Phytoregionalisation of the Andean páramo

Background: The pa´ramo is a high-elevation biogeographical province in the northern Andes, known for its great biodiversity and ecosystem services. Because there have been very few biogeographic studies encompassing the entire province to date, this study aimed at conducting a phytogeographical regionalisation of the pa´ramo. Specifically, (1) clustering analyses were conducted to identify the main phytogeographical units in the three altitudinal belts: sub-pa´ramo, mid-pa´ramo and super-pa´ramo, and examine their diagnostic flora, (2) an ordination complemented the geo-climatic characterization of the obtained units and (3) a hierarchical classification transformation was obtained to evaluate the relationships between units. Methods: The study area included the entire Andean pa´ramo range in northern Peru, Ecuador, Colombia and Venezuela. The analyses were based on 1,647 phytosociological plots from the VegPa´ramo database. The K-means nonhierarchical clustering technique was used to obtain clusters identifiable as phytogeographical units, and the Ochiai fidelity index was calculated to identify their diagnostic species. A principal component analysis was conducted to obtain the geo-climatic characterization of each unit. Finally, the relationships between clusters were traced using a hierarchical plot-based classification. Results: Fifteen clusters were obtained, 13 natural and two artificial, of which two represented the sub-pa´ramo, nine the mid-pa´ramo and four the super-pa´ramo. Even though data representativeness was a potential limitation to segregate certain subpa ´ramo and super-pa´ramo units, the overall bioregionalisation was robust and represented important latitudinal, altitudinal and climatic gradients. Discussion: This study is the first to bioregionalise the pa´ramo province based on a substantial widely distributed biological dataset, and therefore provides important novel scientific insight on its biogeography. The obtained phytogeographical units can be used to support further research on the pa´ramo at smaller scale and on the humid Neotropical high-elevation ecosystems at broader-scale. Finally, several units were highlighted in our results as particularly worthy of further scientific and conservation focus

Fine-scale plant richness mapping of the Andean Páramo according to macroclimate

Understanding the main relationships between the current macroclimate and broad spatial patterns of plant diversity is a priority in biogeography, and although there is an important body of studies on the topic worldwide, tropical mountains remain underrepresented. Because understanding primary drivers of diversity patterns in the Andean páramo is still in its infancy, we focused on evaluating the role of the current macroclimate in form of three complementary hypotheses, energy, seasonality and harshness, in explaining local variation of plant species richness. We relied on 1,559 vegetation plots that offered a fine-scale outlook on real species assemblages due to community rules and species' interactions with their surrounding environment, including climate. Generalized Least Squares (GLS) regression models provided insight on the significance of the different hypotheses in explaining local plant richness, but only the energy and seasonality hypotheses received partial support. The best model was then combined with spatial interpolation Kriging modeling techniques to project species richness for a standardized 25 m2 plot throughout the entire páramo biogeographical province. We highlighted a North-South increase in richness with several species-rich areas, potential local biodiversity hotspots, independent of the general gradient: the Amotape-Huancabamba zone, Sangay and Cotacachi areas, and eastern Venezuelan Andes. Our endeavor to finely map local richness is the first effort predicting macroecological patterns in the emblematic Andean páramo and contributes novel biogeographical knowledge useful to further support in-depth research and conservation focus in the northern Andes

Global patterns and drivers of alpine plant species richness

Aim Alpine ecosystems differ in area, macroenvironment and biogeographical history across the Earth, but the relationship between these factors and plant species richness is still unexplored. Here, we assess the global patterns of plant species richness in alpine ecosystems and their association with environmental, geographical and historical factors at regional and community scales. Location Global. Time period Data collected between 1923 and 2019. Major taxa studied Vascular plants. Methods We used a dataset representative of global alpine vegetation, consisting of 8,928 plots sampled within 26 ecoregions and six biogeographical realms, to estimate regional richness using sample‐based rarefaction and extrapolation. Then, we evaluated latitudinal patterns of regional and community richness with generalized additive models. Using environmental, geographical and historical predictors from global raster layers, we modelled regional and community richness in a mixed‐effect modelling framework. Results The latitudinal pattern of regional richness peaked around the equator and at mid‐latitudes, in response to current and past alpine area, isolation and the variation in soil pH among regions. At the community level, species richness peaked at mid‐latitudes of the Northern Hemisphere, despite a considerable within‐region variation. Community richness was related to macroclimate and historical predictors, with strong effects of other spatially structured factors. Main conclusions In contrast to the well‐known latitudinal diversity gradient, the alpine plant species richness of some temperate regions in Eurasia was comparable to that of hyperdiverse tropical ecosystems, such as the páramo. The species richness of these putative hotspot regions is explained mainly by the extent of alpine area and their glacial history, whereas community richness depends on local environmental factors. Our results highlight hotspots of species richness at mid‐latitudes, indicating that the diversity of alpine plants is linked to regional idiosyncrasies and to the historical prevalence of alpine ecosystems, rather than current macroclimatic gradients

