laguncularia racemosa (white mangrove) did not show a particular spatial pattern, due to its tolerance to open canopy conditions it was commonly found in anthropogenically disturbed areas.

Mauritia flexuosa L.f. (swamp forest palm) stands are widely distributed in the poorly drained zones of flood plains and low terraces. They provide several economic and cultural resources for local human communities and play an important ecological role in Amazonia. To identify the main factors involved in the natural regeneration dynamics of M. flexuosa, we surveyed the recruitment, mortality, and survival rates of seedlings from June 2010 to November 2012 on a 1-ha plot in a flooded forest area of Colombian Amazonia. The recorded mortality and recruitment rates of M. flexuosa were higher compared to its survival rates over time. These three parameters, included in a CCA, were positively correlated to the basal area (BA) of M. flexuosa adults. The CCA the first two axes explained 88% of data variance. While recruitment was positively related to flooding levels, mortality was positively related to basal area of species other than M. flexuosa and to the lowest organic matter percentages in the topsoil. In a PCA first two axes explained 57% of variance and showed positive correlation of both basal area and seedling abundance of M. flexuosa to soil organic matter content, and to poorly drained soils. Pore water pH and percentages of sand and clay increased with improved soil drainage conditions.

The Late Quaternary paleoenvironmental history from Pacific slopes of the western Andes is reconstructed by pollen analysis of 32 samples from two marine sediment cores from the Panama Basin, eastern equatorial Pacific: core ODP 677B (83°44.2200′ W, 1°12.1440′ N, 3473 m water depth) is 185 cm long and spans the last 39,410 years, core TR 163-38 (81.583° W, 1.337° N, 2200 m water depth) is 103 cm long and covers the last 17,380 years. Six ecological groups were established: mangrove, brackish and fresh water swamps, terra firma lowland forests, broad range taxa, Andean forests, and open vegetation. A good correspondence was found between the changes of these ecological groups in the two cores. The records evidence the continuous presence of all vegetation types during the last 39,410 years and specially the uninterrupted occurrence of tropical rain forest. They record a development from: (1) a cold and humid phase (39,410–28,120 yr cal BP) with moderately high sea levels, (2) the coldest and driest phase in the record (28,120–14,500 yr cal BP) accompanied by the lowest sea levels, (3) a transitional phase when sea level rose and humid conditions dominated, (4) a stage (11,300–5600 yr cal BP) of the highest sea levels and moisture conditions including a drier period ∼7000 yr BP, to (5) a final period (5600 yr cal BP–Present) when sea level reached its present height, humidity persisted, and indicators of disturbance expanded. Peaks in pollen and spore concentration, associated with high river discharge periods, indicate periods of higher precipitation around 33,500, 28,000 and 12,000–9000 yr cal BP. Although main vegetation responses seem to reflect rainfall and moisture variations, a good correspondence was found between δ18O values and percentages of Andean and lowland pollen, suggesting that vegetation also responded to tempearture changes.

Successional sequences from forested wetlands in the Middle Atrato River Basin were reconstructed using characterisation of present vegetation communities and palynological analysis. A 4.8 km transect, drawn across a river meander, and two 6 and 8 m deep sediment cores (San Martin and Villanueva) were collected in the floodplain within two different vegetation assemblages. Based on the floristic and environmental characteristics of the local vegetation communities, ecological changes spanning the last 4 ka (cal years BP) were analysed in San Martin and Villanueva cores. Present vegetation is dominated by four communities determined by flood tolerance and drainage conditions. We found Euterpe oleraceae , Mauritiella macroclada – Campnosperma panamensis and Oenocarpus bataua forests, and mixed forest and open vegetation in a gradient from poor to improved drainage conditions. Vegetation changes in the palynological record suggest that sedimentation and erosion processes on flood basins are due to changes in drainage conditions and to variable flooding levels. A wet period in the 4 to 2.7 ka interval is postulated, which might be related to sea level rise or local subsidence. Lower flooding levels and improved drainage conditions dominated the 2.7 to ∼ 1.6 ka interval, whereas a flooding event (and a hiatus) occurred between 1.5 and 0.5 ka. This flooding event might be synchronous with analogous events as recorded in the Colombian Amazonia between 1.6 and 1.45 ka. Forest disturbance, probably of anthropogenic origin, is recorded in both sites since 0.5 ka.

