北京东灵山3种温带森林土壤呼吸及其20年的变化

Soil respiration and the 20-year change in three temperate forests in Mt. Dongling, Beijing

土壤呼吸是陆地生态系统最主要的碳释放过程。为了探讨温带森林土壤呼吸在长时间尺度的变化,利用北京东灵山地区的白桦(Betula platyphylla)林、辽东栎(Quercus wutaishanica)林和油松(Pinus tabuliformis)林3种温带森林永久样地,于2012–2015年对其土壤呼吸进行测定,并与1994–1995年的测定结果进行了比较。结果显示:2012–2015年,白桦林的平均年土壤呼吸量为(574±21)g C·m–2·a–1,显著高于辽东栎林(455±31)g C·m–2·a–1和油松林(414±35)g C·m–2·a–1,比20年前(1994–1995年)的估测值分别增加了85%、17%和73%。这些结果表明,近20年来这3种生态系统的碳周转速率明显加快。

Aims Our objective was to explore changes in soil respiration of three temperate forests in Mt. Dongling, Bei-jing over the last 20 years from the year of 1994–1995 to 2012–2015. Methods We re-investigated the permanent plots of three temperate forests （Betula platyphylla forest,Quercus wutaishanica forest andPinus tabuliformis forest） which were established in 1992. We measured soil respiration for 3 years （2012–2015） using a LI-8100 Soil Respiration System. Continuous soil temperatures at 5 cm depth were measured at the same time. Annual soil respiration was accumulated using a relationship between soil respi-ration and soil temperature . Important findings We found that soil respiration rates were significantly correlated with soil temperature at 5 cm depth and that these correlations differed remarkably among the three forests. Annual soil respiration inB. Platyphylla forest was highest, with a 3-year average of （574 ± 21） g C·m^–2, followed byQ. Wutaishanica forest （（455 ± 31） g C·m^–2） andP. Tabuliformis forest （（414 ± 35） g C·m^–2）. In the past 20 years, annual soil respiration in all these forests increased significantly： compared to 1994–1995, the average in 2012–2015 increased by 85%, 17% and 73% forB. Platyphylla, Q. wutaishanica, andP. Tabuliformis forests, respectively.