Mortality in relation to growth rate and soil resistance varies by species for underplanted Nothofagus seedlings in scarified shelterwoods     

Daniel P. Soto  Pablo J. Donoso  Klaus J. Puettmann 《New Forests》2014,45(5):655-669

This study evaluated early mortality patterns of planted Nothofagus dombeyi (Mirb.) Blume (evergreen, shade intolerant) and Nothofagus alpina (P. et E.) Oerst. (deciduous, mid-tolerant to shade) seedlings established in scarified gaps in a Nothofagus old-growth forest in the Chilean Andes that was subjected to a shelterwood cut. Soils were scarified with heavy machinery that removed up to 40 cm of the upper horizons (e.g. it completely removed the litter layer and organic horizon, and in some cases partially the A horizon) to eliminate bamboo (Chusquea culeou E. Desv) shoots and rhizomes from the scarified areas. Two years after planting, seedlings were growing free of understory competition and mortality patterns were assessed using logistic regression models with the following predictor variables: (1) basal diameter growth in the prior year, and (2) soil strength measured as resistance to penetration. The probability of mortality of both species was highly predictable based on recent basal diameter growth. N. dombeyi seedlings appeared to be less affected by mortality, as reflected in lower sensitivity of mortality at lower growth rates compared to N. alpina. High values of resistance to penetration (>2,000 kPa) induced a higher probability of mortality in N. alpina (up to 40 % at 3,500 kPa). In contrast, N. dombeyi mortality was not significantly influenced by soil strength, which illustrates the more stress-resistant and pioneer character of this species. This study showed that recent growth rates can be used as a predictor of future mortality, but these relationships need to be calibrated for each species. In addition, our results suggest that species characteristics that relate to resource limitations, such as shade tolerance, are not adequate to understand effects of other stressors, such as soil disturbance, on mortality patterns.  相似文献   

Non-target effects of chlorantraniliprole and thiamethoxam on Chrysoperla carnea when employed as sunflower seed treatments     

Pablo C. Gontijo  Valéria F. Moscardini  J. P. Michaud  Geraldo A. Carvalho 《Journal of pest science》2014,87(4):711-719

The use of systemic insecticides as seed treatments has raised concern about the possible impacts of these products on natural enemies. This study assessed the effects of sunflower seed treatments with chlorantraniliprole and thiamethoxam on Chrysoperla carnea by exposing larvae and adults to sunflower stem segments grown from treated seeds and the nectar secreted by their extrafloral nectaries. Confinement of larvae with stem segments for their entire developmental period had no effect on their survival or any life history parameter, except that the sex ratio of resulting adults was lower in the thiamethoxam treatment than in chlorantraniliprole. However, when adult pairs of C. carnea were exposed to treated stem segments during their maturation period, their subsequent survival and fecundity was significantly reduced by both materials, with thiamethoxam reducing median survival (LT₅₀) and fecundity to a greater degree than chlorantraniliprole. Insufficient offspring were obtained from adults exposed to thiamethoxam to permit assessment of their fitness, but the offspring in the chlorantraniliprole-exposed adults had reduced larval survival relative to controls. The greater impact of seed treatments on adult lacewings may be partly attributable to their greater consumption of extra-floral nectar. Our results indicate that seed treatment with systemic insecticides can cause negative effects on beneficial insects, potentially disrupting their population dynamics, and should not be assumed compatible with biological control and IPM simply because this mode of application limits direct exposure.  相似文献   

Natural forage composition decreases deer browsing on Picea abies around supplemental feeding sites     

Pablo Garrido  Sara Lindqvist  Petter Kjellander 《Scandinavian Journal of Forest Research》2014,29(3):234-242

In southern Sweden, maintaining high cervid densities through supplemental feeding has become a common management practice. We aim at investigating deer browsing pressure on young Norway spruce in relation to distance from supplemental feeding sites. Because available forage is considered important in understanding browsing patterns, we modeled several factors affecting food availability, and their interaction effect with distance. We confirmed earlier studies about a locally high browsing pressure on natural vegetation adjacent to supplemental feeding sites where browsing pressure declined with distance and alternative forage abundance. Novel is that browsing on spruce occurred in 27.6% of the investigated plots. The browsing pressure of those plots averaged 9%. Distance was the most important factor in relation to browsing. The interactive effect of occurring field layer (FL), and deciduous trees was also highlighted as these significantly affected the relationship between browsing pressure on spruce and distance. In the studied conditions, browsing pressure ceased at ca. 205 m, whereas in scenarios of an abundant FL, browsing levels were negligible already at 0 m from supplemental feeding sites. We suspect that most of the browsing was caused by fallow deer in our study area.  相似文献   

Participatory development of decision support systems: which features of the process lead to improved uptake and better outcomes?     

