RESUMO
To explore the effects of stand density and climatic factors on radial growth of Quercus mongolica, we used tree ring chronology to examine the radial growth changes in a secondary Q. mongolica forest under different levels of stand density (thinning). The meteorological data combined with the driving factors of Q. mongolica growth were analyzed. The results showed that the radial growth of Q. mongolica was significantly affected by stand density. The mean annual radial growth of Q. mongolica was 3.12 mm in low-density virgin forest, 1.55 and 1.42 mm in the two medium-density secondary forests, respectively, and 0.96 mm in high-density secondary forest. The thinning intensity of 20% had a limited effect on promoting the radial growth recovery of high-density forest (1900 trees·hm-2), but had a significant effect on medium-density forest (1600 trees·hm-2). The radial growth of Q. mongolica was sensitive to the precipitation changes in January and February of the current year. Thinning reduced the sensitivity of Q. mongolica radial growth to climate. Under scenarios of climate warming and drying, density regulation could be beneficial in mitigating the adverse effects of climate change on the growth of Q. mongolica.
Assuntos
Quercus , China , Mudança Climática , Florestas , ÁrvoresRESUMO
BACKGROUND: Enhanced recovery after surgery (ERAS) is a multimodal, multidisciplinary, evidence-based approach to care for surgical patients and aims at optimizing the perioperative management and outcomes. The ERAS approach was first implemented in colorectal surgery patients; however, the reported applications in pancreatoduodenectomy patients are limited. In recent years, studies on ERAS for patients undergoing pancreaticoduodenectomy have been published. The accumulation of new randomized controlled trials and high-quality case-control studies stimulated us to update the analysis. Our study comprehensively collected data to provide the best evidence summary for the clinic. AIM: To evaluate the safety and feasibility of enhanced recovery after surgery in the perioperative management of pancreatoduodenectomy patients. METHODS: A systematic literature search of PubMed, Embase, and the Cochrane Library was performed up to July 2019. All randomized controlled trials and case-control studies that applied ERAS for patients undergoing pancreaticoduodenectomy were considered for inclusion in this study. The patients were divided into two groups: patients who received the ERAS perioperative management approach were defined as the ERAS group and patients who received the traditional perioperative management approach were defined as the control group. All statistical analyses were conducted using the Revman5.3 software, and the outcomes were calculated as odds ratios or weighted mean differences with their corresponding 95% confidence intervals. A funnel plot was created to assess publication bias. Subgroup and sensitivity analyses were performed to explore the sources of heterogeneity. RESULTS: A total of 20 studies involving 3613 patients (1914 patients in the ERAS group vs. 1699 patients in the control group) were included in this study. Among the 20 studies, 4 were randomized controlled trials, and 16 were case-control studies. The overall postoperative complication rate was significantly lower in the ERAS group (OR = 0.62, 95% CI: 0.53-0.74, P < 0.00001) than in the control group. In addition, the minor complication rate (Clavien-Dindo I-II) was also lower in the ERAS group (OR = 0.70, 95% CI: 0.58-0.86, P = 0.0005). The patients in the ERAS group had a lower incidence of delayed gastric emptying (OR = 0.51, 95% CI: 0.42-0.63, P < 0.00001) and shorter length of hospital stay (WMD = -4.27, 95% CI: -4.81~-3.73, P < 0.00001) than in the control group. The rates of pancreatic fistula (regardless of Grade A/B/C), wound infections, abdominal abscesses, readmission, reoperation, and morbidity were not significantly different between the two groups. CONCLUSION: The ERAS approach is safe and effective in the perioperative management of patients undergoing pancreaticoduodenectomy and helps to accelerate the postoperative recovery and improve prognosis.
Assuntos
Recuperação Pós-Cirúrgica Melhorada , Pancreaticoduodenectomia , Estudos de Casos e Controles , Humanos , Segurança do Paciente , Ensaios Clínicos Controlados Aleatórios como Assunto , Resultado do TratamentoRESUMO
Maintaining forest structural diversity is generally considered as an effective way to preserve forest stability and biodiversity. The spatial structure characteristics of the dominant tree species in a climax community were investigated in a primary mixed broadleaved Korean pine (Pinus koraiensis) forest in a mountainous area of eastern Liaoning. Stand spatial structure parameters were determined based on the relationships among neighboring trees. The climax communities were used as a theoretical reference for optimizing the spatial structure of a low-quality secondary forest and monoculture plantation. The diameter distribution of the trees in the pine forest exhibited an inverse J-shape, indicating that understory regeneration was relatively good and with certain proportion of large-diameter trees. The main tree species were randomly distributed across the whole plot (=0.507) and in an intensively mixed state (=0.82). An average DBH comparison of trees in the stand indicated that they were at a intermediate status (=0.506). There was a differentiation among different dominances along the high intensity mixed dimension in the stand, indicating an optimal distribution of understory trees and the rational utilization of resources. Trees in the small diameter category were at a state of complete compression, while canopy trees were at a state of complete dominance in terms of their vertical space. Individuals of each dominant tree species were randomly scattered, with a random pattern of individuals throughout the climax community.
