ALBERT

Description: A comprehensive set of autonomous, ice-ocean measurements were collected across the Canada Basin to study the summer evolution of the ice-ocean boundary layer (IOBL) and ocean mixed layer (OML). Evaluation of local heat and freshwater balances and associated turbulent forcing reveals that melt ponds (MP's) strongly influence the summer IOBL-OML evolution. Areal expansion of MP's in mid-June start the upper ocean evolution resulting in significant increases to ocean absorbed radiative flux (19 Wm −2 in this study). Buoyancy provided by MP drainage shoals and freshens the IOBL resulting in a 39 MJm −2 increase in heat storage in just 19 days (52% of the summer total). Following MP drainage, a near-surface fresh layer deepens through shear-forced mixing to form the summer mixed layer (sML). In late summer, basal melt increases due to stronger turbulent mixing in the thin sML and the expansion of open water areas due in part to wind forced divergence of the sea ice. Thermal heterogeneities in the marginal ice zone (MIZ) upper ocean led to large ocean-to-ice heat fluxes (100-200 Wm −2 ) and enhanced basal ice melt (3-6 cm-day −1 ), well away from the ice edge. Calculation of the upper ocean heat budget show that local radiative heat input accounted for at least 89% of the observed latent heat losses and heat storage (partitioned 0.77/0.23). These results suggest that the extensive area of deteriorating sea ice observed away from the ice edge during the 2014 season, termed the “thermodynamically forced MIZ,” was driven primarily by local radiative forcing. This article is protected by copyright. All rights reserved.

Description: The high prevalence of dioecy in marine angiosperms or seagrasses (〉50% of all species) is thought to enforce cross-fertilization. However, seagrasses are clonal plants, and they may still be subject to sibling-mating or bi-parental inbreeding if the genetic neighborhood is smaller than the size of the genets. We tested this by determining the genetic neighborhoods of the dioecious seagrass Thalassia testudinum at two sites (Back-Reef and Mid-Lagoon) in Puerto Morelos Reef Lagoon, Mexico, by measuring dispersal of pollen and seeds in situ, and by fine-scale spatial autocorrelation analysis with eight polymorphic microsatellite DNA markers. Prevalence of inbreeding was verified by estimating pairwise kinship coefficients; and by analysing the genotypes of seedlings grown from seeds in mesocosms. Average dispersal of pollen was 0.3–1.6 m (max. 4.8 m) and of seeds was 0.3–0.4 m (max. 1.8 m), resulting in a neighborhood area of 7.4 m 2 (range 3.4–11.4 m 2 ) at Back-Reef and 1.9 (range 1.87–1.92 m 2 ) at Mid-Lagoon. Neighborhood area (Na) derived from spatial autocorrelation was 0.1–20.5 m 2 at Back-Reef and 0.1–16.9 m 2 at Mid-Lagoon. Maximal extensions of the genets, in 19 × 30 m plots, were 19.2 m (median 7.5 m) and 10.8 m (median 4.8 m) at Back-Reef and Mid-Lagoon. There was no indication of deficit or excess of heterozygotes nor were coefficients of inbreeding ( F IS ) significant. The seedlings did not show statistically significant deficit of heterozygotes (except for 1 locus at Back-Reef). Contrary to our expectations, we did not find evidence of bi-parental inbreeding in this dioecious seagrass with large genets but small genetic neighborhoods. Proposed mechanisms to avoid bi-parental inbreeding are possible selection against homozygotes during fecundation or ovule development. Additionally, the genets grew highly dispersed (aggregation index Ac was 0.09 and 0.10 for Back-Reef and Mid-Lagoon, respectively); such highly dispersed guerrilla-like clonal growth form likely increases the probability of crossing between different potentially unrelated genets. We expected bi-parental inbreeding in Thalassia testudinum , a dioecious seagrass with large genets but very limited pollen and seed dispersal; thus, small genetic neighbourhoods. However, kinship and seedling analysis did not find any evidence for this, which may be attributed to a highly dispersed guerrilla-like clonal growth form (which is unusual for a clonal climax species) that increases the probability of crossing between different potentially unrelated genets.