En el complejo lagunar de Cispatá se localiza una de las mayores extensiones de manglares del Caribe colombiano. Por medio del análisis de los cambios en la estratigrafía, el registro palinológico, la concentración de calcita y la relación carbono-nitrógeno, en dos secciones de sedimentos, se reconstruyó la dinámica de estos manglares durante los últimos 900 años. Las edades se establecieron con base en dataciones con 210Pb y análisis granulométrico. El establecimiento y expansión de los manglares, se relacionó con los procesos fluviomarinos que involucraron la formación de las lagunas. Entre 1064 A.D. y 1762 A.D. se formó la espiga Mestizos y predominaron condiciones marinas. La colonización de la vegetación herbácea ocurrió entre 1142 y 1331 A.D. y la de los manglares a partir de 1717 A.D., por la progradación del delta. Desde 1849 A.D., la migración del delta hacia la bahía de Cispatá, el incremento en el nivel del mar y las tasas de acreción de sedimentos aluviales, permitieron la expansión del manglar en el área. A partir de 1900 se registró una intrusión marina en ambas lagunas. A partir de 1938 A.D, la migración del delta a su posición actual dio origen al sistema lagunar y mayor expansión de los manglares.Mangrove dynamics in the Cispata lagoon system (Colombian Caribbean) during last 900 years. The lagoon complex of Cispatá (old Sinú river delta) located at the Northwestern coast of the Colombian Caribbean, encloses one of the biggest mangrove areas in this region. This area has changed during the last 330 years because of several environmental and climatic causes, mainly changes in the position of the delta (Sinú River), which is the main freshwater source in this area, and sea level rise. We hypothesized that the climatic and geomorphologic dynamics has caused changes in the extension and composition of mangrove vegetation, especially during last 150 years. The dynamics of mangroves during the last 900 years was reconstructed based on the changes in the stratigraphy, pollen record, calcite concentrations (CaCO3) and C/N ratio, along two sediment cores from La Flotante and Navio lagoons, located in Cispatá complex. The age model was built based on lineal interpolation of 210Pb ages and changes in granulometry. Establishment and expansion of mangrove forests during the last 900 years were related to fluviomarine dynamics in the area and the lagoon formation. During the period encompassed between 1064 and 1762 A.D., the Mestizos spit was formed when marine conditions predominated in the surroundings of La Flotante Lagoon. At the site of Navío, a river dominated lagoon, terrigenous conditions dominated since 1830. Although the colonization of herbaceous pioneer vegetation started between 1142 and 1331 A.D., mangrove colonization only took place since 1717 A.D. Mangrove colonization was a result of the delta progradation. In 1849 A.D. the Sinú river delta migrated to the Cispatá bay. The eustatic sea level rise, the increase in river discharges and sedimentation rates produced the establishment of mangrove forests dominated by Rhizophora since 1849. Since 1900 a marine intrusion was recorded in both lagoons. In 1938, the migration of the delta toward its actual location in Tinajones gave place to the formation of the present lagoon system and to the expansion of mangrove forests, which reflects the balance between the high alluvial sediment input and the current sea level rise as has been recorded in similar ecosystems. Rev. Biol. Trop. 58 (4): 1347-1366. Epub 2010 December 01.

The sequence of Late-glacial and Holocene alluvial sedimentation in the middle Caqueta River Basin of Colombian Amazonia is described, based on the study of the sediments and palynology of several river bank sections and on 30 radiocarbon dates. An early Late-glacial sedimentation cycle is recognised, followed by a minor late Late-glacial erosion phase. The Holocene valley fill consists of grey clays (often present in the lower part of the sections) deposited in open water and silty clays often with faint yellow mottling, deposited under a regime of seasonal flooding. The base of the Holocene sections is formed by sands, where exposed. In two places the transition of sand to open-water grey clay was dated around 10 000 yr BP and there is a suggestion that open water may have been more common at the beginning of the Holocene than later, when sedimentation by seasonal flooding became important. In many places much of the earlier Holocene sediments may have been removed by erosion and replaced by younger sediments, by a process of lateral aggradation. A considerable part of the present valley fill is younger than ca. 3500 yr. However, in several places older Holocene sediments are found, apparently only little affected by later erosion, lying below younger varzea silty clays. During the Holocene more organic sediments were formed in periods with reduced river discharge, related to drier climates in the Andes and possibly in Amazonia. These dry periods, deduced from data in the Caqueta River area, correspond well with dry phases in other parts of northwestern South America (e.g. between approximately 2700-1900 yr BP and approximately 3200-3800 yr BP). Rates of average net sedimentation, calculated from dated sections that apparently lack major hiatuses caused by erosion, were high in the lower Holocene, low during the middle Holocene and increase again in the upper Holocene. Levee deposits became coarser and the high river level of the Caqueta increased during the late Holocene. These phenomena may be explained by the increasing influence of man on the vegetation cover in the Andean headwater areas and possibly also in the Amazonian catchment area of the Caqueta River.

