武夷山自然保护区常绿阔叶林优势种对土壤呼吸的影响

为揭示森林土壤呼吸异质性的影响因素,以武夷山自然保护区常绿阔叶林优势种甜槠(Castanopsis eyrei)、细叶青冈(Cyclobalanopsis tenuifolia)、米槠(Castanopsis carlesii)为研究对象,采用LI-8100碳通量系统测定土壤呼吸速率及其影响因子土壤温度、土壤含水量值,比较不同龄级树种土壤温度、土壤含水率、土壤呼吸速率在不同海拔的差异.结果显示,3种常绿阔叶林优势种中甜槠在海拔700 m土壤呼吸速率最高,为4.75μmol m^-2s^-1,米槠在海拔540 m处土壤呼吸速率最高,为3.12μmol m^-2s^-1;细叶青冈在海拔850 m处土壤呼吸速率最高,为4.39μmol m^-2s^-1.无论是单因素模型(自变量为土壤温度)还是双因素模型(自变量为土壤温度和土壤含水率)拟合结果均体现自变量与土壤呼吸速率呈极显著相关关系(P <0.01).不同龄级甜槠、细叶青冈、米槠土壤呼吸速率变化并不显著(P> 0.05),树种差异对土壤呼吸速率变化不显著(P> 0.05).随着海拔升高,温度敏感性指数Q10增大,高海拔地区Q10值显著高于低海拔地区(P <0.05).因此,在中亚热地区常绿阔叶林带中,土壤呼吸速率的变动主要受土壤温度影响,高海拔地区可能释放更多CO2,上述结果丰富了中亚热带森林土壤碳汇研究.(图6表3参47)

Effects of dominant species of evergreen broad-leaved forest on soil respiration in Wuyi Mountain Nature Reserve

In order to reveal the factors influencing forest soil respiration heterogeneity, the dominant evergreen broad-leaved forest species Castanopsis eyrei, Cyclobalanopsis tenuifolia, and Castanopsis carlesii in Wuyishan Nature Reserve were selected as the research objects of this study. The soil respiration rate and its influencing factors, soil temperature and soil water content, were measured using the LI8100 carbon flux system, and the differences in soil temperature, soil water content, and soil respiration rate of different age classes of tree species at different altitudes were compared. The results showed that among the three dominant evergreen broad-leaved forest species, C. eyrei had the highest soil respiration rate of 4.75 μmol m^-2s^-1 at 700 m above sea level, whereas C. carlesii had the highest soil respiration rate of 3.12 μmol m^-2s^-1 at 540 m above sea level. C. tenuifolia had the highest soil respiration rate at 850 m above sea level, which was 4.39 μmol m^-2s^-1. The fitting results of the single-factor model(independent variable: soil temperature) or two-factor model(independent variable: soil temperature and soil moisture content) both showed that the independent variables had very significant correlations with soil respiration rate(P < 0.01). The differences in soil respiration rate of C. eyrei, C. tenuifolia, and C. carlesii between different age classes were not significant(P > 0.05), and the differences in tree species were not significant(P > 0.05). As the elevation increased, the Q10 index increased, and the Q10 value in high altitude areas was significantly higher than that in low altitude areas(P < 0.05). In the evergreen broad-leaved forest belt in the mid-subtropical regions, the change in soil respiration rate is mainly affected by soil temperature, and the high-altitude region may release more CO2. These results enrich the research on soil carbon sinks in middle subtropical forests.