Pablo Valls-Donderis  Duncan Ray  Andrew Peace  Amy Stewart  Anna Lawrence  Francisco Galiana 《Scandinavian Journal of Forest Research》2014,29(7):71-83

Decision support systems (DSSs) are important in decision-making environments with conflicting interests. Many DSSs developed have not been used in practice. Experts argue that these tools do not respond to real user needs and that the inclusion of stakeholders in the development process is the solution. However, it is not clear which features of participatory development of DSSs result in improved uptake and better outcomes. A review of papers, reporting on case studies where DSSs and other decision tools (information systems, software and scenario tools) were developed with elements of participation, was carried out. The cases were analysed according to a framework created as part of this research; it includes criteria to evaluate the development process and the outcomes. Relevant aspects to consider in the participatory development processes include establishing clear objectives, timing and location of the process; keeping discussions on track; favouring participation and interaction of individuals and groups; and challenging creative thinking of the tool and future scenarios. The case studies that address these issues show better outcomes; however, there is a large degree of uncertainty concerning them because developers have typically neither asked participants about their perceptions of the processes and resultant tools nor have they monitored the use and legacy of the tools over the long term.  相似文献   

Pig farmers’ perceptions,attitudes, influences and management of information in the decision-making process for disease control     

Pablo Alarcon  Barbara Wieland  Ana L.P. Mateus  Chris Dewberry 《Preventive veterinary medicine》2014

The objectives of this study were (1) to explore the factors involved in the decision-making process used by pig farmers for disease control and (2) to investigate pig farmers’ attitudes and perceptions about different information sources relating to disease control.  相似文献   

The use of electrical stimulation to guide epidural and intrathecal needle advancement at the L5‐L6 intervertebral space in dogs     

Pablo E Otero  Natali Verdier  Martin R Ceballos  Lisa Tarragona  Myriam Flores  Diego A Portela 《Veterinary anaesthesia and analgesia》2014,41(5):543-547

ObjectiveTo determine the minimal electrical threshold (MET) necessary to elicit appropriate muscle contraction when the tip of an insulated needle is positioned epidurally or intrathecally at the L_5-6 intervertebral space (phase-I) and to determine whether the application of a fixed electrical current during its advancement could indicate needle entry into the intrathecal space (phase-II) in dogs.Study designProspective, blinded study.AnimalsThirteen (phase-I) and seventeen (phase-II) dogs, scheduled for a surgical procedure where L_5-6 intrathecal administration was indicated.MethodsUnder general anesthesia, an insulated needle was first inserted into the L_5-6 epidural space and secondly into the intrathecal space and the MET necessary to obtain a muscular contraction of the pelvic limb or tail at each site was determined (phase-I). Under similar conditions, in dogs of phase-II an insulated needle was inserted through the L_5-6 intervertebral space guided by the use of a fixed electrical current (0.8 mA) until muscular contraction of the pelvic limb or tail was obtained. Intrathecal needle placement was confirmed by either free flow of cerebrospinal fluid (CSF) or myelography.ResultsThe current required to elicit a motor response was significantly lower (p < 0.0001) when the tip of the needle was in the intrathecal space (0.48 ± 0.10 mA) than when it was located epidurally (2.56 ± 0.57). The use of a fixed electrical stimulation current of 0.8 mA resulted in correct prediction of intrathecal injection, corroborated by either free flow of CSF (n = 12) or iohexol distribution pattern (n = 5), in 100% of the cases.Conclusion and clinical relevanceNerve stimulation may be employed as a tool to distinguish epidural from intrathecal insulated needle position at the L_5-6 intervertebral space in dogs. This study demonstrates the feasibility of using an electrical stimulation test to confirm intrathecal needle position in dogs.  相似文献   

