Surface atmospheric circulation patterns and associated minimum temperatures in the Maipo and Casablanca valleys, central Chile

Abstract This paper analyzes the influence of circulation anomalies on the magnitude of minimum air temperature (T min ) at a daily scale in two important agricultural valleys of Chile (Maipo and Casablanca) during the period [2001][2002][2003][2004][2005][2006][2007]. A statistical classification of synoptic fields was performed, resulting in eight circulation patterns (CPs, 84 % of explained variance). The corresponding anomalies of T min (AT min ) of each CP were analyzed in order to understand their synoptic-scale forcing mechanisms. Results showed a direct association between AT min and the synoptic structure. The average weakening in sea level pressure (SLP) yields positive AT min , while negative AT min is associated with a strengthening in SLP. In the latter case, it was also found that a synoptic structure (10.2 % of frequency) corresponding to a migratory high-pressure system passing eastward across the Andes led to the lowest AT min and a higher probability of frost in both valleys (22 % on average) in winter and springtime

Hallazgo de una segunda población de Miersia chilenos Lindl. var. bicolor M. Muñoz (Alliaceae)

A second population of Miersia chilensis var. bicolor M. Muñoz was found at the Lonquén hill, which extends its distribution 15 km north and its altitudinal range in 200 m. The population abundance was estimated on years 2011 and 2015. Images of the specimens found are presented, with a description of the site and the plant community.Una segunda población de Miersia chilensis var. bicolor M. Muñoz fue encontrada en el cerro Lonquén, lo cual extiende su distribución 15 km al norte y su rango altitudinal en 200 m. Se realizó una estimación poblacional en los años 2011 y 2015. Se muestran fotografías de los especímenes encontrados con una descripción del sitio y la comunidad de plantas

COSORE: A community database for continuous soil respiration and other soil‐atmosphere greenhouse gas flux data

Globally, soils store two to three times as much carbon as currently resides in the atmosphere, and it is critical to understand how soil greenhouse gas (GHG) emissions and uptake will respond to ongoing climate change. In particular, the soil‐to‐atmosphere CO2 flux, commonly though imprecisely termed soil respiration (RS), is one of the largest carbon fluxes in the Earth system. An increasing number of high‐frequency RS measurements (typically, from an automated system with hourly sampling) have been made over the last two decades; an increasing number of methane measurements are being made with such systems as well. Such high frequency data are an invaluable resource for understanding GHG fluxes, but lack a central database or repository. Here we describe the lightweight, open‐source COSORE (COntinuous SOil REspiration) database and software, that focuses on automated, continuous and long‐term GHG flux datasets, and is intended to serve as a community resource for earth sciences, climate change syntheses and model evaluation. Contributed datasets are mapped to a single, consistent standard, with metadata on contributors, geographic location, measurement conditions and ancillary data. The design emphasizes the importance of reproducibility, scientific transparency and open access to data. While being oriented towards continuously measured RS, the database design accommodates other soil‐atmosphere measurements (e.g. ecosystem respiration, chamber‐measured net ecosystem exchange, methane fluxes) as well as experimental treatments (heterotrophic only, etc.). We give brief examples of the types of analyses possible using this new community resource and describe its accompanying R software package

Soil respiration across a disturbance gradient in sclerophyllous ecosystems in Central Chile

