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The 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. [ABSTRACT FROM AUTHOR]

Question: As a result of recent and substantial digitization efforts, herbaria are becoming important sources of data for vegetation scientists. Are such data sets appropriate to describe composition gradients and β‐diversity? When compared with phytosociological data, what are the differences in terms of composition (co‐occurrence) gradients depending on the considered scale? Location: Páramos (Neo‐tropical alpine ecosystems) of Colombia. Methods: We compared vegetation patterns from phytosociological relevés and reconstructed pseudo‐communities from herbarium collections in the Colombian high elevation páramo ecosystem using diversity partitioning and Mantel correlations. Results: Species composition differed in the two data sets, which could be explained by taxonomic bias towards charismatic species and overrepresentation of rare species in the herbarium data set, whereas common species were more frequently represented in the phytosociological data set. The two data sets showed a similarly preponderant importance of large‐scale differences when we looked at species accumulation across different scales. Small‐scale richness contributed more to total richness for the phytosociological data set, while richness at intermediate scales was more important in the herbarium data set. Finally, pairwise β‐diversity analyses did not show correlations between data sets, and common species showed similar ecological distribution patterns. Conclusions: We recommend caution to researchers who wish to describe β‐diversity patterns in local communities using only herbarium data. However, since the two data sets showed some complementarity in their composition patterns, we suggest that combining data from relevés (or plots) and occurrence data (herbarium records, citizen science, etc.) could be an efficient strategy for describing broader diversity patterns. We discuss the circumstances under which it could be advantageous to work with such combined data sets, in particular in relation to conservation issues. [ABSTRACT FROM AUTHOR]

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 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-páramo, nine the mid-páramo and four the super-páramo. Even though data representativeness was a potential limitation to segregate certain subpáramo 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. [ABSTRACT FROM AUTHOR]