水分供应对毛乌素沙地油蒿和羊柴种间关系的影响

The effects of water availabilities on interspecific relationship between Artemisia ordosica and Hedysarum laeve in Mu Us Sandland

油蒿和羊柴为毛乌素沙地的共生优势物种,然而关于土壤水分对其种间关系的研究相对较少。设置低水(200mL)、中水(300 mL)和高水(400 mL)三个水分处理水平及单独和混合生长两种种植方式,通过油蒿和羊柴的生长响应,来研究不同水分供应条件下两物种种间关系的变化。结果表明:水分处理显著提高了油蒿的株高和基径以及羊柴的基径,竞争存在与否对两物种的形态生长指标均没有显著影响。在生物量积累方面,水分处理对于油蒿总干重的影响表现为先增加后降低,且主要是在混合生长条件下;水分显著降低单独生长油蒿的根冠比。竞争对油蒿总干重的促进作用主要是在中水条件下,对其根冠比的抑制作用是在低水条件下。对于羊柴,水分处理显著提高其总干重而降低其根冠比,竞争仅对其总干重有显著的降低作用且是在中水条件下。通过对相对竞争系数的进一步研究发现,油蒿和羊柴的种间关系表现为在低水、高水下竞争,在中水条件下共存,并且两物种的相对竞争能力随处理的时间而变化。上述实验结果表明,中等水分供应条件对两物种的共存是有利的,这可为毛乌素优势群落的管理提供一定的理论参考。

Artemisia ordosica and Hedysarum laeve are the dominant coexistent species in Mu Us Sandland,while the study of interspecific relationship between the two species varying with soil water is limited.Aiming to understand more of this relationship,experiments were conducted with mono-stand and mix-stand under three levels of water availabilities(200 mL,300 mL and 400 mL).The results showed that water significantly increased the height and basal diameter of A.ordosica and the basal diameter of H.laeve,while competition had no significant effects on the growth parameters of the two species.Meanwhile,water availability firstly increased the total biomass of A.ordosica and then decreased it,especially under mix-stand condition;however,water significantly decreased its root/shoot ratio under mono-stand condition.Competition significantly increased the total biomass of A.ordosica under medium water,and decreased root/shoot ratio under low water.As for H.laeve,water significantly increased its total biomass and decreased its root/shoot ratio,and under medium water condition,competition significantly decreased its total biomass.Furthermore,through analyzing the relative competitive intensity indexes,it was found that the interspecific relationship between the two species was competition under low water or high water availability,and coexistence under medium water availability.The above results showed that medium water level would favor the coexistence between the two species,which would probably provide theoretical evidence for managing the dominant communities in Mu Us Sandland.