Ecology. Of predators, prey, and power laws     

Marquet PA 《Science (New York, N.Y.)》2002,295(5563):2229-2230

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Negative effects of energy supplementation at peak lactation of sheep can be offset by the addition of Lactobacillus-fermented plant extracts     

Matthew R Beck  Konagh Garrett  Kenneth J Olejar  Thomas M R Maxwell  Craig R Bunt  Andrew E Greer  Pablo Gregorini 《Journal of animal science》2021,99(5)

Energy supplementation may reduce oxidative stress by correcting a negative energy balance, but in some contexts, it has been shown to increase oxidative stress, especially at peak lactation. The current experiment examined if a pelleted energy supplement with or without the addition of Lactobacillus-fermented seaweed or seaweed plus terrestrial plants extracts affected oxidative stress of ewes from late gestation through to weaning and ewe and lamb production from lambing to weaning. Treatments were either no supplement (CON−), a pelleted supplement only (CON+, 100 g/ewe per d), CON+ with seaweed extract only (SWO, 10 mL/ewe per day), or CON+ with seaweed plus an arrangement of terrestrial plant extract (SWP, 10 mL/ewe per d). Ewes (n = 160; mean initial BW = 72.3 ± 9.5 kg [mean ± SD]) were randomized to pastures (n = 4 pastures per treatment with 10 ewes each). After lambing, ewes with twins were reallocated to pastures (n = 3 pastures per treatment with 10 ewes each) according to lambing date. At 4 wk in milk, supplementation tended to reduce total antioxidant status (TAS; P = 0.10) and increased glutathione peroxidase (GPx) activity compared with nonsupplemented ewes (P = 0.04). The addition of seaweed and terrestrial plants extracts to the concentrate, that is, SWO and SWP, increased TAS and reduced GPx activity compared with CON+ (P < 0.01). Supplementation increased milk yield at weeks 4, 6, and 8 of lactation, and protein, lactose, and total milk solids yield at peak lactation (week 4; P < 0.05). The CON− ewes had greater somatic cell count than the supplemented ewes at weeks 4, 8, and 10 of lactation (P = 0.03). Our results suggest that energy supplementation, alone, increases oxidative stress of lactating ewes, which may relate to increased oxidative phosphorylation. Most importantly, these results indicate that in situations where energy supplementation is needed to increase animal performance, negative effects of energy supplementation around peak lactation can be offset by the addition of Lactobacillus-fermented plant extracts (SWO and SWP) to improve antioxidant status.  相似文献   

Radiological prevalence of osteoarthritis of the cervical region in 104 performing Warmblood jumpers     

Pablo Espinosa-Mur  Kathryn L. Phillips  Larry D. Galuppo  Anthony DeRouen  Philippe Benoit  Eleanor Anderson  Karen Shaw  Sarah Puchalski  Duncan Peters  Philip H. Kass  Mathieu Spriet 《Equine veterinary journal》2021,53(5):972-978

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Zacatecas (Mexico) Companies Extract Hg from Surface Soil Contaminated by Ancient Mining Industries     

Ogura  Tetsuya  Ramírez-Ortiz  Jorge  Arroyo-Villaseñor  Zenaida Maria  Hernández Martínez  Sergio  Palafox-Hernández  Jesús Pablo  García de Alba  Luis Hugo  Fernando  Quintus 《Water, air, and soil pollution》2003,148(1-4):167-177

In Zacatecas, Mexico, four plants are operating to extract Ag, Au, and Hg using CaS₂O₃ solution from surface soil containing tailings from the amalgamation method used during 1550–1900. The metal ions extracted are cemented by scrap Cu wires. Hg is separated by evaporation from the cemented amalgam and Ag and Au are obtained from the residue. A part of the soil to be leached was separated and leached as in the industrial process. Only 121 ppm of Hg was freed from 168 ppm of extractable Hg. About a half of the remaining Hg in the soil evaporated during 18 months. This confirms that the Hg in the soil is metallic. Pb and As are also freed in the same process. It is estimated that 13 000–34 000 t of Hg had been discarded in the extraction of Ag.  相似文献