增温对若尔盖高寒草本沼泽木里薹草氮磷重吸收的影响

Effect of warming on nitrogen and phosphorus resorption of Carex muliensis in an alpine marsh on ZoigêPlateau

养分重吸收是植物重要的营养保存机制和养分循环的重要组成部分,温度变化会影响植物养分吸收。为了探讨若尔盖高原沼泽湿地植物木里薹(Carex muliensis)草养分重吸收特征对气候变暖的响应,本研究通过野外模拟增温实验,测定木里薹草成熟叶片和衰老叶片的氮(N)、磷(P)含量并分析其重吸收效率差异。结果表明:木里薹草叶片N、P含量均值分别为11.44和1.19 mg·g^(-1),N重吸收效率(NRE)、P重吸收效率(PRE)均值分别为61.8%和69.0%,增温显著降低了成熟叶片氮含量,显著提高了衰老叶片磷含量(P<0.01),对成熟叶片磷含量和衰老叶片氮含量没有显著影响;增温显著降低了成熟叶片和衰老叶片N∶P(P<0.01)及NRE(P<0.05)和PRE(P<0.01);木里薹草叶片氮磷重吸收效率与成熟叶片氮磷含量呈显著正相关,与衰老叶片氮磷含量呈显著负相关;木里薹草生长受P限制,而增温可能导致限制情况发生变化,木里薹草叶片养分重吸收还可能受到化学计量调控。研究结果将有助于了解和预测若尔盖高原养分循环对未来气候变化的响应,并为气候变暖下高寒草本沼泽植物养分重吸收效率变化的预测提供数据支持和实验证据。

Nutrient resorption is an important nutrient conservation mechanism of plants and an important component of nutrient cycling.Temperature change can affect nutrient resorption of plants.To explore the responses of nutrient resorption of Carex muliensis in an alpine marsh on Zoige Plateau to climate warming,we measured nitrogen(N)and phosphorus(P)contents of mature and senescent leaves of C.muliensis in a field simulated warming experiment,and analyzed the difference of resorption efficiency.The results showed that the average contents of leaf N and P of C.muliensis were 11.44 and 1.19 mg·g^(-1) respectively,and the average N resorption efficiency(NRE)and P resorption efficiency(PRE)were 61.8%and 69.0%respectively.Warming significantly decreased N content in mature leaves and increased P content in senescent leaves(P<0.01),but did not affect P content in mature leaves and N content in senescent leaves.Warming led to a significant decrease in N:P in mature and senescent leaves(P<0.01),NRE(P<0.05),and PRE(P<0.01).NRE and PRE of C.muliensis were significantly positively correlated with the N and P contents of mature leaves,and negatively correlated with the N and P contents of senescent leaves.Moreover,the growth of C.muliensis was limited by P,and the increase in temperature might lead to the change of nutrient limitation,indicating that the nutrient resorption of C.muliensis may also be regulated by stoichiometry.These results are helpful to understand and predict the responses of nutrient cycling in the Zoige Plateau to future climate changes,and provide data support and experimental evidence for the prediction of NRE change of alpine marshes under climate warming.