Snow damages on trees of an uneven age in mixed broadleaf forests:effects of topographical conditions and tree characteristics     

Farzam Tavankar  Angela Lo Monaco  Mehrdad Nikooy  Rachele Venanzi  Amireslam Bonyad  Rodolfo Picchio 《林业研究》2019,(4):1383-1394

Snow damage on natural stands is an important problem concerning mountainous forest management.In the present research,the frequency and intensity of heavy snow damage on natural stands and the relationship of damages with characteristics of trees,stand and topography were studied in mountainous forests of northern Iran.A systematic sampling design was applied to the study area(140 ha),with 122 circular plots.The grid dimension was100 m and each plot area was 1000 m^2.The four types of snow damage to trees include:crown damage(8.6%),stem breakage(5.4%),uprooting(3.2%),and bending(1.4%).The frequency of crown damage grew with an increase inthe diameter at breast height(DBH),while the frequency of stem breakage,uprooting and bending decreased with an increase the DBH.The frequency of crown damage,stem breakage,and total damages was related to tree species(p<0.01).Not all tree species were equally susceptible to snow damage.The amount of damage grew with increasing elevation and slope angle and decreased with increasing soil depth.Young trees(DBH<25 cm)were more susceptible to snow damage than other trees.Snow damage decreased by as the trees in the stand became more mixed in age.The susceptibility of trees to snow damage increased by height and slenderness coefficient.With adequate silvicultural operation,snow damage can be reduced to a minimum level in these natural forests.  相似文献   

Phenolic composition in grape (Vitis vinifera L. cv. Malbec) ripened with different solar UV-B radiation levels by capillary zone electrophoresis     

Berli F  D'Angelo J  Cavagnaro B  Bottini R  Wuilloud R  Silva MF 《Journal of agricultural and food chemistry》2008,56(9):2892-2898

The responses of Vitis vinifera L. cv. Malbec to different solar ultraviolet-B radiation (UV-B) levels were assessed in two contrasting situations, under sunlight with full UV-B (+UV-B) and filtered UV-B (-UV-B), in three different locations at 500, 1000, and 1500 m above sea level (asl). To evaluate the effects of radiation, a simple, accurate, and rapid method for the separation and simultaneous determination of representative phenolic compounds in grape berry skins by capillary zone electrophoresis was developed. Separation was carried out in less than 20 min with 20 mM sodium tetraborate buffer containing 30% methanol, pH 9.00. The procedure is fast and reliable, and extracted grape berry skins can be directly analyzed without prior sample cleanup procedure. Berry skins from the +UV-B treatment at 1500 m asl showed the highest levels of total polyphenols anthocyanins, and resveratrol, compared with the -UV-B treatment at this altitude.  相似文献   

Characterization and growth conditions of Vibrio parahaemolyticus strains with different virulence degrees that cause acute hepatopancreatic necrosis disease in Litopenaeus vannamei     

Sonia A. Soto‐Rodriguez  Rodolfo Lozano‐Olvera  Daniel A. Palacios‐Gonzalez  Carmen Bolan‐Mejia  Karla G. Rendon‐Aguilar 《Journal of the World Aquaculture Society》2019,50(5):1002-1015

The phenotypic characteristics and growth kinetics at several temperatures, salinities, and pH values of three Vibrio parahaemolyticus (Vp) strains with different virulence and one nonpathogenic strain were evaluated. Independent of the virulence of the strain, a high metabolic diversity was found, which yielded different colored phenotypes on the CHROMagar? Vibrio. All strains were resistant to ampicillin and carbenicillin, and Vp AHPND+ organisms were the most sensitive to enrofloxacin. The exponential growth of Vp strains started at 1–2 hr of incubation, although no relationship was observed between the bacterial density and degree of virulence. Moreover, the growth of the most virulent strain was independent of the nutrients in the incubation media during the initial hour postinoculation. No strain grew at 4°C in 0% NaCl and pH 4, but only Vp AHPND+ grew at 44°C. For all strains, the lag phase was proportional to the NaCl concentration, and the growth was better at pH 8–9. However, the Vp AHPND? strain displayed a greater variability, was more sensitive to extreme conditions, and showed a lag phase of 9 hr independent of the pH.  相似文献   

