Water availability is a stronger driver of soil microbial processing of organic nitrogen than tree species composition     

Tania L. Maxwell  Laurent Augusto  Ye Tian  Wolfgang Wanek  Nicolas Fanin 《European Journal of Soil Science》2023,74(1):e13350

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Identification of relevant morphological, topological and geometrical variables to characterize the architecture of rose bushes in relation to plant shape     

Laurent Crespel  Monique Sigogne  Nicolas Donès  Daniel Relion  Philippe Morel 《Euphytica》2013,191(1):129-140

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Choice of shrinkage parameter and prediction of genomic breeding values in elite maize breeding populations     

Wenxin Liu  Tobias Würschum  Hans P. Maurer  Friedrich H. Longin  Nicolas Ranc  Hans P. Piepho  Jochen C. Reif 《Plant Breeding》2013,132(1):99-106

Genomic selection (GS) is a promising alternative to marker‐assisted selection particularly for quantitative traits. In this study, we examined the prediction accuracy of genomic breeding values by using ridge regression best linear unbiased prediction in combination with fivefold cross‐validation based on empirical data of a commercial maize breeding programme. The empirical data is composed of 930 testcross progenies derived from 11 segregating families evaluated at six environments for grain yield and grain moisture. Accuracy to predict genomic breeding values was affected by the choice of the shrinkage parameter λ², by unbalanced family size, by size of the training population and to a lower extent by the number of markers. Accuracy of genomic breeding values was high suggesting that the selection gain can be improved implementing GS in elite maize breeding programmes.  相似文献   

Effects of edaphic conditions on site quality for Salix purpurea ‘Hotel’ plantations across a large climatic gradient in Canada     

Joel Ens  Richard E. Farrell  Nicolas Bélanger 《New Forests》2013,44(6):899-918

Willow has been identified as a possible species for supplying large quantities of biomass for bioenergy and wood fibers in Canada. However, before site selection occurs, there is a need to know how the soils and climate of the prairies and central regions affect willow productivity. Soil, foliar, and climatic variables were therefore measured along with yields at nine “first rotation” Salix purpurea ‘Hotel’ plantations from central Alberta to southern Ontario. Correlation analysis was used to identify those parameters having the most influence on yields. Relationships between soil and climate and growth were established by regression analysis. The acid–base status of the soil as dictated by bulk elemental composition, in particular the presence of Ca, was found to be the dominant factor affecting productivity (r = 0.967, P < 0.001 total Ca vs. yields) despite large regional differences in climate. From a nutritional standpoint, total soil N (r = 0.743, P = 0.048) and foliar K (r = 0.938, P = 0.009 for sites with adequate moisture) were positively correlated with growth. S. purpurea ‘Hotel’ yields were found to be primarily limited by water availability at the two lowest productivity prairie sites. Soil total Ca concentration, pH and total organic C concentration were all generally correlated with higher yields. Additional deficiencies appeared in the following order of importance: water > N and K > Mg. As a whole, soil properties were the dominant predictors of ‘Hotel’ growth in this study, which suggests that, even at the regional scale, growth was governed in large part by the capacity of soils to retain water and/or nutrients. Climate played a lesser role, except perhaps at two sites which appeared to receive inadequate moisture.  相似文献   

Nutrient concentration and allometric models for hybrid eucalyptus planted in France     

Alain Bouvet  Nicolas Nguyen-The  Francis Melun 《Annals of Forest Science》2013,70(3):251-260

Context

Short rotation coppice (SRC) of hybrid Eucalyptus has been developed in France for almost 30 years for the production of pulp and paper and, since a few years, for energy purposes. In the traditional pulp production, only the stems are harvested, whereas the whole biomass may be harvested for energy purposes. Thus, a range of different harvest scenarios need to be considered with higher plantation densities or younger age of harvest for example.

Aims

The objective of this study was to build models to estimate biomass and nutrient content of eucalyptus at different ages and so to estimate the production and the nutrient exportation of a SRC, depending on the different harvest scenarios.

Methods

Over 250 trees were sampled in 16 stands at ages from 1 to 15 years. For each tree, biomass of different compartments and nutrient contents were recorded.

Results

A complete set of equations for the four compartments (wood, bark, branches, and leaves) of aboveground biomass and for nutrient concentration was set up.

