Neighbour effects on plant biomass and its allocation for forbs growing in heterogeneous soils

邻体作用对土壤异质性环境下非禾本科草本植物生物量及其分配的影响

Focal plants are considerably affected by their neighbouring plants,especially when growing in heterogeneous soils.A previous study on grasses demonstrated that soil heterogeneity and species composition affected plant biomass and above-and belowground allocation patterns.We now tested whether these findings were similar for forbs.Three forb species(i.e.Spartina anglica,Limonium bicolor and Suaeda glauca)were grown in pots with three levels of soil heterogeneity,created by alternatively filling resource-rich and resource-poor substrates using small,medium or large patch sizes.Species compositions were created by growing these forbs either in monocultures or in mixtures.Results showed that patch size×species composition significantly impacted shoot biomass,root biomass and total biomass of forbs at different scales.Specifically,at the pot scale,shoot biomass,root biomass and total biomass increased with increasing patch size.At the substrate scale,shoot biomass and total biomass were higher at the large patch size than at the medium patch size,both in resource-rich and resource-poor substrates.Finally,at the community scale,monocultures had more shoot biomass,root biomass and total biomass than those in the two-or three-species mixtures.These results differ from earlier findings on the responses of grasses,where shoot biomass and total biomass decreased with patch size,and more shoot biomass and total biomass were found in resource-rich than resource-poor substrates.To further elucidate the effects of soil heterogeneity on the interactions between neighbour plants,we advise to conduct longer-term experiments featuring a variety of functional groups.

中心植物在异质土壤中生长时会受到邻体植物的显著影响。先前关于禾本科植物的研究表明,土壤异质性和物种组成会影响植物生物量和地上-地下生物量的分配。本研究旨在探究在非禾本科草本植物中是否也有类似的结果。本研究将3种非禾本科草本植物(即大米草Spartina anglica、二色补血草Limonium bicolor和碱蓬Suaeda glauca)分别种植在3个水平的土壤异质性处理中。通过将资源丰富基质和资源贫瘠基质相间填充到小斑块、中斑块或大斑块中得到不同的土壤异质性处理;通过将上述3种目标植物单一栽培、两两混和栽培以及3种混合栽培种植得到不同的物种组成处理。研究结果表明,斑块大小和物种组成的交互作用显著影响植株生物量、根系生物量、总生物量,而且这种结果体现在不同的研究尺度上。具体而言,在花盆尺度上,植株生物量、根系生物量和总生物量随着斑块大小的增加而增加。在基质尺度上,无论是在资源丰富基质还是资源贫瘠基质中,大斑块中的植株生物量和总生物量都高于中等斑块。最后,在群落尺度上,单一栽培比两两混合栽培或3种混合栽培具有更高的植株生物量、根系生物量和总生物量。上述结果与先前关于禾本科植物的研究结果不同,即禾本科植物植株生物量和总生物量随着斑块大小的增加而减少,并且资源丰富基质的植株生物量和总生物总量高于资源贫瘠基质。为了进一步阐明土壤异质性对邻体植物间相互作用的影响,我们建议对包含多功能群植物在内的植物群落开展长期的实验研究。