Los matorrales y bosques esclerófilos son la formación vegetacional dominante en Chile Central, existiendo una larga data de degradación producto del fuego, cultivos, extracción de leña y pastoreo. El objetivo del estudio fue comparar la respiración de suelos y los factores que la controlan a lo largo de un gradiente de perturbaciones en ecosistemas esclerófilos en la Reserva Nacional Roblería del Cobre de Loncha en Chile Central. En bajos de ladera en una exposición norte se identificaron cuatro grados de perturbación: bosques esclerófilos que fueron levemente- (D1) y moderadamente perturbados (D2), matorral espinoso fuertemente perturbado (D3) y sabana de A. caven completamente perturbada (D4). Se establecieron doce parcelas de 25×25 m (625 m²) distribuidas equitativamente en D1, D2, D3 and D4. La respiración de suelos (Rs), temperatura de suelos (Ts), contenido volumétrico de agua en el suelo (θv) y nitrógeno intercambiable (Ns) fueron medidos en todas las parcelas en seis fechas entre Agosto de 2009 y Mayo de 2010. Adicionalmente, Ts y θv fueron registrados de forma continua, desde Julio de 2010 hasta Agosto de 2012 (cada 30 minutos), en una parcela por nivel de perturbación (i.e. 4 de 12 parcelas). Los valores de Rs aumentaron linealmente con θv con similares pendientes pero diferentes interceptos que aumentaron en la medida que las perturbaciones disminuyeron. Una vez contabilizado el contenido de agua en el suelo, Rs aumentó con Ts con la misma pendiente pero con un intercepto que depende del nivel de perturbación. Adicionalmente la respuesta de Rs a Ts fue más pronunciada en la medida que θv aumentó. Los valores de Ns no se correlacionaron con Rs. Los valores acumulados de Rs fueron 4.4 mayores en D1 (1735 g C m-2 yr-1) comparado con D4 (392 g C m-2 yr-1). Las perturbaciones presumiblemente disminuyeron Rs mediado por reducciones en la capa de hojarasca, materia orgánica del suelo, biomasa de raíces y contenido de agua particularmente en la temporada seca y cálida. Bajo un escenario de cambio climático que implica una disminución de 40% de las precipitaciones y un aumento de 4°C en la temperatura del aire para el año 2100, encontramos que el Rs anual se reduciría en promedio en 28% comparado con el clima actual, con esta reducción siendo más pronunciada en las condiciones más perturbadas sugiriendo que las condiciones menos perturbadas serían más resistentes al cambio climático justificando aún más la restauración de estos ecosistemas.Sclerophyllous shrubs and forests are predominant in semiarid Central Chile and have a long history of degradation by fire, cultivation, firewood extraction and grazing. The aim of this study was to compare the amount and environmental drivers of soil respiration across a disturbance gradient in sclerophyllous ecosystems in the National Reserve Roblería del Cobre de Loncha in Central Chile. In a north-facing toe slope, four disturbance conditions were identified: slightly (D1) and moderately disturbed (D2) sclerophyllous forest, (D3) strongly disturbed thorn scrub and (D4) most disturbed A. caven savanna. Twelve 25×25-m plots (625 m²) were distributed equally across D1, D2, D3 and D4. Soil respiration (Rs), soil temperature (Ts), volumetric water content (θv) and exchangeable nitrogen (Ns) were measured at six dates in each plot between August 2009 and May 2010. Additionally, Ts and θv were continuously recorded from July 2010 to August 2012 (30-minute intervals) in one plot per disturbance condition (i.e., 4 out of 12 plots). The values of Rs increased linearly with θv with similar slopes but different intercepts, which increased as the disturbance receded. Once soil water content was taken into account, Rs increased with Ts with the same slope but with a disturbance-dependent intercept. Additionally, the response of Rs to Ts was more pronounced as θv increased. The values of Ns were uncorrelated with Rs. The annual values of Rs were 4.4-fold greater in D1 (1,735 g C m-2 yr-1) compared with D4 (392 g C m-2 yr-1). Disturbance presumably decreased Rs by reducing the litter layer, soil organic matter, root biomass and soil water content, particularly in the hot-dry season. Under a predicted climate change scenario of a 40% decrease in rainfall and 4°C increase in air temperature by the year 2100, we found that annual Rs would be reduced on average by 28% compared with the current climate, with that reduction being more pronounced under more disturbed conditions, suggesting that less disturbed conditions would be more resistant to climate change, thus further justifying the restoration of these damaged ecosystems

Hallazgo de una segunda población de <em>Miersia chilenos</em> Lindl. var. bicolor M. Muñoz (Alliaceae)

Una segunda población de Miersia chilensis var. bicolor M. Muñoz fue encontrada en el cerro Lonquén, lo cual extiende su distribución 15 km al norte y su rango altitudinal en 200 m. Se realizó una estimación poblacional en los años 2011 y 2015. Se muestran fotografías de los especímenes encontrados con una descripción del sitio y la comunidad de plantas

Land Use Influences Carbon Fluxes in Northern Kazakhstan

A mobile, closed-chamber system (CC) was used to measure carbon and water fluxes on four land-use types common in the Kazakh steppe ecoregion. Land uses represented crop (wheat or barley, WB), abandoned land (AL), crested wheatgrass (CW), and virgin land (VL). Measurements were conducted during the growing season of 2002 in northern Kazakhstan at three locations (blocks) 15-20 km apart. The CC allowed the measurement of the carbon flux components of net ecosystem exchange (NEE), ecosystem respiration (RE) and soil respiration (RS), together with evapotranspiration (ET). Nonlinear regression analyses were used to model gross primary production (GPP) and ET as a function of photosynthetically active radiation (Q); RE and RS were modeled based on air (Tair) and soil (Ts) temperature, respectively. GPP, RE, RS, and ET were estimated for the entire year with the use of continuous 20-min means of Q, Tair, and Ts. Annual NEE indicated that AL gained 536 g CO2 m-2, WB lost – 191 g CO2 m-2, CW was near equilibrium (–14g CO2 m-2), and VL exhibited considerable carbon accumulation (153g CO2 m-2). The lower GPP values of the land-use types dominated by native species (CW and VL) compared to WB and AL were compensated by positive NEE values that were maintained during a longer growing season. As expected, VL and CW allocated a larger proportion of their carbon assimilates belowground. Non-growing-season RE accounted for about 19% of annual RE in all land-use types. The results of this landscape-level study suggest that carbon lost by cultivation of VLs is partially being restored when fields are left uncultivated, and that VLs are net sinks of carbon. Estimations of carbon balances have important management implications, such as estimation of ecosystem productivity and carbon credit certification. The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202