Community Impacts of Prosopis Juliflora Invasion: Biogeographic and Congeneric Comparisons

We coordinated biogeographical comparisons of the impacts of an exotic invasive tree in its native and non-native ranges with a congeneric comparison in the non-native range. Prosopis juliflora is taxonomically complicated and with P. pallida forms the P. juliflora complex. Thus we sampled P. juliflora in its native Venezuela, and also located two field sites in Peru, the native range of Prosopis pallida. Canopies of Prosopis juliflora, a native of the New World but an invader in many other regions, had facilitative effects on the diversity of other species in its native Venezuela, and P. pallida had both negative and positive effects depending on the year, (overall neutral effects) in its native Peru. However, in India and Hawaii, USA, where P. juliflora is an aggressive invader, canopy effects were consistently and strongly negative on species richness. Prosopis cineraria, a native to India, had much weaker effects on species richness in India than P. juliflora. We carried out multiple congeneric comparisons between P. juliflora and P. cineraria, and found that soil from the rhizosphere of P. juliflora had higher extractable phosphorus, soluble salts and total phenolics than P. cineraria rhizosphere soils. Experimentally applied P. juliflora litter caused far greater mortality of native Indian species than litter from P. cineraria. Prosopis juliflora leaf leachate had neutral to negative effects on root growth of three common crop species of north-west India whereas P. cineraria leaf leachate had positive effects. Prosopis juliflora leaf leachate also had higher concentrations of total phenolics and L-tryptophan than P. cineraria, suggesting a potential allelopathic mechanism for the congeneric differences. Our results also suggest the possibility of regional evolutionary trajectories among competitors and that recent mixing of species from different trajectories has the potential to disrupt evolved interactions among native species

Plant dispersal strategies of high tropical alpine communities across the Andes

Dispersal is a key ecological process that influences plant community assembly. Therefore, understanding whether dispersal strategies are associated with climate is of utmost importance, particularly in areas greatly exposed to climate change. We examined alpine plant communities located in the mountain summits of the tropical Andes across a 4,000-km latitudinal gradient. We investigated species dispersal strategies and tested their association with climatic conditions and their evolutionary history. We used dispersal-related traits (dispersal mode and growth form) to characterize dispersal strategies for 486 species recorded on 49 mountain summits. Then we analysed the phylogenetic signal of traits and investigated the association between dispersal traits, phylogeny, climate and space using structural equation modelling and fourth-corner analysis together with RLQ ordination. A median of 36% species in the communities was anemochorous (wind-dispersed) and herbaceous. This dispersal strategy was followed by the barochory-herb combination (herbaceous with unspecialized seeds, dispersed by gravity) with a median of 26.3% species in the communities. The latter strategy was common among species with distributions restricted to alpine environments. While trait states were phylogenetically conserved, they were significantly associated with a temperature gradient. Low minimum air temperatures, found at higher latitudes/elevations, were correlated with the prevalence of barochory and the herb growth form, traits that are common among Caryophyllales, Brassicaceae and Poaceae. Milder temperatures, found at lower latitudes/elevations, were associated with endozoochorous, shrub species mostly from the Ericaceae family. Anemochorous species were found all along the temperature gradient, possibly due to the success of anemochorous Compositae species in alpine regions. We also found that trait state dominance was more associated with the climatic conditions of the summit than with community phylogenetic structure. Although the evolutionary history of the tropical Andean flora has also shaped dispersal strategies, our results suggest that the environment had a more predominant role. Synthesis. We showed that dispersal-related traits are strongly associated with a gradient of minimum air temperatures in the Andes. Global warming may weaken this key filter at tropical alpine summits, potentially altering community dispersal strategies in this region and thus, plant community structure and composition.Fil: Tovar, Carolina. Royal Botanic Gardens; Reino UnidoFil: Melcher, Inga. University of Amsterdam; Países BajosFil: Kusumoto, Buntarou. Royal Botanic Gardens; Reino Unido. University Of The Ryukyus, Okinawa; JapónFil: Cuesta, Francisco. Universidad de Las Américas.; EcuadorFil: Cleef, Antoine. University of Amsterdam; Países BajosFil: Meneses, Rosa Isela. Universidad Católica del Norte; ChileFil: Halloy, Stephan. Ministry For Primary Industries; Nueva ZelandaFil: Llambi, Luis Daniel. Universidad de Los Andes; VenezuelaFil: Beck, Stephan G.. Universidad Mayor de San Andrés; BoliviaFil: Muriel, Priscilla. Pontificia Universidad Católica del Ecuador; EcuadorFil: Jaramillo, Ricardo Luis. Pontificia Universidad Católica del Ecuador; EcuadorFil: Jacome, Jorge. Pontificia Universidad Javeriana; ColombiaFil: Carilla, Julieta. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentin

