川西北高寒沙地不同年限高山柳林下优势植物碳、氮、磷生态化学计量特征

通过采集川西北高寒沙地不同年限(6、18、24年)高山柳林下3种优势植被藏沙蒿、裂叶独活和镰荚棘豆,分别测定分析3种植被叶片、根部C、N、P化学计量特征变化特征。结果表明:不同年限高山柳林下植被C、N、P含量及其比值间存在显著差异且呈现出不同变化趋势。林下植被C含量整体下降;叶N含量呈上升趋势,根N含量随年限增长而下降;除藏沙蒿外,林下植被P含量变化不显著;C∶N变化范围为1.92~12.86;C∶P为29.18~196.88;不同年限高山柳林下植被N∶P间虽存在差异,但均表现出主要受到P限制,表明该区域植被生长主要受P限制,应注意P养分的适当补充。

Variation of C,N and P stoichiometry in dominant understory plants during stand development in Salix cupularis plantations in alpine grassland in Northwestern Sichuan,China

In order to understand the stoichiometric relationships of C,N and P in tissues of understory plants of Salix cupularis at different stand ages,we collected three species of dominant understory plants (Artemisia wellbyi,Heracleum millefolium and Oxytropisfalcata) from under 6,18 and 24 year old S.cupularis stands in Northwestern Sichuan,China.Then the carbon (C),nitrogen (N) and phosphorus (P) concentrations,as well as their ratios in plant organs (leaf and root) were analyzed.The C concentration of the understory plants and the N concentrations of their roots decreased with increase in plantation age,while conversely,the N concentration of leaves increased with plantation age.No significant variation in P concentration was found.The C ∶ N ranged from 1.92 to 12.86 and the C ∶ P ranged from 29.18 to 196.88.There were significant differences in N ∶ P of the understory plants at different plantation ages,but the results suggested that understory plants were mainly limited by P nutrient status.The finding that growth of plantations in this region is mainly limited by P nutrient supply indicates that attention to the adequate addition of P nutrients is needed.