红壤侵蚀区植被恢复过程中土壤有机碳组分变化

为了解土壤有机碳组分在植被恢复过程中的变化规律,选取了红壤区本底条件基本一致的不同恢复年限马尾松林为研究对象,以未治理的侵蚀裸地(CK1)和恢复后的次生林(CK2)为对照,采用物理化学分组法,将土壤有机碳分为由溶解性有机碳(DOC)和颗粒有机碳(POM)组成的活性碳库、物理保护态的团聚体与粉粒和黏粒组合成的缓效性碳库以及化学结构稳定的惰性碳库。结果表明:在植被恢复过程中(0~30年)活性碳库储量及其分配比例在植被恢复7~10年显著提高(P0.05),并在植被恢复27~30年保持较稳定水平,缓效性碳库储量及其分配比例在27~30年呈显著变化(P0.05),而活性碳库分配比例有所降低,且POM、DOC与缓效性碳库均达显著相关(P0.01),说明活性碳库在恢复7~10年后逐渐向缓效性碳库转化;惰性碳库储量随恢复年限不断增加,但其分配比例保持较稳定水平。相关性分析显示,恢复年限、不同组分与不同碳库均达显著相关(P0.01),且缓效性碳库随植被恢复最敏感,说明在马尾松恢复过程中土壤有机碳以活性碳库积累逐渐转化为缓效性碳库积累为主,进而影响惰性碳库的积累,有利于土壤有机碳的长期保持。

Dynamies of Soil Organic Carbon Fractions with the Restoration Process of Pinus massoniana Plantation in Eroded Red Soil Region

To study the variation of soil organic carbon in fractions with the restoration process,we selected the different ages of Pinus massoniana plantations as the research object and take the bare land (CK1) and secondary forest (CK2) as the control,which is basically consistent with the similar management histories in erosive red soil area.The physical and chemical fractionation method was applied,three pools were isolated in soil organic carbon.The active carbon was composed of dissolved organic carbon (DOC) and particulate organic matter (POM);the slow carbon was composed of SOC bound to silt and clay and SOC attached to sand particles or occluded in aggregates;the passive carbon is a chemically recalcitrant fraction.The results showed that,in the process of vegetation restoration (0～30 years),the storage of active carbon and its distribution proportion in vegetation restoration was significantly improved in the recovery of 7 ～ 10 year (P＜0.05),its storage and distribution remained at a relatively stable level in the vegetation recovery of 27～ 30 year;the storage of slow carbon and its distribution was significant changes in the recovery of 27～30 year (P＜0.05).The distribution of active carbon pool was decreased,there was significantly correlated between active carbon pool (POM,DOC) and slow carbon pool (P＜0.01),indicating that the active carbon pool in the recovery gradually transformed to the slow carbon pool after 7～10 year;the stocks of recalcitrant carbon pool continued to increase along with the chronosequences,but its proportion remained relatively stable level.Correlation analysis showed that there was a significant correlation between the chronosequences and the factions with the pools (P＜0.01),at the same time,the slow carbon pool was the most sensitive in the process of vegetation,indicating that the soil organic carbon in activated carbon accumulation gradually transformed into slow carbon pools accumulation in P.massoniana recovery,thereby affecting the recalcitrant carbon accumulation,which was good for the long-term preservation of soil organic carbon.