[Carbon Sequestration Characteristics Under Natural Vegetation Restoration in Ziwuling Area of the Loess Plateau].

The aim of this study was to analyze the carbon sink effect under natural vegetation restoration and the influence of changes in vegetation community characteristics on ecosystem carbon density in ecologically fragile areas of the Loess Plateau. In this study, the changes in carbon sequestration of a vegetation-soil system under eight successional stages[slope cropland, abandoned cropland for 10 years, abandoned cropland for 20 years, Sophora davidii (Franch.) Skeels., Betula platyphylla Suk., Pinus tabulaeformis Carr., Quercus wutaishanic Mary+P. tabulaeformis Carr mixed forests, and Q. wutaishanic Mary] in Ziwuling area over 150 restoration periods were investigated using the common method of spatial and temporal substitution. This study also discussed the relationship between changes in vegetation community characteristics and vegetation-soil system carbon density. The results showed that the community coverage of the investigated vegetation fluctuated from 85% in the slope cropland stage to 100% in the arbor stage. The number of species, Margalef index, Shannon-Wiener index, Pielou index, and Simpson index initially increased rapidly, then declined slowly until becoming stable, and reached a peak in the middle of the succession (B. platyphylla Suk.). The biomass and carbon density of vegetation components (above-ground biomass, below-ground roots, and litter) increased exponentially during the succession, i.e., increased slowly before B. platyphylla Suk. but increased significantly in B. platyphylla Suk. and P. tabulaeformis Carr.(P<0.05). The biomass and carbon density reached the maximum values of 27858.08 g·m-2 and 13232.51 g·m-2, respectively, in Q. wutaishanic Mary+P. tabulaeformis Carr mixed forests and tended to be stable in the late succession stage. Soil organic carbon density showed a power function relationship with vegetation restoration, with the greatest increase in the stages of abandoned cropland for 10 years and B. platyphylla, but no significant changes in the subsequent stages (P>0.05). In the early succession stage, the carbon density of the farmland ecosystem was the lowest (4395.70 g·m-2), whereas the other seven stages increased by 55.54%, 40.37%, 69.96%, 202.48%, 326.35%, 357.43%, and 351.07%, respectively, compared with the farmland ecosystem. Community coverage, Margalef index, Shannon-Wiener index, above-ground biomass, root biomass, and litter biomass were significantly positively correlated with vegetation-soil system carbon density (P<0.05). The carbon sink effect of long-term natural restoration in Ziwuling Region was significant, and the carbon density of the vegetation-soil system under interspecific competition tended to be stable in the late succession stage. Dynamic changes in the vegetation community structure and plant diversity during the succession process increased vegetation carbon density and soil carbon density. This study helps to clarify the carbon sink effect of natural vegetation restoration in ecologically fragile areas of the Loess Plateau and provides a theoretical basis for promoting natural forest conservation and achieving carbon neutrality.

Duraplasty with autologous nuchal ligament fascia to reduce postoperative complications in pediatric patients undergoing neoplasia resection with a suboccipital midline approach.

OBJECTIVE: The authors sought to explore the safety and efficacy of an autologous nuchal ligament for dural repair in pediatric patients undergoing tumor resection through a suboccipital midline approach. METHODS: Pediatric patients diagnosed with posterior fossa neoplasia who underwent surgery through a suboccipital midline approach were retrospectively reviewed. The patients were divided into artificial graft and autograft groups according to whether artificial duraplasty material or autologous nuchal ligament was used to repair the dura. Postoperative complications were reviewed and analyzed, including CSF leak, pseudomeningocele, and meningitis, during hospitalization and follow-up. Univariate and multivariate logistic regression analyses were used to investigate the relationship between duraplasty material and postoperative complications, as well as other risk factors for postoperative complications. Furthermore, multinomial logistic regression analysis was used to clarify which postoperative complications the autologous nuchal ligament tended to reduce. RESULTS: This retrospective study included 66 pediatric patients who underwent tumor resection through a suboccipital midline approach. The clinical baseline characteristics were comparable between the two groups. The results showed that the autograft group had significantly fewer postoperative complications, especially pseudomeningocele, compared with the artificial graft group. Moreover, the time required to repair the dura in the autograft group was significantly less than that in the artificial graft group. Further results revealed that the duraplasty material, ependymoma, preoperative severe hydrocephalus requiring an external ventricular drain (EVD), and postoperative hydrocephalus exacerbation were independent risk factors for postoperative complications. In particular, the autologous fascia of the nuchal ligament tended to reduce pseudomeningocele more than CSF leak and meningitis. However, compared with pseudomeningocele and CSF leak, both ependymoma and postoperative hydrocephalus exacerbation were more likely to increase the occurrence of meningitis. In contrast, preoperative severe hydrocephalus requiring EVD led to increased rates of postoperative complications. CONCLUSIONS: For pediatric patients with intracranial tumors who need to undergo resection through a suboccipital midline approach, dural repair using the nuchal ligament is safe, cost-effective, and time saving and significantly reduces postoperative complications.