Seasonality in Saint Croix male lamb reproductive development in northern Mexico     

Fernando Snchez‐Dvila  Rodolfo Ungerfeld  Alejandro Sergio del Bosque‐Gonzlez  Hugo Bernal‐Barragn 《Reproduction in domestic animals》2019,54(2):391-400

The aim of this study was to determine the influence of the season of birth on the body weight, testicular size, testosterone concentrations, semen output and sexual behaviour in Saint Croix male lambs. Thirty‐three lambs were born in spring (n = 10), summer (Sum; n = 12) or autumn (n = 11). Body weight and the scrotal circumference were weekly recorded; semen was also weekly collected by electroejaculation; and sexual behaviour towards oestrous ewes was weekly evaluated. Data were recorded from 15 to 33 weeks of age. The reproductive development of Saint Croix male lambs differed according to the period in which they were born. More lambs born in spring than in summer and autumn achieved puberty during this study and were also more precocious in semen production and displayed sexual behaviour earlier. Lambs born in summer delayed their semen production; however, season‐related negative effects were less pronounced at the end of the study than in autumn born lambs born. In conclusion, despite the apparently low seasonality of the breed, Saint Croix male lambs showed in this study a seasonal pattern in their reproductive development at least until they achieve the puberty.  相似文献   

Development of two immunochromatographic tests for the serodiagnosis of bovine babesiosis     

Kim C  Alhassan A  Verdida RA  Yokoyama N  Xuan X  Fujisaki K  Kawazu S  Igarashi I 《Veterinary parasitology》2007,148(2):137-143

In this study, we developed two immunochromatographic tests (ICTs), which are nitrocellulose membrane-based immunoassays for the convenient and rapid serodiagnosis of bovine babesiosis caused by Babesia bovis (BoICT) and Babesia bigemina (BiICT). The efficacy of two ICTs was evaluated using 13 positive sera from experimentally infected cattle with B. bovis or B. bigemina. Clear results showed that the BoICT and ELISA detected antibodies in sera collected from 14 to 93 days post-infection, while BiICT and ELISA detected from 13 to 274 days post-infection. In additon, non-infected cattle, Neospora caninum, and Cryptosporidium parvum were negative in two ICTs. To evaluate the field utility of the ICTs, we tested 186 field bovine sera collected from cattle living in Yanbian (China) and Mato Grosso do Sul (Brazil). The results of ICTs were compared to those of classical serodiagnostic methods, enzyme-linked immunosorbent assay (ELISA) and the indirect immunofluorescence assay (IFAT). The overall concordances of BoICT were determined as 92.5 and 90.3% when the results of ELISA and IFAT were set as the reference standards, respectively. In contrast, those of BiICT showed 96.8 and 92.5% relative to the results of standard ELISA and IFAT, respectively. Conventional and rapid diagnosic devices for bovine babesiosis may provide a valuable tool in clinical and field applications.  相似文献   

Effect of three diets on the gametogenic development and fatty acid profile of Paracentrotus lividus (Lamarck, 1816) gonads     

Andreia I. G. Raposo  Susana M. F. Ferreira  Rodolfo Ramos  Pedro M. Santos  Catarina Anjos  Teresa Baptista  Carla Tecelo  Jos L. Costa  Ana Pombo 《Aquaculture Research》2019,50(8):2023-2038

