黄河三角洲滨海草甸与土壤因子的关系

Relationships between coastal meadow distribution and soil characteristics in the Yellow River Delta

黄河三角洲滨海草甸群落的分布和变化与土壤因子密切相关。于2010年6月对黄河三角洲的草甸植被进行了样方调查,并对土壤进行了取样分析。在所调查的67个草本样方中,共出现52种植物。利用典范对应分析(CCA)分析了9种土壤因子与草甸群落分布的关系,结果显示,前两轴总共解释了物种-环境关系方差的46.4%,土壤含水率和电导率对群落分布的影响最大。双向指示种分析(TWINSPAN)将67个样方分为7种群落类型,将其标示在CCA排序图上后,沿第一轴分成三大类群:盐地碱蓬群落→芦苇-盐地碱蓬群落→其他草甸群落,这反映了黄河三角洲滨海草甸群落在盐分梯度上的演替规律。相关分析显示,物种多样性指数与土壤电导率、速效钾和速效磷呈极显著负相关(P<0.01),与pH值呈显著正相关(P<0.05)。解释了黄河三角洲滨海草甸群落与土壤因子的关系和变化规律,对黄河三角洲植被保护和恢复有一定的指导意义。

The Yellow River Delta,one of China′s three major river deltas,has recently been the subject of numerous important research projects.Soil is an important environmental factor in the delta and heavily influences plant physiology and vegetation distribution.In previous studies,soil salinity and moisture have been proven to be main driving forces of terrestrial vegetation succession in the Yellow River Delta.However,vegetation in the Yellow River Delta is prone to retrograde succession and secondary succession resulting from both natural forces and human disturbance.Currently,changing salinity patterns and soil conditions in the Yellow River Delta are causing a deeper penetration of salinity into the soil.This change in soil salinity has been brought on by a rise in sea level and other natural or societal causes such as dredging,shoreline modifications,and so on,and the local vegetation is adapting to these changes out of necessity.Our research looked at the relationships between community diversity and soil conditions as well as analyzing the classification of the coastal meadows in the Yellow River Delta.Gaining an understanding of these relationships will not only enlighten us on the relationships between vegetation and soil;it also has theoretical significance for vegetation conservation and restoration in the Yellow River Delta.Sixty-seven vegetation quadrats were selected in June,2010,and nine soil characteristics were analyzed,including soil moisture content（MC）,soil electrical conductivity（EC）,soil pH（pH）,total carbon（TC）,total nitrogen（TN）,total phosphorus（TP）,available nitrogen（AN）,available phosphorus（AP） and available potassium（AK）.Vegetative analysis of the quadrants found 52 species,belonging to nineteen families and forty-six genera.The abundance of Compositae,Gramineae and Chenopodiaceae,the three plant families with the largest number of species found during this study,demonstrates their wide range of adaptability.Also,the species of the Chenopodiaceae are mostly salt-tolerant,and some of them are edificators,or environment-forming species,in some communities,so this family is of special importance to the Yellow River Delta vegetation communities.Many past ecological studies confirm the rationality of the wide use of Canonical Correspondence Analysis（CCA） and Two-way Indicator Species Analysis（TWINSPAN） in quantitative vegetation ecology.Canonical Correspondence Analysis was performed to analyze the relationships between the vegetation quadrats and the nine soil factors.The CCA results show the first two axes explained 46.4% of the variance within the species-environmental relationships,and electrical conductivity and moisture content most heavily influenced the community distribution.Using TWINSPAN,we classified the quadrats into seven communities as follows： Community.Aeluropus sinensis,Com.Phragmites australis,Com.Imperata cylindrica＋Phragmites australis,Com.Cynanchum chinense,Com.Phragmites australis-Suaeda glauca,Com.Phragmites australis-Suaeda salsa and Com.Suaeda salsa.The seven communities were classified into three groups along the first axis of the CCA： Com.Suaeda salsa,Com.Phragmites australis-Suaeda salsa and other meadow communities.The results indicate the succession series of coastal meadow in the Yellow River Delta develops along the salinity gradient,and may also indicate a transitional role for the Com.Phragmites australis-Suaeda salsa,a role which should be explored in the future studies.The Shannon-Wiener（H′） and Simpson（D） indices were calculated.Correlation analysis shows species diversity had a highly significant negative correlation with EC,AP and AK（P0.01）,and a significant positive correlation with pH（P0.05）.In this study,the combination of CCA and TWINSPAN performed well since classification increased the effectiveness of ordination,and ordination helped one understand the classification results.These findings helped the authors develop a theoretical basis for vegetation conservation and restoration in the Yellow River Delta.