稻田改为旱地后土壤有机碳矿化及微生物群落结构的变化  

Variation in soil organic carbon mineralization and microbial community structure induced by the conversion from double rice fields to drained fields

作　　者：刘长红[1,2] 袁野[2] 杨君[1] 戴晓琴[2,3] 王辉民[2,3] 

机构地区：[1]湖南农业大学资源环境学院,长沙410128 [2]中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室千烟州生态试验站,北京100101 [3]江西省区域生态过程与信息重点实验室,泰和343725

出　　处：《应用与环境生物学报》2015年第5期960-966,共7页Chinese Journal of Applied and Environmental Biology

基　　金：国家重点基础研究发展计划项目(2012CB417103);国家自然科学基金项目(41001179)资助~~

摘　　要：土地利用变化是驱动陆地与大气之间碳迁移变化的主要因素,为正确评估土地利用方式变化后土壤有机碳固持和稳定性,对南方双季稻田(RR)改为玉米-玉米(MM)和大豆-花生(SP)2年后土壤化学性质、有机碳矿化及微生物群落结构的变化进行研究.结果表明,RR改为MM和SP后,土壤p H值显著降低(0.50-0.52,P=0.002),而可溶性有机碳显著提高(23%-35%,P=0.016).土壤有机碳的矿化速率没有显著变化,但在培养13 d后SP累积矿化量显著降低(P=0.019).稻田改旱地后,土壤微生物总磷脂脂肪酸(PLFAs)、细菌、革兰氏阳性菌(G+)、革兰氏阴性菌(G-)和放线菌PLFAs显著降低(P<0.05),而真菌PLFAs/细菌PLFAs(F/B)显著增加(P=0.006),但改MM和SP没有显著差异.培养初期,土壤放线菌PLFAs与累积碳矿化显著相关(P=0.034),土壤F/B与培养13 d累积碳矿化显著相关(P=0.004),而土壤微生物群落主成分分析的PC1(P=0.014)和总的PLFAs(P=0.033)与培养108 d累积碳矿化显著相关.本研究发现稻田改旱地后土壤p H和总氮含量是影响土壤微生物群落结构和生物量进而影响土壤有机碳矿化的关键因素.Land use conversion is an important factor influencing the carbon gas exchange between land and atmosphere.The effect of land use conversion on soil organic carbon mineralization and microbial function is important for soil organic carbon sequestration and stability.This research studied the effects of land use conversion on soil chemical properties,organic carbon mineralization and microbial community structure after two years of conversion from double rice cropping（RR） to maize-maize（MM） and soybean-peanut（SP） double cropping systems in southern China.The results showed that soil pH significantly decreased by 0.50（MM） and 0.52（SP,P = 0.002）,and dissolved organic carbon significantly increased by 23%-35%（P = 0.016）.No significant difference was found in soil organic carbon mineralization rate with the land use conversion,though the accumulated mineralization decreased after 13 days of incubation（P = 0.019）.Land use conversion from paddy to upland significantly changed soil microbial community structure.The total PLFAs,bacterial,gram-positive bacterial（G＋）,gram-negative bacterial（G-） and actinomycetic PLFAs decreased significantly（P〈 0.05）,the ratio of fungal PLFAs to bacterial PLFAs（F/B） increased significantly（P = 0.006）.But no significant differences in microbial groups were found between MM and SP.The accumulated mineralization at the beginning period of the incubation were significantly positively correlated with soil actinomycetic PLFAs（P = 0.034）.After 13 days of incubation,soil F/B showed a positive correlation with the accumulated mineralization（P = 0.004）.However,soil microbial community structure（P = 0.014） and total PLFAs（P = 0.033） showed a positive correlation with the accumulated mineralization after 108 days of incubation.Our results indicated that after conversion from paddy soils to drained soils,soil pH and total nitrogen are the key factors regulating the variations in soil microbial community structure and biomass,and then in

关 键 词：土地利用变化 土壤有机碳矿化 微生物群落 磷脂脂肪酸 

分 类 号：S153.6[农业科学—土壤学] S154.3[农业科学—农业基础科学]