In this study, the effects of three diets were investigated to enhance Paracentrotus lividus production for commercial purposes. P. lividus were fed ad libitum for 80 days with: diet A—fresh Codium tomentosum Stackhouse, 1797; diet B—formulated using a jellified mix of macroalgae and vegetables, including C. tomentosum (20%), Coralina sp. Linnaeus, 1758 (17%), cabbage Brassica oleracea var. capitata Linnaeus, 1753 (30%), carrot Daucus carota Linnaeus, 1753 (30%) and agar (3%) as a gelling agent. Diet C consisted of maize Zea mays Linnaeus, 1753 (56%) and New Zealand spinach Tetragonia tetragonoides (Pallas, 1781) Kuntze, 1891 (44%). Their effects on the gonadal and somatic growths, gonadosomatic index (GI) and gametogenesis were evaluated, as well as on the total lipid content and fatty acid composition of sea urchin's gonads. Diet A provided high values of eicosapentaenoic acid (EPA). Gonads of sea urchins fed with diet A were found mostly in growth and maturation stages of gametogenesis and showed the lowest lipid content. Sea urchins fed with diet B presented their gonads in the reabsorption stage and had the highest values of omega‐3 polyunsaturated fatty acids (PUFAs). Sea urchins fed with diet C were in the early stages of gametogenesis and had the highest values of lipid content, plus omega‐6 PUFAs. Once as an ingredient in a balanced mix with vegetables, C. tomentosum can be a key factor to the development of new promising high‐quality and low‐cost feed for P. lividus roe enhancement.  相似文献   

Assessment of Anthropogenic Impacts on the Water Quality of Marreco River,Brazil, Based on Principal Component Analysis and Toxicological Assays     

Soraya Moreno Palácio  Fernando Rodolfo Espinoza-Quiñones  Aline Roberta de Pauli  Pitágoras Augusto Piana  Caroline Bressan Queiroz  Simony Camila Fabris  Márcia Regina Fagundes-Klen  Márcia Teresinha Veit 《Water, air, and soil pollution》2016,227(9):307

  相似文献   

Ex‐post facto analysis of diseases of the Gulf of Mexico′s white shrimp Litopenaeus setiferus     

Rodolfo Enrique del Rio‐Rodriguez  Atahualpa Sosa‐Lopez  Daniel Pech 《Aquaculture Research》2014,45(5):907-912

This study presents an Ex‐Post Facto analysis of diseases of wild juvenile and adults of Litopenaeus setiferus collected from a field survey at the Natural Protected Area of Terminos lagoon, southern Mexico. The objective of the present approach was to determine if sampling site and/or shrimp age were contributing risk factors for disease between juvenile and adult shrimp; if there was a determined period of time in a year cycle when diseases were more critical, and if the analysis would help to decision‐ making considering what population would pose less risk of disease‐carrying when withdrawn for experimental purposes; all under an after‐the‐fact (ex‐post facto) approach. We identified that juvenile shrimp were at more risk of contracting some diseases in the estuarine environment and June, July and August months, were found to be a critical period when colonizing and parasitic diseases maintained a significant high prevalence in the shrimp population. These assumptions may help for decision‐making when wild shrimp have to be withdrawn from their natural environment for research purposes.  相似文献   

Bradford-reactive soil proteins and aggregate stability under abandoned versus tilled olive groves in a semi-arid calcisol     

Chiquinquirá Hontoria  Rodolfo Velásquez  Marta Benito  Javier Almorox  Ana Moliner 《Soil biology & biochemistry》2009,41(7):1583-1585

Glomalin, a substance produced by arbuscular mycorrhizal fungi, is reported to play a role in soil aggregation, but this role has been questioned in soils rich in calcium carbonate. We studied the relationship between aggregation stability and glomalin in a Haplic Calcisol comparing abandoned and active cultivation of olive groves. Abandonment was associated with increases in soil organic carbon, the percentage of water stable aggregates (WSA_1-2mm), and easily extractable and total Bradford-reactive soil protein. WSA_1-2mm was strongly positively correlated with both easily extractable and total Bradford-reactive soil protein. While easily extractable Bradford-reactive soil protein measured in both stable and unstable aggregates did not show any significant differences, Bradford-reactive soil protein was twice as high in stable than in unstable aggregates under both tillage and abandonment. Our results suggest that Bradford-reactive soil protein influences aggregate stability, even in soils with low organic matter and high calcium carbonate contents. However, more research is needed to elucidate the role of easily extractable Bradford-reactive soil protein in soil aggregation.  相似文献   

Collision-free inverse kinematics of the redundant seven-link manipulator used in a cucumber picking robot     

E.J. Van Henten  E.J. Schenk  L.G. van Willigenburg  J. Meuleman  P. Barreiro 《Biosystems Engineering》2010,106(2):112-124

  相似文献