黄土丘陵区不同土地利用方式对土壤碳库及碳库管理指数的影响

Effects of different land-use practices on soil carbon pool and its management index in loess hilly region

【目的】探讨黄土丘陵区土壤有机碳组分及碳库在不同土地利用方式下的分布特征和变化规律。【方法】以黄土丘陵区撂荒地为对照、选取云杉林地、沙棘灌木林、苜蓿地、小麦地等5种土地利用方式为研究对象,分析其土壤有机碳组分及碳库的变化。【结果】5种土地利用方式下,随着土层深度增加土壤有机碳和活性有机碳含量逐渐降低,且活性有机碳含量在各处理间较有机碳含量差异显著。在0~100 cm土层云杉林地土壤有机碳(SOC)、土壤易氧化有机碳(EOC)、土壤可溶性有机碳(DOC)含量及土壤碳库管理指数(CPMI)最高,云杉林地CPMI分别比撂荒地、沙棘灌木林、小麦地、苜蓿地的碳库管理指数高出42.69%、56.65%、156.41%、173.40%。相关性分析表明,CPMI指数与土壤容重、含水量、TN和碳组分之间均存在显著正相关关系(P<0.05)。【结论】不同土地利用方式土壤理化性质的差异可能显著影响了土壤活性有机碳组分,进而影响了土壤碳库管理指数。在本试验条件下,云杉林地能够通过增加土壤有机碳组分含量来提高土壤碳库管理指数,对土壤有机碳的储存有积极作用。

【Objective】The study aimed to explore the distribution characteristics and change patterns of soil organic carbon fraction and carbon pool in the loess hills under different land use practices.【Method】Five types of land use,including spruce woodland,sea buckthorn shrubland,alfalfa land,wheat land,and abandoned land in the loess hilly area as the control,were selected to determine the changes in soil organic carbon fraction and carbon pool.【Result】1)Under the five land-use practices,soil organic carbon and active organic carbon contents gradually decreased with increasing soil depth,and the active organic carbon content differed significantly among treatments compared to the organic carbon content.2)The highest SOC,EOC,DOC contents and soil CPMI were found in spruce woodland in the 0~100 cm layer of soil,and the CPMI of spruce woodland was 42.69%,56.65%,156.41%and 173.40%higher than that of the abandoned land,buckthorn shrubland,wheat land and alfalfa land,respectively.3)Correlation analysis showed that CPMI index was significantly positively correlated with soil bulk,soil water content,TN and carbon fraction(P<0.05).【Conclusion】The differences in soil physicochemical properties among different land-use practices significantly affected the soil active organic carbon fraction and thus the soil carbon pool management index.Under the present experimental conditions,spruce woodland could improve the soil carbon pool management index by increasing the content of soil organic carbon fraction,which had a positive effect on soil organic carbon storage.