雍城湖湿地土壤理化性质与微生物及植物群落的关系

以陕西凤翔县雍城湖湿地为对象，研究湿地对土壤理化性质、土壤微生物和植物群落的影响及相互关系。按照离岸0、10、20、30、40、50 m分别划取6个标准样方（D0、D10、D20、D30、D40、D50），以水体（W）、淤泥（S）为对照，采用多种土肥分析方法测定各样方土壤理化性质；利用高通量测序技术分析土壤微生物的结构特点和多样性特征；利用样方法调查植物的种类、数量及分布特征；对比探究土壤理化性质、土壤微生物及植物群落变化间的联系。结果表明:1）研究区域内土壤均为碱性；随着离岸距离的增加，土壤含水量下降，全N（TN）、速效N（AN）和有机质（OM）含量均表现为D0~D20高于后D30~D50；全K（TK）含量变化不明显；速效K（AK）含量在D30~D50样方逐渐增加；全P（TP）含量呈现先升高后降低的趋势。土壤OM与TN、AN之间两两极显著正相关（P<0.01）。土壤pH值与TN和OM呈现显著负相关（P<0.05）。2）土壤微生物群落多样性指数整体呈现随离岸距离的增加而逐渐减小的趋势。聚类分析结果表明，D0~D20和D30~D50群落结构各自相似，且两组间具有差异性。3）由D0到D50、植物呈现空心莲子草-青麻-稗草-野塘蒿的群落变化趋势。物种丰富度呈现出先下降后升高的趋势。4）变形菌门丰度变化与全N含量的变化趋势一致；酸杆菌门和放线菌门的丰度变化与有机质含量的变化趋势相反。无论是土壤理化性质还是土壤微生物群落，在研究区域内总表现出前D0~D20与D30~D50间的显著差异性。距湿地水体50 m范围内，土壤TN、AN、OM、微生物多样性指数总体随含水量减少、pH增加而下降，并呈现以30 m为阶梯的阶段性变化；TK、AK、TP变化规律性不强。土壤理化性质与土壤微生物多样性及其群落构成具有一定的相关性。植物群落优势物种随与湿地水体距离的变化趋势明显。植物群落对土壤微生物群落结构及分布的影响规律不明显。

The Relationship among Soil Physicochemical Properties&Microorganisms and Phytocommunity in Yongcheng Lake Wetland

Taking the wetland of Yongcheng Lake in Fengxiang,Shaanxi Province as research object,soil physicochemical properties,microorganisms,and plant communities as well as their interrelations were investigated.Six standard quadrats ( D0,D10,D20,D30,D40 and D50) were settled according to the offshore distances of 0,10,20,30,40 and 50 m,respectively.The soil physicochemical properties were measured by different soil analytical methods.The structure and diversity of soil microorganisms were analyzed by high throughput sequencing.The species,quantity and distribution of plants were analyzed by quadrat method.Interrelations between soil physicochemical properties,plant communities and soil microorganisms were explored by One-Way ANOVA and clustering analysis.1)Soil in the study area was all alkaline.The soil moisture content declined with the increase of the distance from water shore.The contents of total nitrogen (TN),available nitrogen (AN),organic matter (OM) from D0-D20 were higher than those from D30-D50.The change of total potassium (TK) content was not significant and the available potassium (AK) content gradually increased from D30-D50.The total phosphorus (TP) content increased first and then decreased.Soil OM content was positively correlated with TN and AN (P<0.01).Soil pH was negatively correlated with TN and OM content (P<0.05).2) Soil microbial diversity index showed a decreasing trend with the increase of the distance from water shore.The results of clustering analysis showed that the structures of microorganism community were similar within the groups of D0-D20,D30-D50,respectively,while differed between the two groups.3) From D0 to D50,dominant plant communities were Alternanthera philoxeroides-Abutilon theophrasti-Echinochloa crusgalli-Conyza bonariensis.With the increase of the distance from the water shore,the specie richness decreased first and then increased.4) The variation trend of Proteobacteria abundance was consistent with the variation trend of TN content.The variation trend of Acidobacteria,and Actinobacteria abundance was opposite to the variation trend of OM content.Soil physicochemical properties and soil microbial community,all showed a significant difference between the first three sample plots of D0-D20 and the last three plots of D30-D50.Within 50 m from the water shore,TN,AN,OM,microbial diversity index decreased with the decrease of water content and the increase of pH,and showed a stage-change character with 30 m as a ladder.TK,AK and TP changed not regularly.Soil physicochemical properties had certain correlation with soil microbial diversity and community composition.The dominant species of plant community changed significantly with the distance from water shore.The effect of plant community on soil microbial community structure and distribution was not obvious.