五台山高山林线典型植被土壤有机碳特征

在全球变暖背景下,土壤有机碳(SOC)已经成为全球碳循环和全球变化生态学研究热点,特别是高山林线生态交错带这一气候变化敏感区。对五台山高山林线附近亚高山草甸(CD)、华北落叶松林(HL)和云杉×华北落叶松混交林(YH)SOC含量与土壤有机碳密度(SOCD)进行探讨,结果表明:3种植被SOC含量随土壤深度增加而减少,SOCD则与之相反,且其SOC和SOCD分布均具有"表聚效应"。五台山亚高山森林(HL、YH)土壤SOC总含量和总SOCD都高于亚高山草甸(CD),与中国亚高山土壤一致,但与亚洲以外的世界各大洲不同;且五台山亚高山土壤总SOC含量和SOCD与中国亚高山土壤均值近似,大于其他各大洲均值。显著影响五台山SOC的因素(P0.05)与世界尺度亚高山土壤不同,且土壤厚度和气候因子(P0.05)对世界尺度亚高山森林SOC的影响比亚高山草甸/草原土壤(P0.05)显著。因此,五台山亚高山森林土壤固碳能力比亚高山草甸强,其亚高山土壤的SOC总含量和总SOCD在全国范围内处于平均水平,而中国亚高山土壤碳库在世界范围内占据领先地位,但仍需进一步探讨来减少多尺度研究的不确定性。

Soil Organic Carbon under Typical Vegetations at Alpine Timberline in Wutai Mountain

Under the background of global warming, soil organic carbon (SOC) has become one of the most important issues in study of global carbon cycle and global change ecology, especially in the alpine timberline ecotone with sensitivity of climate change. Therefore, both of SOC contents and density (SOCD) were studied under subalpine meadow (CD), Larix principis-rupprechtii forest (HL) and Picea meyeri×Larix principis-rupprechtii mixed forest (YH) near the alpine timberline in Wutai Mountain. The results showed that SOC contents of all three vegetations were decreased with soil depth. SOCD values of studied soils were increased with soil depth. SOC and SOCD were mainly concentrated in surface soil, showed surface assembly effect. As the same as the subalpine soils in China, in our study region, total SOC contents and SOCD of subalpine forest (HL, YH) soils were both larger than those of subalpine meadow soils (CD). But it was different from subalpine soils in other continentals except Asia. Total SOC contents and SOCD in subalpine soils of Wutai Mountain were approximately equal to the mean total SOC and SOCD of subalpine soils in China, and they were larger than those of other continentals except Asia. The differences of significant impact factors (P<0.05) on subalpine SOC were observed between Wutai Mountain and global scale. On the global scale, soil depth and climate factors (P<0.05) in subalpine forests had more significant effects on SOC than subalpine meadow/grassland (P>0.05). Thus, in Wutai Mountain, subalpine forest soils have more capability of carbon sequestration than subalpine meadow soils. Their total SOC contents and SOCD are both approximately equal to the mean values of Chinese national scale. Carbon pool of subalpine soils in China takes a leading position from a global view. However, more researches are desired in order to reduce the uncertainties in multi-scale studies.