Abstract
Climate change is expected to increase the frequency and intensity of droughts and heatwaves in Europe, leading to effects on forest growth and major forest dieback events due to hydraulic ...failure caused by xylem embolism. Inter-specific variability in embolism resistance has been studied in detail, but little is known about intra-specific variability, particularly in marginal populations. We evaluated 15 European beech populations, mostly from geographically marginal sites of the species distribution range, focusing particularly on populations from the dry southern margin. We found small, but significant differences in resistance to embolism between populations, with xylem pressures causing 50% loss of hydraulic conductivity ranging from −2.84 to −3.55 MPa. Significant phenotypic clines of increasing embolism resistance with increasing temperature and aridity were observed: the southernmost beech populations growing in a warmer drier climate and with lower habitat suitability have higher resistance to embolism than those from Northern Europe growing more favourable conditions. Previous studies have shown that there is little or no difference in embolism resistance between core populations, but our findings show that marginal populations have developed ways of protecting their xylem based on either evolution or plasticity.
Tree pruning is carried out to reduce conflict with infrastructure, buildings, and any other human activity. However, heavy pruning may result in a diminished tree crown capacity for sugar production ...and exposure to fungal infection. This risk leads to a decrease in tree stability or vigour. In this work, we analysed the effect of heavy pruning of roadside trees on the photosynthetic performance process compared to neighbouring unpruned trees. Four years of tree crown growth was studied by terrestrial imaging. Tree vitality (Roloff's classification) and risk (Visual Tree Assessment) were evaluated. Over-pruned trees showed intensified photosynthetic efficiency during the growing season following pruning. Particularly ET0/TR0 and PIABS tended to increase in pruned trees while higher Fv/Fm was noted only in late October, suggesting delayed leaf senescence. After four years, pruned trees rebuilt their crowns, however not in their entirety. Results obtained from biometric, vitality, and risk assessment showed high differentiation in pruned tree crown recovery. Our results revealed that despite the intensified efforts of trees to recover from wounding effects, severe pruning evokes dieback occurrence and a higher risk of failure in mature trees.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This article is a study of risk assessment of trees with hollows, cavities and fruiting bodies for the improvement of the management and protection of urban trees growing along pedestrian routes. 317 ...trees were examined using TRAQ risk classes, VTA and ISA BMP methodology, Roloff's vitality classification, and sonic tomography (SoT) during the spring and summer of 2021. The collected data was analysed using the Kruskal-Wallis H-test, the Dunn multiple comparison test, the pairwise comparison of proportions with Holm correction, the U-Manna-Whitney test, and the Fisher exact test. The analysed trees grow alongside public footpaths and footways in central Zakopane, Poland. The study results indicate that tree trunk hollows are judged to have no adverse effects on a tree's vitality when assessed using visual methods and are deemed to have a limited effect on vitality estimated with SoT. Though most high and moderate-risk trees, according to SoT (88% and 80%, respectively), had hollows, such trees were a small fraction of all 171 trees with hollows, cavities and/or fruiting bodies, 2.3% and 8.8%, respectively. Therefore, the decision to remove a tree should be based on advice from a professional arborist, supported by sonic tomography (SoT) or similar objective methods.
The paper is a study of risk assessment posed by trees in selected urban woodlands (urban forests) of Warsaw. Two groups of trees were analysed and compared: exhibiting signs of maturity and ageing ...(hollow-bearing trees with open or hidden cavities and/or caries) and with no signs of decay. 373 individual trees growing near routes frequently or continuously used for recreational purposes were examined using Roloff's vitality classification, and tree risk assessment method, complemented by instrumental studies: a resistance resistograph, pulling tests, and sonic tomography (SoT). The collected data was analysed using the Chi-square test. The results indicate that it is not possible to conclude unequivocally that the presence of hollows in aged trees significantly increases the risk of falling. According to the safety factor results from the SoT and pulling tests, no correlation was demonstrated between the presence of hollow trees and an increase in risk class. The highest proportion of hollow trees (89.42%) was in the low risk group for trunk fracture and uprooting. The results also indicate the coherence of the diagnostic methods to be necessary for providing sufficient information to assess the statics and, ultimately, as our study showed, the protection of hollow trees.
•Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) enhancement patterns of the canine liver are reported.•A hepatocyte-specific contrast agent, gadoxetic acid, was administered.•A liver ...parenchymal signal intensity curve following administration of gadoxetic acid in healthy dogs was created.•Results may serve to optimise MR protocols and may be used for studies on DCE-MRI of diseased liver in dogs.
