[Background] The soil nitrogen mineralization is controlled by various factors,including environmental factors,soil properties and plant residue qualities,etc.The objectives of our study are to clarify the soil mineralization characterization in typical vegetation community of riparian buffer strip in the Danjiangkou Reservoir,and to understand the correlation between plant chemical properties and soil nitrogen mineralization.[Methods] The soil used in experiment was collected from the upper 10 cm of the riparian buffer strips at 20 m interval.The leaves and roots of two typical plant species (Abutilon theophrasti Medicus and Cnidium monnier L.Cuss) from riparian buffer strips were collected,dried,cleaned,and ground for the incubation experiment and chemical analysis.Soil,ground leaves and roots were mixed as 9 treatments of control (CK without any plants added),single A.theophrasti leaf (QL) and single C.monnier leaf (SL),single A.theophrasti root (QR) and single C.monnier root (SR),mixed leaf and/or root (QL + SL,QL + SR,QR + SL,and QR + SR) for the laboratory incubation experiment.The soil mineralization rates were measured after 1,3,7,14,21,31,41,51 and 61 day (s) of incubation.[Results] 1) There were 3 stages on soil mineralization after adding plants:the first stage (day 1-7) in which the rates of nitrogen mineralization declined,the second stage (day 7-41) in which the rates of nitrogen mineralization increased remarkably,and the last stage (day 41-61) in which the rates of nitrogen mineralization stayed in steady.The rates of soil mineralization in all treatments were less than that in the control (CK) of 79.53 mg/kg,the one with only A.theophrasti leaf (QL) was the highest with 71.62 mg/kg among single treatments,while the mixed treatment with the A.theophrasti leaf + C.monnier root treatment (QL + SR) resulted in the highest mineralization rate of 26.43 mg· kg-1 among the mixed treatments.2) The content of soil microbial biomass increased significantly after adding plant residues (P ＜ 0.05) as the order in:QL ＞ all 4 mixed treatments ＞ other 3 single treatments (except QL).3) A significant correlation (P ＜ 0.05) presented between soil N mineralization and the contents of total carbon and total nitrogen of plants during the whole experiment.The Principal Component Analysis (PCA) showed that the plant nitrogen content possessed the largest proportion in all factors,the significance was followed as:N ＞ C:N ＞ Cellulose ＞ L:N ＞ Polyphenols.4) All the measured N mineralization rates were significantly less than the predicted values (P ＜ 0.01).[Conclusions] These results indicated that added plants restrained the soil nitrogen mineralization,and mixed treatments of root and leaf did not promote combined effect.This study may provide a reference basis for the regional restoration of vegetation,soil and water conservation,and the pollution control of non-point resources.%为明确库滨带典型植物群落矿化特征,探究植物化学性质与土壤氮矿化的关系,选取丹江口水库库滨带的苘麻和蛇床群丛.试验采取单一叶处理、单一根处理和根+叶混合等9种处理,分别测定第1、3、7、14、21、31、41、51和61 d的土壤氮矿化量,系统分析添加植物后土壤氮矿化特征.结果表明:1)添加植物后,土壤氮矿化可分为3个阶段,即前期(1 ～7d)各处理矿化量均减小,中期(7 ～41 d)各处理矿化量都有所增加,幅度变化较大,后期(41 ～61d)基本保持平衡,所有处理的土壤矿化量均小于对照(CK)的79.53 mg/kg,单一处理中,苘麻叶(QL)矿化量最高,达到71.62 mg/kg,混合处理最高为苘麻叶+蛇床根(QL+ SR) 26.43 mg/kg;2)添加植物后,土壤微生物的质量分数显著增加(P＜0.05),QL＞4个混合处理＞另外3个单一处理;3)整个试验期间,土壤氮矿化量与植物全碳和全氮质量分数显著相关(P＜0.05),主成分分析(PCA)结果显示全氮质量分数对土壤有机氮矿化影响最明显,重要程度为全氮＞C∶N＞纤维素＞L∶N＞多元酚;4)所有混合处理中,实测氮素矿化量均显著小于预测值(P＜0.01).说明添加苘麻和蛇床后,土壤氮矿化表现为抑制作用,根茎混合处理没有激发效应.该研究为区域植被生态恢复、水土保持与非点源污染治理提供参考依据.
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