Conclusion

Biomass and its allocation to different compartments and nutrient concentrations depended on the dimension and/or the age of the tree. In particular, nutrient concentration decreased with increasing tree diameter.  相似文献   

Description of a new procedure to estimate the carbon stocks of all forest pools and impact assessment of methodological choices on the estimates     

Nicolas Latte  Gilles Colinet  Adeline Fayolle  Philippe Lejeune  Jacques Hébert  Hugues Claessens  Sébastien Bauwens 《European Journal of Forest Research》2013,132(4):565-577

Forest ecosystems play a major role in atmospheric carbon sequestration and emission. Comparable organic carbon stock estimates at temporal and spatial scales for all forest pools are needed for scientific investigations and political purposes. Therefore, we developed a new carbon stock (CS) estimation procedure that combines forest inventory and soil and litter geodatabases at a regional scale (southern Belgium). This procedure can be implemented in other regions and countries on condition that available external carbon soil and litter data can be linked to forest inventory plots. The presented procedure includes a specific CS estimation method for each of the following forest pools and subpools (in brackets): living biomass (aboveground and belowground), deadwood (dead trees and snags, coarse woody debris and stumps), litter, and soil. The total CS of the forest was estimated at 86 Tg (185 Mg ha^?1). Soil up to 0.2 m depth, living biomass, litter, and deadwood CSs account, respectively, for 48, 47, 4, and 1 % of the total CS. The analysis of the CS variation within the pools across ecoregions and forest types revealed in particular that: (1) the living biomass CS of broadleaved forests exceeds that of coniferous forests, (2) the soil and litter CSs of coniferous forest exceed those of broadleaved forests, and (3) beech stands come at the top in carbon stocking capacity. Because our estimates differ sometimes significantly from the previous studies, we compared different methods and their impacts on the estimates. We demonstrated that estimates may vary highly, from ?16 to +12 %, depending on the selected methods. Methodological choices are thus essential especially for estimating CO₂ fluxes by the stock change approach. The sources of error and the accuracy of the estimates were discussed extensively.  相似文献   

Natural enemies of the South American moth, Tuta absoluta, in Europe, North Africa and Middle East, and their potential use in pest control strategies   总被引：1，自引：0，他引：1  

Lucia Zappalà  Antonio Biondi  Alberto Alma  Ibrahim J. Al-Jboory  Judit Arnò  Ahmet Bayram  Anaïs Chailleux  Ashraf El-Arnaouty  Dan Gerling  Yamina Guenaoui  Liora Shaltiel-Harpaz  Gaetano Siscaro  Menelaos Stavrinides  Luciana Tavella  Rosa Vercher Aznar  Alberto Urbaneja  Nicolas Desneux 《Journal of pest science》2013,86(4):635-647

The South American tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is an invasive Neotropical pest. After its first detection in Europe, it rapidly invaded more than 30 Western Palaearctic countries becoming a serious agricultural threat to tomato production in both protected and open-field crops. Among the pest control tactics against exotic pests, biological control using indigenous natural enemies is one of the most promising. Here, available data on the Afro-Eurasian natural enemies of T. absoluta are compiled. Then, their potential for inclusion in sustainable pest control packages is discussed providing relevant examples. Collections were conducted in 12 countries, both in open-field and protected susceptible crops, as well as in wild flora and/or using infested sentinel plants. More than 70 arthropod species, 20 % predators and 80 % parasitoids, were recorded attacking the new pest so far. Among the recovered indigenous natural enemies, only few parasitoid species, namely, some eulophid and braconid wasps, and especially mirid predators, have promising potential to be included in effective and environmentally friendly management strategies for the pest in the newly invaded areas. Finally, a brief outlook of the future research and applications of indigenous T. absoluta biological control agents are provided.  相似文献   

Genotype by climate interaction in the genetic evaluation for growing traits of Braunvieh cattle in Mexico     

Luis A. Saavedra-Jiménez  Rodolfo Ramírez-Valverde  Rafael Núñez-Domínguez  José G. García-Muñiz  Nicolas Lopez-Villalobos  Agustín Ruíz-Flores 《Tropical animal health and production》2013,45(7):1489-1494

