简介：根据野外70个样方的调查数据，运用2×2列联表的X^2检验方法、Pearson相关系数和Spearman秩相关系数检验，研究了山西壶流河流域湿地植被33种优势种，共528个种对的种间关联和相关关系。结果表明X^2检验有209个种对呈正相关，其中极显著正相关种对16个（n=70，P〈0．01），显著正相关种对21个（n=70，P〈0．05），共占总对数的7．01％；317个种对呈负相关，其中显著负相关种对3个（n=70，P〈0．05），占总对数的0．57％；2个种对不相关，正负相关比为0．6593，显著种对共占总对数的4．54％；Pearson相关分析中极显著相关的种对有20个（n=70，P〈0．01），显著相关的种对有11个（n=70，P〈0．05），全部为正相关，共占总对数的5．87％；Spearman秩相关系数检验207个种对呈正相关，其中极显著的种对有34个（n=70，P〈0．01），正相关显著的种对有22个（n=70，P〈0．05），共占总对数的10.61％，321个种对呈负相关，负相关显著的种对16个（n=70，P〈0．05），占总对数的3．03％，正负相关比为0．6448，显著种对占总对数的7．20％，群落优势种种间多呈不显著关联。按照33个优势种对环境的适应方式和主导生态因素，它们被划分为3个生态种组：水烛生态种组（Typhagroup）、鹅绒委陵菜生态种组（Potentillagroup）和赖草生态种组（Leymusgroup）。

简介：Thegoalofthisstudyistoprovideinformationontheprocessofpotholegrowthonagorgestreambed.PotholegeometriesweremeasuredinareachoftheDaburiverbedattheheadofagorgemorethan200mdeeplyincisingintoa650-750mhighplanationsurfaceformedinthemiddleMioceneinnorthernGuangdong,China.Geometricandderivativedataofthepotholesobtainedfromfieldworkwereinterpretedusingstandardstatisticalmethodologies.Ourstudyshowsthattheformationanddevelopmentofastreampotholewereonlyrelatedtolocalconditionsofastreamreachwherethepotholeoccurs;theweaknesses,whichareusuallyintersectfractures,typicallyinterconnectedverticaljoints,ortriangularpitsgeneratedbyhittingofrockfragmentsduringfloods,initiatethepotholedevelopmentonastreambed;thegeometricaldimensionsofthepotholesarecontrolledbytectonicjointsdevelopedinbedrockofthestreamreach;theradiusandthedepthofpotholesarestrongly(log)positivecorrelated;thepotholeshapesandtheflowpatternsareinconstantduringpotholegrowth;apotholecanbeformedwithinashortperiod,butcannotbefullydevelopedandmaintainedforalongtimeinastrongincisionstreambed.ThefindinginourstudycanimprovetheunderstandingofQuaternaryenvironmentinGuangdong.