ABSTRACT Páramo ecosystems are of great importance because they are considered hotspots within the Tropical Andes. They are also very important for their role as producers and regulators of water processes in the Neotropic. However, the human occupation of the Colombian Páramos has generated conflict between environmental benefits and productive land uses, specifically the potato cultivation and livestock. To assess possible changes associated with potato cultivation (Solanum tuberosum L.) and livestock on the microbial communities of Páramo soils, the objective of this research was to evaluate the possible effects of potato cultivation and livestock farming on the soil microorganisms associated with different functional groups (nitrogen fixers, phosphate solubilizers and cellulolytic) in the Páramo of Nevados National Natural Park (Nevados NNP), Colombia. Samples were collected from soils under potato cultivation, livestock, and Páramo conservation areas over two climatic seasons (rainy and dry) in three farms at different elevations (3769, 3590, and 3432 m a.s.l.). The microorganisms were isolated using selective culture media for each functional group and identified using molecular markers; microbial diversity was analyzed using multivariate statistical tools. Changes were dependent on land use, elevation, and climate and were statistically significant in the rainy season on all three farms and one of the farms during the dry season. Similarly, the results indicated that climate has a greater impact on the evaluated microbial communities than land use does; the changes were significantly different between the soil under potato cultivation and in conserved Páramo sites at most of the evaluated locations and between soil subjected to livestock farming and Páramo in certain locations. However, the differences between potato cultivation and livestock farming were smaller. This study showed for the first time that the microbial structure (abundance and composition) of microorganism functional groups was different as a result of potato cultivation and livestock farming on Páramo soils, although these changes were dependent on farm elevation and climate.

Colombia is a country biologically and culturally megadiverse. Presented inside the largest expanse of páramos of the world, which are considered the planet's water plants and habitats of high biological diversity. However, human occupation of the Colombian Páramos has generated conflict between environmental regulations and productive land uses. This article analyzes the alternative proposed solutions to the conflict between environmental authorities of protected areas and inhabitants of the Páramos in Colombia. Previously there were two types of alternatives: The first suggested granting ecotourism services in parks and land purchases by mixed companies. The second proposed the abandonment of the production activities of farmers, mediated by educational processes and in compliance with environmental standards on pain of facing punitive action by the state. We propose a third alternative, that involves community management plans with time and institutional funding, and implementation of agroecological models, biocultural rescue memory and changes in agrarian structure.

Colombia es uno de los países denominados megadiversos biológica y culturalmente. Presenta a su interior la mayor extensión de páramos del mundo, los cuales son considerados fábricas de agua del planeta y hábitats de rica diversidad biológica. Por otro lado, la ocupación humana de los páramos colombianos ha generado conflictos entre las normativas ambientales vigentes y los usos productivos del suelo. El presente artículo analiza las alternativas aplicadas ante el conflicto entre autoridades ambientales de áreas protegidas y habitantes de los páramos en Colombia. Se encontraron dos tipos de alternativas: la primera plantea la concesión de servicios ecoturísticos en los parques naturales y la compra de tierras por parte de sociedades de economía mixta. La segunda plantea el abandono de las actividades productivas de los agricultores, mediado por procesos educativos o de cumplimiento de las normas ambientales vigentes, so pena de enfrentar acciones punitivas por parte del Estado. Este trabajo presenta una tercera alternativa, que parte de la crítica a las dos anteriores e incluye diferentes estrategias: planes de manejo comunitario con tiempo y financiación institucional pertinente, aplicación de modelos agroecológicos y rescate de la memoria biocultural y cambios en la estructura agraria.

En una finca ecológica del municipio de Tenjo (Cundinamarca-Colombia) se estudió el efecto de varios materiales preparados a partir de chipaca (Bidens pilosa) y de aislamientos microbianos, sobre la incidencia y severidad de P. infestans en un cultivo de papa criolla (Solanum phureja), utilizando un diseño completamente al azar (DCA) con submuestreo y ocho tratamientos: purín de flores; purín mezcla; actinomiceto AC 12 (Streptomyces sp.); mezcla de actinomicetos; aislamiento bacteriano (Bacillus subtilis); mezcla bacterias (Bacillus subtilis y Burkholderia cepacia); Hongo (Geotrichum sp.) y un control (agua destilada estéril). Los resultados mostraron rápida incidencia de la enfermedad, que fue evidente a los 36 días después de la siembra (dds) y alcanzó 100% de afectación a los 52 dds sin diferencias entre tratamientos. La severidad fue estadísticamente diferente únicamente en el tratamiento de "purín de flores", que se diferenció significativamente del tratamiento control entre los 56 y 70 dds (27,8% menos) lo que fortalece resultados de ensayos anteriores sobre su potencial como posible producto biocontrolador de la Gota. Resultados menores de severidad frente al control (no significativos) también se obtuvieron con los tratamientos "purín mezcla" y "mezcla de actinomicetos", entre los 60 y 87 dds.

