喜旱莲子草入侵群落土壤对植物生长的影响

Effects of soil under Alternanthera philoxeroides-invaded plant community on the growth of plants

分别以受喜旱莲子草(Alternanthera philoxeroides)入侵和未受喜旱莲子草入侵的当地植物群落土壤为生长基质,比较不同基质上入侵植物喜旱莲子草和同属的土著植物莲子草(A.sessilis)的生长指标,探讨喜旱莲子草入侵群落土壤对喜旱莲子草及莲子草生长的影响机制。结果表明,喜旱莲子草入侵群落土壤抑制了莲子草的生长,显著降低了根生物量、茎生物量和总生物;改变了形态特征,显著降低了分枝数量、茎长度、根长、根体积;减少了对根的生物量分配,显著抑制了根质量比与根冠比。喜旱莲子草入侵群落土壤对入侵植物喜旱莲子草的生物量、分枝数量、茎长度、根长、根体积没有显著的抑制作用,而显著增加了其叶片数量和叶质量比。这种效应将有利于喜旱莲子草在入侵地形成单优群落,表明土壤在喜旱莲子草成功入侵中起了重要作用。

The soiis under native plant comnunity with and without Alternanthera philoxerodies invasion were taken as the growth medium to study whether plant-soil feedback contributes to the invasion success of A. philoxeroides. The soil under A. philoxeroides-invaded community inhibited the growth of native A. sessilis significantly, which manifested in the decreases of root biomass, stem biomass, total biomass, relative growth rate, and net assimilation rate, and in the changes of morphological traits, e. g. , the decreases of stem length, branch number, root length, and root volume. The biomass partitioning of native A. sessilis also changed, with a significant decrease of leaf/mass ratio and increased root/mass ratio and root/shoot ratio. However, the soil under A. philoxeroides-invaded community did not significantly affect the growth of invasive A. philoxeroides, according to the data of biomass and morphological traits. The soil under A. philoxeroides-invaded community only significantly increased the leaf number and leaf/mass ratio of invasive A. philoxeroides. The significant negative and neutral effects of soil under A. phi- loxeroides-invaded community on the native A. sessilis and invasive A. philoxeroides, respectively might contribute to a positive feedback loop, leading to the increased dominance of invasive A. philoxeroides in the invaded community. The results indicated that soil might play important role in the successful establishment and maintenance of A. philoxeroides population in its invaded area.