青藏高原不同气候区高寒沙地两种优势植物及其根际土壤的养分特征

Characteristics of nutrients in two dominant plant species and rhizospheric soils in alpine desert of the Qinghai-Xizang Plateau under contrasting climates

为了探究青藏高原寒冷沙地上优势植物及其根际土壤的养分对不同气候的响应过程,选取半干旱和半湿润沙地上的优势植物中国沙棘(Hippophae rhamnoides subsp.sinensis)和沙蒿(Artemisia desertorum)为对象,调查自然条件下青藏高原半干旱和半湿润沙地上两种植物枝叶和根的碳、氮、磷含量,及其根际0–10 cm和10–20 cm土壤的有机碳、全氮、全磷、铵态氮、硝态氮、有效磷含量,并探讨两种优势植物和根际土壤的养分含量的关系及其影响因子。结果表明,半干旱和半湿润条件下中国沙棘和沙蒿及其根际土壤的养分差异明显。半干旱和半湿润气候条件下两种植物碳、氮、磷的积累差异显著。半湿润条件下,沙蒿根际土壤中的有机碳、全氮、铵态氮、硝态氮、有效磷的含量高于半干旱条件,而中国沙棘根际土壤养分的结果却相反。不同气候条件下,沙蒿和沙棘的养分和根际土壤的养分显著相关,两种植物的养分比差异显著,沙蒿氮磷比与其根际土壤的氮磷比以及中国沙棘的碳氮比与其根际土壤的碳氮比显著负相关。

Aims This study was conducted to determine the responses of nutrients in plants and rhizospheric soils to climate in alpine-cold desert on the Qinghai-Xizang Plateau. Methods Tissue samples for two dominant plant species, Hippophae rhamnoides subsp. sinensis and Artemisia desertorum, and associated rhizospheric soil samples were collected from sites representing semi-arid and sub-humid climates in the alpine-cold desert on the Qinghai-Xizang Plateau. Measurements were made on the contents of carbon, nitrogen and phosphorus in roots and shoots, as well as on organic carbon, total nitrogen, total phosphate, ammonium nitrogen, nitrate nitrogen and available phosphate in rhizospheric soils in the 0-10 cm and 10-20 cm layer. The relationship between nutrients in plant tissues and rhizospheric soils and the influencing factors were analyzed. Important findings There were significant differences between the semi-arid and the sub-humid sites in tissue nutrients and rhizospheric soil nutrients for the two specie. Specifically, the contents of carbon, nitrogen, phosphorus in plant tissues differed significantly between the semi-arid and the sub-humid sites. Soil organic carbon, total nitrogen, ammonium nitrogen, nitrate nitrogen and available phosphate for the rhizosphere of A. desertorum were significantly higher on site under sub-humid climate than that under semi-arid climate; whereas the trend was reversed for the rhizosphere of H. rhamnoides subsp. sinensis. We found significant relationships between the tissue nutrients and soil nutrients, and significantly different plant nutrient ratios between the two species. There were negative correlations between tissues and rhizosheric soils in N：P ratio for A. desertorum and C：N ratio for H. rhamnoides subsp. sinensis under different climates.