Elevation and latitude drives structure and tree species composition in Andean forests: Results from a large-scale plot network

Our knowledge about the structure and function of Andean forests at regional scales remains limited. Current initiatives to study forests over continental or global scales still have important geographical gaps, particularly in regions such as the tropical and subtropical Andes. In this study, we assessed patterns of structure and tree species diversity along ~ 4000 km of latitude and ~ 4000 m of elevation range in Andean forests. We used the Andean Forest Network (Red de Bosques Andinos, https://redbosques.condesan.org/) database which, at present, includes 491 forest plots (totaling 156.3 ha, ranging from 0.01 to 6 ha) representing a total of 86,964 identified tree stems ≥ 10 cm diameter at breast height belonging to 2341 identified species, 584 genera and 133 botanical families. Tree stem density and basal area increases with elevation while species richness decreases. Stem density and species richness both decrease with latitude. Subtropical forests have distinct tree species composition compared to those in the tropical region. In addition, floristic similarity of subtropical plots is between 13 to 16% while similarity between tropical forest plots is between 3% to 9%. Overall, plots ~ 0.5-ha or larger may be preferred for describing patterns at regional scales in order to avoid plot size effects. We highlight the need to promote collaboration and capacity building among researchers in the Andean region (i.e., South-South cooperation) in order to generate and synthesize information at regional scale.Fil: Malizia, Agustina. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Blundo, Cecilia Mabel. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Carilla, Julieta. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Osinaga Acosta, Oriana. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Cuesta, Francisco. Universidad de Las Américas; Ecuador. Consorcio para el Desarrollo Sostenible de la Ecorregión Andina; EcuadorFil: Duque, Alvaro. Universidad Nacional de Colombia. Sede Medellín; ColombiaFil: Aguirre, Nikolay. Universidad Nacional de Loja. Centro de Investigaciones Tropicales del Ambiente y la Biodiversidad; EcuadorFil: Aguirre, Zhofre. Universidad Nacional de Loja. Centro de Investigaciones Tropicales del Ambiente y la Biodiversidad; EcuadorFil: Ataroff, Michele. Universidad de Los Andes; VenezuelaFil: Baez, Selene. Escuela Politécnica Nacional; EcuadorFil: Calderón Loor, Marco. Universidad de Las Américas; Ecuador. Deakin University; AustraliaFil: Cayola, Leslie. Herbario Nacional de Bolivia; Bolivia. Missouri Botanical Garden; Estados UnidosFil: Cayuela, Luis. Universidad Rey Juan Carlos; EspañaFil: Ceballos, Sergio Javier. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Cedillo, Hugo. Universidad de Cuenca; EcuadorFil: Farfán Ríos, William. Universidad Nacional de San Antonio Abad del Cusco. Herbario Vargas; PerúFil: Feeley, Kenneth J.. University of Miami; Estados UnidosFil: Fuentes, Alfredo Fernando. Herbario Nacional de Bolivia; Bolivia. Missouri Botanical Garden; Estados UnidosFil: Gámez Álvarez, Luis E.. Universidad de Los Andes; VenezuelaFil: Grau, Hector Ricardo. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; ArgentinaFil: Homeier, Juergen. Universität Göttingen; AlemaniaFil: Jadan, Oswaldo. Universidad de Cuenca; EcuadorFil: Llambi, Luis Daniel. Escuela Politécnica Nacional; EcuadorFil: Loza Rivera, María Isabel. University of Missouri; Estados Unidos. Herbario Nacional de Bolivia; Bolivia. Missouri Botanical Garden; Estados UnidosFil: Macía, Manuel J.. Universidad Autónoma de Madrid; EspañaFil: Malhi, Yadvinder. University of Oxford; Reino UnidoFil: Malizia, Lucio Ricardo. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; ArgentinaFil: Peralvo, Manuel. Consorcio para el Desarrollo Sostenible de la Ecorregión Andina; EcuadorFil: Pinto, Esteban. Consorcio para el Desarrollo Sostenible de la Ecorregión Andina; EcuadorFil: Tello, Sebastián. Missouri Botanical Garden; Estados UnidosFil: Silman, Miles. Center for Energy, Environment and Sustainability; Estados UnidosFil: Young, Kenneth R.. University of Texas at Austin; Estados Unido