In an organic farm of Tenjo (Cundinamarca, Colombia) the effect of various materials prepared from chipaca (Bidens pilosa) and microbial isolates, on the incidence and severity of P. infestans in potato (Solanum phureja) were studied using a completely randomized design (CRD) with subsampling and eight treatments: flowers slurry, mixed slurry; actinomycete AC 12 (Streptomyces sp.), mix actinomycetes; isolation bacterial (Bacillus subtilis ); mixed bacteria (Bacillus subtilis and Burkholderia cepacia); fungus (Geotrichum sp.) and a control (sterile distilled water). The results showed rapid disease incidence, which was evident at 36 days after planting (dap) and reached 100% involvement at 52 dap, with no differences between treatments. The severity was statistically different only in the treatment of "purin of flowers", which differed significantly from the control treatment between 56 and 70 dap (27.8,% less) which strengthens results of previous tests as a potential biocontrol product. Lower percentages of severity versus control (not significant) were also obtained with the treatments "slurry mixture" and "mixed actinomycetes", between 60 and 87 dap.

Se estudió el efecto inhibidor de los actinomicetos presentes en purines o extractos fermentados de plantas de chipaca (Bidens pilosa L.), sobre el crecimiento de Phytophthora infestans (Mont) de Bary, causante del tizón tardío de la papa. Se elaboraron cuatro purines de flores, raíces, hojas-tallos y su mezcla. De estos purines se obtuvieron 25 aislamientos de actinomicetos, cada uno de los cuales se enfrentó con P. infestans en placas de medio de cultivo, utilizando la técnica de anillos de Gauze y estableciendo las concentraciones iniciales de esporas mediante conteos microscópicos en cámara de Neubauer. Los actinomicetos no crecieron en el purin de flores debido, posiblemente, a que en él no se utiliza suelo rizosférico o porque su pH (9) es mayor que el rango normal de crecimiento de estos microorganismos ( pH 6 -; 8). Se evidenció inhibición del crecimiento del oomycete por parte de 8 aislamientos de actinomicetos con porcentajes de inhibición entre 33,3 - 77,8%, provenientes de los purines de raíces, tallos-hojas y mezcla de partes de la planta. La mayor inhibición se obtuvo en los aislamientos AC001, AC010, AC011 y AC025 con conteos de 0,4, 6,0, 3,0, y 3,6 x10(5) esporas mL-1).

Purins or liquid fermented extracts of chipaca (Bidens pilosa L.) were prepared to establish the inhibitory effect of the actinomycetes found in such biopharmaceutical preparations on the growth of Phytophthora infestans (Mont) de Bary, the causative of potato late blight disease. Four purins made from flowers, roots, leaf-steams and a mixture of them were prepared; 25 actinomycete isolates were obtained from these purins and their ability to resist challenge by P. infestans was ascertained in medium plates using the ring Gauze technique and establishing initial concentrations of spores by microscopic counting in Neubauer chamber. Actinomycetes did not grow in flower purin as rhizosphere soil was not used in its preparation or because this particular pH (9) was higher than the normal range of 6 to 8 pH. Oomycete growth was inhibed in 8 actinomycete isolates (33.3% - 77.8% inhibition) from roots, stem-leaves and plant part purin mixtures. The greatest inhibition was obtained from isolates AC001, AC010, AC011 and AC025 (0.4, 6.0, 3.0 and 3.6 x 10(5) spore mL-1 count).

En una finca ecológica (FE) y una convencional (FC) se comparó el comportamiento de poblaciones de babosas y su relación con algunos carábidos predadores, la presencia de arvenses, prácticas agrícolas y la productividad de cuatro variedades de lechuga (Lactuca sativa. L.). Semanalmente se realizaron capturas de babosas, conteos de nivel de daño, altura y número de hojas en 10 plantas. Se recolectaron arvenses y coleópteros en las dos fincas. Los conteos totales de babosas en la FE fueron estadísticamente superiores. Se colectaron cuatro especies (Deroceras. reticulatum, Milax gagates, Deroceras. laeve y Limax. maximux) frente a dos encontradas en FC. Con excepción de la variedad "Morada Lisa", no se encontraron diferencias significativas en el nivel de daño en las otras variedades entre las dos fincas, pero sí en la variable peso seco de FE. En FE se presentaron 5 especies de carábidos y 25 de arvenses frente a ninguna y 6 en FC, respectivamente. Los datos anteriores se explican en función de las prácticas agronómicas de cada sistema de manejo.

In an organic (FE) and a conventional (FC) farm system the population behavior of slugs and their relationship with some carabids predators was compared, as well as, the presence of weeds, agricultural practices and productivity of four varieties of lettuce. Weekly catches of slugs were made and the damage level, height and the number of leaves in ten plants was measured. Weeds and carabids were collected in both farms. The total number of slugs in the FE was statistically higher and four species (D. reticulatum, Milax gagates, D. and L. laev maximux) were collected compared with two found in FC. With the exception of the variety "Morada Lisa", there were no significant differences in the level of damage in the other varieties between the two farms. There were significant differences in the dry weight variable in favour of the organic farm. In FE, 5 carabids species and 25 weeds were presented compared to none in FC and 6, respectively. The data above are explained in terms of the agronomic practices of each management system.