Plant diversity and vegetation of the Andean Páramo

[spa] La región biogeográfica que incluye los ecosistemas naturales y semi-naturales de alta montaña distribuidos entre el bosque montano y las nieves perpetuas en los Andes del Norte recibe el nombre de páramo, el cual es considerado un hotspot de biodiversidad, con más de 3.400 especies de plantas vasculares y un alto grado de endemismo. La gran biodiversidad del páramo se debe en gran parte a su reciente origen y a su insularidad continental. Los páramos proporcionan muchos servicios ecológicos a las poblaciones humanas, sobretodo en el subministro de agua y el secuestro de carbono. Las actividades antrópicas como la agricultura y el pastoreo, y el cambio climático son las principales amenazas para el equilibrio ecológico del ecosistema. Consecuentemente, es imprescindible aumentar nuestro conocimiento científico y proponer nuevas estrategias de gestión y de conservación. La mayoría de estudios botánicos y ecológicos sobre el páramo, al igual que los planes de gestión, se desarrollan desde escala local hasta nacional. Aunque estos estudios son aportaciones de gran valor científico, también es importante considerar el ecosistema en toda su extensión para obtener unos resultados y patrones válidos en la región biogeográfica. Los estudios regionales sobre la biogeografía de plantas en el páramo son muy escasos, siendo las principales limitaciones la dificultad de establecer colaboraciones científicas y de gestión internacionales y la falta de fuentes de datos biológicos de buena calidad y de libre acceso. Consecuentemente, construimos VegPáramo, una base de datos de flora y vegetación para el páramo andino, que contiene 3.000 inventarios de vegetación muestreados con el método fitosociológico en la región, y que proceden tanto de la literatura como de nuestro trabajo de campo. Creamos un portal web para VegPáramo, www.vegparamo.com, a partir del cual se pueden consultar y descargar los datos libremente. Usamos los datos de VegPáramo para clasificar la vegetación de páramo a nivel de la región. Con una metodología de clustering no-jerárquico, clasificamos el páramo en 17grupos (o clusters) de los cuales 14 representan a unidades fitogeográficas naturales conteniendo una o varias comunidades vegetales y 3 son artificiales. Caracterizamos los 17 grupos por su flora diagnóstica y los comparamos a nivel de diversidad alpha y beta. Finalmente, usamos los datos de VegPáramo y los resultados de nuestra clasificación para estimar y comparar la diversidad de plantas a escala local y regional en los pisos altitudinales del páramo con el objetivo de destacar y entender los principales patrones de riqueza florística en la región. Evaluamos el poder explicativo del ambiente en la riqueza florística mediante modelos de regresión. Finalmente, modelamos la riqueza florística potencial en la región y destacamos unos hotspots de biodiversidad. Nuestro proyecto contribuye a entender mejor el páramo como región biogeográfica y propone primeras sugerencias de áreas concretas para la conservación. Pensamos que los esfuerzos futuros de investigación y de gestión deberían enfocarse particularmente en los impactos del cambio climático sobre la flora y la vegetación del páramo.[eng] The páramo is a high mountain ecosystem that includes the natural and semi-natural habitats located between the montane treeline and the permanent snowline in the humid Northern Andes. Given its recent origin and continental insularity among tropical lowlands, the páramo evolved as a biodiversity hotspot, with a vascular flora of more than 3400 species and high endemism. Moreover, the páramo provides many ecosystem services for human populations, essentially water supply and carbon storage. Anthropogenic activities, mostly agriculture and pasture practices, as well as climate change are major threats for the páramo’s ecological integrity. Consequently, further scientific research and conservation strategies must be oriented towards this unique region. Botanical and ecological knowledge on the páramo is extensive but heterogeneous. Moreover, most research studies and management strategies are carried out at local to national scale and given the vast extension of the páramo, regional studies are also needed. The principal limitation for regional páramo studies is the lack of a substantial source of good quality botanical data covering the entire region and freely accessible. To meet the needs for a regional data source, we created VegPáramo, a floristic and vegetation database containing 3000 vegetation plots sampled with the phytosociological method throughout the páramo region and proceeding from the existing literature and our fieldwork. We made VegPáramo accessible online through a webportal, www.vegparamo.com, from which the data can be freely consulted and downloaded. We then used the VegPáramo data to conduct a regional vegetation classification of the páramo. We used a clustering technique and classified the region into 17 clusters, 14 representing natural phytogeographical units of one or several plant communities and 3 artificial ensembles. We characterized the 17 clusters and estimated the alpha diversity and beta diversity to highlight species richness and floristic similarities. Our last study focused on the plant diversity patterns in the páramo region. We used the VegPáramo data and our classification results to estimate and compare plant diversity at local and regional scale in the altitudinal belts of the páramo. We evaluated the importance of the environment as driver of species richness using regression models. Finally, we modeled the predicted species richness in the páramo region and highlighted biodiversity hotspots. Our project contributes to a better understanding of the páramo biogeography and makes primarily suggestions for conservation. We believe further research should focus on the impacts of climate change on the páramo flora and vegetation