Dynamic contrast enhanced (DCE)-magnetic resonance imaging (MRI) consists of acquisition of native baseline images, followed by a series of acquisitions performed during and after administration of a contrast medium. DCE-MRI, in conjunction with hepatobiliary-specific contrast media, such as gadoxetic acid (GD-EOB-DTPA), allows for precise characterisation of the enhancement pattern of the hepatic parenchyma following administration of the contrast agent. The aim of the study was to assess the pattern of temporal resolution contrast enhancement of the hepatic parenchyma following administration of GD-EOB-DTPA and to determine the optimal time window for post-contrast assessment of the liver. The study was carried out on eight healthy beagle dogs. MRI was performed using a 1.5T scanner. The imaging protocol included T1 weighted (T1-W) gradient echo (GRE), T2 weighted (T2-W) turbo spin echo (TSE) and dynamic T1-W GRE sequences. The dynamic T1-W sequence was performed using single 10mm thick slices. Regions of interest (ROIs) were chosen and the signal intensity curves were calculated for quantitative image analysis. The mean time to peak for all dogs was 26min. The plateau phase lasted on average 21min. A gradual decrease in the signal intensity of the hepatic parenchyma was observed in all dogs. A DCE-MRI enhancement pattern of the hepatic parenchyma was evident in dogs following the administration of a GD-EOB-DTPA, establishing baseline data for an optimal time window between 26 and 41min after administration of the contrast agent.
There are multiple dynamic changes associated with the metabolism of the extracellular matrix (ECM) which occur in the course of liver fibrosis. Therefore, the evaluation of parameters reflecting the ...deposition of ECM, the activity of myofibroblasts and the synthesis and degradation of collagen may aid in the diagnosis of liver fibrosis. Hyaluronic acid is considered to be a marker of ECM deposition. It is a glycosaminoglycan synthesized by hepatic stellate cells and degraded by hepatic sinusoidal endothelial cells. The aim of this study was to evaluate the concentration of hyaluronic acid in dogs with different degrees of liver fibrosis. The study was carried out on 29 dogs with liver disease. A core needle biopsy of the liver was performed in order to assess the degree of hepatic inflammation. Then, hyaluronic acid serum concentrations were measured. The dogs were divided into five groups based on the histopathological examination and the evaluation of the degree of hepatic fibrosis. The study showed that serum hyaluronic acid concentrations were low in patients with first stage liver fibrosis and in controls, while they were twice as high as control values in the group of dogs with second stage liver fibrosis. These concentrations were three-fold greater than control values in patients with third stage liver fibrosis, and seven-fold greater in patients with liver cirrhosis. Based on the results, it was concluded that serum hyaluronic acid is a useful marker of liver fibrosis and may aid in determining the degree of its advancement.
The aim of this study was to assess whether the serum levels of the 7S fragment of type IV collagen may aid in diagnosing liver fibrosis in dogs. The study was carried out on 20 dogs with liver ...disease. Serum levels of the 7S fragment of type IV collagen were measured in all dogs. The analysis showed that healthy dogs and dogs with type 1, 2 and 3 liver fibrosis had low serum concentrations of the 7S fragment of type IV collagen compared to dogs with type 4 liver fibrosis. The study revealed that the assessment of serum levels of the 7S fragment of type IV collagen is useful in the diagnosis of advanced liver fibrosis and cirrhosis.
The aim of the study was to assess the physiological stiffness of the normal canine jejunal mucosa based on shear wave elastography. The study was carried out on 60 dogs. In all the animals studied, ...the abdominal ultrasound was carried out using the SuperSonic Imagine Aixplorer system. The site of the jejunal elastography was determined using standard ultrasonography and all the measurements were carried out thrice. The stiffness of the area examined was determined during each measurement. Mean values were calculated based on the results obtained. The normal stiffness of the jejunal mucosa ranged from 1.305 kPa to 9.319 kPa (mean 5.31 ± 2.04 kPa). Based on our findings, we determined the range of normal values of the jejunal mucosal stiffness in healthy dogs. In addition, shear wave elastography was found to be safe and easy to perform. Moreover, it did not require anaesthesia or patient immobilisation for long periods.
The aim of this study was to assess the suitability of invasive and non-invasive methods used to diagnose Helicobacter spp. in the stomachs of dogs. The study was carried out on 30 dogs of both sexes ...and different breeds, between one and 15 years old. A histopathologic examination, a microbiological culture, a rapid urease test, a direct bacteriological preparation and a nested PCR assay were carried out. Gastric Helicobacter spp. was identified in gastric biopsy specimens from 16 (53.3%) dogs using direct bacteriological preparation, in four (13.3%) dogs based on a culture, in 23 (76.6%) dogs using the rapid urease test and in 21 (70,0%) dogs based on a histopathological assessment of the biopsy specimens. The nested PCR of the gastric biopsy specimens revealed gastric Helicobacter spp. in all the dogs (100%). A saliva PCR assay revealed gastric Helicobacter spp. in 23 (76.6%) dogs, while stool PCR revealed the bacterium in seven (23.3%) dogs. We found that invasive methods were more accurate than non-invasive methods in detecting a Helicobacter spp. infection in dogs. In addition, the nested PCR method used to evaluate the gastric mucosal biopsy specimens was the most accurate test for detecting Helicobacter spp. It was further found that the PCR-based saliva assay was the best non-invasive method for detecting Helicobacter spp. However, taking into consideration that most of the diagnostic methods used to detect this bacterium have drawbacks, at least two diagnostic methods should be used to detect Helicobacter spp. as is done in human medicine.
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