Scientific Journals of INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria)
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Does pollen diversity influence honey bee colony health?
Get PDFAim of study: Colony losses of the western honey bee Apis mellifera have increased alarmingly in recent years. These losses have been attributed to nutritional deficiency, environmental conditions, viral infection and the global presence of the ectoparasite mite Varroa destructor. Ensuring pollen availability may improve colony health, so the present study aimed to examine whether the diversity of pollen collected by the colony as well as landscape characteristics of apiaries influence colony health.Area of study: Tenerife Island (Canary Islands, Spain).Material and methods: Colonies at eight apiaries were sampled in late summer to determine colony strength, presence of varroa and load of DWV. Pollen was collected during six months and analyzed. Landscape of each apiary was spatially analyzed.Main results: Pollen diversity did not correlate significantly with colony strength or the load of DWV, but it positively correlated with varroa levels. In contrast, DWV load correlated with varroa infestation, and both variables negatively correlated with colony strength. Weak colonies were located in landscapes with areas less suitable for bee nutrition.Research highlights: These results suggest that DWV and varroa infection as well as landscape characteristics influence colony survival, while pollen diversity on its own does not seem to have direct relationship. Our findings highlight the usefulness of DWV and varroa as predictors of colony losses, and they suggest the need to carefully assess honey bee apiary location in order to ensure adequate nutritional resources
Assessing localization impact on land values: a spatial hedonic study
No full textAim of study: To obtain spatial land valuing models using Geographic Information Systems (GIS), which collect spatial autocorrelation and improve the conventional models estimated by OLS (Ordinary Least Squares) to determine and quantify the factors explaining these values.Area of study: The Spanish Autonomous Community of Aragón, Spain.Material and methods: The mean land values per municipality and the land uses published by the Aragonese Statistics Institute were used, as well as the geographic, agricultural, demographic, economic and orographic characteristics of these municipalities. The Spatial Lag Model and the Spatial Error Model were compared with OLS in general terms and for uses.Main results: The statistics (R2, log likelihood, Akaike’s information criterion, Schwarz’s criterion) demonstrated that spatial models always outperformed conventional models. The tests based on the Lagrange Multiplier and Likelihood Ratio tests were significant at 99%. The importance of both agricultural and non-agricultural factors for determining the arable land value was confirmed. The land value increased with irrigation availability (by a mean of 2.2-fold for the set of all land uses), plot size (by 5.7% for each 1 ha increase), population size, income and location in nature reserves (11.02-12.89%).Research highlights: Results indicate the need to develop spatial models when modeling land prices by implementing GIS
Evaluation of direct and indirect methods for modelling the joint distribution of tree diameter and height data with the bivariate Johnson’s SBB function to forest stands
Get PDFAim of study: In this study, both the direct and indirect methods by conditional maximum likelihood (CML) and moments for fitting Johnson’s SBB were evaluated. To date, Johnson’s SBB has been fitted by either indirect (two-stage) method using well-known procedures for the marginal diameter and heights, or direct methods, where all parameters are estimated at once. Application of bivariate Johnson’s SBB for predicting height and improving volume estimation requires a suitable fitting method.Area of study: E. globulus, P. pinaster and P. radiata stands in northwest Spain.Material and methods: The data set comprised of 308, 184 and 96 permanent sample plots (PSPs) from the aforementioned species. The suitability of the method was evaluated based on height and volume prediction. Indices including coefficient of determination (R2), root mean square Error (RMSE), model efficiency (MEF), Bayesian Information Criterion (BIC) and Hannan-Quinn Criterion (HQC) were used to assess the model predictions. Significant difference between observed and predicted tree height and volumes were tested using paired sample t-test at 5% level for each plot by species.Main results: The indirect method by CML was the most suitable method for height and volume prediction in the three species. The R2 and RMSE for height prediction ranged from 0.994 – 0.820 and 1.454 – 1.676, respectively. The percentage of plot in which the observed and predicted heights were significant was 0.32%. The direct method was the least performed method especially for height prediction in E. globulus.Research highlights: The indirect (two-stage) method, especially by conditional maximum likelihood, was the most suitable method for the bivariate Johnson’s SBB distribution.Keywords: conditional maximum likelihood; moments; two-stage method; direct method; tree volume
Biodiversity study of endophytic fungi associated with two Quercus species in Iran