Biogeography of South American highlands, in Earth Systems and Environmental Sciences

Alpine environments in South America occur essentially in the Andes, which extend along a latitudinal gradient between 11N in Colombia and 55S in Chile. The alpine biodiversity of the Andes is the richest in the world and it displays remarkable patterns of endemism, species radiations and morphological/physiological adaptations. In this article we aim at discussing the major biogeographical drivers of alpine biodiversity in the Andes and their consequent spatial patterns (i) in the past, (ii) at present, and (iii) in a near future under the influence of global change. Moreover, we briefly discuss the biogeography of smaller alpine environments in South America, that is, the Guayana highlands, Campos de Altitude and Tristan da Cunha Island. First, the evolution of the South American continent during the Mesozoic and Cenozoic greatly shaped biodiversity patterns in the Andes through mountain uplift and successive periods of geographic connectivity and isolation. Mountain building led to new niches that became available for colonization by both temperate and tropical species, while important topographic changes and the continental connection with North America provided either biotic corridors or sky islands. Second, Pleistocene glacial dynamics accelerated taxonomic diversification but also exacerbated extinction processes that substantially changed Andean biodiversity. Third, human activities have progressively influenced the structure and function of alpine ecosystems, leading to today’s Andean biogeography. Current drivers of biodiversity distribution can be described at three spatial scales. At the continental scale, latitudinal shifts create strong variations in temperature seasonality, influencing, for example, snow cover duration and generating distinctive adaptations from the North to the South. At the regional scale, rain shadow effects, the Humboldt Current and trade winds combine with topographical and bedrock variations to create hotspots of endemism such as are found in the Sierra Nevada de Santa Marta (Colombia) or alpine deserts with specific life forms such as are found in the Central Andes. At the local scale, the spatial distribution of species is extended through habitat amelioration by nurse/engineering plants. These unique alpine ecosystems are highly vulnerable to the combined effects of climate and land use changes. High-Andean biota will undoubtedly respond to these changes by either adaptation, local/regional migration, or extinction. Extinction is already occurring at alarming rates in many taxonomic groups. Finally, we predict that new threats, such as biotic invasions and the creation of non-analog communities will directly affect biodiversity response

Phytoregionalisation of the Andean páramo

Background The páramo is a high-elevation biogeographical province in the northern Andes, known for its great biodiversity and ecosystem services. Because there have been very few biogeographic studies encompassing the entire province to date, this study aimed at conducting a phytogeographical regionalisation of the páramo. Specifically, (1) clustering analyses were conducted to identify the main phytogeographical units in the three altitudinal belts: sub-páramo, mid-páramo and super-páramo, and examine their diagnostic flora, (2) an ordination complemented the geo-climatic characterization of the obtained units and (3) a hierarchical classification transformation was obtained to evaluate the relationships between units. Methods The study area included the entire Andean páramo range in northern Peru, Ecuador, Colombia and Venezuela. The analyses were based on 1,647 phytosociological plots from the VegPáramo database. The K-means non-hierarchical clustering technique was used to obtain clusters identifiable as phytogeographical units, and the Ochiai fidelity index was calculated to identify their diagnostic species. A principal component analysis was conducted to obtain the geo-climatic characterization of each unit. Finally, the relationships between clusters were traced using a hierarchical plot-based classification. Results Fifteen clusters were obtained, 13 natural and two artificial, of which two represented the sub-páramo, nine the mid-páramo and four the super-páramo. Even though data representativeness was a potential limitation to segregate certain sub-páramo and super-páramo units, the overall bioregionalisation was robust and represented important latitudinal, altitudinal and climatic gradients. Discussion This study is the first to bioregionalise the páramo province based on a substantial widely distributed biological dataset, and therefore provides important novel scientific insight on its biogeography. The obtained phytogeographical units can be used to support further research on the páramo at smaller scale and on the humid Neotropical high-elevation ecosystems at broader-scale. Finally, several units were highlighted in our results as particularly worthy of further scientific and conservation focus

Automatic seed classification for four páramo plant species by neural networks and optic RGB images

