RESUMO
As the key and hot topic in landscape ecology, ecological security pattern plays an important role in maintaining regional ecological security and achieving regional sustainable development. Based on land use data of 2016, we used the InVEST model to evaluate the habitat quality of Tang County to determine the ecological source. The resistance surface was constructed by selecting the resistance factors such as land use type, habitat quality index, vegetation coverage, distance to water, distance to settlements, distance to roads, with the resistance threshold being used to partition the ecological security pattern. Finally, the ecological security pattern of Tang County was constructed by determining the ecological corridor with the MCR model. The results showed that the ecological source of Tang County accounted for 3.3% of the total area, mainly distributed in forest land and waters with large plaque area, and the Western Ocean Reservoir (one of the four major reservoirs in Hebei Province). According to the cost resistance mutation point, the research region could be divided into prohibited development zone, restricted development zone, optimized development zone, and key development zone. The percentage of each zone was 18.9%, 43.6%, 27.6% and 9.9%, respectively. The total length of the potential ecological corridors in Tang County was 333.52 km, and was 263.91 km after optimization, which was helpful for various ecological exchanges. Our results had important guiding significance for the rational and sustainable use of land resources in Tang County, and could provide theoretical and technical supports for the decision-making of land planning and layout in Tang County.
Assuntos
Ecossistema , China , FlorestasRESUMO
To compare the biomechanical stability of various pin configurations for pediatric supracondylar humeral fractures under varus, internal rotation, and extension conditions. After electronic retrieval, 11 biomechanical studies were included. Stiffness values of pin configurations under different loading conditions were extracted and pooled. There were no statistically significant differences between two cross pins and two divergent lateral pins on the basis of the 'Hamdi method' (P=0.249-0.737). An additional pin did not strengthen two-pin construct (P=0.124-0.367), but better stabilized fractures with medial comminution (P<0.01). Isolated lateral pins are preferable because of a better balance of a lower risk of nerve injury and comparable fixation strength. Limitations such as differences in experimental setup among recruited studies and small sample size may compromise the methodologic power of this study.
