青海云杉叶寿命与比叶重随海拔变化特征

Variations of Leaf Lifespan and Leaf Mass Per Area of Picea crassifolia along Altitude Gradient

以祁连山北坡中部的青海云杉纯林为对象,沿海拔梯度调查了7个样点的叶寿命、比叶重及相应的土壤温度和水分状况,探讨其叶寿命和比叶重随海拔梯度变化特征及其与水分、温度的关系。结果表明：（1）青海云杉叶寿命变化范围为10.4～13.2年（平均11.8年）,不同海拔间具有极显著差异（P〈0.001）;青海云杉当年叶比叶重变化范围为261.78～324.31 g·m^-2（平均303.45 g·m^-2）,一年叶比叶重变化范围为299.04～355.85 g·m^-2（平均324.05 g·m^-2）;青海云杉比叶重与叶寿命之间存在显著正相关关系（P〈0.05）,当年叶和1年叶的相关系数分别为0.806 2和0.871 8。（2）青海云杉分布带土壤水分变化范围为19.9%～50.9%,沿海拔梯度增加呈现上升趋势,土壤年均温度变化范围为-1.67℃～1.45℃,沿海拔梯度增加呈现递减趋势。（3）青海云杉叶寿命、比叶重与土壤水分、温度之间存在显著的二次曲线关系,在土壤水分较低、温度较高的低海拔地带,以及土壤水分较高、温度较低的高海拔地带,叶寿命和比叶重均较高,且二者最大值均分布在林线地带。可见,青海云杉对于干旱、低温环境具有强烈适应性,土壤温度对其比叶重和叶寿命的影响较水分更为明显。

Variations of leaf lifespan and leaf mass per area of Picea crassifolia,as well as soil temperature and moisture were investigated along altitude gradient in the northern slope of Qilian Mountains in September,2005.The results showed that the leaf lifespan of P.crassifolia differed significantly among altitudes（P〈0.001）,with mean leaf lifespan of 11.8 years（10.4～13.2 a）.Moreover,current year and last year leaf mass per area（LMA） were 261.78～324.31 g·m^-2 and 299.04～355.85 g·m^-2,respectively.LMA was positively related to leaf lifespan（r=0.806 2,871 8,P〈0.05）.Furthermore,soil moisture increased with altitude varying from 19.9% to 50.9%,and mean annual soil temperature varied from-1.67℃～1.45℃ with the altitude increase.Both LMA and leaf lifespan were related to soil moisture and temperature,which could be fitted with quadric curves.The higher values of LMA and leaf lifespan distributed at the lowermost boundary of P.crassifolia forest,as well as the treeline.The maximum LMA and leaf lifespan were observed at treeline,which was an adaptation of P.crassifolia to local arid and low temperature environments.Additionally,the results showed that temperature is more effective on the leaf traits than moisture.