ABSTRACTThere is a need for robust methodological approaches to improve our capacity to automatically detect plant species from seed samples tohelp support plant management strategies. In this study, we tested different neural network techniques to automatically detect native species from seeds from the Andean páramo region based on optic RGB images. Specifically, we compared i) simple feed-forward networks (SNNs), consisting of feed-forward nets with error back-propagation, holding one hidden layer with different number of neurons; and ii) deep convolutional neural networks (CNNs), which have their convolutional layers-built form multiple 3x3 kernels. First, we sampled 50 seeds from four common plant species in the La Rusia Páramo (Colombia): Espeletia congestiflora, Bucquetia glutinosa, Calamagrostis effusa and Puya santosii. We took RGB images of individual seeds for each species on contrasted white and black backgrounds, and then classified all images under both SNNs and CNNs. Under a double cross-validation scheme, the SNN approach with 14 neurons approached 88% of test accuracy, while CNN achieved 93%. Moreover, when increasing the image sample in the training dataset fed to models, CNN performed with 100% accuracy when used on testing and validation datasets. Overall, the neural network approach explored here suggests a promising methodology for species prediction from seeds based on optical RGB images, with potential for automatic seed recognition and counting on the field

Mapping the páramo land-cover in the Northern Andes

International audienceThe Andean páramo is a biodiverse and vulnerable tropical high-mountain region, whose spatio-ecological patterns remain understudied. The lack of general characterization of its overall extent, land-cover classes, and treeline spatial features hinders our capacity to understand its responses to human impacts and predict future land-system changes. To address this knowledge gap, we classified the land-cover of the páramo in the Northern Andes. Moreover, we estimated (1) the páramo’s total extent and its distribution among the Andean countries, (2) the relative extent of 12 of its main land-cover classes, categorized into natural vegetation, natural abiotic and anthropogenic groups, and (3) the preliminary position and anthropogenic influence of its bordering treeline. Relying on Landsat 8 imagery, we performed hybrid manual-automated classifications using the Maximum Likelihood and Random Forest algorithms. The two resulting final classifications were manually checked for errors compared to Google Earth and VegPáramo data, and used to produce the expert classification. Finally, we delimited the treeline based on regional forest connectivity, and applied it to the expert classification to evaluate páramo elevations, surface areas and land-cover classes above the Andean treeline. The páramo extent was estimated at 24,301 km2, distributed between Ecuador (47%), Colombia (43%), Venezuela (8%) and Peru (2%). Natural vegetation, especially shrublands, rosette plant communities and grasslands were dominant (altogether, 65%), whereas classes reflecting intense land-use covered 12% overall. The average treeline reached 3546 m and was bordered uphill at 16% with anthropogenic land-cover classes. The páramo’s extent is smaller than previously suggested. It remains a (semi-) natural region, yet the expansion of crops and pastures towards high elevations is a critical concern for long-term sustainability. Future research can build on our findings to predict land-system changes and assess priority areas for conservation. We recommend for future research to focus on remnant forest patches and treeline connectivity in priority

Phytoregionalisation of the Andean páramo

Background: The pa´ramo is a high-elevation biogeographical province in the northern Andes, known for its great biodiversity and ecosystem services. Because there have been very few biogeographic studies encompassing the entire province to date, this study aimed at conducting a phytogeographical regionalisation of the pa´ramo. Specifically, (1) clustering analyses were conducted to identify the main phytogeographical units in the three altitudinal belts: sub-pa´ramo, mid-pa´ramo and super-pa´ramo, and examine their diagnostic flora, (2) an ordination complemented the geo-climatic characterization of the obtained units and (3) a hierarchical classification transformation was obtained to evaluate the relationships between units. Methods: The study area included the entire Andean pa´ramo range in northern Peru, Ecuador, Colombia and Venezuela. The analyses were based on 1,647 phytosociological plots from the VegPa´ramo database. The K-means nonhierarchical clustering technique was used to obtain clusters identifiable as phytogeographical units, and the Ochiai fidelity index was calculated to identify their diagnostic species. A principal component analysis was conducted to obtain the geo-climatic characterization of each unit. Finally, the relationships between clusters were traced using a hierarchical plot-based classification. Results: Fifteen clusters were obtained, 13 natural and two artificial, of which two represented the sub-pa´ramo, nine the mid-pa´ramo and four the super-pa´ramo. Even though data representativeness was a potential limitation to segregate certain subpa ´ramo and super-pa´ramo units, the overall bioregionalisation was robust and represented important latitudinal, altitudinal and climatic gradients. Discussion: This study is the first to bioregionalise the pa´ramo province based on a substantial widely distributed biological dataset, and therefore provides important novel scientific insight on its biogeography. The obtained phytogeographical units can be used to support further research on the pa´ramo at smaller scale and on the humid Neotropical high-elevation ecosystems at broader-scale. Finally, several units were highlighted in our results as particularly worthy of further scientific and conservation focus