El páramo revalorado

Las fuerzas de la modernización y la intensificación agrícola impulsadas durante las últimas décadas en el páramo, han coexistido con otras que han llevado a su creciente re-valorización como un escenario que puede ser mucho más que un simple espacio para la producción. Así, se han ido configurando visiones alternativas del páramo como espacio de conservación, como escenario para la innovación agroecológica, como fuente de agua o como ecosistema único de la alta montaña tropical. Entre los pr..

Créer des liens entre montagnes et entre disciplines : à la recherche de terrains d'ententes

Llambi Luis Daniel. Créer des liens entre montagnes et entre disciplines : à la recherche de terrains d'ententes. In: Revue de géographie alpine, tome 89, n°2, 2001. pp. 46-49

El páramo revalorado

Las fuerzas de la modernización y la intensificación agrícola impulsadas durante las últimas décadas en el páramo, han coexistido con otras que han llevado a su creciente re-valorización como un escenario que puede ser mucho más que un simple espacio para la producción. Así, se han ido configurando visiones alternativas del páramo como espacio de conservación, como escenario para la innovación agroecológica, como fuente de agua o como ecosistema único de la alta montaña tropical. Entre los pr..

Estructura, diversidad y dinámica de la vegetación en el ecotono bosque-páramo: revisión de la evidencia en la cordillera de mérida

En los Andes tropicales, el límite altitudinal de los bosques corresponde a una compleja zona de transición entre el bosque paramero y el páramo andino. En el límite inferior de esta zona ocurre a su vez una transición gradual entre el bosque y las selvas nubladas. La ordenación del territorio en estos ecosistemas se ha convertido en un tema prioritario en virtud de la creciente amenaza que representan para su conservación las actividades agropecuarias y la minería. En este trabajo se revisaron las investigaciones realizadas en la Cordillera de Mérida (Venezuela) sobre los cambios en la estructura, diversidad y respuesta a disturbios de la vegetación a lo largo del ecotono bosque-páramo. Los resultados de estas investigaciones documentan la alta riqueza de especies y formas de vida que caracterizan la vegetación del ecotono, así como una alta tasa de recambio de especies a lo largo del gradiente de elevación. Así mismo, estudios sobre la dinámica sucesional de la vegetación en áreas intervenidas por la agricultura en diferentes posiciones a lo largo de la transición, indican que las leñosas del bosque muestran una capacidad mucho menor de colonización de las áreas perturbadas que las especies dominantes del páramo. Con base en la evidencia disponible, se discuten elementos estructurales que pueden servir de base para la delimitación de los ecosistemas presentes en la zona de transición y se enfatiza la necesidad de diseñar estrategias de conservación y restauración asistida que partan de interpretar el ecotono bosque-páramo como una unidad dinámica integrada.Universidad Andina Simón Bolívarhttp://www.revistas.unal.edu.co/index.php/actabiol/article/view/46721/5337

