土壤养分异质性和种间竞争对互花米草和芦苇生长繁殖特性的影响

Effects of soil nutrient heterogeneity and interspecific competition on growth and reproductive traits of Spartina alterniflora and Phragmites australis

土壤养分异质性在自然界中普遍存在。土壤养分异质性对克隆植物生长繁殖有一定影响,但耦合竞争对入侵植物和本土植物生长繁殖影响的研究却相对匮乏。以入侵克隆植物互花米草和本土克隆植物芦苇为研究对象,通过温室控制实验模拟设置了土壤养分同质和养分异质处理(保证两种土壤的总养分含量相同),交叉3种定植模式(实验容器内单植入侵种6株,单植本土种6株以及两物种各3株交替种植),探究土壤养分异质性和种间竞争对入侵种互花米草和本土种芦苇生长繁殖的影响。结果表明:土壤养分异质性显著降低了互花米草的单株叶片数,而增加了其单株节间长以及芦苇的单株根状茎长;种间竞争模式下,互花米草的单株分株数,以及两种植物的单株节间长、根状茎节数和根状茎长都显著高于单植模式,而芦苇的单株地上生物量、叶生物量、茎生物量都显著低于单植模式;土壤养分异质性和种间竞争对互花米草单株的叶片数和茎生物量产生了显著的交互作用,而对芦苇各指标无显著影响。这些结果说明,土壤养分异质性可以影响互花米草与芦苇的种间竞争关系。

Soil nutrient heterogeneity is ubiquitous in natural ecosystems,which affects the growth and reproduction of clonal plants. Relatively little is known about the interactive effect of soil nutrient heterogeneity and competition on the growth and reproduction of invasive and native plants. In a greenhouse experiment,we grew an invasive clonal species Spartina alterniflora and a native one Phragmites australis in either monoculture or mixture in both homogeneous and heterogeneous soil nutrient conditions. In the monoculture,each pot was grown with six ramets of each species,and in mixture each pot was planted with three ramets of both species. The amount of soil nutrients in each pot was exactly the same in the homogeneous and heterogeneous treatments.Soil nutrient heterogeneity significantly decreased the number of leaves of S. alterniflora,but increased internode length and rhizome length of P. australis. Competition increased leaf number,ramet number,internode length,rhizome number,and rhizome length of S. alterniflora,but decreased aboveground biomass,leaf mass and stem mass of P. australis. There were interactive effects of soil nutrient heterogeneity and competition on number of leaves,stem mass and internode length of S. alterniflora,but not on any of the growth characters of P. australis. These findings suggest that soil nutrient heterogeneity can alter the competition between S. alterniflora and P. australis.