敦煌绿洲边缘植物群落与土壤养分互馈关系

Mutual Feedback Relationship between Vegetation Communities and Soil Nutrient in the Edge of Dunhuang Oasis

植物群落与土壤性状相互作用研究对于认识生态系统结构与功能有着重要的意义。通过对敦煌绿洲边缘典型植物群落21个样地(20m×20m)的植被和土壤系统取样调查,在分析植物群落及其土壤养分特征的基础上,采用CCA典范对应分析法研究了土壤养分对植物群落物种分布的影响。结果表明:调查区域植被群落共出现植物27种,隶属于15科,26属,以藜科(Chenopodiaceae)植物居多,占总物种数的29.6%。柽柳(Tamarix chinensis)群落的物种丰富度最大,胡杨(Populus euphratica)群落的物种丰富度最小。植被0~80cm土壤有机质、全氮、速效磷、速效钾含量排序为柽柳>黑果枸杞(Lycium ruthenicum)>梭梭(Haloxylon ammodendron)>沙拐枣(Calligonum mongolicum),全磷、全盐、速效氮含量排序为柽柳>黑果枸杞>沙拐枣>梭梭,全钾含量排序为黑果枸杞>柽柳>梭梭>沙拐枣,pH值排序为梭梭>沙拐枣>黑果枸杞>柽柳。不同植被覆盖各养分指标之间差异显著。随土层深度的增加,柽柳和黑果枸杞群落土壤全氮、有机质、全盐、速效氮、速效钾含量逐渐降低,表聚效应明显,土壤全磷、全钾、速效磷含量逐渐增大后减小,梭梭与沙拐枣养分层次特征不明显。4种植被群落土壤pH值随土层深度的增大呈波动的趋势。CCA排序结果表明植被群落物种分布的土壤环境调控因子重要性排序为全氮>pH>全钾,土壤全氮是植物群落物种分布的最重要调控因子。

Reaserch on interaction relationship between vegetation community and soil properties has significance to understanding the structure and funcation.Through the systematic sampling and survey of 21 samples plots of 20 m×20 m dimensions,based on the analysis of the characteristics of communities and soil nutrient,the relationship between species distribution of communities and soil nutrient were investigated with the methods of canonical corresponding analysis（CCA）.The results show that：there were 27 kinds of species in study area,which belong to 15 families and 26 genera.The majority of species were Chenopodiaceae plant and accounted for 29.6% of total species number.The species richness of Tamarix chinensis community was the highest,and that of Populus euphratica was the lowest.Four vegetation cover including T.chinensis community,Lycium ruthenicumcommunity,Haloxylon ammodendron community and Calligonum mongolicum community in edge of Dunhuang Oasis were selected as a case study.Soil samples were collected at depths of0-5,5-20,20-40,40-60 and60-80 cm,to analyze their physicochemical properties.The soil in depths of 80 cm organic matter content（SOM）,total nitrogen（TN）,available phosphorus（AP）,available potassium（AK）decreased in order of T.chinensis〉L.ruthenicum〉H.ammodendron〉C.mongolicum;Total phosphorus（TP）,total salt（TS）and available nitrogen（AN）decreased in order of T.chinensis〉L.ruthenicum〉C.mongolicum〉H.ammodendron;Total potassium（TK）decreased in order of L.ruthenicum〉T.chinensis〉H.ammodendron〉C.mongolicum;pH decreased in order of T.chinensis〉L.ruthenicum L.ruthenicum〉T.chinensis.There were significant difference of each nutrient index among different vegetation cover.The TN,SOM,TS,AN and AK of T.chinensis and L.ruthenicumcommunity presented a decreasing trend with the increase of soil depths,which reflected an obvious surface aggregation effect.That of H.ammodendron and C.mongolicumcommunity were in a fluctuation trend.With increase of soil depths,the content of TP,TK and AP increased first and then decrease in T.chinensis and L.ruthenicumcommunity,which of H.ammodendron and C.mongolicumcommunity were also in a fluctuation trend.The trend of pH all four community showed a fluctuation.The result of CCA ordination show that importance rank of environmental factors which regulated the distribution of species in study area were TN〉pH〉TK.Soil total nitrogen is an important regulatory factor for the distribution of plant communities.Key words：soil nutrient;communitys characteristic;mutual feedback relationship;canonical corresponding analysis;Dunhuang oasis