Description: Paleoclimate data assimilation has recently emerged as a promising technique to estimate past climate states. Here we test two of the underlying assumptions of paleoclimate data assimilation as applied so far: (1) climate proxies can be modeled as linear, univariate recorders of temperature; and (2) structural errors in GCMs can be neglected. To investigate these two points and related uncertainties, we perform a series of synthetic, paleoclimate data assimilation-based reconstructions where ‘pseudo’ proxies are generated with physically-based proxy system models (PSMs) for coral δ 18 O , tree-ring width, and ice core δ 18 O using two isotope-enabled atmospheric general circulation models. For (1), we find that linear univariate models efficiently capture the GCM's climate in ice cores and corals, and do not lead to large losses in reconstruction skill. However, this does not hold for tree-ring width, especially in regions where it is dominated by moisture supply; we quantify how the breakdown of this assumption lowers reconstruction skill for each proxy class. For (2), we find that climate model biases can introduce errors that greatly reduce reconstruction skill, with or without perfect proxy system models. We explore possible strategies for mitigating structural modeling errors in GCMs, and discuss implications for paleoclimate reanalyses. This article is protected by copyright. All rights reserved.

Description: In order to contribute to a better understanding of the electrostatic phenomena appearing during splash filling of liquids and to clarify the reasons why this process is suspected to increase static electrification especially due to atomization, accurate experiments of charge measurements were made on droplets of various liquids falling over a large distance (5 m). Eleven liquids of different conductivity and surface tension were tested. The results confirm that no charge evolution appears even over a long falling distance. A possible explanation of the static charge increase in splash filling is presented. Due to the generated electrostatic charges, the splash filling process poses some dangers. Here, the charge evolution of a single droplet is examined along its fall. From experiments with droplets of many different liquids, falling over 5 m, it is confirmed that the assumption that droplets are charged by friction with air, as still discussed in the explosion hazard community, does not hold true.

Description: Forest encroachment following land abandonment had no significant effect on the woody plant species richness in the Balkans; elevation and temperature had a negative effect locally. Woodlots, broad‐leaved forests, hedges and shrublands held the highest woody species richness, and vertical vegetation heterogeneity was higher in open forests and woodlots. Different land‐cover types should be maintained, enhancing landscape heterogeneity. Abstract Question What are the woody vegetation encroachment patterns after agricultural land abandonment? Focusing on two parameters, woody plant species richness and vertical vegetation heterogeneity (number of different vegetation strata and their relative cover) we investigated: (a) the effect of forest encroachment following land abandonment; (b) the comparative importance of forest encroachment vis‐a‐vis topographic and climatic parameters, and finally; (c) the ecological importance of eight land‐cover types encountered in abandoned agricultural landscapes. Location The Balkan Peninsula (Albania, Bulgaria, Croatia, Greece). Methods We set up a standard methodology for 1 × 1 km site selection (70 sites) and data collection within 497 plots, along a well‐defined forest encroachment gradient that reflects land abandonment in terms of woody vegetation cover. Results The pattern that emerged was neither clear nor common for the Balkan region, regarding the effect of forest encroachment on the woody plant species richness in young forests, formed from 20 to 50 years after land abandonment. However, at national level, species diversity was significantly affected by elevation (Bulgaria and Croatia) and temperature (Croatia), with lower and cooler areas being richer. Elevation was of great importance in determining vertical vegetation heterogeneity. Woodlots, broad‐leaved forests, hedges and shrublands held the highest woody species richness in comparison to the more open land‐cover types, and vertical vegetation heterogeneity was higher in open forests and woodlots. Conclusions We expect the expansion of broad‐leaved forests following land abandonment to enhance woody species richness. However, other land‐cover types that were found to be important for woody plants should be maintained. As woody plants play a key role in supporting overall biodiversity, by providing suitable habitat for many species, we consider the preservation of a mosaic of patches of different land‐cover types essential for the conservation of both plant and animal species diversity. Young forests should be preserved at intermediate stages of succession, through intermediate disturbance activities, including medium intensity grazing and the enhancement of wild ungulates.

