RESUMEN
The allocation dynamics of soil carbon pools during soil development and land use are the key to revealing the carbon cycle process. To clarify the distribution of the soil carbon pool and its change trend, a soil reclamation chronosequence (0 a, 60 a, 160 a, 280 a, 1 000 a, and 1 500 a reclamation) was established in a typical alluvial plain in the Lower Yangtze River, and the content and density of soil organic carbon (SOC), soil inorganic carbon (SIC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC), along with carbon sequestration potential (CSP) indicators of topsoil under different land use types were measured and analyzed. The results showed that after approximately 1 500 a reclamation, the SOC content developed from the Yangtze River alluvial deposits generally increased by 4.9% after the initial decline, whereas the SIC content decreased to 0.2% from 25.8% of the total carbon content due to its rapid leaching. The MAOC content was normally higher than that of POC, and MAOC was contributing 48.0%-79.7% of the SOC accumulation. In this region, the soil organic carbon density (SOCD) accounted for 57.4%-100% of the total carbon density, the soil carbon sequestration levels (CSL) ranged from 18.6% to 56.1%, and CSP under paddy-dryland rotation increased by 20.8% compared to that under dryland. The C/N ratio and total nitrogen content are key factors in explaining soil carbon accumulation processes, and the reclamation year plays an important role in evaluating soil carbon sequestration levels. After long-term utilization, the cultivated soil in the Yangtze River floodplain must be carefully managed through balanced fertilization to maintain soil productivity, promote the accumulation of SOC, and avoid the decline in soil carbon sequestration capacity.
RESUMEN
Objective: To systematically review and analyze the effects of exercise interventions on health behavior among middle-aged and older adults. Methods: A Meta-analysis was performed using NoteExpress software to screen randomized controlled trials (RCTs) published between January 1, 2000, and March 31, 2023, which were identified through databases including CNKI, Web of Science, Pubmed, and 6 more sources, based on predefined literature inclusion criteria. Following the quality assessment, we conducted both the overall and subgroup Meta-analyses of the exercise intervention moderator variables using Review Manager 5.4.1 software, encompassing data among the 18 RCTs. The effect size was measured as the standardized mean difference within its corresponding 95% confidence interval. Heterogeneity was assessed using the I2 metrics. Results: (1) The overall results indicate a significant impact of exercise intervention on health behaviors, characterized by a large effect size [SMD = 1.02 > 0.8, 95% CI (0.73, 1.32), P < 0.001]. (2) The highest degree of heterogeneity in the relationship between exercise interventions and health behaviors was associated with the duration of one exercise session (I2= 71.2%), which was the most influential moderator variable. (3) The aerobic and resistance intervention in group exercise lasting 30-60 min per time a day, 6-7 times per week over a period of 8-12 weeks demonstrated the most substantial effect size. Conclusion: (1) The exercise intervention significantly promotes the health behavior in middle-aged and older adults, emphasizing the importance of carefully considering the duration of individual exercise sessions when designing and implementing exercise intervention. (2) Considering the accessibility for middle-aged and older adults, the optimal exercise intervention should include the means of group practice, the types of aerobic and resistance exercise, with a duration of 30-60 min per time a day, beginning with a lower weekly frequency and gradually increase to 6-7 times per week, and lasting for 8 to 12 weeks. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42024506750.
