干旱区湿地芦苇各器官生态化学计量对土壤因子的响应

了解植物养分浓度及其化学计量对土壤因子的响应,对预测脆弱而敏感生态系统对环境变化的响应至关重要。以敦煌阳关湿地优势种芦苇(Phragmites australis)为对象,通过野外调查与实验分析,研究芦苇不同器官生态化学计量特征及其影响因素。结果表明:芦苇各器官C、P含量为叶>根>茎,N含量及N∶P为叶>茎>根,C∶N为根>茎>叶,C∶P则为茎>根>叶。叶、根C含量显著高于茎(P<0.05),叶、根C含量之间无显著差异(P>0.05),根、茎和叶N、P含量及C∶N、C∶P和N∶P差异显著(P<0.05);芦苇根N∶P<14,叶片N∶P>16,茎N∶P介于14~16;C含量在各器官之间均无显著相关性(P>0.05),根与茎、叶N含量之间呈极显著正相关(P<0.01),根与茎P含量呈极显著正相关(P<0.01),茎与叶N含量呈显著正相关(P<0.05);土壤盐分与芦苇根和茎N含量呈极显著正相关(P<0.01),土壤P含量与茎P含量呈极显著正相关(P<0.01),土壤有效P与根、茎N含量呈极显著正相关(P<0.01);土壤P是影响芦苇根、茎化学计量的主要因素,土壤盐分是影响叶片化学计量的主要因素,芦苇趋向提高各器官N含量来应对高盐、低P的土壤环境。

Stoichiometric responses of Phragmites australis organs to soil factors in a wetland from arid area

Understanding the response of plant element concentrations and stoichiometry to the changes of soil factors is essential to predict the responses of fragile and sensitive ecosystems to environmental changes.We examined the ecological stoichiometry of different organs in Phragmites australis and the driving factors in a wetland of Yangguan,Dunhuang.The results showed that carbon(C)and phosphorus(P)concentrations in different organs of P.australis were in a descending order of leaf>root>stem,nitrogen(N)concentration and N∶P were in order of leaf>stem>root,C∶N was in order of root>stem>leaf,and C∶P was in order of stem>root>leaf.The concentration of C in leaves and roots was significantly higher than that in stems(P<0.05),but there was no difference between leaves and roots(P>0.05).The concentrations of N,P and C∶N,C∶P and N∶P varied among organs(P<0.05).Root N∶P of P.australis was<14,leaf N∶P was>16,and stem N∶P was between 14 and 16.The C concentrations of different organs were not significantly correlated(P>0.05).The N concentrations between root and stem and that between root and leaf showed a significantly positive correlation(P<0.01).The P concentrations between root and stem were positively correlated(P<0.01).There was a positive correlation between soil salinity and N concentration in roots and stems(P<0.01).The P concentrations in stems and leaves were significantly positively correlated(P<0.05).Soil P concentration was positively correlated with stem P concentration(P<0.01).Soil available P concentration was positively correlated with root and stem N concentration(P<0.05).Soil P was the main factor driving the stoichiometry of roots and stems of P.australis,while soil salinity was the main factor driving the stoichiometry of leaves.P.australis tended to adapt to the high salinity and low P conditions by increasing the N concentration in various organs.