Description: The eddy field across the Arctic Ocean's Canada Basin is analyzed using Ice-Tethered Profiler (ITP) and moored measurements of temperature, salinity and velocity spanning 2005 to 2015. ITPs encountered 243 eddies, 98% of which were anticylones, with approximately 70% of these having anomalously cold cores. The spatially and temporally varying eddy field is analyzed accounting for sampling biases in the unevenly-distributed ITP data and caveats in detection methods. The highest concentration of eddies was found in the western and southern portions of the basin, close to topographic margins and boundaries of the Beaufort Gyre. The number of lower halocline eddies approximately doubled from 2005-2012 to 2013-2014. The increased eddy density suggests more active baroclinic instability of the Beaufort Gyre that releases available potential energy to balance the wind-energy input; this may stabilize the Gyre spin up and associated freshwater increase.

Description: Contamination with oily wastes containing natural radionuclides is a potential hazard for soil health and function. Our study aimed to reveal both structural and functional changes of the microbial community resistant to and able to decompose oily wastes in soil. To do this, we determined CO 2 efflux, microbial biomass (by the extraction-fumigation method), and community structure (by PCR-SSCP) for 120 d after application of radioactive oily wastes to the soil at the ratio 1:4. The addition of the waste resulted in an increase of the activity concentration of 226 Ra by 130 times (up to 643 Bq kg −1 ) and of 232 Th by 29 times (up to 254 Bq kg −1 ). The calculated weighted dose for the radionuclide 226 Ra was found to be below the values that are known to affect microorganisms. However, the cumulative effect of a repeated deposition of radioactive oily waste may result in an increase of the weighted dose up to an effective level. During the incubation, the hydrocarbon (HC) content of the waste-treated soil decreased from 156 to 54 g kg −1 of soil indicating intensive decomposition of added organics by soil microorganisms. The waste application, however, led to an inhibition of soil microbial biomass compared with the control (by 26–47%). Microbial respiration was stimulated in the first month of incubation and then decreased until the end of the incubation period (by up to 74% compared to the control). The qCO 2 was estimated to be 3-fold higher than the control on day 1 of incubation and equal to the control on day 120 of incubation. The bacterial diversity decreased in the contaminated soil compared with the control soil. The bacterial community structure was altered by domination of new oil degrader species belonging to the genera Dyella, Pseudoxanthomonas, Sinobacter , and Parvibaculum . Thus, disposal of radioactive petroleum waste strongly altered the structure of the microbial community resulting in the selection of resistant species able to decompose pollutants and also affected the community function (inhibition of microbial biomass and stimulation of respiration) which tended to stabilize after long-term incubation.

Description: After several years of decreased annual rainfall and water shortages, the Chilean society is demanding that forest plantations take accountability of their role in consuming scarce water resources. Evidence has shown that interception losses are considerable when determining water production in watersheds. The aim of this study was to determine if site and stand variables explain interception losses by Chilean forests for the development of an empirical model that could predict the potential impacts of forest management practices and land-use change. A total of 127 data from annual water balance plot studies in Chile were compiled to derive relationships between interception and precipitation, species composition, plantation age and other stand and site variables. The reviewed data indicated that annual interception losses are mainly explained by annual rainfall and basal area of the forest stands, with a clear difference between the northern (dryer) and southern (wetter) regions of Chile. For a wide latitudinal gradient, forest composition and age, annual interception accounted for approximately 21% of incoming precipitations. Broadleaved forest stands (including native broadleaved and eucalypt forests) generally presented higher interception losses than conifers. Interception was higher in northern zones indicating that forests have greater impacts on water resources in dryer regions. Our results were compiled in empirical models, which can be used to estimate forest interception in a latitudinal gradient in Chile and to support policy making. These results are also proposed as an approximate analogue of the changes in forest interception losses which may occur as vegetation belts shift latitudinally due to the impact of climate change.

Description: Stirring along isopycnals is a significant factor in determining the distribution of tracers within the ocean. Salinity anomalies on density surfaces from Argo float profiles are used to investigate horizontal stirring and estimate eddy-mixing lengths. Eddy mixing length and velocity fluctuations from the ECCO2 global state estimate are used to estimate horizontal diffusivity at a 300-km scale in the upper 2000 m with near-global coverage. Diffusivity varies by over two orders of magnitude with latitude, longitude, and depth. In all basins, diffusivity is elevated in zonal bands corresponding to strong current regions, including western boundary current extension regions, the Antarctic Circumpolar Current, and equatorial current systems. The estimated mixing lengths and diffusivities provide an observationally-based dataset that can be used to test and constrain predictions and parameterizations of eddy stirring.