Get PDFAim of study: In this study, frequency and diversity of fungal endophyte communities inhabiting twigs and branches of apparently healthy Q. macranthera and Q. brantii in East Azerbaijan and Lorestan provinces of Iran is presented.Area of study: East Azerbaijan and Lorestan provinces in Iran.Materials and methods: Culturable fungal endophytes were recovered from wood tissues using routine technique for isolation of fungal endophytes. The identity of fungal isolates were determined based on morphological characteristics and sequences data of ITS-rDNA region and Beta-tubulin gene. Frequency and diversity among fungal communities were analyzed using chi-square test and biodiversity indices.Main results: The highest frequency and diversity was detected for fungal endophyte community recovered from Q. macranthera and East Azerbaijan province. The assemblage of endophytic fungi characterized in this study in healthy tissues of oak trees indicates that some of the fungi are possible latent pathogens such as Biscogniauxia mediterranea with 18.28% frequency followed by Alternaria alternata and Trichothecium roseum respectively. Two fungal taxa of Pyronema domesticum and Valsa persoonii are reported for the first time in Iran. Overall, the results of this study show that the plant species and growth location influence frequency and diversity of culturable fungal endophytic communities of Quercus in Iran.Keywords: Quercus macranthera, Quercus brantii, Fungal endophytes, Molecular identification.Abbreviations used: CBS (Centraal Bureau voor Schimmelcultures); CCTU (Culture Collection of University of Tabriz); GTR (General Time Reversible); HKY (Hasegawa Kishino Yano); ITS-rDNA (Internal Transcribed Space); km (kilometer) ; PDA (Potato Dextrose Agar); TUB (Tubulin)
Optimizing thinnings for timber production and carbon sequestration in planted teak (Tectona grandis L.f.) stands
Get PDFAim of study: We developed an optimization model for determining thinning schedules in planted teak (Tectona grandis L.f.) stands that maximize the financial output in terms of soil expectation value (SEV) and net present value (NPV) considering a) the simultaneous optimization of timber production and carbon (C) sequestration and b) only for C sequestration.Area of study: Planted teak forests in the western alluvial plains of Venezuela.Material and methods: We integrated a stand growth and yield model with a constrained optimization model based on genetic algorithms (GA) for determining optimal thinning schedules (number, age, and removal intensity) that maximize SEV when simultaneously managing for timber production and C sequestration. The data came from permanent plots established in planted teak stands with remeasurements from 2 to 32 yr.-old. Plots differ in site quality, initial spacing, and thinning schedules. We obtained optimal thinning schedules for several scenarios combining site quality, initial spacing, interest rates, harvest and transport costs, as well as timber and C prices. The stand growth and yield model estimates timber products and C flows (storage and emissions) until most stored C is reemitted to the atmosphere.Main results: When considering simultaneously both, timber production and C sequestration, the scenario with the maximum SEV consisted of initial stand densities = 1,111 trees ha-1, site quality (SQ) I, harvest age 20 years, and four thinnings (ages 6, 10, 14, 17 with removal intensities 26 %, 28 %, 39 %, and 25 % of stand basal area respectively). For maximizing C sequestration only, the best schedule consisted of 1,600 trees ha-1, SQ I, harvest age 25 years, with no-thinning. A sensitivity analysis showed that optimal schedules and SEV were highly sensitive to changes in interest rates, growth rates, and timber prices.Research highlights:The management schedules favoring merchantable timber production are not the same that favor C sequestration.For planted teak, the objectives of maximizing timber production and carbon sequestration are in conflict because the thinning schedules that maximize financial gains from C sequestration reduce economic gains from timber and vice versa.With actual timber teak and market C prices, optimal NPVW is much larger than optimal NPVC.For C prices under 40 $US MgC optimizing simultaneously for timber production and C sequestration is the best option, as additional although sub-optimal revenues can be obtained from C payments.Lengthening the rotation, avoiding thinnings, or reducing their intensity increase carbon storage in planted teak, although, under the analyzed scenarios, after 120 yr. almost all carbon has been re-emitted to the atmosphere.Additional keywords: heuristics, genetic algorithms, operations research, forest management planning, stand level model, carbon stocks.Abbreviations used: C (Carbon); GA (genetic algorithm); NPVW, NPVC, NPVT (net present value from the cash flows of timber (wood), carbon, and total); SEV (Soil (land) expectation value); dbh (diameter at 1.3 m from the ground); G (stand basal area); Gp (potential site carrying capacity in terms of G); SQ (site quality); R (rotation, harvest age); A (age); I (thinning intensity); Vob, Vub (overbark, underbark volume); gr (basal area growth rate); r (interest rate); harvest and transport costs (Hc); Pc (C price).
