克隆整合对无芒雀麦在异质性盐分环境中存活和生长的影响

无芒雀麦是浑善达克沙地植物群落中占优势的多年生根茎禾草.研究了克隆整合特性对无芒雀麦在异质性盐分环境中存活和生长的影响.结果表明,克隆整合显著提高了无芒雀麦分株在高盐环境中的存活能力,耗-益分析表明无芒雀麦在高盐斑块中分株的生物量、分株数、根茎节数和根茎总长显著受益于克隆整合,而与之相连的非盐分斑块中的分株却没有产生显著的损耗.因而,克隆整合特性是无芒雀麦对异质性环境形成的重要适应对策,它使无芒雀麦能够扩展到不适合植物生长的高盐分斑块中,从而增加了无芒雀麦在浑善达克沙地中的存活和生长,提高了其在半干旱沙化地区的适合度.

Effects of clonal integration on growth and survival of Bromus inermis (Poaceae) in heterogeneous saline environments of the Otindag Sandland

Bromus inermis Leyss. is a dominant rhizomatous grass in the Otindag Sandland of North China, where the environment is heterogeneous, and non-saline, low-saline, and high-saline patches form a mosaic of habitats. Ramets of B. inermis simultaneously inhabit many patches at different salinity levels. We hypothesized that clonal fragments in high- saline patches benefit from clonal integration. A factorial greenhouse pot experiment with salinity and rhizome- severing as main effects was conducted in which each clonal fragment consisted of two interconnected ramets. In one treatment, the proximal part of the clonal fragment received a salt treatment (300 mmol/L NaCl solution), and in another treatment the distal part received a salt treatment. Rhizome connections between neighboring ramets were severed or left intact. Rhizome severing dramatically decreased survival of salt-treated ramets. A cost-benefit analysis based on biomass production, number of shoots, number of rhizome nodes, and total rhizome length showed that untreated ramets supported connected ramets treated with salt by clonal integration but did not incur any cost from resource export. We speculate that clonal integration may be an important adaptation of B. inermis to heterogeneous saline environments that increases its growth and survival, and thus fitness, in semiarid sandy lands.