Variability of wood properties in two wild cherry clonal trials

There has been an increase in wild cherry cultivation over recent decades, revealing a need for improvements in planting material to be used for the production of high quality timber. To date, trial tests have been carried out mainly on growth and tree architectural traits, while no investigations have focused on wood properties. The present study investigated the variability of the growth traits and the physical and mechanical properties of wild cherry wood, both within the tree, within and among clones and between sites. The aims of the study are to provide useful information on the genetics of wood traits in valuable hardwoods and to discuss how within-tree variation can affect early selection of genotypes. The results suggest that site was the most important source of variation in growth traits and in the proportion of heartwood, although differences among clones were highly significant. The number of sapwood rings was very homogeneous both between sites and among clones. Concerning the wood traits, most variation was detected within the tree, rather than within or among clones or between sites. Within tree variability seems to be mainly due to heartwood/sapwood presence. However, since there is a high correlation between heartwood and sapwood properties, a quite efficient selection made on the basis of sapwood should provide an efficient means of selecting heartwood traits.     

Structural Investigation of the Oligosaccharide Portion Isolated from the Lipooligosaccharide of the Permafrost Psychrophile Psychrobacter arcticus 273-4

Psychrophilic microorganisms have successfully colonized all permanently cold environments from the deep sea to mountain and polar regions. The ability of an organism to survive and grow in cryoenviroments depends on a number of adaptive strategies aimed at maintaining vital cellular functions at subzero temperatures, which include the structural modifications of the membrane. To understand the role of the membrane in the adaptation, it is necessary to characterize the cell-wall components, such as the lipopolysaccharides, that represent the major constituent of the outer membrane. The aim of this study was to investigate the structure of the carbohydrate backbone of the lipooligosaccharide (LOS) isolated from the cold-adapted Psychrobacter arcticus 273-4. The strain, isolated from a 20,000-to-30,000-year-old continuously frozen permafrost in Siberia, was cultivated at 4 °C. The LOS was isolated from dry cells and analyzed by means of chemical methods. In particular, it was degraded either by mild acid hydrolysis or by hydrazinolysis and investigated in detail by ¹H and ¹³C NMR spectroscopy and by ESI FT-ICR mass spectrometry. The oligosaccharide was characterized by the substitution of the heptose residue, usually linked to Kdo in the inner core, with a glucose, and for the unusual presence of N-acetylmuramic acid.     

An improved estimate of leaf area index based on the histogram analysis of hemispherical photographs

Leaf area index (LAI) is a key parameter that affects the surface fluxes of energy, mass, and momentum over vegetated lands, but observational measurements are scarce, especially in remote areas with complex canopy structure. In this paper we present an indirect method to calculate the LAI based on the analyses of histograms of hemispherical photographs. The optimal threshold value (OTV), the gray-level required to separate the background (sky) and the foreground (leaves), was analytically calculated using the entropy crossover method (Sahoo, P.K., Slaaf, D.W., Albert, T.A., 1997. Threshold selection using a minimal histogram entropy difference. Optical Engineering 36(7) 1976–1981). The OTV was used to calculate the LAI using the well-known gap fraction method. This methodology was tested in two different ecosystems, including Amazon forest and pasturelands in Brazil. In general, the error between observed and calculated LAI was ～6%. The methodology presented is suitable for the calculation of LAI since it is responsive to sky conditions, automatic, easy to implement, faster than commercially available software, and requires less data storage.     

Evaluation of an open portable chamber system for measuring cover crop water use in a vineyard and comparison with a mini-lysimeter approach

Cover crops are largely used in viticultural areas because of the many positive agronomic and environmental benefits they provide. However, there is insufficient data describing the amount of water they use. A portable chamber used as an open measurement system and its suitability to measure the cover crop evapotranspiration (E) in a vineyard are described in this study. The performance of the chamber was tested by a calibration experiment (R² = 0.97). The lowest air flow rate used (9.2 l s⁻¹) was found to be suitable to limit the chamber from overheating beyond 3.1 K above the outside temperature. Furthermore, an experiment was designed to compare the daily cover crop (Festuca arundinacea var. barfelix) water use measured by the chamber system with measurements using a mini-lysimeter (ML) method and with estimates using the FAO-56 PM equation (Eo). The experiment was carried out in one inter row of a vineyard over the course of 4 days following an irrigation event. Although the field experiment was limited to 4 days, the results obtained together with the calibration trials support the possibility of the chamber being a useful tool for measuring the cover crop E. The ability of the MLs to represent the water use of the cover crop in the rest of the vineyard was limited to the first two days of the experiment, after which time the soil water content inside the containers was significantly (p = 0.007, p = 0.03) lower than in the surrounding field.     

Leiopathes glaberrima millennial forest from SW Sardinia as nursery ground for the small spotted catshark Scyliorhinus canicula

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New sites expanding the “Sardinian cold‐water coral province” extension: A new potential cold‐water coral network?

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The role of species composition in the emergence of alternate vegetation states in a temperate rainforest system

Landscape Ecology - Forest systems are dynamic and can alternate between alternative stable states in response to climate, disturbance and internal abiotic and biotic conditions. Switching between...