The ongoing dispersion of the Eucalyptus bronze bug (Thaumastocoris peregrinus) in Spain
Get PDFAim of study: Thaumastocoris peregrinus (Carpintero & Dellapé, 2006) is notable for its dispersion potential, and for its damage to a wide range of hosts of the genus Eucalyptus. The intense movement of people and cargo between continents contributes to the success of its geographical distribution on the globe and hinders the adoption of preventive measures. The celerity and precision in the identification of T. peregrinus, as well as its invasion and dispersion routes are fundamental for the implementation of measures to prevent new invasions.Area of Study: Park of Retiro in the community of Madrid, Spain, where T. peregrinus is present.Material and methods: We analyzed a fragment of COI mtDNA gene in T. peregrinus specimens, using samples collected at a public park in Madrid urban area, to study the possible pathways of incursion of this insect in Spain. The goal was achieved using molecular tools, with PCR amplification of partial mtDNA COI and sequencing the fragment, which is used as a barcode of life for identification at species level. Species identity was confirmed using the database in GenBank.Results: The results confirms that the specimens found in Madrid are T. peregrinus, and all are from the same maternal lineage.Research highlights: We present the first molecular information of T. peregrinus population present in Spain, and suggest and discuss possible routes of incursion of this pest.Keywords: Invasive pest;DNA Barcoding;Invasion Routes; Forest Entomology
Effects of simulated nitrogen deposition on soil microbial biomass and community function in subtropical evergreen broad-leaved forest
Get PDFAim of the study: The aim of this study was to examine the effects of a 5-year simulated nitrogen (N) deposition on soil microbial biomass carbon (MBC), nitrogen (MBN), microbial community activity and diversity in subtropical old-growth forest ecosystems.Area of study: The study was conducted in forest located at subtropical forest in Anhui, east China.Material and methods: Three blocks with three fully randomized plots of 20 m × 20 m with similar forest community and soil conditions were established. The site applied ammonium nitrate (NH4NO3) to simulate N deposition (50 and 100 kg N ha−1 year −1). From three depths (0–10, 10–20 and 20–30 cm), were collected over four seasons (December, March, June and September), and then measured by community-level physiological profiles (CLPPs).Main results: N addition had no significant effect on MBC and MBN. The spatiotemporal variations in MBC and MBN were controlled by seasonality and soil depth. Soil microbial activities and diversity in the growing season (June and September) were apparently higher than the dormant season (March and December), there were significantly lower diversity indices found following N addition in September. However, N addition enhanced microbial activities and increased diversity indices in the dormant season. Redundancy analysis showed that pH, soil moisture, NO3--N and total phosphorus were the most important factors controlling the spatial pattern of microbial metabolic activity.Research highlights: These results suggest that soil microbial community function is more easily influenced than microbial biomass. The site has a trend of P-limited or near-N saturation, and will threaten the whole forest ecosystem with the increasing duration of N addition.Keywords: Nitrogen deposition; Seasonality; Soil microbial biomass; Microbial community; Subtropical old-growth forest
Replacing an oriental beech forest with a spruce plantation impacts nutrient concentrations in throughfall, stemflow, and O layer
