藏北高寒草原紫花针茅根系碳氮磷生态化学计量学特征

Root C∶ N∶ P Stoichiometry of Stipa purpurea in Apine Steppe on the Northern Tibet

植物碳（C）、氮（N）和磷（P）元素平衡是当前生物地球化学循环和全球变化生态学研究的热点和焦点.以往关于植物营养元素的研究多集中于植物叶片水平,而对植物根系元素的研究较少.为此,沿藏北高寒草原安多-那曲-班戈-申扎-尼玛-改则-革吉-噶尔样带,在34个样点采集优势物种紫花针茅（Stipa purpurea）根系样品,分析其C、N和P元素含量及其相互比值与环境因子的关系.研究结果显示：紫花针茅根系C、N和P含量变化范围分别为357.17 ～458.99 mg/g,6.49 ～ 16.42 mg/g,和0.22 ～ 0.77 mg/g;紫花针茅根系N含量与全球植物根系平均值基本一致,但是其根系P含量低于全球平均值;紫花针茅根系C∶N∶P生态化学计量学特征受纬度、经度、生长季降水量、土壤磷含量的影响较为显著,而海拔、生长季均温和土壤氮含量对其影响则不显著.紫花针茅通过对高寒环境因子的长期适应,其根系C∶N∶P生态化学计量学特征已经形成了一定的空间分布格局.研究结果有助于揭示极端环境下植物对营养物质的分配和利用策略,为应对未来气候变化对高寒生态系统的影响提供参考.

Plant carbon, nitrogen, and phosphorus balance has been a hotspot and focus of biogeochemical cycle and global change ecology research. However, previous studies mainly focused on the nutrient of leaves, relatively few study were conducted on the root. In present study, we investigated root C： N： P of S. purpurea and its relation- ships with environmental factors at 34 sites along a 1 300 km transect （ Anduo - Naqu - Bange - Shenzha - Nima - Gaize - Geji - Gaer） across the alpine grassland of Northern Tibet. The result showed that root C, N and P concen- trations ranged from 357.17 to 458.99 mg/g, 6.49 to16.42 rag/g, 0.22 to 0.77 rag/g, respectively. The root N concentration of S. purpurea had a similar value with the N concentration of global roots, whereas the P concentra- tion was much lower than those of global root. Latitude, longitude and precipitation significantly influcenced root C ： N： P,while altitude and temperature had no effects on root C： N： P stoichiometry. Our research suggested that the strong relationship between root C： N： P stoiehiometry and geographic, climate factors and soil nutrient concentra- tions reveal that, to some extent, stoichiometry characteristics of S. purpure are adaptive to local environmental fac- tors. Exploring the influences of environmental factors on root C： N： P stoichiometry is helpful for us to reveal plant nutrients allocation and utilization strategies in extreme environments, offering insights into quantifying the respon- ses of alpine ecosystem to future climate changes.