The late Quaternary history of the middle Caqueta River area in Colombia, northwestern Amazonia is described, based on observations of river bank sections, radiocarbon dates and palynological analyses of organic layers in floodplain and low terrace sediments of the Caqueta River. It is shown that the Late Pleistocene and Holocene climatic changes that took place in the Andean Cordilleras, were related to the depositional and erosional history of the Caqueta River in the Colombian Amazonian lowlands. The low terrace sediments consist of sandy and gravelly deposits covered by clays that sometimes contain lenses of peaty material. From these organic low terrace sediments, seven finite radiocarbon dates were obtained of Middle Pleniglacial age, between 56 000 and 30 000 yr BP. The coarse textured basal deposits of the low terrace apparently stem from the early part of the Middle Pleniglaciai period, during which the effective rainfall in the Andes was relatively high and the Andean glaciers had a considerable extension. Palynological data from silty sediments with organic remains at one site, show an interval when drier and more open types of vegetation on poor soils must have covered a larger area than today, but Amazonian forest was still the dominating type of vegetation. This interval might correspond to one of the Middle Pleniglacial savanna intervals from eastern Amazonia (Carajas). No organic sediments from the Upper Pleniglacial period were found and hence radiocarbon dates were not obtained. In the Andes this period had a very cold climate with low effective rainfall and in the east Amazonian Carajas area it is characterised by the relative extension of open savanna vegetation. The river run-off and sediment transport must have been much lower than in the Middle Pleniglacial and the Caqueta River cut itself down in its own sediments. Two Late-glacial radiocarbon datings obtained at one site (ca. 12 500 yr BP) indicate the existence of a Late-glacial sedimentation phase, separated from the Holocene sequence by a minor erosional phase. Organic layers in the Holocene floodplain sediments yielded 28 radiocarbon dates between 10 000 and 355 yr BP. Holocene sedimentation started with the rapid deposition of (sandy) clay possibly in a partly permanently inundated Caqueta valley. During the major part of the Holocene (silty) clays were deposited, with a dominant seasonal inundation cycle.

Mangroves are plant associations that are easily adapted to saline conditions and fluctuating levels of flooding. This ecosystem provides a wide variety of goods and services as carbon storage. Structural differences, species composition and micro-environmental characteristics between physiographic types involve differences in carbon storage in their soils. This research aimed to identify the variation of mangrove species through changes in the physical-biotic variables of mangrove forest of Cispatá bay, Colombia. We measured structural variables of forest (D, H, density of individuals) as well as physico-biotic variables (flood level, A. aureum coverage, water interstitial salinity, soil pH, % N, % COs, roots and apparent density soil) in 12 plots established randomly. With a CCA it was identified three mangroves: basin, fringe in good condition and fringe with anthropogenic intervention. The first was dominated by A. germinans and the others by R. mangle. The basin mangrove differs from fringe in physical-biotic variables and structurally, it presented the highest values of COs, salinity, apparent density and pH. Although the two fringe mangrove exhibit similar physical-biotic variables, human disturbance may strongly change the structure of one of them. It was concluded that the distribution of mangrove species of bay responds to a spatial variation in environmental characteristics. However, anthropogenic intervention is a determining variable in the structure of mangroves which affects estimations of the role of different types of mangrove forests as carbon sinks. Los manglares son asociaciones de plantas que se adaptan fácilmente a las condiciones salinas y los niveles fluctuantes de inundación. Estos ecosistemas suministran gran cantidad de bienes y servicios tales como el almacenamiento de carbono. Diferencias estructurales, de composición de especies y de características micro-ambientales entre tipos fisiográficos implican diferencias en el almacenamiento de carbono en sus suelos. La presente investigación tuvo como objetivo identificar la variación de las especies de mangle a través de los cambios en las variables físico-bióticas de bosques de manglar de la bahía Cispatá, Colombia. Se realizaron mediciones de variables estructurales del bosque (D, H, densidad de individuos) y medición de variables físico-bióticas (nivel de inundación, cobertura de A. aureum, salinidad del agua intersticial, pH del suelo, % N, % limo, % arena, % COs, raíces y densidad aparente en el suelo) en 12 parcelas establecidas aleatoriamente. Con un CCA identificaron tres manglares: cuenca, borde en buen estado de conservación y borde con intervención antropogénica. El primero dominado por A. germinans y los otros por R. mangle. El manglar de cuenca se diferencia de los de borde en términos estructurales y en variables físico-bióticas, presentó los valores más altos de COs, salinidad, densidad aparente y pH. Aunque los dos manglares de borde presentan características físico-bióticas similares, la alteración antropogénica cambia fuertemente la estructura de uno de ellos. Se ha concluido que la distribución de las especies de manglar de la bahía responde a la variación espacial de las características ambientales. Sin embargo, la intervención antropogénica es una variable determinante en la estructura de los manglares lo cual afecta las estimaciones del papel de diferentes tipos de manglar como sumideros de carbono.