浙江古田山亚热带常绿阔叶林不同干扰强度下土壤呼吸的日动态与季节变化
摘要
The aims of this study were to investigate the diurnal and seasonal variations in soil respiration in different broad-leaved forest types with different degrees of human disturbance, to identify the major abiotic and biotic factors affecting the daily and seasonal patterns of soil respiration, and to evaluate the effects of different forest management types and human disturbance on soil respiration in subtropical forests. We selected four different 1 hm<sup>2</sup> forests with different degrees of human disturbance in Gutianshan, Zhejiang Province: An old-growth forest (OF, almost no human disturbance); two secondary forests (SF1, a secondary forest regrown after clear cutting about 50 years ago, and SF2, a secondary forest regrown after clear cutting about 50 years ago and selective cutting about 20 years ago); and a plantation forest (AF, planted about 20 years ago). We measured the diurnal and seasonal changes in soil respiration rates in each plot every month from May 2011 to July 2012. We also measured soil temperature and water content of the surface soil layer during sampling. The annual means of daily accumulated soil carbon release were 1.48, 1.48, 1.51, and 0.87 g C m<sup>-2</sup> d<sup>-1</sup> in OF, SF1, SF2, and AF plots, respectively. The soil respiration rate in AF was significantly lower than those in the other three forest types. On the diurnal scale, there were no significant variations in soil respiration rates among the four forest types. Our results indicated that the rate of soil respiration measured any time during the day can be used to predict daily accumulated soil carbon release. Significant positive relationships were found between soil respiration and surface soil temperature (<italic>R</italic><sup>2</sup>=0.88-0.94) for all four forest types. There were no significant relationships between soil respiration and soil water content. The Q<sub>10</sub> value of OF was significantly higher than those of the other three forest types. The r