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Glacial extent and mass balance are sensitive climate proxies providing solid information on past climatic conditions. However, series of annual mass-balance measurements of more than 60 years are scarce. To our knowledge, this is the first time the latewood density data (MXD) of the Swiss stone pine (Pinus cembra L.) have been used to reconstruct the summer mass balance (Bs) of an Alpine glacier. The MXD-based Bs well correlates with a Bs reconstruction based on the May to September temperature. Winter precipitation has been used as an independent proxy to infer the winter mass balance and to obtain an annual mass-balance (Bn) estimate dating back to the glaciological year 1811/12. The reconstructed MXD/precipitation-based Bn well correlates with the data both of the Careser and of other Alpine glaciers measured by the glaciological method. A number of critical issues should be considered in both proxies, including non-linear response of glacial mass balance to temperature, bedrock topography, ice thinning and fragmentation, MXD acquisition and standardization methods, and finally the ‘divergence problem’ responsible for the recently reduced sensitivity of the dendrochronological data. Nevertheless, our results highlight the possibility of performing MXD-based dendroglaciological reconstructions using this stable and reliable proxy.

Glacial extent and mass balance are sensitive climate proxies providing solid information on past climatic conditions. However, series of annual mass-balance measurements of more than 60 years are scarce. To our knowledge, this is the first time the latewood density data (MXD) of the Swiss stone pine (Pinus cembra L.) have been used to reconstruct the summer mass balance (B s ) of an Alpine glacier. The MXD-based B s well correlates with a B s reconstruction based on the May to September temperature. Winter precipitation has been used as an independent proxy to infer the winter mass balance and to obtain an annual mass-balance (B n ) estimate dating back to the gla- ciological year 1811/12. The reconstructed MXD/precipitation-based B n well correlates with the data both of the Careser and of other Alpine glaciers measured by the glaciological method. A number of critical issues should be considered in both proxies, including non-linear response of glacial mass balance to temperature, bedrock topography, ice thinning and fragmentation, MXD acquisition and standardization methods, and finally the 'divergence problem' responsible for the recently reduced sensitivity of the dendrochronological data. Nevertheless, our results highlight the possibility of performing MXD-based dendroglaciological reconstructions using this stable and reliable proxy.

The Late Pleistocene to Holocene transition in the Northern Hemisphere was characterized by abrupt millennial-scale climatic changes testified in the Alpine Chain by proxy records derived from glacial landforms and deposits. A detailed reconstruction of the paleo-glaciers during the deposition of the pre-Little Ice Age (LIA) moraines and newly obtained 10Be exposure ages provide information on the timing of a glacier advance in the Gran Paradiso Group (Western Alps, Italy) related to the regional Egesen stadial as a response to the climatic deterioration at around 12.9–11.7 ka (corresponding to the Younger Dryas in northern Europe and to the Greenland stadial 1 in the INTIMATE event stratigraphy). The study area represents a key site to define the behaviour of the Egesen paleo-glaciers, since they are located in a significant climatic area between the moister Maritime Alps and the Northern Alps. The ELA reconstructions and the comparison with other Alpine sectors provide evidence that current relatively drier conditions in the area postdate the LGM and were already present during the Egesen stadial. Our results support a strong positive YD Arctic Oscillation index, which led to drier conditions in southern Europe and caused negative winter precipitation anomalies., Quaternary Science Reviews, 255, ISSN:0277-3791

