Several studies have demonstrated the relevance of endophytic bacteria on the growth and fitness of agriculturally-relevant plants. To our knowledge, however, little information is available on the composition, diversity, and interaction of endophytic bacterial communities in plants struggling for existence in the extreme environments of Chile, such as the Atacama Desert (AD) and Patagonia (PAT). The main objective of the present study was to analyze and compare the composition of endophytic bacterial communities associated with roots and leaves of representative plants growing in Chilean extreme environments. The plants sampled were: Distichlis spicate and Pluchea absinthioides from the AD, and Gaultheria mucronata and Hieracium pilosella from PAT. The abundance and composition of their endophytic bacterial communities was determined by quantitative PCR and high–throughput sequencing of 16S rRNA, respectively. Results indicated that there was a greater abundance of 16S rRNA genes in plants from PAT (1013 to 1014 copies g−1 DNA), compared with those from AD (1010 to 1012 copies g−1 DNA). In the AD, a greater bacterial diversity, as estimated by Shannon index, was found in P. absinthioides, compared with D. spicata. In both ecosystems, the greater relative abundances of endophytes were mainly attributed to members of the phyla Proteobacteria (14% to 68%), Firmicutes (26% to 41%), Actinobacteria (6 to 23%) and Bacteroidetes (1% to 21%). Our observations revealed that most of operational taxonomic units (OTUs) were not shared between tissue samples of different plant species in both locations, suggesting the effect of the plant genotype (species) on the bacterial endophyte communities in Chilean extreme environments, where Bacillaceae and Enterobacteriacea could serve as keystone taxa as revealed our linear discriminant analysis.
Abstract. A critical aspect of predicting soil organic carbon (SOC) concentrations is the lack of available soil information; where information on soil characteristics is available, it is usually focused on regions of high agricultural interest. To date, in Chile, a large proportion of the SOC data have been collected in areas of intensive agricultural or forestry use; however, vast areas beyond these forms of land use have few or no soil data available. Here we present a new SOC database for the country, which is the result of an unprecedented national effort under the framework of the Global Soil Partnership. This partnership has helped build the largest database of SOC to date in Chile, named the Chilean Soil Organic Carbon database (CHLSOC), comprising 13 612 data points compiled from numerous sources, including unpublished and difficult-to-access data. The database will allow users to fill spatial gaps where no SOC estimates were publicly available previously. Presented values of SOC range from 6×10-5 % to 83.3 %, reflecting the variety of ecosystems that exist in Chile. The database has the potential to inform and test current models that predict SOC stocks and dynamics at larger spatial scales, thus enabling benefits from the richness of geochemical, topographic and climatic variability in Chile. The database is freely available to registered users at https://doi.org/10.17605/OSF.IO/NMYS3 (Pfeiffer et al., 2019b) under the Creative Commons Attribution 4.0 International Public License.
ResumenEl Parque Nacional Torres del Paine (TDP) es un área donde las plantas invasoras son una amenaza creciente para la conservación. El aumento de turistas ha propiciado durante los últimos años un incremento de invasoras en sitios donde el turismo tiene impacto directo (e.g. áreas de camping, senderos). En ocasiones, turistas negligentes han provocado mega-incendios que han favorecido la dispersión de estas plantas. En este trabajo se revisa la información concerniente a las plantas exóticas en TDP, y se utiliza un marco conceptual para abordar esta problemática, que incluye conceptos jerárquicos de invasibilidad. Se presentan resultados para dos experiencias en donde este marco conceptual tiene aplicación: a) una prospección en que se evalúa la distribución y abundancia de exóticas post-incendio; b) un experimento de campo donde se evalúa el efecto del control de invasoras en la supervivencia de plántulas de lenga (Nothofagus pumilio). Además se entregan antecedentes que permiten calcular el costo de la operación de control. La investigación sobre plantas exóticas en TDP incluye listados de especies que categorizan a priori las invasoras, careciendo de información ecológica de campo. Se detectó la presencia de 34 especies de plantas exóticas en sitios incendiados, algunas de ellas con gran potencial de invasión postincendio. La supervivencia de plántulas de Lenga es mayor cuando se han controlado las malezas mediante remoción mecánica, posiblemente debido a la facilitación inducida. Los costos de control de especies de malezas mediante remoción mecánica pueden fluctuar desde CLP$ 700.000 a $1.400.000 para el control de 1 hectárea. Este estudio resalta la necesidad de considerar a las especies invasoras como un fenómeno contextodependiente, que puede o no persistir dependiendo del tipo de perturbación que facilite su dispersión, grados de severidad, tiempo post-perturbación y resiliencia ecosistémica. Palabras clave:Ecosistemas subantárticos, invasión post-incendio, Rumex acetosella, Plantago lanceolata, Fuego, control de plantas invasoras. AbstractTorres del Paine National Park (TDP) is an area in which invasive plants are a growing threat for
Abstract. One of the critical aspects in modelling soil organic carbon (SOC) predictions is the lack of access to soil information which is usually concentrated in regions of high agricultural interest. In Chile, most soil and SOC data to date is highly concentrated in 25 % of the territory that has intensive agricultural or forestry use. Vast areas beyond those forms of land use have few or no soil data available. Here, we present a new database of SOC for the country, which is the result of an unprecedented national effort under the frame of the Global Soil Partnership that help to build the largest database on SOC to date in Chile named “CHLSOC" comprising 13,612 data points. This dataset is the product of the compilation from numerous sources including unpublished and difficult to access data, allowing to fill numerous spatial gaps where no SOC estimates were publicly available before. The values of SOC compiled in CHLSOC range from 6×10−5 to 83.3 percent, reflecting the variety of ecosystems that exists in Chile. Profiting from the richness of geochemical, topographic and climatic variability in Chile, the dataset has the potential to inform and test models trying to predict SOC stocks and dynamics at larger spatial scales. Dataset available at https://www.doi.org/10.17605/OSF.IO/NMYS3 (Pfeiffer et al., 2019b).
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