鹤山不同植被土壤有机碳分布特征

不同植被类型下土壤有机碳(SOC)储量和动态变化是全球变化研究的热点之一。对南亚热带鹤山6种不同植被类型(灌草、马尾松林、桉树林、乡土树林、马占相思林、季风常绿阔叶林)SOC干湿季、空间(0~10,10~20,20~40 cm)变化特征、土壤惰性指数及其与土壤有效氮(TAN)的关系研究表明:(1)6种植被中,干季SOC含量显著高于湿季,SOC含量随土层深度降低,马占相思林SOC含量最高,马尾松林和灌草最低;(2)6种植被SOC储量在0~10 cm土层所占比例最高,占0~40 cm土层SOC含量40%以上;(3)土壤惰性指数随土壤深度增加而下降,常绿阔叶林、乡土树林和马占相思林烷基碳和ROC惰性指数高于桉树林和马尾松林,揭示这3种植被SOC具有更高稳定性;(4)SOC与土壤TAN含量呈显著正相关。结果揭示,在植被恢复过程中,选择豆科植物,辅以乡土树种营造常绿阔叶林,有利于提高森林潜在碳汇功能。

Characteristics of Soil Organic Carbon Under Different Forest Types in Heshan of Southern China

The storage and dynamics of soil organic carbon (SOC) under different forest types is one of the important concerns of global change. We determined the seasonal (dry and wet seasons) and spatial (0 - 10, 10 - 20 and 20 - 40 cm depths) variations of SOC under six forest types (Shrub-grass forest, SF; Masson pine forest, PF; Eucalyptus forest, EF; Native-species forest, NF; Acacia forest, AF; Monsoon evergreen broadleaved forest, MF) in Heshan, southern China. Carbon recalcitrant indexes (RIC) and its relationships with total available nitrogen (TAN) in soils of the forest types were also detected. The results showed that: 1) the contents of SOC under 6 forest types were higher in wet season than in dry season with a declining trend with the increase of soil depth, SOC content was highest in AF while lowest in PF and SF; 2) 0 - 10 cm depth soils had highest proportion of SOC storage (more than 40%) for 0 - 40 cm depth soils; 3) RIC decreased with increase of soil depth. The higher contents of Alkyl-C and ROC in MF, NF and AF than in EF and PF implied that SOC in the former three forest types had higher stability; and 4) SOC contents significantly positively correlated with soil TAN contents in all forest types. The results suggested that in the process of vegetation restoration, the selection of legume species coupled with native species constructing evergreen broadleaved forest would improve potential carbon sink of forests.