The objective of this study was to determine the magnitude of genotype by climate interaction (GCI) in the national genetic evaluation for weaning (WW) and yearling (YW) weights of Mexican Braunvieh cattle. The numbers of performance records and animals in the pedigree were 12,364 and 25,173 for WW, and 7,991 and 18,072 for YW, respectively. Performance records were clustered based on climatological variables into: dry tropic (DT), wet tropic (WT), and temperate (TE) climates. Animal models were used to estimate genetic parameters and predict breeding values in each of the climates. Bivariate analyses were carried out for pairwise combinations of climates on each trait, considering the same trait in different climates as a different trait. Criteria to evaluate GCI were genetic correlations (r _g), correlations between predicted breeding values (r _BV), and frequencies of coincidence (FC) in the ranking of the top 25 sires. Results of comparisons between pairs of climates were variable, depending on specific cases. For WW, the r _g, r _BV, and FC ranged from ?0.36 to 0.84, ?0.60 to 0.97, and 0.16 to 0.92, respectively; whereas for YW, they fluctuated between 0.23 and 0.99, 0.33 and 1.00, and 0.60 and 1.00, respectively. For both traits, the results suggest absence of GCI between DT and TE; however, GCI was detected in the other pairs of climates, where WT was involved. To maximize genetic progress, the joint genetic evaluation should be performed only for animals with performance data in DT and TE, whereas a separated evaluation is suggested for animals with performance records generated under WT conditions.  相似文献   

Population structure of the fish pathogen Flavobacterium psychrophilum at whole-country and model river levels in Japan     

Erina Fujiwara-Nagata  Céline Chantry-Darmon  Jean-Fran?ois Bernardet  Mitsuru Eguchi  Eric Duchaud  Pierre Nicolas 《Veterinary research》2013,44(1):34

The bacterium Flavobacterium psychrophilum is a serious problem for salmonid farming worldwide. This study investigates by multilocus sequence typing (MLST) the population structure of this pathogen in Japan where it is also a major concern for ayu, a popular game fish related to salmoniforms. A total of 34 isolates collected across the country and 80 isolates sampled in a single model river by electrofishing were genotyped. The data accounting for 15 fish species allowed identifying 35 distinct sequence types (ST) in Japan. These ST are distinct from those reported elsewhere, except for some ST found in rainbow trout and coho salmon, two fish that have been the subject of intensive international trade. The pattern of polymorphism is, however, strikingly similar across geographical scales (model river, Japan, world) in terms of the fraction of molecular variance linked to the fish host (~50%) and of pairwise nucleotide diversity between ST (~5 Kbp^-1). These observations go against the hypothesis of a recent introduction of F. psychrophilum in Japan. Two findings were made that are important for disease control: 1) at least two independent F. psychrophilum lineages infect ayu and 2) co-infections of the same individual fish by different strains occur.  相似文献   

Dynamics of influenza A virus infections in permanently infected pig farms: evidence of recurrent infections,circulation of several swine influenza viruses and reassortment events     

Nicolas Rose  Séverine Hervé  Eric Eveno  Nicolas Barbier  Florent Eono  Virginie Dorenlor  Mathieu Andraud  Claire Camsusou  Fran?ois Madec  Ga?lle Simon 《Veterinary research》2013,44(1):72

Concomitant infections by different influenza A virus subtypes within pig farms increase the risk of new reassortant virus emergence. The aims of this study were to characterize the epidemiology of recurrent swine influenza virus infections and identify their main determinants. A follow-up study was carried out in 3 selected farms known to be affected by repeated influenza infections. Three batches of pigs were followed within each farm from birth to slaughter through a representative sample of 40 piglets per batch. Piglets were monitored individually on a monthly basis for serology and clinical parameters. When a flu outbreak occurred, daily virological and clinical investigations were carried out for two weeks. Influenza outbreaks, confirmed by influenza A virus detection, were reported at least once in each batch. These outbreaks occurred at a constant age within farms and were correlated with an increased frequency of sneezing and coughing fits. H1N1 and H1N2 viruses from European enzootic subtypes and reassortants between viruses from these lineages were consecutively and sometimes simultaneously identified depending on the batch, suggesting virus co-circulations at the farm, batch and sometimes individual levels. The estimated reproduction ratio R of influenza outbreaks ranged between 2.5 [1.9-2.9] and 6.9 [4.1-10.5] according to the age at infection-time and serological status of infected piglets. Duration of shedding was influenced by the age at infection time, the serological status of the dam and mingling practices. An impaired humoral response was identified in piglets infected at a time when they still presented maternally-derived antibodies.  相似文献