Get PDFAim of study: To measure the nutrient leaching from canopy and the O layer in a natural oriental beech (Fagus orientalis Lipsky) forest and a Norway spruce (Picea abies) plantation.Materials and methods: From mid-July to early November, 2013, we measured throughfall (TF) (n=45), stemflow (SF) (n=12) and leaching from the O layer (n = 30) in a 0.5 ha sample plot in the Caspian region, Mazandaran province in northern Iran.Main results: Concentrations of PO43-, Na+, Mg2+, Ca2+ and K+ in the throughfall and the O layer in both beech and spruce forests significantly increased relative to gross rainfall. Concentrations of Ca2+ and Na+ in TF and SF were significantly higher in the spruce forest compared with the beech forest. Furthermore, in both forests, cumulative fluxes of all studied elements (with the exception of NH4+ and NO3-) during the study period were statistically different from those of GR (P<0.05).Research highlights: This study demonstrates that changing from a natural beech forest to a spruce plantation significantly alters nutrient fluxes exiting the canopy and the O layer. This information provides essential information on how planting exotic species will affect nutrient cycles in this region.Keywords: Beech forest; Norway spruce plantation; Throughfall; Nutrient leaching; O layer
Influence of density on growth and survival of freshwater prawn Macrobrachium americanum (Bate, 1868) (Caridea: Palaemonidae) cultured in a cage-pond system
Get PDFThe domestication and culture of freshwater shrimp native of tropical and subtropical American Pacific zone requires the study and development of technologies in open systems where their response to types of farming, feeding and management strategies generate practical information for the production of this species. The aim of this study was to evaluate the effect of stocking density on growth and survival in M. americanum juvenile-adult, cage-cultured and to determine the optimal density for grow-out production. The caridean shrimp Macrobrachium americanum was cultured for 152 days in a 16 cage-culture (3 m3 each) at densities of 1, 3, 6 and 9 org / m3, respectively, with stocking sizes from 12.1 ± 1.7 to 13.5 ± 2.3 g. The prawns were fed twice daily with Camaronina 35%. Water quality parameters were within standard range for caridean shrimp culture. There was a significant effect of density on final weight, growth rate, specific growth rate, K condition and survival, and an inversely proportional relationship with the feed conversion ratio. The growth was affected by density, resulting to a maximum increase of 6 org / m3 in the asymmetry of the prawn and also increasing the number of small organisms by 9 org / m3. However, it is necessary to study such aspects as the rate and frequency of feeding, the initial size-grade and the implementation of shelter, among others
The use of physiological, biochemical and morpho-anatomical traits in tree breeding for improved water-use efficiency of Quercus robur L.
Get PDFAim of study: In the present paper the nature and level of co-dependence between leaf functional traits and intrinsic water-use efficiency (WUEi) were studied in one-year-old Quercus robur L. seedlings, grown in a common garden experiment under moderate drought conditions. The study was established to identify those traits that might potentially be utilized to improve leaf-level WUEi, and therefore be used in breeding programmes to enhance drought adaptation of Q. robur.Area of study: The study was carried out at the common garden site within the UNESCO Biosphere Reserve Mura-Drava-Danube.Material and methods: The study involved one-year-old seedlings of eight half-sib lines of Q. robur. Eighteen leaf parameters were analyzed; i.e. physiological, biochemical, morphological and anatomical. The data were processed using multivariate statistical methods: a) principal component analysis, b) stepwise regression analysis, and c) path coefficient analysis.Main results: The results showed that leaf stomata traits, particularly stomatal density (SD), and leaf dry mass per unit leaf area (LMA) were the most important traits, closely associated with WUEi. Stomatal density achieved the highest score on PC1 (0.825), in which WUEi had the highest loading (0.920), as well. SD was also included first in stepwise regression model.Research highlights: These results demonstrate that under moderate water stress WUEi in Q. robur half-sib lines were mainly the result of the plants’ structural acclimation to surrounding environmental conditions. Keywords: Quercus robur L.; half-sib line; intrinsic water-use efficiency; leaf functional traits