Cushion plant community data from an Andean alpine ecosystem in Venezuela

Site These data were collected in the northern-most reaches of the Andes Mountains in the Piedras Blancas páramo, Sierra de La Culata National Park, Venezuela, during January-March 2014 (dry season). Sites were located in the high Andean páramo (superpáramo), between 4250m-4350m, with slopes of 15-25 degrees, and on northeast facing aspects. We sampled three sites in a 5 km area: Rio Azul (8.8866, -70.8685), Avenida (8.8847, -70.8666), and Gloria (8.8928, -70.8714). Life in this region is subject to harsh and dynamic tropical alpine conditions.This region is the driest in Venezuela’s high alpine, with an annual precipitation of 860 mm (Pico El Águila weather station, 4,118 m). The soils at the study sites are coarse, shallow and subject to constant disturbance by needle-ice formation due to frequent freeze-thaw cycles in the soil. The plant community in our study sites sparsely covers the landscape (generally less than 50% cover) and the vegetation is highly clustered. This cover is partitioned into two strata, one dominated by giant rosettes and shrubs, and the other consisting of cushions, disperse grasses, forbs, cushions, and acaulescent rosettes. We studied the two most abundant cushion species in the area, Azorella julianii and Arenaria musciformis. A. julianii is commonly found in the northern Andes from Ecuador to Venezuela (3500-4700 m), while A. musciformis is present in Colombia and Venezuela (3500 and 4300 m). Soil Methods Measurements of soil relative water content (SWC) and organic matter (SOM) were performed by taking soil samples from 5 to 10 cm below the soil surface near midday on a clear day of the dry season (March 2014). One sample was taken from each of eight different haphazardly chosen cushions of Arenaria and Azorella and eight open sites away from the cushions influence (but always within 2-4 m from each replicate pair). SWC measurements were made by calculating the percentage of water in the sample through differences between wet and dry weights. SOM content determinations were obtained using the weight difference between a sample of dry soil, and the remnants of the sample after heating to 400 o C for 4 hours. For measuring shallow soil temperatures within each cushion species, we haphazardly chose three individuals with more than 30 cm in diameter and placed one replicate Onset HOBO TidbiT v2 sensor within each. Sensors were buried 2 cm below the leaf surface at the center of each cushion. Then, we haphazardly sampled three nearby open soil sites away from the direct influence of the cushions and placed one replicate temperature sensor in each, 2 cm below the soil surface. These nine sensors recorded temperatures every 15 minutes during five consecutive clear days between the 27 and 31st of March 2014. From each sensor´s data we calculated the mean, maximum and minimum temperatures and averaged them between the replicate sensors in each microhabitat (inside Azorella and Arenaria and in open areas). Vegetation Sampling Methods At each of the three study sites we haphazardly selected 35 individual cushions of each species within a 200 x 200 m area. For each individual, we placed a wire ring on the cushion and recorded the presence and number of individuals of all vascular plant species within. We defined individuals as ramets, as many species in the páramo are interconnected underground. Then, we randomly sampled open substrate 1 m from each cushion (in 35 paired samples for each cushion species) and measured richness and density within the wire rings in the same way we did in the cushion. In the case of Azorella, there were many cushions that exceeded a mean diameter of 50 cm. However, in the case of Arenaria, the majority of individuals in the population were smaller than that. Hence, we used a 40 cm diameter flexible sampling ring for Azorella (and the paired samples outside) and a 20 cm diameter ring for Arenaria (and paired samples). The area of the rings in each case was then used to calculate plant density for each species. We only sampled individual cushions with a minimum length in one dimension of at least 40 cm for Azorella and at least 20 cm for Arenaria

Les páramos andins

Pour le biogéographe, le páramo constitue un écosystème de haute montagne tropicale, tel est le sens primaire de ce mot qui recouvre en fait bien d’autres réalités. Les páramos andins constituent un espace enchanteur, magique, chargé d’histoire, de mystère, voire même de mystique, une source d’inspirations pour peintres et poètes. Ainsi, Andrés Eloy Blanco dans Luz Caraballo (1935) célèbre un personnage légendaire de la tradition orale andine et Gonzalo Ramón Picón Febres Cordero magnifie dan..