克隆整合对无芒雀麦(Bromus inermis)忍受沙埋能力的影响

Effects of clonal integration on growth and survival of Bromus inermis (poaceae) in response to burial in sand

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忍受沙埋能力的影响。结果表明,克隆整合显著提高了远端完全沙埋分株的存活,耗-益分析表明远端沙埋分株的生物量、分株数、叶片数、根茎节数和根茎总长显著受益于克隆整合,而与之相连的近端非沙埋分株却没有产生显著的损耗,并且随着沙埋程度增加时,远端沙埋分株的收益有增大的趋势。因而,克隆整合特性是无芒雀麦对严酷沙埋环境形成的重要适应对策,它能够缓解沙埋对无芒雀麦存活、生长的胁迫,提高其在半干旱沙化地区的适合度。

Bromus inermis Leyss. is a spring, strong winds move sand dunes patches of different sizes within lowland dominant rhizomatous grass in the Othidag Sandland. In late autumn and early quickly, depositing new sand on the edge of lowland meadows and creating sand meadows. Frequently, clonal fragments （ i. e. interconnected ramets） of B. inermis inhabiting the lowland meadows are partially buried in sand, i.e. some ramets are buried in sand and some are not. We hypothesized that partially-buried clonal fragments benefit from clonal integration. A pot experiment was conducted in a greenhouse in the Otingdag Sandland. In the experiment, each clonal fragment consisted of four interconnected ramets. The two proximal （older）ramets were not buried, while the two distal （younger） ramets were either not buried （unburied control） or buried at depths of 10, 20, or 30 cm in sand （burial treatments）. Rhizome connections between proximal and distal ramets were severed or left intact. Rhizome severing dramatically decreased survival of distal ramets buried in sand. A cost-benefit analysis based on plant performance in terms of biomass production, number of shoots, number of leaves, number of rhizome nodes and total rhizome length showed that proximal ramets supported connected distal ramets buried in sand by clonal integration but did not incur any cost from resource export. Furthermore, effects of clonal integration on growth and survival of B. inerm/s were greater at deeper depths of burial in sand. We speculate that clonal integration may be an important adaptation of B. inermis to harsh burial condition in sand that increases its growth and survival, and thus fitness, in semiarid sandy lands.