Ecology of bryophytes along altitudinal and latitudinal gradients in Chile

The bryophyte vegetation in twenty-eight hectare plots in forests of S-Chile between 38° and 42°S and sea level and the forest line has been studied. Since bryophytes are fully dependend on atmospheric water and nutrient supply, they are good indicators of ecological conditions, especially for humidity. Therefore cover of epiphytic bryophytes, percentage of hepatics, composition of life forms and phytomass of epiphytic bryophytes were used as parameters. Cover and phytomass of epiphytic bryophytes as well as percentage of hepatics show moderate values in the lowlands, peak values in the montane belt (400-800m) and low values in the high montane to subalpine forests. This zonation corresponds with the composition of life forms and is attributed to a higher humidity in the montane belt. Life forms characteristic for the lowlands and submontane belts are pendants, those for the montane belt are wefts and tails, and those for the high montane and and subalpine belts are mats and cushions. The same zonation is found in New Zealand at comparable latitudes. The altitudinal differences are much stronger than the latitudinal ones. Compared with similar transect studies in New Zealand, there is a comparable zonation based on bryphytes. The percentage of hepatics as a good indicator of humidity, is – both in Chile and New Zealand - higher in the transects along the coast with higher precipitation, lower in transects in the inland with less precipitation, and increasing with altitude. Compared with tropical rain forests, the “mossiness” of temperate rain forests expressed by phytomass of epiphytic bryophytes per hectare, cover and percentage of hepatics is comparable to tropical rain forests above 2000 m, which is the corresponding elevation with regard to the mean annual precipitation. In Chile, however, there is a distinct decrease of “mossiness” in the high montane and subalpine forests, which is attributed to special climatological conditions, whereas bryophytes reach maximum cover and phytomass in the tropical high montane and subalpine forests. A comparison with montane forests in Europe in 48°N reveal, that phytomass and percentage of hepatics is distinctly less than in the true rain forests of the southern hemisphere

Macrophytes assemblages in mountain lakes of Alerce Andino National Park (41° S, Lakes Region, Chile).

The lakes studied (Chapo, Sargazo, Chaiquenes and Triángulo) are located in the Alerce Andino National Park (41°30'S, 71°32'W), Chile. An inventory of the aquatic and riparian species was performed between December 2010 and January 2011. A null model analysis was done to determine the existence of regulatory factors of species associations, and the Jaccard index was applied to determine floristic similarities. It identidied 23 species, the high number was reported (14) and the most introduced species number (4) were reported at Sargazo lake, whereas the low species number was observed in Triángulo lake with three species. The analysis of the null model revealed the presence of regulatory factors in one of the three simulations. However, in the other two simulations, the species associations appeared to be random, presumably because many species were repeated at the study sites. According to the Jaccard index, Triángulo Lake is noticeably different from the other lakes, probably due to its marked oligotrophy

Progress in South America Dendrochronology

South America extends from 11°N to 62°S. Major boundaries such as the Andes on the western side of the continent and the land mass in the tropics create north-south and west-east variations in climate and ecosystems. Tropical forest covers 44% of the total land surface. Between 36 and 56°S, a temperate forest composed of high longevity trees dominates. The northern and central highlands are covered by small trees, shrubs and grasses. The central western part (Peru, Chile, the Andes, western Argentina and eastern Patagonia) is composed of deserts. These diverse climatic zones and ecosystems offer various potential sites for dendrochronological studies. The ideal conditions for paleoclimatic reconstructions using tree-rings are those that support the existence of long-living trees required to develop long chronologies, and/or the presence of subfossil woods. Over the last decade, the search for areas with some of these conditions has been one of the major goals of dendroclimatological studies in South America.Fil: Boninsegna, Jose Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

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Temporal Stamp Classifier: Classifying Short Sequences of Astronomical Alerts

In this work, we propose a deep learning-based classification model of astronomical objects using alerts reported by the Zwicky Transient Facility (ZTF) survey. The model takes as inputs sequences of stamp images and metadata contained in each alert, as well as features from the All-WISE catalog. The proposed model, called temporal stamp classifier, is able to discriminate between three classes of astronomical objects: Active Galactic Nuclei (AGN), Super-Novae (SNe) and Variable Stars (VS), with an accuracy of approximately 98% in the test set, when using 2 to 5 detections. The results show that the model performance improves with the addition of more detections. Simple recurrence models obtain competitive results with those of more complex models such as LSTM.We also propose changes to the original stamp classifier model, which only uses the first detection. The performance of the latter model improves with changes in the architecture and the addition of random rotations, achieving a 1.46% increase in test accuracy.Comment: Accepted in International Joint Conference on Neural Networks 202