Ongoing climate change strongly affects high-elevation environments in the European Alps, influencing the cryosphere and the biosphere and causing widespread retreat of glaciers and changes in biomes. Nevertheless, high-elevation areas often lack long meteorological series, and global datasets cannot represent local variations well. Thus, proxy data, such as tree rings, provide information on past climatic variations from these remote sites. Although maximum latewood density (MXD) chronologies provide better temperature information than those based on tree-ring width (TRW), MXD series from the European Alps are lacking. To derive high-quality temperature information for the Rhaetian Alps, Pinus cembra L. trees sampled at approximately 2000 m a.s.l. were used to build one MXD chronology spanning from 1647 to 2015. The MXD data were significantly and highly correlated with seasonal May-September mean temperatures. The MXD chronology showed a generally positive trend since the middle of the 19th century, interrupted by short phases of climatic deterioration in the beginning of the 20th century and in the 1970s, conforming with the temperature trends. Our results underline the potential for using Pinus cembra L. MXD to reconstruct mean temperature variations, especially during the onset and latter part of the growing season, providing additional information on parts of the growing season not inferred from TRW. Future studies on MXD for this species will increase the availability of temporal and spatial data, allowing detailed climate reconstructions.

The ongoing increase in the global mean temperature at an unprecedented recorded rate is well documented. Nevertheless, knowledge of past climate variations is fundamental for a better understanding of ongoing climate change. This need is crucial in high mountain areas, where the effects of global warming are amplified and induce an accelerated glacial retreat. Thus, the use of climatic proxies such as tree-ring width offers tools to better understand the environmental dynamics in remote, sensitive sites. Here, we present the "Bosco Antico" site chronology, a six-century long dataset from the most ancient living stand in the Val di Sole area (southern Rhaetian Alps, Italy), and its relationship with summer mean temperatures. The analyses were performed on earlywood and latewood separately, as well as on tree-ring widths using static and moving correlations. The results showed that tree-rings and earlywood width are linked with June temperatures, whereas latewood width is mainly driven by July temperatures. All the analysed series were greatly influenced by June to July and June to August temperatures. Finally, a mean summer latewood-based temperature reconstruction since 1525 is proposed. It highlighted that during the last six hundred years, the summer temperatures span between -2.3 to +1.9 degrees C compared to the 1960-90 mean temperature (between 6.2 and 10.4 degrees C at the stand elevation). The coolest phase is recorded in the 1810s-20s underlining the strongest pulse of the Little Ice Age; other phases of negative anomalies are recorded in the first half of the 17th century, around 1700, and 1900 and during the 1970s. Our results add an important dataset for a specific climatic area, providing new information that will contribute to a better understanding of the climate dynamics for the study site as well as on a larger scale.

"Se evaluó el efecto del consorcio Glomus spp. Zacatecas 19 (Zac19), seis cepas de rizobacterias (Pseudomonas aeruginosa 11PS, Burkholderia cepacia P13, Hafnia alvei aislamientos S1AS, P25 y P27, Enterobacter cloacae S3DER) y dos tipos de suelos (limoso y arenoso) en alfalfa (Medicago sativa L. var. Valenciana), en invernadero. Se estableció un experimento factorial 2 x 2 x 7 en un diseño experimental completamente al azar, con seis repeticiones por tratamiento. La inoculación de Zac19 estimuló significativamente el crecimiento y el estado nutricional (NPK) de alfalfa, en particular en suelo limoso. Se observó sinergismo entre Zac19 y las rizobacterias H. alvei aislamientos P25 y P27, con P. aeruginosa 11PS y con E. cloacae S3DER. Las bacterias se comportaron diferencialmente, al inocularse en forma individual o con el consorcio Zac19. Existió sinergismo entre Zac19 con P. aeruginosa 11PS y H. alvei P25, para la absorción de N;mientras que la doble inoculación de Zac19 y las cepas P. aeruginosa 11PS, H. alvei P25 y P27, y B. cepacia P13, resultó en sinergismo para la absorción de P y K. El tipo de suelo fue un factor determinante en el comportamiento y en la expresión del beneficio hacia la planta,tanto por la inoculación de las rizobacterias, como por el consorcio micorrízico Zac19. Las rizobacterias P. aeruginosa 11PS y las cepas H. alvei S1AS, P25 y P27, tienen potencial de uso como promotoras del crecimiento de alfalfa."