Anemophilous species depend on wind for sexual reproduction. When plants do not receive enough pollen and/or pollen has poor quality, they may experience pollen limitation. This can reduce the production of fruits and seeds with negative consequences on population dynamics. The self-compatibility system also plays an important role on the likelihood of a species suffering pollen limitation as it determines if plants can produce fruits and seeds in the absence of compatible mates. Here, we studied the breeding system of the Andean anemophilous tree Polylepis incarum, a critically endangered species endemic to Lake Titicaca. We conducted controlled experimental pollination experiments and florescence microscopy analysis to assess whether pollen limitation and the incompatibility system constrain fruit and seed production. Results showed that the seed set is limited by pollen availability, that P. incarum exhibits a pre-zygotic compatibility system and early inbreeding depression manifested during seed development. Therefore, self-pollination is a factor that could be partially associated with the production of non-viable seeds.

R������.En el presente estudio se evaluó la fenología de la queñua (Polylepis incarum, Rosaceae) durante un ciclo anual en la puna mesofítica de La Paz, Bolivia. Esta especie es endémica de la cuenca del Lago Titicaca y, al igual que otras especies del género, P. incarum está categorizada como En Peligro para Bolivia debido a actividades antrópicas como la extracción de leña y la expansión de cultivos. Durante un año (marzo 2015 -febrero 2016) se realizaron evaluaciones mensuales en un parche de bosque en la comunidad de Kopacati, departamento de La Paz, Bolivia. Los objetivos del estudio fueron identificar las épocas de floración y fructificación, y relacionar el éxito reproductivo con el tamaño de la planta y con factores ambientales. P. incarum produce botones florales entre julio y agosto. La producción de flores en estado femenino se produce entre julio y noviembre, y la de flores en estado masculino, entre julio y octubre. La mayor producción de frutos inmaduros ocurrió a partir de noviembre; los frutos alcanzaron la madurez entre de diciembre y enero. Tanto la precipitación como la temperatura mostraron una influencia significativa en la producción de flores y frutos. El diámetro a la altura del pecho (DAP) fue el único carácter alométrico que influyó de manera significativa en la producción de flores y de frutos. No se detectaron diferencias significativas en la producción de flores y frutos entre árboles y arbustos. Los patrones fenológicos informados para esta especie son similares a los reportados para P. tomentella y P. besseri. Los resultados de este trabajo contribuyen al conocimiento de la biología reproductiva de Polylepis incarum y a la promoción de programas de conservación y reforestación de la especie.[Palabras clave: biología reproductiva, Copacabana, floración, fructificación] A�������. Reproductive phenology of queñua (Polylepis incarum, Rosaceae) during an annual cycle in the mesophytic puna of La Paz, Bolivia. In this study, the phenology of queñua (Polylepis incarum, Rosaceae) was evaluated during an annual cycle in the mesophytic puna of La Paz. The species is endemic to the Lake Titicaca basin. Like other species of the genus Polylepis, P. incarum is categorized as Endangered for Bolivia due to anthropic activities as firewood extraction and crop expansion. During one year (March 2015 -February 2016), we conducted monthly evaluations in a woodland located in the community of Kopacati, Copacabana department, La Paz, Bolivia. The objectives of the study were to identify flowering and fruiting times, and to assess the relationships between plant size, environmental factors and plant reproductive success. The species produces floral buds between July and August. The production of flowers in the female state occurs between July and November, and flowers in the male state, between July and October. The highest production of immature fruits took place in November, reaching maturity in December and January. Both precipitation and temperature showed a significant influence on flowers and fruits...

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The effects of climate change may be more evident in mountainous areas. In these areas, an increase in temperature and a decrease in precipitation can reduce the amount of snow, which represents a source of water for human consumption and vegetation. To analyze the effects of climate change on vegetation, it is possible to examine the climate–vegetation relationship in the past and observe the influence of variation in temperature and precipitation on the dynamics of plant communities. The aim of the present work was to describe the climate–vegetation dynamics of the last 4,500 years in the high subtropical Andes of Chile (30°S). The paleoclimatic reconstruction was carried out through the analysis of fossil pollen and macroscopic carbon obtained from sediment cores from two high Andean lakes. The dynamics of the vegetation was analyzed taking into account the alpha and beta diversity. The pollen and carbon records showed three contrasting periods during the last 4,500 years. From the beginning of the sequences until ∼1900 cal. yr BP, relatively dry climatic conditions are suggested, with a slight trend toward more humid conditions after 2,700 cal. yr BP. Pollen records from ∼1900 to ∼600 cal. yr BP suggest wetter conditions than today. Finally, relatively arid conditions have reappeared in the last ∼600 years. The diversity analysis showed that the climate mainly influences the composition of taxa in the communities (beta diversity) and not the richness (alpha diversity). In periods of dry/wet transition and vice versa, beta diversity changes. On the other hand, richness remains relatively constant throughout the record.